Arsenault, WJ. "The effect of planting
small whole seed on yield and tuber size distribution of Russet Burbank potatoes."
[Vol. 81, No. 1, Pg. 45]
Traditionally, in North America, potato growers plant their crops using cut seed pieces. However, in
Europe, small whole seed is planted. Planting small whole seed eliminates the cost of cutting seed, reduces
the transmission of seed-borne pathogens, minimizes seed piece decay and enhances the performance of some
potato planters, especially “cup type” planters. To meet market demand, some potato seed, mostly
small whole seed, was imported to PEI in the late 1990’s. In 2000, a three year study was initiated
to determine the effect of whole seed, rates of N fertility, and in-row seed piece spacing on the yield
and tuber size distribution of Russet Burbank potatoes grown for the processing market. Nitrogen was
applied at 168, 196 and 224 kg/ha. Each year, whole seed was sized as less or greater then 56 g (depending
on the seed available) and a cut seed treatment was included as a check. Total yields varied among years
and were low in 2001. Little gain in yield was achieved by increasing the rate of nitrogen more then 168
kg/ha. In-row seed piece spacing's were 28, 33, 38 and 43 cm for seed less then 56 g and 33, 38, 43 and
48 cm for seed greater then 56 g while cut seed pieces were planted 38 cm apart. At a similar spacing
(38 cm), results suggest that both sizes of whole seed produced similar yields to cut seed while the
larger whole seed produced a larger number of smaller size tubers. Whole seed less then 56 g, spaced
at 38 to 43 cm, and seed greater than 56 g, spaced at 43 to 48 cm, produced similar yields of tubers
greater than 280 g in size compared to cut seed.
Arsenault, Walter J and Bert R. Christie. "Effect of Whole Seed Tuber Size and Pre-plant
Storage Conditions on Yield and Tuber Size Distribution of Russet Burbank."
[Vol. 81, No. 6, Pgs. 371-376]
Field experiments were conducted in 1995, 1996, and 1997 at Agriculture and Agri-Food Canada’s
Harrington Research Farm to assess the effect of whole seed tuber size and pre-plant seed storage
conditions on processing yield (>51 mm dia.) of potato (Solanum tuberosum L. cv Russet Burbank).
Following commercial storage, seed tubers were stored at 4.4 C then subjected to one of three
pre-plant treatments: (1) planted directly from storage, (2) held at 10 C for 3 wk before planting,
or (3) green-sprouted for 3 wk before planting. Five sizes of whole seed were used (28, 42, 56, 70,
and 84 g) with a variable size cut seed treatment added for comparison. Plots were harvested 138, 134,
and 131 days after planting in 1995, 1996, and 1997, respectively. Cut seed produced a higher yield of
tubers >51 mm diameter in comparison to all whole tuber seed sizes, with the exception of the 28 and
56 g sizes. In terms of total yield, the 28- and 42-g whole seed tubers yielded significantly less than
all other seed sizes examined. Warming or green-sprouting seed tubers prior to planting did not increase
tuber yield. The larger whole seed tuber sizes tended to result in greater numbers of stems and tubers
per plant. To maximize marketable yield of Russet Burbank planted from whole seed tubers, it is
recommended that the seed be between 28 and 42 g in size.
Bamberg, JB and Alfonso del Rio. "Hypothetical obscured recessive
traits in tetraploid Solanum estimated by RAPDs." [Vol. 81, No. 1, Pg. 45]
White tuber flesh, some nematode and virus resistances, glandular hairs, 2n gametes, cold acclimation
and starch types are examples that demonstrate that recessive traits can be important in potato. However,
recessive phenotypes will not be detected in populations of tetrasomic tetraploid germplasm (e.g.,
cultivated andigena, wild sucrense) unless the allele frequency is high or very many
progeny are screened. We inferred the extent of this problem from RAPD band frequencies. The proportion
of banded plants from a sample of 24 was determined with respect to a total of 214 RAPD loci within 7
populations of the wild tetraploid species Solanum sucrense. We then calculated the proportion
of recessive phenotypes that would be expected if these bands were recessive alleles, and calculated the
sample size needed to detect them. If these random RAPD loci reflected the frequencies of recessive alleles,
only 50% of corresponding recessive traits would be detected even with a sample size of 250 tetraploid
individuals (p>=0.95). However, if haploids were generated, 50% of these hypothetical recessive traits
would be detected with a sample of only 30 random diploid individuals (p>=0.95). The US Potato Genebank
has over 900 populations of tetraploid tetrasomic species, nearly 1/5 of the collection. Considering that
researchers typically evaluate far less than hundreds of plants per population, many valuable undiscovered
recessive traits may be practically undetectable at the tetraploid level.
Bamberg, JB and AH del Rio. "Genetic Heterogeneity Estimated by RAPD Polymorphism of Four Tuber-bearing Potato Species
Differing by Breeding Structure." [Vol. 81, No. 6, Pgs. 377-383]
Most wild potato germplasm in genebanks is collected, preserved, and evaluated as botanical seed populations that may be highly
heterozygous and heterogeneous. However, some species are selfers so potentially very homozygous, perhaps also homogeneous.
Intrapopulation heterogeneity increases sampling error that can undermine consistency in seed regeneration in the genebank, screening
results, germplasm collecting, and estimates of taxonomic relationships. Thus, knowledge of genetic heterogeneity (GH) can predict the
need to commit more resources for larger sample sizes or replication when populations of a given species are being regenerated, evaluated,
collected, and classified. This study investigated within-population GH in 32 potato populations comprising four different breeding systems
observed in Solanum species: S. fendleri (2n=4x=48, disomic selfer), S. jamesii (2n=2x=24, outcrosser), S.
sucrense (2n=4x=48, tetrasomic outcrosser), and S. verrucosum (2n=2x=24, selfer). RAPD markers were used to estimate
heterogeneity among 24 individuals per population. Populations of S. verrucosum were quite homogeneous with an average
GH of 6.0%. Similarly low heterogeneity was detected among the eight populations of S.fendleri (average GH=7.1%). In contrast,
S. jamesii and S. sucrense had a much higher GH of 29.4% and 44.1%, respectively. These results demonstrate and
quantify the great difference in intrapopulation heterogeneity among wild potato species. Calculations based on intrapopulation
heterogeneity indicate that samples should be composed of 25 to 30 random plants for low sample variation that is uniform for all species.
Barone, Amalia. "Molecular Marker-assisted Selection for Potato
Breeding." [Vol. 81, No. 2, Pgs. 111-117]
The use of molecular markers in potato breeding offers new opportunities for the selection of
genotypes. To date, many markers linked to useful traits have been found. Indeed, the potato molecular
map is saturated with more than 350 markers uniformly distributed on 12 chromosomes. More than 25 single
dominant genes have been localized on the potato map, most of them being pest-resistance genes, together
with some quantitative trait lock (QTL) controlling yield and tuber quality traits. Molecular markers
linked to these genes are now available for rapid, efficient assisted selection (positive assisted
selection). Moreover; in order to transfer useful genes, interspecific crosses between wild and
cultivated genotypes are often performed, and in this case the use of species-specific molecular
markers would allow the wild genomic content to be reduced in few backcross generations (negative
assisted selection). The following review discusses the progress achieved in potato breeding
through molecular marker-assisted selection.
Bateman, Melinda, P Nolte, PB Hamm and B Geary. "The effect of Potato
Virus A (PVA) on yield of Russet Burbank and Russet Norkotah potatoes."
[Vol. 81, No. 1, Pg. 45]
Potato Virus A (PVA), found in Idaho seed in 1996, had increased to problem levels for certified
seed producers in 1999. PVA is a mosaic virus and under the Idaho rules of certification, seed lots
with more than 2% mosaic were not eligible for recertification. Information on how this virus effects
yield under western US production conditions was nonexistent. For this project, seed lots of Russet
Burbank and Russet Norkotah containing significant amounts of PVA were obtained and individual tubers
were tested to identify and separate healthy from PVA-infected tubers. Healthy and PVA-infected tubers
were cut into seed pieces which were blended together into 50 seed piece portions to artificially
create seed lots with 0, 4, 10, 20, 50, and 75% PVA. Plots consisting of four replications of each
infection level were planted in Parma, Idaho and in Hermiston, Oregon. To determine actual virus levels,
each plant was tested for virus once at emergence and again at the end of the growing season. Whole
plots and single plant harvests were performed to determine the amount of yield loss associated with
PVA infection. The single plant harvest data showed a more severe impact on yield than the whole plot
data, indicating that healthy plants can probably compensate for infected ones to some extent.
Yield loss appears to be less with seed-borne PVA than it is with PVY but some plants with PVA still
suffered up to a 30% decrease in yield. Russet Norkotah seems to be more severely affected by
PVA than Russet Burbank.
Beutler, Brent R, PJS Hutchinson and FE Fletcher. "Efficacy and
economics of tank mixtures for preemergence weed control in potato."
[Vol. 81, No. 1, Pg. 46]
Pacific northwest potato growers rely on herbicide tank mixtures for weed control. The majority of potato herbicides are applied in at
least two-way tank mixtures, with a third herbicide often added for broader spectrum weed control. Replicated field trials were conducted at
the Aberdeen Research and Extension Center over a three year period to compare the efficacy and economic benefits of two-way tank
mixtures to three-way mixtures. All herbicide treatments were applied preemergence in trial areas with moderate to heavy, and light to
moderate broadleaf and grass infestations, respectively. Visual weed control evaluations were performed throughout each growing season.
Tubers were harvested from the center rows of each 4-row plot to determine yield and grade according to USDA standards. Gross and
net return were calculated, on a per acre basis, using eastern Idaho enterprise budget information, and a process contract model potato
price including a process cull flat rate, and U.S. No. 1, large size, and specific gravity incentives. Two-way herbicide mixture costs, including
application and sprinkler incorporation costs, ranged from $27 to $52/A, and three-way mixture costs ranged from $40 to $61/A. Three-way
mixtures generally provided more consistent weed control than two-way mixtures over the multiple years the study was conducted, especially
for hairy nightshade control. Although improved three-way mixture control did not always result in improved yield, net returns of the majority
of three-way mixtures were equal to or greater than two-way mixture net returns.
Bing, Wang, LB Perkins and Alan R Langille. "Levels of cis-zeatin riboside and jasmonic acid
in ‘Katahdin’ potato tissues during first 48 hours following initiation of inducing conditions."
[Vol. 81, No. 1, Pg. 46]
Thirty-six ‘Katahdin’ plants were grown in a growth chamber adjusted to 30 C day and 28 C night with an 18 hr photoperiod
(non-inducing conditions) for eight weeks. When plants had reached a height of 80-85 cm, half of the plants were transferred to an inducing
chamber (28 C day and 13 C night with a 10 hr photoperiod (inducing conditions). After initiation of induction, three plants were harvested
from each chamber at 8, 16, 24, 32, 40 and 48 hrs. Tissues were separated into above- and below-ground portions, washed, frozen,
lyophilized and ground, prior to extraction. HPLC analyses revealed that cis-zeatin riboside (ZR) did not change appreciably due to
induction for the first 40 hrs, although levels were higher in above-ground tissues. Between 40 and 48 hrs, ZR increased significantly in
below-ground tissues with a concomitant decrease in above-ground portions. Jasmonic acid levels in above- and below-ground tissues
tracked one another for the first 24 hrs. Between 24 and 32 hrs, however, induced tissues showed higher levels of JA than non-induced.
Between 32 and 48 hr, a leveling trend was noted in induced, below-ground tissues for JA. It continued to increase in induced,
above-ground tissues for the balance of the sampling period. Theses results will be discussed in light of our previous laboratory findings
relating to tuber initiation and current literature.
Bohl, WH, SL Love and PE Patterson. "Effect of four seed piece spacings on economic return of Russet
Burbank potatoes." [Vol. 81, No. 1, Pg. 47]
Numerous studies have reported the effects of in-row seed piece spacing on total and U.S. No. 1 yields. Many were conducted for no
more than three years, and few included an economic evaluation. Data were collected 1997 through 2001 and evaluated for yield and
economic return. The economic analysis was based on a fresh-pack market-pricing model. Russet Burbank seed pieces were planted at
in-row spacings of 20, 30, 40, or 50 cm in rows 91 cm apart. Total yield significantly decreased with each 10-cm increase in seed
piece spacing. The highest total yield was 45.0 Mg per ha at 20 cm, and the lowest was 36.7 Mg per ha at 50 cm. U.S. No. 1 yield followed
a similar trend. The 20-cm spacing produced a U.S. No. 2 yield that was significantly less than the other three seed piece spacings.
The 20-cm seed piece spacing produced the lowest cull yield and the 50-cm spacing produced the highest. The 30-cm spacing
produced the highest percentage of U.S. No. 1 tubers (59.4) while the 40-cm spacing produced the highest percentage of U.S. No.
1 carton-size tubers (84.8). The fresh-pack market economic analysis indicated that the 40-cm spacing resulted in the highest value
per Mg (net return to grower) at U.S. $144 per Mg while the 20-cm spacing returned the lowest at U.S. $124 per Mg. The highest gross
receipts per ha, U.S. $5,858, was from the 30-cm spacing. This study illustrates that seed piece spacing impacts yield, quality and
economic return. The best economic return depends on the intended market and local environment. Potato quality parameters will
vary by market, as will their relative value. Market-based parameters will determine the price received by the grower.
Bonierbale, M, W Amorós, R Gomez and T Bernet. "Value-added options for native potato
diversity." [Vol. 81, No. 1, Pg. 47]
Native potatoes comprise an estimated 4000 cultivars that are grown by the poorest farmers of the Andes. Their intrinsic value lies in
their heterogeneity, which provides plasticity to environmental challenges and supports a wide variety of uses. This diversity is highly prized
for household consumption and ceremonial use, but penetration of the market economy into the Andes is increasingly discouraging
subsistence crops in favor of income-generating crops with high market demand. In efforts to reinforce the on farm conservation of native
potatoes and contribute to improving rural incomes, CIP is seeking to help develop new opportunities for the wider use of traditional
varieties. To date, more than 300 colored-flesh cultivars have been evaluated for yield, stability and processing parameters, and preliminary
information is available on nutritional features. Determination of dry matter, chip color, oil absorption, and cooking time 10 days after
harvest, and following 60 days of ambient and cold temperature storage revealed a high frequency of varieties apt for frying. Low oil content
associated with high dry matter, and consistent light chip color, were found in about ¼ of the cultivars, relating favorably to both economic
and health concerns. Cultivars from the ‘goniocalyx’ group were most outstanding. Added to their excellent flavors and attractive
colors, the varied shapes and pigmentation patterns of Andean potatoes result in products with considerable novelty appeal. These
characteristics combined with native potatoes’ adaptation to harsh environmental conditions show them to be a valuable source of
germplasm for breeding, and to present potentially important opportunities for small farmers to access value-added markets such as the
health and snack food industries.
Boydston, R, H Mojtahedi, JM Crosslin, PE Thomas, E Riga and T Anderson. "Influence of
nightshade species on corky ringspot persistence in crop rotations." [Vol. 81, No. 1, Pg. 47]
Corky ringspot disease in potato is caused by tobacco rattle virus (TRV) and vectored by the stubby root nematode, Paratrichodorus
allius, in the Pacific Northwest potato producing regions. TRV rarely infects alfalfa (Medicago sativa) and Scotch spearmint
(Mentha cardiaca) and viruliferous P. allius populations feeding on these crops are cleansed of TRV after one month.
However, weeds in these rotation crops or in potato may serve as hosts for the virus and nematode. In greenhouse trials, over thirty weed
species were tested for host suitability for P. allius and TRV. Hairy nightshade (Solanum sarrachoides), black nightshade
(Solanum nigrum), and cutleaf nightshade (Solanum triflorum) were particularly suitable hosts of P. allius and TRV.
Viruliferous P. allius added to mixtures of hairy nightshade with alfalfa and/or Scotch spearmint remained viruliferous over a 3- to
4-month period, whereas P. allius maintained on pure alfalfa or Scotch spearmint were rarely carrying TRV to transmit to tobacco
or potato after 1 to 2 months. Potato grown in soil containing P. allius that were maintained on mixtures of hairy nightshade with
alfalfa or Scotch spearmint for 3- to 4-months exhibited severe corky ringspot symptoms on new tubers. The presence of weeds that serve
as hosts of both TRV and P. allius may nullify the positive effects of growing alfalfa or Scotch spearmint for corky ringspot control.
Furthermore, transmission of TRV in weed seed could spread the disease to previously uninfected fields. Weed control efforts in rotational
crops should target known hosts of P. allius and TRV to successfully eliminate CRS from fields.
Boydston, RA, H Mojtahedi, JM Crosslin, PE Thomas, T Anderson and E Riga. "Evidence for
the Influence of Weeds on Corky Ringspot Persistence in Alfalfa and Scotch Spearmint Rotations."
[Vol. 81, No. 3, Pgs. 215-225 ]
Corky ringspot disease (CRS) of potato is caused by tobacco rattle virus (TRV). The virus is transmitted by the stubby root nematode
(Paratrichodorus allius) in the Pacific Northwest potato-producing regions. Alfalfa (Medicago sativa L.) and Scotch spearmint
(Mentha cardiaca Baker) rarely serve as hosts for TRV. Therefore, P. allius reared on these plants for 1 to 3 months are
cleansed of TRV in greenhouse trials. However, weeds in alfalfa and Scotch spearmint rotation crops may serve as hosts for the virus.
In greenhouse trials, hairy nightshade (Solanum sarrachoides), prickly lettuce (Lactuca serriola), henbit (Lamium
amplexicaule) and, green foxtail (Setaria viridis) grown alone were found to be suitable hosts of P. allius, whereas
Powell amaranth (Amaranthus powell) was not. Viruliferous P. allius added to hairy nightshade, prickly lettuce, henbit, green
foxtail, or Powel amaranth in mixtures with alfalfa and/or Scotch spearmint occasionally remained viruliferous over a 3-to 4-month period,
whereas P. allius maintained on weed-free alfalfa or Scotch spearmint became virus-free after 1 to 2 months. Potato grown in soil
containing P. allius that had been maintained on weed-alfalfa or weed-Scotch spearmint mixtures for 3 to 4 months exhibited slight
to severe CRS symptoms on new tubers, whereas potato following weed-free Scotch spearmint or alfalfa were free from CRS symptoms.
Severe CRS symptoms on potato tubers were only observed when potatoes were grown in soil containing P. allius that were
maintained on hairy nightshade or hairy nightshade mixtures with alfalfa or Scotch spearmint. These preliminary data suggest that the
presence of weeds that serve as hosts of both TRV and P. allius may nullify the positive effects of growing alfalfa or Scotch spearmint
for CRS control. Targeted control efforts of known weed hosts may be required to successfully eliminate CRS from fields using alfalfa and
Scotch spearmint rotational crops.
Brandt, Tina L, GE Kleinkopf, N Olsen and S Love. "Storage management of Gem Russet and
Summit Russet potatoes." [Vol. 81, No. 1, Pg. 48]
Storage management is an important factor in the successful utilization of new potato cultivars. The USDA/ARS and experiment
stations of Idaho, Oregon, and Washington recently released the cultivars Gem Russet (2000) and Summit Russet (2002). Both are
russet-skin cultivars suitable for both frozen processing and fresh market sale. These cultivars were grown, stored (~9 months) and
evaluated for quality over three storage seasons at the Kimberly R&E Center in Southern Idaho. After harvest, potatoes were cured for
14 days at 12.8°C, the temperature was subsequently decreased by 0.3°C/day to 5.6, 7.2 and 8.9°C. Relative humidity was maintained at
95% throughout the study. Samples used for dormancy length estimation were not treated with a sprout inhibitor. Tubers for sugar and fry
color analysis were treated with chlorpropham (22 mg/kg) approximately 60 days after harvest (DAH). Results of this study suggest a
recommended storage temperature of 8.9 °C for Gem Russet. At 8.9 °C, glucose did not exceed 0.05% fresh weight (FW) and sucrose
concentrations ranged from a high of 0.16% FW at harvest, decreasing to 0.09% FW at 260 DAH. In comparison, at 7.2°C, glucose levels
were as high as 0.13% FW at 260 DAH. At 8.9 °C, average fry color was a USDA 1 until 270 DAH and dormancy length was approximately
125 days. The recommended storage temperature for Summit Russet is 7.2 °C. Glucose concentrations ranged from a high of 0.08% FW
to a low of 0.015% FW over the three-year study. Sucrose concentrations were highest at harvest (0.17% FW) and decreased over time in
storage to a low of 0.07% FW at 240 DAH. Average fry color at 7.2°C did not exceed a rating of USDA 1 in the study and dormancy length was
approximately 145 days for Summit Russet.
Brown, Charles R, D Culley, C-P Yang and RA Navarre. "Carotenoid and anthocyanin
concentrations and associated antioxidant values in high pigment potatoes." [Vol. 81, No. 1, Pg. 48]
Potatoes may contain anthocyanins and carotenoids to varying degrees. Previous breeding work has shown that high levels of both
categories can be selected by taking advantage of variation available in North American breeding programs and in certain native cultivars
of South America. The antioxidant potential is measured by the Oxygen Radical Absorption Capacity (ORAC) a method of assaying an
extract’s ability to forestall the loss of fluorescence of a fluorogenic compound in the presence of a radical generator. The method
establishes a fluorescence “area-under-the-curve” which is calibrated against suitable standards. For instance, a solidly
red fleshed clone had 38 mg of anthocyanin (predominantly acylated glycosides of pelargonidin) per 100 g fresh weight. The aqueous
extract of this clone showed an antioxidant potential of 354 mg Trolox equivalents per 100 g fresh weight. This clone’s ORAC value
is approximately three and half times higher than white and lightly yellow flesh clones. In the case of carotenoids, white flesh clones
generally have about 50 micrograms per 100 g fresh weight of total carotenoid, which is extracted with organic solvent (e.g. chloroform).
Light yellow flesh clones have about 150 micrograms, while brilliantly yellow to orange flesh clones (YO) in the breeding program at
Prosser have as much as 800 micrograms per 100 g fresh weight. White flesh and light yellow clones show about 3 micrograms
tocopherol equivalents per 100 g fresh weight in ORAC assays while YO clones measure roughly twice that. Although significant antioxidant
value has not previously been attributed to potato for the human diet, these results suggest that a revision is needed.
Brown, CR, H Mojtahedi and J Bamberg.
"Evaluation of Solanum fendleri as a source of resistance to Meloidogyne
chitwoodi. [Vol. 81, No. 6, Pgs. 415-419].
Twelve accessions of Solanum fendleri collected in the United States
and Mexico were inoculated with 5,000 eggs of host-races 1 and 2 of Meloidogyne
chitwoodi, Columbia root-knot nematode. The test seedlings that were derived
from plant introduction true seed lots were maintained for 55 days before
harvest and egg count. The results revealed that two accessions PI 275162 and PI
275165, were non-hosts (final egg count/initial egg inoculation <0.1) for M.
chitwoodi race 1. The results were uniformly confirmed in the second
experiment. No resistance was found to race 2. The tetraploid S. fendleri
accessions were crossed to a nematode-susceptible cultivated diploid potato
clone from a S. phureja-stenotomum population. The triploid hybrids
expressed resistance to race 1 at the non-host level. After somatic doubling,
the resulting hexaploids also expressed non-host-level resistance to race 1. The
two resistant accessions had been collected in south eastern Arizona, one each
from the Huachuca and Chiricahua Mountains. Each range is an isolated island of
high-elevation mesic flora surrounded by typical lower-elevation Sonora-type
desert habitat. These accessions are the only known sources of resistance to M.
chitwoodi from wild Solanum species in the USA.
Bussan, Alvin J and M Drilias. "Influence of in-row spacing on yield and quality of potato
genotypes." [Vol. 81, No. 1, Pg. 48]
Size distribution of potato is potentially influenced by tuber planting rate or by altering in-row spacing. The objective of this
research was to quantify the impact of in-row spacing on stem and tuber set, yield, and size distribution of multiple potato lines. Russet Burbank
and 5 breeding lines with potential processing value were hand planted at in-row spacings of 30, 40, and 50 cm. Yield and size were impacted by main
effects but there was not an interaction in 2002. Yields varied from 350 to 550 kg/ha across the six potato lines and undersized
(less than 5 cm in diameter) ranged from 20 to 35%. Increasing the in-row spacing from 30 to 50 cm reduced overall yield 10%.
Overall reduction in yield was due to loss of potatoes less than 5 cm in diameter. Stem per plant did not vary across spacing
treatments, but tuber set per stem increased with in-row spacing. Thus, intraspecific competition likely influenced tuber set but not the number
of stems per plant. The total number of tubers per acre was reduced at wider in-row spacings even though tubers per plant increased.
The lack of interaction suggests a common seeding rate would be suitable for all potato varieties. However, closer examination of the
data indicated trends that suggested each of the lines will require different in-row spacings to achieve optimal yield and size distribution.
Busse, James S and Jiwan P Palta. "Uptake and transport of calcium to potato tubers using
45Ca." [Vol. 81, No. 1, Pg. 49]
Potato tubers are low transpiring organs known to be calcium deficient. Calcium concentration in the tuber can be increased by
placing calcium in the tuber area during the time of tuber bulking. In the present study, uptake and mobilization of calcium was investigated
using 45Ca. Experiments with Russet Burbank and Dark Red Norland were conducted utilizing a divided pot. 45Ca
was fed to either the main root system or the stolon and tuber portion of the plant. Radioactivity was detected in the above ground shoot
regardless of which portion of the plant was labeled. Radioactivity was detected in tubers only when 45Ca was applied to the
stolon and tuber producing portion of the plant. Redistribution of calcium from the aerial shoot to the tubers did not occur. Direct uptake of
calcium through tuber periderm did not occur. These results support previous studies and demonstrate that: (i) Calcium can be
supplied to the leaves by both the stolon and tuber area as well as by the main roots. (ii) Tubers obtain calcium only from the soil surrounding
the tuber and stolon area. Furthermore, calcium in leaves and stems does not mobilize to the tuber. (iii) Calcium does not move from the
soil directly into the tuber.Thus calcium moves into the tuber along with water via tuber and stolon roots.These results have very important
implications in the placement and timing of calcium for enhanced tuber uptake.
Campbell, WL. "Alaska’s potato growing problems."
[Vol. 81, No. 1, Pg. 49]
Potato growers in Alaska are beset by numerous problems. Fresh market sales require a high level of “eye appeal”.
The short growing season with cold soil temperatures at harvest limits skin set. The consequence is ugly potatoes, especially with reds and
russets. In addition to this problem, several diseases that cause skin blemishes have emerged and are causing severe grade out and
economic losses. Although the longstanding war with Rhizoctonia has been reduced to minor skirmishes thanks to better rotations, clean
seed and chemical seed treatments, Silver scurf, caused by Helminthosporium and a disorder of unknown cause, Pink Eye, are rising
to the top of the list of bad things. One grower has reported a 25% loss from grade out caused by pink eye. The white skinned cultivars
Shepody, Cal White, Bake-King and Green Mountain are susceptible. The reddish brown blemishes, which look a lot like windburn damage,
occur on all sizes of tubers. Crop inspections over several years have failed to find this damage at harvest, however the condition becomes
evident within a month of storage.
Cantle, SE and G Wang-Pruski. "Identification of cinnamic acid 4-hydroxylase in potato (Solanum
tuberosum L.) and its relationship to after-cooking darkening." [Vol. 81, No. 1, Pg. 49]
After-cooking darkening (ACD), one of the most undesirable quality traits in potato (Solanum tuberosum L.), occurs in every potato
growing area in the world. It is a gray-black discoloration of the potato tuber that is formed after cooking as a result of the oxidation of a
ferric-chlorogenic acid complex. The biosynthetic pathway of chlorogenic acid in potato involves a number of intermediates, one of which is
believed to be cinnamic acid 4-hydroxylase (C4H). As there is no known sequence information available for C4H in potato, six pairs of
degenerative primers were designed based on the C4H genetic sequence from Capsicum annuum and expressed sequence tags
(ESTs) from Lycopersicon esculentum. Total RNA from tubers of the cultivar Russet Burbank was used as a template for reverse
transcriptase-polymerase chain reaction (RT-PCR), to partially amplify the C4H gene. The resulting nucleotide sequences were found to be
89% to 96% identical to C4H in Capsicum annuum. In order to obtain the full-length transcript of the C4H gene, 3’ and 5’
rapid amplification of cDNA ends (RACE) was used. The gene expression profile was analyzed using Northern hybridization in selected
diploid clones known for both low and high degrees of ACD and in cultivars used in commercial French fry production. The relationship
between the levels of C4H gene expression and the degree of ACD will be presented.
Carlson, Carrin, HI Groza and J Jiang. "Induction of in vitro minimum potato plant growth and
microtuberization." [Vol. 81, No. 1, Pg. 50]
In order to avoid frequent subculturing of tissue culture plantlets, several growth media have been tested for minimum plant growth
or for a rapid induction of microtuberization. Mannitol (20g/L and 40g/L) and daminozide (0.025 g/L) were used as growth inhibitors at
24oC, 18oC and 14oC, in addition to the regular Murashige and Skoog (MSMO Sigma) medium.
For inducing microtuber formation, cycocel (CCC) 0.5 g/L or coumarin 0.025 g/L have been added to a regular MSMO medium where the
level of sucrose was increased to 80g/L sucrose. Plant length and the number of leaflets, roots, branches and microtubers were monitored
and measured along a 91-day period. The daminozide treatment was equal to the control but mannitol treatments considerably slowed
the plant growth. Mannitol 40g/L at 14oC was the most inhibiting treatment but, due to the higher rate of mutations, the
treatment using mannitol 20g/L at 18oC is recommended. The fastest microtuberization was reached with coumarin
treatments. However many tubers converted back in shoots. The solid CCC medium induced fewer microtubers. When a liquid CCC
medium was poured over the plantlets grown on regular medium, a good microtuberization was obtained but much contamination occurred.
Consequently, a medium containing 0.025 g/L coumarin and a growth temperature of 18oC are recommended.
Chen, Q, D Lynch, HW (Bud) Platt, HY Li, Y Shi, HJ Li, D Beasley, L Rakosy-Tican and R Theme.
"Interspecific Crossability and Cytogenetic Analysis of Sexual Progenies of Mexican Wild Diploid 1EBN Species Solanum
pinnatisectum and S. cardiophyllum." [Vol. 81, No. 2, Pgs. 159-169]
Mexican wild diploid species, Solanum pinnatisectum (S. pnt) (2n=2x=24, 1EBN: endosperm balance number) is a useful
germplasm source of late blight and Colorado potato beetle (CPB) resistance in potato improvement. However, it is very difficult to cross
this species with other 1EBN Solanum species. Sexual hybrids among three accessions of S. pnt and two accessions of
S. cardiophyllum (S. cph) (2n=2x=24,1EBN) were studied. There were large differences in the cross-compatibility among the
genotypes and accessions from these two 2x-1EBN species. Interspecific incompatibility existed in the crosses between S. pnt
and S. cph, in which S. cph functioned only as the male parent. The crosses with accessions PI 275236 of S. pnt produced 35
hybrids following the conventional propagation procedures. Seven hybrids were obtained with the S. pnt accession PI 275233 with
the aid of embryo rescue, while hybridization involving accession PI 253214 resulted in no fruit. The cytogenetic analysis indicated that all of
the hybrids derived from crosses of accession PI 275233 of S. pnt with S. cph had 2n = 24 chromosomes and were pollen
fertile. Crosses involving accession PI 275236 of S. pnt produced both 2x (2n=24) and 3x (2n=36) hybrids. Meiotic analysis at
metaphase I of pollen mother cells (PMCs) showed a fairly high rate of chromosome pairing that averaged between 10.10 and 11.10 bivalents
per cell in most of the 2x hybrids, indicating S. pnt and S. cph have the similar genome. A high frequency of trivalents and
quadrivalents were observed in 3x hybrids derived from S. pnt 2 x S. cph 1, indicating homology exists among these
chromosomes. These results suggest that specific gene(s) and not either differences between genomes or EBN-controlled interspecific
crossability and embryo development. The disease and insect tests on the 2x and 3x hybrids revealed that all have high levels of resistance
to both late blight and CPB. Thus it could appear that selection of genotypes is a key for successful interspecific hybridization when using
Mexican wild diploid species as a source of economic important traits.
Choi, Seon-Phil, Dhital, Shambhu Prasad and Hak-Tae Lim. "Evaluation of tuber susceptibility to variation
in tuber yield and processing quality at seedling generations performed in different potato breeding farms."
[Vol. 81, No. 1, Pg. 50]
Potato is susceptible to environmental conditions; soil conditions, temperatures, and rainfalls. Samples at generation three seedlings
were selected from three different locations with distinct environmental conditions, and examined for marketable yield, processing quality
and other traits. Also data of year to year in terms of variation of the chipping quality was included. Harvested samples in Pyeong-Chang (R3)
were suited for the cultivation of potato for processing. In every respect, the samples harvested from Pyeong-Chang have shown
remarkable data. The yield was averaged 850g/plant and the rate of marketable tuber was average 79.95%. It was higher than average
817g/plant and 74.9% of Chun-Chon(R1). Also specific gravity of all of the seedlings was average 1.073g of R3, which was higher than
1.057g of R1. There was no significant difference in the correlation of chip color based on color meter, average 62.5(L) of R1 with
64.29(L) of R3. But, potatoes grown in R3 region showed higher lightness in potato chips than the same clones grown in other regions.
Cooke, Louise R, C Donaghy, DJ Carlisle and M Quinn. "Changes in phenylamide resistance and
mtDNA haplotype in the Northern Ireland Phytophthora infestans population." [Vol. 81, No. 1, Pg. 50]
Phytophthora infestans isolates, from commercial Northern Ireland potato crops infected with late blight, were characterized for
a range of phenotypic and genotypic markers including mitochondrial DNA (mtDNA) haplotype and phenylamide resistance (using the
floating leaf disc method). In a previous study in 1995-96, the isolates were all A1 mating type, the majority were phenylamide-sensitive and
over 90% possessed mtDNA haplotype IIa (in contrast to elsewhere in Europe where haplotype Ia predominated). In the period 1998-2002,
c. 200 isolates have been typed. All isolates proved to be A1 mating type and either mtDNA haplotype Ia or IIa. In each successive
year up to 2001, the proportion of haplotype IIa isolates declined with a concomitant increase in Ia isolates and also in the proportion of
isolates containing phenylamide-resistant strains. There was a marked association between mtDNA haplotype and phenylamide
resistance: haplotype Ia was associated with metalaxyl resistance whereas haplotype IIa was more commonly associated with sensitivity
to metalaxyl. In 2002 recommendations to growers using products containing phenylamides were changed; they were advised to apply
no more than two (instead of three) applications early in the season and to switch to another type of product no later than 15 July. In that year,
the proportion of isolates containing resistant strains declined compared with 2001 and the occurrence of haplotype Ia isolates was also
reduced.
Coombs, Joseph, David Douches, Susannah Cooper, Edward Grafius and Walter Pett. "No-choice
cage study of glandular trichomes, glycoalkaloids and Bt-Cry3A potato resistance mechanisms for control of Colorado potato beetle."
[Vol. 81, No. 1, Pg. 51]
The Colorado potato beetle, Leptinotarsa decemlineata Say, is the leading insect pest of potato (Solanum tuberosum L.)
in northern latitudes. Host plant resistance is an important tool in an integrated pest management program for controlling insect pests.
A no-choice field study was conducted in 2002 to compare natural (glandular trichomes and glycoalkaloid-based), engineered
(Bt-cry3A), and combined (glandular trichomes + Bt-cry3A and glycoalkaloids + Bt-cry3A transgenic potato lines) host
plant resistance mechanisms of potato for control of Colorado potato beetle in no-choice, cage field studies. Cages (1 m3)
were arranged in a randomized complete block design consisting of three replications of 10 field-grown plants per cage. Fifty first generation
adult beetles were placed in each cage. Observations were recorded weekly for a visual estimation of percent defoliation and the
number of individuals per plant. The Bt-cry3A transgenic lines and the combined resistance lines were effective in controlling feeding
by Colorado potato beetle adults and larvae. Effectively no feeding was observed in the glycoalkaloid + Bt-cry3A transgenic line. The
high glycoalkaloid line had less feeding, but the adults clipped the petioles, which led to inflated initial defoliation. The glandular trichome
line suffered less feeding than the susceptible control. The Bt-cry3A gene in combination with glandular trichomes or glycoalkaloid-
based host plant resistance mechanisms is an effective strategy that could be used to develop potato varieties for use in a resistance
management program for control of Colorado potato beetle.
Coombs, Joseph J, Lynn M Frank and David S Douches. "An Applied Fingerprinting System for Cultivated Potato Using Simple
Sequence Repeats." [Vol. 81, No. 4, Pgs. 243-250]
The ability to quickly and accurately identify potato (Solanum tuberosum L.) clones is important to potato-breeding programs, seed and
commercial potato growers, and marketing and utilization of potato cultivars. Since 1990, the Michigan State University Potato Breeding and
Genetics Program has used an isozyme-based fingerprinting system to identify potato cultivars. Isozyme analysis is an economical and
effective means of discriminating potato clones; however, isozyme analysis requires fresh, healthy tuber or leaf tissue. DNA-based
fingerprinting using simple sequence repeats (SSRs or microsatellites) has been shown to discriminate between potato clones. The
objective of this study was to identify the most useful SSR primer pairs that accurately and efficiently distinguish clones for an applied
fingerprinting system of cultivated potato. SSR primer pairs with high polymorphism were selected from previous tetraploid potato studies.
DNA isolated from 17 potato clones representing round-white, russet, and red market classes were visualized on both polyacrylimide
(PAGE) and agarose gel systems. Polymorphism was observed in all 18 primer combinations on PAGE and 14 using agarose gel
electrophoresis. All 17 cultivars were discriminated on PAGE with various combinations of two primer pairs: STIIKA using STACCAS3,
STINHWI, or STM0031; and STACCAS3 using STGBSS1, POTM1-2, STM1104, or STM0031. The combination of STM0019, STM0031,
STGBSS1, and POTM1-2 was able to differentiate all 17 clones using agarose gel electrophoresis. PAGE was determined to be the
preferred system for variety identification, but agarose gel electrophoresis can be used to differentiate lines when specific varietal
comparisons are needed. In addition, five different DNA source tissue types were evaluated (fresh foliar, freeze-dried foliar, fresh tuber,
freeze-dried tuber epidermis, and freeze-dried tuber tissue). Amplification products were similar for all five tissue sources used for DNA
isolation. This ability to isolate DNA from freeze-dried tissue will allow cultivar identification when fresh tissue is not available. The SSR
primer pairs presented here can be used as a practical fingerprinting system for cultivated potato identification.
Cooper, Susannah, Edward Grafius and David Douches. "Effectiveness of combining host plant
resistance factors for managing Colorado potato beetle, (Coleoptera: Chrysomelidae, Leptinotarsa decemlineata)."
[Vol. 81, No. 1, Pg. 51]
Colorado potato beetle (Leptinotarsa decemlineata Say) has adapted to every insecticide used to control it. Therefore, it is a
model organism for investigating for evaluating different control strategies, in particular the effectiveness of combining host plant
resistance into a single cultivar to delay the development of pest resistance. The consumption of the three Colorado potato beetle strains,
insecticide susceptible (S) and insecticide resistant (IR) and a Bt-cry3A tolerant (Cry3A-sel), was assessed on four potato clones:
non-transformed control (Yukon Gold), leptines (USDA8380-1), Bt-cry3A (Yukon Gold-Bt-cry3A), and combined resistance
Bt-cry3A+leptines (USDA8380-1-Bt-cry3A) in a no-choice detached leaf bioassay to determine the relative effectiveness of the
resistance strategies. Detached leaf bioassays were performed individually for each four instar stars of each beetle strain in a 5d no-choice
situation. For all instars of both beetle strains, the leptines deterred feeding significantly greater than the control. For S and IR beetle strains,
Bt-cry3A potato clone deterred feeding significantly greater than leptines, while for Cry3A-sel beetle strain leptines generally
deterred feeding significantly greater equal to or greater than Bt-cry3A alone. For the fourth instar of the S beetle strain and the third
and fourth instars of IR and the Cry3A-sel beetle strains, the combined resistanceBt-cry3A+leptines deterred feeding significantly
greater than the control, leptines or Bt-cry3A alone clones. The results suggest that by combining leptines with Bt-cry3A
provides significantly more effective host plant resistance than either leptines or Bt-cry3A alone.
Culley, David, CP Yang, M Bonierbale and C Brown. "Determining the lipid-soluble antioxidant capacity
of pigmented tubers: application in assessing the antioxidant potential of potato germplasm."
[Vol. 81, No. 1, Pgs. 51-52]
In recent years, much attention has focused on the importance of dietary antioxidants in preventing heart disease and some types of
cancer. Potato is already a rich source of vitamin C, one of the more famous antioxidants, but in most modern cultivars the levels of many
other potential antioxidant compounds, (e.g. anthocyanins and carotenoids) is limited. Fortunately, potato germplasm collections provide
a rich source of material to improve the antioxidant content of tubers. Direct measurement of these compounds is one method of selecting
for increased antioxidant capacity, but this approach has several inherent limitations: 1) Determining the concentration of these compounds
is often difficult and expensive; 2) Only those compounds being assayed for are considered in selections; and 3) The levels of these
compounds provides only an indirect measure of the antioxidant capacity of tubers. A direct measure of the ability of the tuber to absorb
reactive oxygen species, (i.e. the useful antioxidant capacity of tubers), is provided by the ORAC (Oxygen Radical
Absorption Capacity) assay. This assay measures the ability of tuber extracts to protect a target molecule from reactive
oxygen and, while it is relatively straightforward for water-soluble antioxidants, has been difficult to apply to lipid-soluble antioxidants such
as carotenoids and vitamin E. To address this problem, we have modified existing protocols to allow the use of a microplate fluorometer
to perform relatively high throughput assays of the antioxidant capacity of the lipid-soluble fraction of tuber extracts. We will describe the
development of the lipid ORAC assay, and show results from some determinations of the antioxidant capacity of pigmented potatoes.
Curless, M, K Kelling and P Speth. "Influence of time of manure application on potato yield, quality,
and disease incidence." [Vol. 81, No. 1, Pg. 52]
This study evaluates whether timing of manure application can reduce or eliminate potentially negative impacts of applying manure
preceding potatoes. Four potato varieties with varying levels of scab and verticillium susceptibility were planted where liquid dairy manure
had been applied at a rate of 280,500 L ha-1 to separate plot areas 18, 6, or 1 month before planting in each of 2 years.
Fertilizer was applied to the no-manure plots at N and P rates approximately equivalent to the available N and P in the manure treatments
6 months before planting. Results of the 2001 tuber yield data showed a significant interaction between time of manure application and
variety, with two varieties (R. Norkotah and W-1151R) showing lower yields compared to the control when manure application was made
closer to planting. This trend was also weakly observed in 2002. Tuber dry matter was significantly reduced by the manure applications in
both years, but was not consistently related to time of manure application. Russet Norkotah and W-1151R also tended to show more scab
with the more recent manure applications (p=0.14) in 2001, but not in 2002. Incidence of foliar disease symptoms was affected by time of
manure application for susceptible varieties (Superior and R. Norkotah) in both years, with the greatest incidence associated with the
treatments that resulted in the lowest levels of inorganic N present in the soil at harvest. These data tend to show that where manure
was applied immediately ahead of planting potato yields and quality of some varieties decreased, therefore, it may be safest to apply manure
as one rotates out of potatoes rather than in preparation for planting potatoes.
Daniels-Lake, Barbara, Robert Prange, David McLachlan and Roberto de Antueno. "Severe
musty off-flavour in potatoes produced in the Annapolis Valley, NS, in 2001 is associated with use of Lindane™ to control
wire worm." [Vol. 81, No. 1, Pg. 52]
Musty or earthy flavours and odours occasionally affect various food commodities, often with serious consequences. Such
uncharacteristic off-flavours are objectionable, and affected foods are usually rejected by consumers. Several chemicals are associated
with musty off-flavours; the most active is 2,4,6-trichloroanisole (TCA), detectable by humans at 2-10 ppb. TCA causes corkiness in wines,
Rio flavour in coffee and off-flavours reported in beer, chicken, pastries, dried fruits and chocolate. Earthy or musty flavours and odours in
potatoes are due to several compounds naturally produced by tubers, but not TCA. In the Fall of 2001 in Nova Scotia’s Annapolis
Valley, several million kg of processing and table stock (most of the local crop) was affected by a severe musty off-flavour of unknown origin
which persisted after cooking. Analysis by solid-phase micro-extraction and GC-mass spec revealed the presence of high levels of TCA in
the skin (to 1.5 mm deep), lower levels in the centre of the tubers, and also in potato chips made from these tubers. A majority of the tuber
samples containing TCA were from fields treated with Lindane to control wireworm. Subsequent soil assays confirmed the linkage between
Lindane and high levels of TCA in the potatoes, and also revealed that even untreated soils can have low levels of TCA. We believe
this is the first report of TCA causing musty off-flavours in raw potatoes. Previous cases of off-flavour in which a specific cause was not
identified may also have been due to TCA from various sources. Research leading to these conclusions will be described and the
implications of our findings will be discussed.
Davenport, JR, MJ Hattendorf and JM Marden. "Ion exchange resin capsules for nitrogen
monitoring in potato." [Vol. 81, No. 1, Pg. 53]
In irrigated potato production systems in central Washington, a portion of the nitrogen (N) is applied prior to planting with the remainder
applied throughout the growing season through the irrigation system. To monitor how much supplemental N is needed during the growing
season, growers may use petiole tissue to assess current nitrate uptake and/or soil samples to assess current nitrate and/or ammonium
levels. These techniques are destructive, require careful sample handling, and laboratory analysis. Ion exchange resins have been developed
as an alternative to plant tissue and soil testing. The research conducted in this project evaluated the use of ion exchange resins that
have been enclosed in a mesh capsule and are commercially available (Unibest Co, Pasco, WA). Potatoes were fertilized with various N
rates ranging from 0 - 500 kg/ha in replicated plots on a Quincy sand soil in Paterson, WA. Ion exchange resin capsules (IER) were inserted
in the soil at two depths (20 and 65 cm) between plant emergence and row closure. Potato petioles and soil samples were collected from
each plot weekly and IER were removed at 1, 2, 3, 4 and 8 week intervals, replacing the removed capsule with a new capsule at each
sampling until harvest. Soil, plant tissue, and IER were extracted and analyzed for NO3-N and NH4-N. Results
from the IER were positively correlated with both N fertilizer rate and plant tissue N status. There were differences in IER N with depth and
with sampling interval and these relationships varied depending on time during the season, measured as days after planting. The results
suggest that there may be an optimal timing for utilizing this technology.
David, Nick, RE Ingham, ND McKinley and BA Charlton. "Control of Columbia root-knot nematode
(Meloidogyne chitwoodi) in potato cv Russet Norkotah with Vydate C-LV.®"
[Vol. 81, No. 1, Pg. 53].
Columbia root-knot nematode (Meloidogyne chitwoodi, CRKN) is a serious pathogen of potato (Solanum
tuberosum) in many areas of the western United States. Tuber infection by CRKN reduces tuber quality by inducing surface
galling and/or internal brown spots. Trials at Hermiston, OR in 2001 demonstrated that Vydate C-LV® (oxamyl) applications
of 1 lb. a.i./a beginning at planting (in-furrow) and continuing through the season at two-week intervals after 950 soil degree-days base
5C (DD5C) had significantly less infection than the non-treated control. However, waiting until crop emergence or 950
DD5C to make the initial application was not significantly different from the non-treated control. Trials in Klamath Falls, OR
during 2002 further substantiated findings from Hermiston in 2001. All treatment schedules with 1 lb. a.i./a per application in Klamath
Falls had significantly lower infection than the non-treated control. However, treatment schedules with an in-furrow application of oxamyl
at planting had significantly less infection than schedules beginning at 950 DD5C. Moreover, the schedule of oxamyl in-furrow,
at crop emergence, and at 950 DD5C had significantly less infection than the schedule of oxamyl at 950 DD5C,
two-weeks later, and four-weeks later. In-furrow applications clearly enhance oxamyl efficacy against CRKN in potato. Furthermore,
the Klamath Falls study suggests that early season oxamyl applications may be adequate to control CRKN in potato in short, cool growing
regions.
Davis, Jeffrey A, EB Radcliffe and DW Ragsdale. "A new vector of PVY: Soybean aphid,
Aphis gylcines (Matsumura)." [Vol. 81, No. 1, Pgs. 53-54]
Since its discovery in North America in 2000, Aphis glycines (Matsumura) has spread to 20 states, representing more than 60
million acres of soybean. Soybean aphids are competent vectors of Alfalfa mosaic virus (Genus Alfamovirus), Soybean mosaic
virus (Genus Potyvirus) and Tobacco vein-banding mosaic virus (Genus Potyvirus) a presumed variant of Potato virus Y
(PVY, Genus Potyvirus). Soybean aphid is closely related and biologically similar to the efficient PVY vectors, the cotton aphid,
Aphis gossypii (Glover), and the buckthorn aphid, Aphis nasturtii (Kaltenbach). Field studies conducted in 2001 and 2002
implicated soybean aphid in the spread of PVY in potato. We conducted greenhouse experiments to determine if soybean aphid could
transmit PVYO, PVYN, and PVYN/NTN. Thirteen cages, approximately 1.2 m2, were
used. Five cages contained a PVY positive center plant and eight cages contained a PVY negative center plant. Nine ELISA-tested potato
plants were placed around each center plant. A soybean plant infested with soybean aphids was placed adjacent to the PVY source plant.
After four weeks of exposure to soybean aphid alatae and apterae, all potato plants were tested again for PVY by ELISA and RT-PCR.
One-way analysis of variance was performed. Results indicate soybean aphid can transmit PVYO, PVYN, and
PVYN/NTN (P < .00002). Fourteen of 45 (31%) test plants caged with a PVY source became infected. Control cages had
a small amount of transmission with 2 of 72 test plants infected (3%). We believe transmission in control cages represents plants that
initially tested negative with ELISA when in fact they were infected. This is the first report that soybean aphid can transmit PVY.
Davis, JR, OC Huisman and DO Everson. "Verticillium control and increased yields
following continuous potato with a single season of green manure." [Vol. 81, No. 1, Pg. 54]
Two field studies investigated the effect of several green manure treatments on Verticillium wilt of Russet Burbank (RB) potato
(Verticillium dahliae Kleb). Following 2-3 growing seasons of several green manure treatments, both investigations showed
various degrees of verticillium control. Best control occurred with monocots (sudangrass, oat, and sweet corn). When compared
with a fallow treatment, monocot green manures reduced Verticillium wilt and increased both yield and quality of RB during the first growing
season but not the 2nd season when RB was cropped continuously. Following the 2nd season of continuous
cropping, V. dahliae soil populations increased 3-7 fold to populations exceeding 200 cfu g-1 of soil. Following the
2nd season of continuous cropping, the first study demonstrated Verticillium control following a subsequent oat green manure
with a 3rd season RB crop that produced higher yields than the first crop of potatoes that had immediately followed 2-3 years
of green manure treatments. A second study confirmed this response of a single green manure treatment following the continuous
cropping of potato. Again, when potato was grown for two consecutive seasons and accompanied by increased V. dahliae
populations, increased disease, and lower yields, this was again corrected by a single season of a green manure treatment (involving
either corn or barley). When compared with a fallow control this response was not evident. Again, yields that followed were higher than
the first crop of potatoes.
Davis, JR, OC Huisman, DO Everson and AT Schneider. "Comparative assays of wheat feeder
roots with potato roots for the quantification of biological factors associated with potato yield." [Vol. 81, No. 1, Pg. 54]
The infection of potato feeder roots by Verticillium dahliae Kleb. is often the most accurate single variable for the prediction
of Verticillium wiltof potato. However, since potato root assays are not always practical, comparisons were made of roots of several
other plant species for this purpose. When greenhouse studies showed wheat feeder roots to provide similar results to potato, additional
evaluations were made in potato fields by removing soil samples from fields and growing wheat in these soils under laboratory conditions.
Following the quantitative assays of V. dahliae on the roots of either potato or wheat, results were similar and highly correlated
(P=0.01). Additionally, a non-sporulating, unidentified red fungus (URF) was abundant in the fields of investigation. Again, techniques
were similar for the recovery of URF. Both V. dahliae and URF were closely related to yield responses of Russet Burbank. V. dahliae
was negatively correlated with yield and URF was positively correlated. Under the conditions of the fields evaluated, URF was most closely
associated with potato yield. The log of URF counts from either wheat or potato feeder roots were highly correlated with total yield
(P=0.01) and No. 1 tubers >280 g (P=0.05) occurring in either of two 32 ha potato fields of 1999. Similarly, V. dahliae
was correlated with yields of No. 1 tubers >280 g (P=0.05).
Davis, JR, OC Huisman, DT Westermann, DO Everson, A Schneider and LH Sorensen. "Some Unique Benefits with
Sudangrass for Improved U.S. #1 Yields and Size of Russet Burbank Potato." [Vol. ]
Three studies provided additional knowledge of beneficial effects of sudangrass for yield and quality increases of the Russet Burbank
potato. Two of these studies showed significant increases of both U.S. #1 and smooth tubers >280 g following green manures of
sudangrass. These sudangrass (HS-33) effects did not differ from a sorghum-sudan hybrid (Trudan-8). When a sudangrass green manure
was compared with a fallow treatment, results of the first study showed mean yield increases of 36% for U.S. #1 tubers >280 g and yields
of a second study by 34% for U.S. #1 tubers. This same sudangrass treatment out performed green manures of either Austrian winter pea,
barley, or sweet corn by increased U.S. #1 yields that ranged from 27% to 61%. By several lines of evidence, these benefits were found to
extend beyond the effect of Verticillium suppression. Soil N was significantly increased following green manures of
sudangrass,
and these increases were in turn negatively correlated with wilt incidence and positively correlated with yields of both U.S. #1 tubers and
tubers >280 g. Additional benefits also included significant increases of tuber grade percentages for marketable tubers and of smooth
tubers >280 g. Benefits from sudangrass green manures beyond the effects of Verticillium suppression became further evident
following a greenhouse study that involved field soil and sudangrass that had been grown in the same field. This study corroborated both
field experiments by showing increased yields with green manures of sudangrass that approximated 5.5 t ha1
dry wt. As with the field studies, these yield benefits also extended beyond the effects of Verticillium suppression and were closely associated
with significant increases of Fusarium equiseti, F. oxysporum, and F. solani. Throughout all studies, sudangrass green
manures significantly increased microbial activities with increased populations of Fusarium spp. and increased concentrations in
soil of mineralizable N, organic P, K, Mn, along with the percent soil organic matter – all factors that could have contributed to significant
increases of yield and quality.
Deahl, K. "Population dynamics of Phytophthora infestans assessed by mitochondrial DNA."
[Vol. 81, No. 1, Pg. 54]
Late blight caused by the oomycete Phytophthora infestans, is the most destructive disease of potato cultivation worldwide.
Novel strains of P. infestans have evolved which possess the potential to overcome genetic resistance introgressed by conventional
breeding from wild potato species into commercial varieties. Future breeding efforts, both conventional and molecular, may be further
endangered by the pathogenic capabilities of this organism, since many studies have provided evidence of worldwide migrations that have
introduced new, more aggressive and virulent strains. Moreover, workers have recently detected an increase in genotypic diversity which
may have resulted from sexual recombination of migrant genotypes. Characterization of mitochondrial DNA (mtDNA) haplotype may provide
insights into the population dynamics of this pathogen in the US, not given by other phenotypic and genetic markers. Isolates collected from
natural infections on potato and tomato hosts were characterized for frequency and distribution of specific mtDNA haplotypes. Three were
found among the isolates from the 12 years examined viz. Ia, Ib, IIb. The IIa haplotype was not found among US isolates. Further examination
of field isolates and comparison with archival strains can provide information on the population structure over time. This information is vital
if we are to continue to make effective use of disease resistance genes in late blight control strategies.
De Jong, W, De Jong and M Bodis. "An approach to measure allele dosage in autotetraploid
potato." [Vol. 81, No. 1, Pg. 55]
We have recently identified an allele of dihydroflavonol 4-reductase (dfr) that cosegregates with the ability of potato to produce red
pelargonidin-based anthocyanin pigments. To determine if a fluorogenic '5' nuclease (TaqMan®) assay could measure dosage of this
allele relative to all other alleles in cultivated tetraploid potato a portion of dfr was sequenced from several cultivated and wild potato
clones. A total of four different dfr sequence classes were observed. In one region the sequence of the ‘red’ dfr
allele differed at two nucleotide positions from the other three sequence classes. An oligonucleotide probe labeled with the fluorescent dye
6-FAM was designed to anneal specifically to the red allele in this region while a second probe labeled with VIC was designed to anneal
to the other three dfr sequence classes. PCR primers that annealed to conserved sequences flanking the variable region were
also developed. When subjected to a fluorogenic '5' nuclease allelic discrimination assay all diploid clones tested clustered into three
distinct groups based on the relative amounts of FAM and VIC released. These three groups represented clones homozygous for the red
allele, heterozygous for the red allele, and homozygous for not-red allele(s). When tetraploid clones were tested they separated into five
distinct clusters, three of which were shared with diploid clones. The five clusters were interpreted to represent clones quadruplex, triplex,
duplex, simplex, and nulliplex for the red dfr allele. This interpretation was supported by monitoring the segregation of red allele
dosage in several tetraploid crosses. Fluorogenic '5' nuclease allelic discrimination assays thus appear to be well suited for marker
assisted selection in autopolyploid breeding programs.
De Medeiros, Ane H, Ward M Tingey and Walter S De Jong. "Mechanisms of Resistance to Potato Leafhopper, Empoasca
fabae (Harris), in Potato." [Vol. 81, No. 6, Pgs.
431-441]
Potato genotypes were evaluated for resistance to natural infestations of the potato leafhopper, Empoasca fabae (Harris), in the field.
Characterization of Type A and B glandular trichomes, phenolic properties of Type A
trichomes, glycoalkaloid content and composition,
E. fabae adult and nymph infestation, leaf damage (hopperburn), yield, and yield reduction were determined on genotypes
PI 473331 and PI 473334 (accessions of Solanum berthaultii (Hawkes)), NY123 and Q174-2 (advanced hybrids), and Elba and
Allegany (commercial cultivars). Regarding the Type A trichome, PI 473334 was most pubescent, followed by PI 473331, both had high
levels of enzymatic browning; on PI 473334 no glycoalkaloids were detected, while on PI 473331 solamargine and solasonine
were present. Those genotypes were the least infested by adults; moreover, nymphs were never found on their leaves. PI 473331 and
Q174-2 possess Type B trichomes, the latter had levels of Type A trichome comparable to the first and to NY123, while displaying high
levels of phenolic oxidation of Type A and very low levels of glycoalkaloids. Although Q174-2 had intermediate infestation of E. fabae,
it suffered a yield reduction comparable to the control cultivar Allegany. The density of Type A trichomes of NY123 was relatively low, even
though the browning assay results were significantly elevated. Foliage of this genotype was found to contain the four types of glycoalkaloids
studied at high levels. Empoasca fabae infestation on NY123 was intermediate, and it yielded well on infested plots, but suffered an
intermediate yield reduction. Elba presented densities of Type A similar to NY123. It suffered the lowest yield reduction despite its high
levels of leafhopper infestation and hopperburn. Its tolerance might be associated with its
phenology, since it is a late-maturing cultivar.
High scores of the modified enzymatic browning assay were correlated with high infestation and high leaf damage. Results indicated a
significant correlation between leafhopper infestation and hopperburn.
del Rio, Alfonso and JB Bamberg. "Geographical parameters and proximity to related species
predict genetic variation in the inbred potato species Solanum verrucosum Schlechtd." [Vol. 81, No. 1, Pg. 55]
A major goal of crop genebanks is to maximize the genetic diversity they keep. Finding ecological or geographical parameters
associated with genetic variation would guide prioritization of populations for collection and maintenance. Previous studies in S.
fendleri (a disomic polyploid selfer), S. jamesii (a diploid outcrosser) and S. sucrense (a polysomic polyploid outcrosser)
revealed no significant associations between genetic and ecogeographic variation. These species represent three of the breeding systems
found among Solanum species. These previous studies are expanded here by investigating the relationship between genetics and
geographic parameters for a fourth type of breeding system: a diploid inbreeder, modeled by wild S. verrucosum from Mexico.
The objective was to assess whether genetic differences between populations are predicted by differences in geographic parameters
at the natural site of origin. Proximity of the S. verrucosum populations to other Mexican wild potato species (some known to be
sympatric with S. verrucosum) was also analyzed. A total of 27 S. verrucosum populations were studied using Random
Amplified Polymorphic DNA (RAPD) markers to estimate genetic differences between pairs of populations. A total of 352 pairwise
comparisons based on 152 RAPD markers showed that the average genetic distance (GD) of all pairs of populations was 12.8 %
(ranging from 0% to 29.3%). The greatest correlations with GD were: latitude (70%), longitude (51%), physical separation (47%),
altitude (-27%); proximity to S. demissum (59%), S. hjertingii (80%), and S. hougasii (-56%).
de Souza-Dias, Jose A Caram and Haiko E Sawasaki. "Monalisa and Atlantic potato cultivars
have differential sensitivity to tuber symptom expression to PVYNTN as a function of their resistance to PVYO
and PVYN." (Supported by FUNDAG.) [Vol. 81, No. 1, Pgs. 55-56]
The exotic variant of PVYN, named PVYNTN causes superficial tuber necrotic ring and/or arc-shaped
symptoms. PVYNTN was firstly observed in Brazil in 1997 in potato tubers from a first generation increase of imported
seed-potatoes, cv. Atlantic (Souza-Dias et al., 1998. Summa Phytopath. 24(1):74). The PVYNTN strain was identified by
bioassay (transmission to indicator test plants) and molecular analysis (Adgen Inc. PVYNTN PCR kit), in comparison with
the two most common PVY strains: PVYO and PVYN. Although Atlantic is highly susceptible to the common
PVYO and PVYN strains, it responded to PVYNTN with no or only one small (<2 cm)
necrotic ring on tuber surfaces. Based on primary or secondary experimentally infected plants in the field and in greenhouse isolation.
‘Monalisa’ and ‘Aracy’ which are highly resistant to PVYO and PVYN were consistently
susceptible to PVY NTN, with many arcs and rings on the tuber surface, specially on the side exposed to light, turning tubers
totally unmarketable (Souza-Dias et al, 1999. Summa Phytopath. 25(1):36). The Monalisa responses to PVY NTN show
inverse correlation between susceptibility to common PVY strains and tuber sensitivity to PVYNTN, as observed to other
cultivars (Mc Donald & Sing, 1996. Am. Potato J. 73(7):317-323). It is suggested that to solve seed-potato certification questions
(Nolte & Withworth, 2002. Potato Grower, 31(3):34-35) cv. Monalisa could be used as a differential indicator test plant to confirm
PCR results distinguishing PVYO and PVYN from PVYNTN.
De Weerd, Jan W. "Evaluation of the sprout suppressant capacity of 1,4-Dimethylnaphthalene
in common North American potato varieties." [Vol. 81, No. 1, Pg. 56]
Two pilot scale storage experiments were conducted with four commonly grown, North American potato varieties to test the sprout
suppressant capacity of the dormancy enhancer1,4-Dimethylnaphthalene (1,4DMN) at elevated, sprout inducing, storage temperatures.
Sprout growth was significantly suppressed by the treatment of 1,4DMN for all varieties in both studies at storage temperatures of
12.5 C –15 C. During the course of the studies, applying 1,4DMN twice at 20 ppm prevented any notable sprouting in Norkotah and
Yukon Gold, while limited sprouting was observed in Ranger Russet and, after increasing the temperature to 18 C-21 C, in Russet
Burbank. Depending on variety, untreated samples had sprouts ranging from 30 to 100 mm, while treated samples ranged from less
than 1 mm to 22 mm in sprout length. The degree and duration of suppression was a function of 1,4DMN residue maintained
above a minimum critical level in the potato. This critical level appeared to be dependent on storage temperature, variety and lot.
Therefore, to completely prevent peeping and subsequent sprouting, potatoes need to be treated with 1,4DMN on a repeated basis.
Treatment of 1,4DMN had no significant impact on the number of eyes ultimately able to peep or sprout.
Dhital, Shambhu Prasad, Seon-Phil, Choi and Hak-Tae Lim. "An evaluation of growing conditions for
the production of mini-tuber of potato both in the soil and air under the glasshouse condition."
[Vol. 81, No. 1, Pg. 56]
Disease free potato plants (Solanum tuberosum L. cv. Superior and Purple valley) were multiplied in in-vitro, and plantlets
were acclimated under glasshouse condition. Different pot sizes, planting media, and plant growth regulators were evaluated for the mini-tuber
production. Bigger the pot size, higher the plant height, main stem/plant and higher the tuber yield. However, percentage of medium size
tuber (2-5 g/tuber) and total weight were higher in the medium and small pot. Equal volume of commercial soil and perlite or vermiculite
produced significantly higher tuber yield, plant growth regulators (PGR), BAP, CCC, B-9, and PCL and their different combinations were
sprayed 5 times in a weekly interval to the plant, and high humidity condition was maintained. Maximum tuber number and tuber yield per
plant was observed in the treatment sprayed with BAP (10 mg/l) and B-9 (250 mg/l). Similarly, maximum number and weight of medium
size tuber was observed in the pots treated with B-9 (500ppm) alone, which was significantly different from the control. Maximum number
and weight of aerial tuber was produced in the pots treated with the combination of PCL (0.4 mg/l) and B-9 (250 mg/l). In contrast, higher
the aerial tuber lower the under ground tuber number and weight in both tested potato cultivars.
Dhital, Shambhu Prasad, Seon-Phil, Choi and Hak-Tae Lim. "Effect of leaf age, leaf area,
plant growth regulator, and genotypes on the production of potato mini-tubers derived from of shoot cuttings."
[Vol. 81, No. 1, Pg. 57]
Potato plants (Solanum tuberosum L. cv. Superior and Atlantic) were grown for one and half months in pots, and then they were
placed under dark shading for their shoot cuttings to be taken. In all experiments, auxiliary buds and the basal portions of the petiole were
buried in a moist medium (equal volume of commercial soil and vermiculite), and then placed under continuous light and examined for the
production of mini-tubers after three weeks. Defoliated stem with four nodes produced significantly lower percentage of mini tubers as well
as lower average tuber weight than the shoot with leaf and apex or without apex in both cultivars of potato. It was shown that young and fully
expanded leaves produced better tuberization and bigger tuber size than the very young or very old and less leaf area in the single node
cuttings. For the treatments of plant growth regulator on the cuttings, BAP (10mg/l) produced significantly higher tuberization and bigger
tuber size as compared to kinetin (50 mg/l) and the control. Commercial soil mixed with vermiculite (1:1) found the most effective medium
both in tuberization and tuber size. Potato cultivars, however, did not show any significant difference in the tuberization and tuber size.
Dinu, Ioana and CA Thill. "Endosperm and embryo development in interspecific incompatible
Solanum crosses." [Vol. 81, No. 1, Pg. 57]
Seed production in interspecific Solanum hybrids depends on compatibility of the combined parental genomes in the embryo
and endosperm, and on genetic/biochemical interactions between embryo, endosperm, and maternal sporophytic tissue. In crosses of
distantly related species, ovules abort at different stages of development following endosperm and embryo collapse. The research objective
was to explore post-zygotic reproductive barriers in these crosses. Species tested were 2x 1EBN S. pinnatisectum PI 230489,
PI 275233, PI 275236, PI 347766; 2x 2EBN S. verrucosum PI 161173, PI 195171; S. tuberosum haploids and F2
haploid-species (HS) hybrids. Among 1658 reciprocal pollinations between chromosome-doubled genotypes of pnt 4x 2EBN-HS,
no fruits were produced. Confocal microscopy evidenced that within 3-4 days after pollination, endosperm cells broke down in pnt
4x-tbr 2x and pnt 4x-HS crosses despite EBN ratios. In these cases true embryos never formed; a mass of cells proliferating
instead. Among 208 pnt 4x-HS crosses, with growth regulators applied to ovules post-fertilization, 76 fruits (inclusive parthenocarpic)
yielded 119 immature seeds cultured in vitro at 14-21 days after pollination. Even with chemical treatment, in parallel with
endosperm collapse, hyperplastic endothelial cells actively divided in the central cavity of the ovules and embryos were not found. In
ver 2x-pnt 2x and ver 2x-pnt 4x crosses, irrespective of EBN ratios, incipient normal endosperm and embryo
growth was observed, followed by aborting mature seeds. Control crosses of ver 2x-tbr 2x and selfed pnt
4x developed normally. Our studies suggest that control mechanisms except gene dosage for EBN are involved during early endosperm
formation and/or embryogenesis in divergent species crosses.
Douches, David, Kim Felcher, Joseph Coombs and Willie Kirk. "Field evaluation of foliar resistance
to Phytophthora Infestans in potato." [Vol. 81, No. 1, Pgs. 57-58]
Late blight disease of potato, caused by Phytophthora infestans, is the most important disease of potato worldwide. The
objective of our research was to identify germplasm that can be used in breeding cultivars with foliar resistance to P. infestans. From
1997 to 2002, replicated experiments were conducted at the Muck Soils Research Farm in Bath, Michigan. Approximately 50 days after
planting an isolate mixture of the US8 genotype of P. infestans was applied through the sprinkler irrigation system to
inoculate the foliage. Percent infection of late blight on the foliage and stems were visually estimated on 2-4 day intervals until 100%
infection was recorded in susceptible lines. Relative area under the disease progress curve was calculated for each line. Over the 6-year
period, more than 650 advanced breeding lines and varieties were tested. We have at least 8 sources of foliar resistance to the US8 genotype
of P. infestans that have different pedigrees from which their resistance is derived. The most resistant lines were A90586-11,
AWN86514-2, B0718-3, Jacqueline Lee (MSG274-3), MSJ317-1, MSJ461-1, NY121, LBR8, LBR9 and Tollocan. The resistance in Jacqueline
Lee has now held resistance for six years of testing. MSJ461-1, a chip-processing selection, has the same late blight resistance source
as Jacqueline Lee. In each of the late blight resistant lines listed above, the resistance is based on a single resistance source. Our
current breeding strategies include combining resistance from different sources to build a more durable resistance.
Esplin, David L and CA Thill. "Selection for cold chipping genotypes in populations derived by sexual
polyploidization." [Vol. 81, No. 1, Pg. 58]
Cold chipping (CC) is the ability of a genotype to make light colored potato chips directly from cold storage. This trait is useful to potato
producers due to expanded tuber marketability and reducing storage costs and losses from warm temperature storage. The objectives
of this research were to determine if 1) CC genotypes could be identified in a seedling transplant population (FTR) derived by sexual
polyploidization (SP), and 2) genetic variation contributing to CC differs in progeny developed by SP. Good (G), intermediate (I), and poor
(P) diploid and tetraploid parents differing in CC ability were crossed in all combinations. Progeny were classified into 4 mating types
(MT) and 9 chip classes (CL); MT1=2x-2x, 2=2x-4x, 3=4x-2x, and 4=4x-4x (control); and CL1=GxG, 2=GxI, 3=GxP, 4=IxG, 5=IxI, 6=IxP,
7=PxG, 8=PxI, and 9=PxP. At harvest 2100 clones were selected randomly from 138 families, and 154 clones were selected for visual
merit. Chips were made directly from 3 months storage at 4C. Color scores were determined on tuber slices fried in vegetable oil for 80s
at 185C. Color scores ranged from 1 to 10 where <4 was considered acceptable. The mean color score for the FTR population
was 7.3. CC genotypes were identified in FTR with 6.5% of the random and 3.4% of the selected clones being acceptable. MT color means
differed significantly (MT1=6.6, 2=7.4, 3=7.3, and 4=8.0). A significantly higher frequency of acceptable clones were derived from SP (MT1,
2, and 3) compare to MT4 (control) (X2=5.01). Bilateral SP produced a higher frequency of acceptable clones (13.9%)
compared to unilateral SP (4.9%) (X2 =37.88). Significant differences between CL color means were also found
(CL1=6.7, 2=6.5, 3=7.5, 4=7.3, 5=6.7, 6=7.6, 7=7.7, 8=8.3, and 9=8.9).
Essah, SYC and CW Honeycutt. "Dry matter accumulation, partitioning, and leaf area
index in potatoes: Influence of tillage and green-sprouting." [Vol. 81, No. 1, Pg. 58]
Cultural practices influence dry matter (DM) accumulation and partitioning in crops. Partitioning of DM in potatoes is of interest because
crop yield depends on partitioning of crop biomass to tubers. Tillage and green-sprouting are known to impact potato yield, but less is known
about their effects on biomass partitioning (BP) and leaf area index (LAI). This study was conducted in Maine to determine the effects of
green-sprouting (GS) and tillage regime [fall raised beds (RB), fall ridge till (RT), and spring chisel plow (CP)] on biomass accumulation,
partitioning, and LAI in Russet Burbank potato. Plant samples were taken at weekly intervals during 2000 and 2001 and separated into
leaves, stems + petioles, and tubers. DM accumulation and LAI were measured. Plants from non-sprouted (NS) seed generally maintained
green leaf area further into the tuber bulking phase and increased BP to tubers compared to GS plants in both RT and CP. In the dry year of
2001, GS plants growing in RB maintained green leaf area further into the tuber bulking phase and increased DM partitioning to tubers
compared to plants from NS seed. However, in the wetter year of 2000, LAI and DM partitioning to tubers were higher towards the end of
tuber bulking in plants from NS seed. These results demonstrate how different tillage and seed sprouting treatments can influence leaf
area duration and the ability of potatoes to modify BP under these management practices. The earlier and greater LAI associated with GS
plants in RB suggest that these management practices can produce earlier and higher yield for long season cultivars in climates with short
growing seasons.
Essah, SYC and CW Honeycutt, "Tillage and Seed-Sprouting Strategies to Improve Potato Yield
and Quality in Short Season Climates." [Vol. 81, No. 3, Pgs. 177-186]
Management practices that accelerate crop development and allow earlier harvest would be beneficial in short-season potato
(Solanum tuberosum L.) production areas. Yield and quality of the potato cultivar ‘Russet Burbank’ were evaluated in a 2-yr.
study in northern Maine to determine effects of soil tillage and seed-sprouting treatments designed to dry soil early in the spring and hasten
seed emergence. The tillage treatments, consisting of fall raised bed (RB), fall ridge till (RT), and spring chisel plow (CH), were tested in
combination with green-sprouted and non-sprouted seed tubers on a Caribou gravelly loam (coarse-loamy, mixed, frigid, Typic
Haplorthod). Plants from green-sprouted seed emerged earlier than from non-sprouted seed tubers (87%-96% vs 21%-37%,
respectively, at 18 days after planting [DAP] in 2000; and 73%–88% vs 18%-23%, respectively, at 20 DAP in 2001). Green-sprouted
seed tubers in RB yielded 4.6 to 5.9 T ha-1 more than non-sprouted seed tubers in RB. However, non-sprouted seed tubers
yielded higher than green-sprouted seed tubers in RT by 2.9 to 4.2 T ha-1 and in CH by 1.1 to 4.1 T h-1. Similarly,
green-sprouted seed tubers in RB and non-sprouted seed tubers in RT and CH produced higher marketable yield, greater tuber length,
and greater tuber diameter than the corresponding seed-sprouting treatment. In the comparatively wetter year (2000), the use of
green-sprouted seed tubers in RB significantly increased total and marketable yields, and produced longer and larger tubers than all
other treatments. However, in 2001 (relatively dry year), yield and quality from green-sprouted seed tubers in RB did not differ from
non-sprouted seed in RT or CH. Green-sprouted seed produced fewer sunburned and rotten tubers, but more misshapen tubers
than non-sprouted seed in RB tillage. The technique of producing Russet Burbank potatoes in raised beds is a promising system in
regions with short growing seasons for enhancing early soil drainage during spring and improving soil water retention during critical
periods of crop growth and development.
Ewing, EE, I Simko, EA Omer and PJ Davies. "Polygene mapping as a tool to study the physiology of
tuberization and dormancy." [Vol. 81, No. 1, Pgs. 58-59]
Efforts to breed for the ability to tuberize under long days or for the length of tuber dormancy should benefit not only from information on
the location of genes associated with these traits, but also from an understanding of the hormones the genes control. Understanding the
role of the respective genes is a logical step in developing the best breeding strategy, both for conventional breeding and for gene transfer
using biotechnology. Polygene mapping affords a way to achieve such understanding and is also a tool to study the physiology of potato
tuberization and potato tuber dormancy. The addition of DNA markers to a plant population facilitates the mapping of polygenes that control
quantitatively inherited traits segregating in the population. A quantitative trait locus (QTL) denotes a region of chromosome that is linked to
the marker gene and which has a significant effect on the quantitative trait under study. Our approach has been to find the QTLs associated
with tuberization and tuber dormancy in a segregating diploid population, and then to map the population for QTLs associated with levels
of hormones implicated in the control of these two traits. We are using a population from M. W. Bonierbale, who developed it in work with
R. L. Plaisted, S. D. Tanksley, and their groups. These researchers crossed a haploid of Solanum tuberosum with S. berthaultii,
backcrossed the hybrid to a different haploid of S. tuberosum, and put 81 evenly spaced RFLP markers on the map of the backcross
population. We have used their mapping information to find ten QTLs for the ability to tuberize under long days and eight QTLs for tuber
dormancy. In the same population we have found QTLs for polyamines, abscisic acid, tuberonic acid, tuberonic acid glucoside, cytokinins,
and gibberellin A1. Some of the hormone QTLs have coincided with QTLs for tuberization or dormancy. Two QTLs for
abscisic acid levels in tubers interacted, matching closely the interaction between QTLs for tuber dormancy linked to the same two markers.
Spermidine and spermine QTLs were linked to a known gene for the synthesis of these polyamines. QTLs common to both tuberization
and gibberellin A1 level in leaves were linked to a marker that on the tomato map (highly co-linear with the potato map) is
closely linked to a gene for GA20-oxidase—a key enzyme in gibberellin synthesis. Implications of such commonality will be considered,
as well as the usefulness and limitations of the methods.
Ewing, EE, I Simko, EA Omer and PJ Davies. "Polygene Mapping as a Tool to Study the Physiology of Potato Tuberization and
Dormancy." [Vol. 81, No. 4, Pgs. 281-289]
This paper was originally presented as part of a symposium entitled “Recent Advances in the Physiology of Tuberization and Tuber
Dormancy.” The symposium was held on 11 August 2003, by the Potato Association of America, in Spokane, WA.
Efforts to breed for the ability to tuberize under long days or for the length of tuber dormancy should benefit not only from information on
the location of genes associated with these traits, but also from an understanding of the hormones the genes control. Understanding the
role of the respective genes is a logical step in developing the best breeding strategy, both for conventional breeding and for gene transfer
using molecular techniques. Polygene mapping affords a way to achieve such understanding and is also a tool to study the physiology of
potato tuberization and potato tuber dormancy. The addition of DNA markers to a plant population facilitates the mapping of polygenes that
control quantitatively inherited traits segregating in the population. A quantitative trait locus denotes a region of chromosome that is linked
to the marker gene and which has a significant effect on the quantitative trait under study. Our approach has been to find the quantitative trait
loci associated with tuberization and tuber dormancy in a segregating diploid population, and then to map the population for quantitative trait
loci associated with levels of hormones implicated in the control of these two traits. We are using a population derived from a hybrid between
haploid Solanum tuberosum and S. berthaultii that was backcrossed to a different haploid S. tuberosum. We have found
ten quantitative trait loci for the ability to tuberize under long days and eight quantitative trait loci for tuber dormancy. In the same population we
have found one or more quantitative trait loci for polyamines, abscisic acid, tuberonic acid, tuberonic acid glucoside, zeatin riboside, and
gibberellin A1. Some of the hormone quantitative trait loci have coincided with quantitative trait loci for tuberization or dormancy. Implications
of such commonality are discussed, along with the usefulness and limitations of the methods.
Feingold, Sergio E, Donna Knauber, Abbas Lafta and James Lorenzen. "Mapping P450 related
genes in potato." [Vol. 81, No. 1, Pg. 59]
Cytochrome P450 monooxygenases consist of a large group of heme-dependent oxidases, which are present both prokaryotic and
eukaryotic organisms. Animal species may contain from 60 to 250 P450 genes, while in plants this number can be as high as 400. Many
P450 genes have been isolated cDNA amplification or random cDNA sequencing. P450 enzymes catalyze oxidation on different substrates
and have a wide range of in vivo functions. They have been shown to be involved in the biosynthesis of alkaloids, anthocyanins,
fatty acids, flavonoids, gibberellins, polyphenolic acids, steroids and terpenes, as well as in detoxicative processes against herbicides,
UV light protection and insect defense. Thus, the potential for discovery of useful genes in this family is high. We have searched the potato
database from TIGR (www.tigr.org) using 11 known Arabidopsis thaliana P450 sequences that
represent most of the plant P450 clades. As a result we have retrieved 221 potential P450 sequences, with additional non-redundant P450s
from the tomato database. Primers had been designed, and PCR amplification was done for parental genotypes of two diploid breeding
populations. Sequencing of P450s PCR products revealed single nucleotide polymorphisms (SNPs) between the parents that have been
used to map P450s using SSCP or direct sequencing. P450 genes have mapped to 11 of the 12 known potato chromosomes. Correlation
with already available phenotypic data may suggest putative function of some genes and/or allelic variants, which can be confirmed through
anti-sense transformation or other gene knock-out strategies.
Frazier, MJ, GE Kleinkopf and RR Brey. "High-energy ionizing radiation for potato sprout
control." [Vol. 81, No. 1, Pgs. 59-60]
Low doses of ionizing radiation from Cobalt-60 sources inhibits potato tuber sprouting by preventing cell division in bud meristem
tissue. This technique for sprout control has been extensively evaluated worldwide since the 1960’s. Today, the commercial
use of irradiated potatoes for fresh market consumption is limited to a facility in Hikkedo, Japan that treats over 100,000 tons annually.
However, with the production of smaller, portable industrial linear accelerators, it may be possible to use high-energy electrons to control
sprout development in commercially stored potatoes. This research focuses on high-energy irradiation from a linear accelerator, a
non-radioactive source. Russet Burbank potatoes were treated with relatively low doses of ionizing irradiation by rotating them in a
drum perpendicular to the incident pulsed beam of rastered electrons from an 18-MeV linear accelerator. The effects of dose and dose
rate on potato storage quality were investigated. Doses above 20 Gy were effective for long-term sprout control at standard storage
temperature (7.2°C). This 20 Gy effective dose is 20% of the effective dose for sprout inhibition previously reported in the literature.
A significant increase in reducing sugars was seen in treated potatoes except at the low dose applied at the highest dose rate.
Reducing sugars on some treatments decreased with time in storage to acceptable processing levels. Reconditioning was also effective
in reducing sugar levels. Fry color was similarly affected. Dry rot (Fusarium sambucinium) and soft rot (Erwinia spp.) potential
was significantly increased by does higher than 50Gy. Doses of 20-25 Gy did not significantly increase rot potential.
Frost, KE, DI Rouse and SH Jansky. "Introduction of Verticillium wilt resistance into advanced
clones via 2x x 4x and 4x x 2x crosses between (2x) Solanum tuberosum - wild species hybrids and (4x) potato."
[Vol. 81, No. 1, Pg. 60]
Interspecific hybridization at the diploid level combined with sexual polyploidization to return to the tetraploid level provides a method to
introduce disease resistance into advanced potato selections. To determine if resistance to Verticillium dahliae (Vd)
found in (2x) S. tuberosum - wild species hybrids can be transferred to tetraploid offspring, 150 clones of tetraploid progeny
from 2x x 4x and 4x x 2x crosses were planted in a Verticillium (Vd) screening field and
a “clean” field. Plant vigor, vine maturity, disease and yield were evaluated for each plot. A large amount of variation was seen
in the progeny. Yields averaged 46% (+/- 31%) lower and area under the disease progress curve (AUDPC) averaged 1353 (+/- 629) units
greater in the Vd screening field. Seventeen % of the tetraploid progeny had a significantly lower AUDPC than Atlantic and 36 % had
lower yield losses than Atlantic. No significant yield loss was observed in clones D12, G1, and F3. Stem colonization by Vd is currently
being used to further assess resistance. Results suggest that resistance to Vd can be incorporated into advanced clones using
sexual polyploidization.
Funk, S and BG Hopkins. "Elemental sulfur use in potato production."
[Vol. 81, No. 1, Pg. 60]
Elemental sulfur (S0) is a commonly applied soil amendment in western soils, where pH tends to be high. High soil pH
results in reduced solubility of essential nutrients such as phosphorus, zinc, manganese, iron, copper, and boron. Although elemental S
effectively lowers soil pH over time, the rates required to do so are cost prohibitive. Alternatively, a strategy that is employed by growers is to
concentrate the elemental S with the fertilizer band in an effort to lower the pH in the immediate vicinity of the nutrients. Although this strategy
seems logical, its effectiveness has not been quantified. Therefore, the oxidation rates of two elemental S sources, with drastically different
particle size, were measured under varying soil textural classes with both broadcast and band application. Not surprisingly, the powdered S
source’s oxidation rate greatly exceeded that of the pelleted S source, corresponding proportionally to the amount of reactive surface
area of each source. The increased oxidation rate of the powder-S was especially substantial when it was broadcast applied and then lightly
mixed or tilled into the soil. The extremely small particle size coupled with soil mixing results in superior surface contact of S and soil, which
results in enhanced S oxidation rates. In contrast, elemental S that is applied in concentrated bands reduces the oxidation rate of elemental
S. Although the powdered elemental S has a much smaller diameter and a resulting increased oxidation rate, amending the soil via a
concentrated band nearly neutralizes this advantage. Additionally, this S oxidation inhibition in the band results in a lack of pH change as
compared to S that is lightly mixed with the soil. These results bring into question the grower practice of band application of elemental S
and fertilizer materials.
Geary, Brad, J Stark, S Love, B Hopkins, J Ellsworth, D Atkinson and J Windes. "Potato varietal
responses to nitrogen rate and timing." [Vol. 81, No. 1, Pgs. 60-61]
Increasing demands on growers to produce a superior crop with minimal inputs has produced a need to determine optimal N
management requirements for new cultivars that are increasing in acreage. This study was undertaken to evaluate different N rate and
timing effects on yield and grade of Russet Burbank, Bannock Russet, Gem Russet, Summit Russet, Ranger Russet, Alturas and A8893-1.
Experiments were randomized complete block designs at Aberdeen and Parma, ID. Russet Burbank, Gem Russet, Bannock Russet and
Summit Russet at Aberdeen, were treated with NH4NO3 (34-0-0) at 0, 90, 180, or 270 lb N/A. Nitrogen was
applied either 1) 2/3 pre-plant plus 1/3 in-season (early treatment), or 2) 1/3 pre-plant plus 2/3 in-season (late treatment). At Parma,
NH4NO3 was applied to Alturas, Ranger Russet and A8893-1 at 0, 100, 200, 300, or 400 lb N/A, with the same
two split applications. Bannock Russet required significantly less N than Russet Burbank, Gem Russet or Summit Russet, while the average
optimal N rates for the latter three varieties were fairly similar. Nitrogen timing had relatively little effect on N utilization by Bannock Russet
and Gem Russet, but Russet Burbank and Summit Russet used early N more efficiently than late N. Alturas and Ranger also performed
better when N applications were split with most of the N applied early. However, A8893-1 performed best with most of the N applied late.
Gillen, AM and R Novy. "Development of molecular markers for introgression of viral resistance genes
from Solanum etuberosum." [Vol. 81, No. 1, Pg. 61]
Potato virus X (PVX), potato virus Y (PVY) and potato leafroll virus (PLRV) are important viral pathogens of potato.
Solanum etuberosum, a wild relative of potato, is a source of resistance to these viruses that has yet to be fully exploited by
plant breeders. A 1 EBN species, S. etuberosum cannot be readily crossed to diploid or tetraploid clones of the cultivated potato.
Therefore, somatic hybridization between S. etuberosum (2n=2x=24) and a Gp. Tuberosum haploid x S. berthaultii hybrid
(2n= 2x=24) was employed. Somatic hybrids have been successfully crossed to cultivated potato (2n=4x=48) and resistances to PVX, PVY
and PLRV have been found to segregate in the BC2 progeny. The S. etuberosum genome (E genome) is distinct from
the cultivated potato genome (A genome). The impact of homology on intergenomic recombination and the possible preferential
transmission of certain S. etuberosum chromosomes are being investigated using RFLP markers. We are using RFLP probes
that have been previously mapped in tomato and potato (A genome and E genome) to correlate S. etuberosum chromosomal
regions and disease resistance phenotypes in the BC2. RFLP markers will facilitate localizing the PVX, PVY and PLRV
resistance genes in the potato genome(s). These molecular markers combined with GISH may detect desirable A and E genome
recombinant genotypes, or, if no recombinants are found, progeny can be screened to select individuals that retain chromosomal segments
correlated with viral resistance. Further marker saturation and analysis in the BC3 will be done to identify markers closely
linked to resistance genes that can be used for marker-assisted selection.
Groza, HI, BD Bowen, D Kichefski, SJ Peloquin and J Jiang. "Red Pearl: A New Gourmet Red Potato Variety."
[Vol. 81, No. 3, Pgs. 209-213]
Red Pearl is a medium-late variety with round tubers of stable dark red skin and white flesh. It is an ideal gourmet and canning variety
due to its high tuber set and high proportion of tubers less than 4.76 cm diameter (up to 71% of the total yield). Red Pearl has good boiling
and baking qualities. Its specific gravity is slightly higher and the tuber dormancy is longer than Dark Red Norland. Red Pearl yields only
54% to 77% of Red Norland because of its small tuber size. Red Pearl is less susceptible to common scab (Streptomyces scabiae)
than Dark Red Norland, significantly more resistant to corky ring spot (tobacco rattle virus) than Dark Red Norland and is resistant to
bacterial wilt and brown rot (Ralstonia solanacearum). Red Pearl showed similar susceptibilities to several other diseases,
including early blight, late blight, pink rot, and tuber soft rot, compared to Dark Red Norland. Red Pearl is more susceptible to shatter
bruise and blackspot than Dark Red Norland when handled from storage at 7.2 C.
Grünwald, Niklaus J, Cadena Hinojosa, MA, Rubio Covarrubias, O, Rivera Peña, A, Lozoya-Saldaña,
H, Brown, CR and WE Fry. "Resistance in Mexican potato germplasm to late blight is high and durable."
[Vol. 81, No. 1, Pg. 61]
The Mexican national potato program has produced several cultivars with high levels of field resistance. We evaluated levels and
durability of resistance to potato late blight of a selection of 12 such cultivars using data from 1960 to the present. Most of these cultivars end
up in less than 25% disease severity without a fungicide application. Data for evaluating durability were extracted from the field notebooks
located in the archives of the Mexican National Potato Program in the John S. Niederhauser Library in Toluca, Mexico. There was a trend to
indicate that field resistances to potato late blight of Mexican cultivars released between 1965-1999 is durable. At least two of the cultivars,
namely Sangema and Tollocan, have been grown on at least 4-5% of the potato acreage and over long periods of time without decay in levels
of field resistance. Pedigrees of the 12 cultivars indicate that most of the field resistance was introgressed from Solanum demissum
and are available from the first author upon request.
Guenthner, JF. "Private varieties in the US fresh potato market."
[Vol. 81, No. 1, Pg. 62]
US plant property rights provide a powerful economic incentive to bring new, branded varieties to market. California-Oregon Seed, Inc
(COS) responded to that incentive with Sierra Gold, a variety with russet skin and yellow flesh. Dr Creighton Miller developed Sierra Gold at
Texas A&M University, which made a property rights agreement with COS. Sierra Gold is coming to the fresh retail market as a premium
branded potato in three special packages. The smallest potatoes are packaged in 2.2-pound (1 kg) bags that include recipes for using the
entire contents in one meal. The medium sized tubers are in 5-pound poly bags with reclosable slide-rite tops. The largest potatoes are
individually labeled in 25-pound Euro cartons. COS contracted with a major retailer for 2003 Sierra Gold production. Test marketing conducted
by COS subsidiary Discovery Gardens provided information for future marketing efforts. Sierra Gold will not be the only player in the private
variety game. Green Giant is marketing Klondike Rose, a red-skinned potato with yellow flesh. COS plans to bring another branded potato
variety – Ivory Rose – to the long white market. New private varieties, with higher prices derived from top quality and supply
control, are expected to gain market share.
Guenthner, JF, AA Araji, LL Atchley and KM Maredia. "Economic impacts of genetically
modified potatoes in Egypt and South Africa." [Vol. 81, No. 1, Pg. 62]
The Agricultural Biotechnology Support Project (ASBP) at Michigan State University developed a genetically modified potato that is
resistant to potato tuber moth (PTM) (Phthoimaea operculella) for use in Egypt and South Africa. The objectives of this economic
analysis were to describe the countries’ potato industries, estimate the value of PTM-resistance and analyze biotechnology issues
in both countries. The potato industries are expanding, with per capita consumption expected to reach about 35 kg in both countries in 2020,
but PTM is a serious problem. An ex ante cost benefit model was used to quantify the potential value of the PTM-resistant potato. Categories
of on-farm value include increased yield, reduced PTM control costs, improved quality and reduced post-harvest losses. The present value of
PTM resistance at the farm level is estimated at $US92 million in Egypt and $US130 million in South Africa. The total benefit-cost ratio
estimate is 31 percent and the internal rate of return is 21 percent. An index number model indicated that consumer benefits – including
larger supplies, lower prices and better quality potatoes – would be larger than producer benefits. Results were sensitive to grower
adoption rates, government approval delays and changes in potato demand, but less sensitive to introduction costs. Spillover effects were
not quantified but would increase the value of the technology. Consumer acceptance was not expected to be a long-run barrier to development.
Gupta, Sanjay and Joe Sowokinos. "Recombinant expression and transformation of a unique isozyme
of UDP-glucose pyrophosphorylase (UGPase) associated with resistance to cold-induced sweetening (CIS) in potato tubers."
[Vol. 81, No. 1, Pg. 62]
UGPase catalyzes the first reaction of the hexogenic pathway in potato tubers leading to the formation of the hexose-reducing
sugars, glucose and fructose. The problem that these reducing sugars cause in the development of chips and fries is well known.
Anion-exchange chromatography with DEAE-Sephacel has been used to separate UGPase into two groups of isozymes designated
A-I and A-II from the cultivar Snowden. Group A-II, which is more basic in nature than A-I, has been associated with potato progeny that
demonstrate resistance to CIS. The gene Ugp A, which is required for the expression of the A-II isozymes of UGPase (i.e.,
predominately UGP5), has been expressed in E. coli using bacterial expression vectors. Immunoblotting of the recombinant protein
(RP) on SDS-PAGE and activity staining of native gels indicated that the RP was of the same subunit size (53 kD) and ionic charge
respectively, of the UGP5 polypeptide found in the mother tubers. These findings suggest the RP protein does not require post-translational
modification for activity. Kinetic properties of the RP are presently under investigation. Constructs containing the UgpA gene were
developed using the binary vector pBIN + ARS (provided by Dr. Bill Belknap) under the control of a constitutive (CaMV35S) or a tuber specific
granule bound starch synthase (GBSS) promoter. The Agrobacterium-mediated transformation system was used to transform
internode and minituber explants of the chipping cultivars Norchip and Dakota Pearl. Transgenic plants are presently being developed.
Guzmán-Galindo Leonel, Héctor Lozoya-Saldaña and Sylvia Fernández-Pavia. "Specificity of
resistance components to late blight. (Phytophthopra infestans Mont. De Bary) in Mexican potato varieties."
[Vol. 81, No. 1, Pg. 63]
Any host factor influencing processes that limit the disease progress or interfering with the life cycle of a pathogen is a component of
resistance (infection, colonization, number and/or size of lesions, incubation period, sporulation). In order to identify some of these factors
and to determine host-pathogen specificity, highly sporulating P. infestans strains isolated from the Mexican varieties Norteña (N,
resistant) and Rosita (R, resistant), as well as from Alpha (A, susceptible), were inoculated to the same three varieties and incubated in
laboratory (detached leaves, moist chamber) or in greenhouse (whole plants). Sporulation took place 68-84 hours after inoculation in the
lab. The combination R-R (isolate-host), A-R, and R-A induced the largest damaged area (92-75%), and A-A and A-R produced the highest
sporulation in detached leaves. In the greenhouse sporulation took place in more than 84 hrs; the largest lesions were observed in R-N,
R-A, N-A, N-R, and N-N (39-32 %), while R-A, A-A, and R-N sporulated the most. Damaged area-sporulation were host resistance
components, and no host-pathogen specificity was detected. However, foliage infection in this study is not reflected in the field in Toluca,
where Alpha dies to the disease at midseason and Norteña and Rosita do not reach the damage observed here.
Hadders, Jan. "Control of late blight by event driven timing of applications."
[Vol. 81, No. 1, Pg. 63]
Seasonal advances in chemistry and application machinery are not rewarded in terms of control of late blight which continues
to inflict damage to potatoes across the nation. In a fast growing crop a weekly fungicide application leaves a protection gap of 2 –
3 days, making a timed spraying a necessity. To get an infection the crop has to be relatively unprotected, numerous spores have to be
present and an infection event has to take place. In general terms, these conditions are modeled into the Dacom system as developed
by Dacom. The unprotected part of the crop is calculated from the date of emergence or from the last spraying date. As the product and
dose rate are known, the wear off is calculated based on weather conditions and product characteristics. In time, this reduces the
protection of the crop. Also new, unprotected leaves are formed and the sum of these two factors generates the unprotected leaf area.
The number of spores produced on an infected leaf is dependent on weather conditions. If spore ejection is established, the spore
pressure above the field is calculated. This is based on geographically recorded infected fields and wind direction or by regional
estimates of disease presence. For a spore which lands on an unprotected leaf, the germination and penetration time is calculated
based on the variety resistance, the temperature and the leaf wetness duration, also calculated by the model. If these three
parameters are calculated above a threshold a spraying will be advised. Depending on the moment, this will be identified as a contact
or a systemic treatment. A season review makes it possible to trace all sprayings for their justification. Farmers across the world base
the timing of spraying and the product type on the advice generated by the PP system and demonstrate improved control of late blight.
Halseth, DE, ER Sandsted, RJ Bushway and LB Perkins. "Impact of cultural practices on
glycoalkaloid levels in Atlantic, Marcy and Snowden." [Vol. 81, No. 1, Pgs. 63-64]
High concentrations of total glycoalkaloids (TGA) are a concern in selected cultivars and it is important to have a better understanding
of the impact that cultural practices may provide on TGA levels in newly released cultivars. The newest Cornell release, Marcy (NY112), was
compared to Atlantic, known for low TGA levels and Snowden, known for higher levels of TGA. Because both Marcy and Snowden are late in
maturity it was a concern that cultural practices that might delay plant maturity and harvest might negatively impact TGA levels. A randomized
complete block design of four replications was conducted during the 2000 and 2001 seasons at our Freeville, NY research farm. Three
cultural practices were employed: nitrogen rates of 167, 222 and 278 kg ha-1; mid-September and mid-October harvest; and
artificially bruising tubers (dropping 20 times from 50 cm). Total glycoalkaloids were determined 45 days after harvest at the Chemical Food
Safety Lab at the University of Maine, Orono, ME. Highly significant values were found for year, handling (bruising), harvest date and
cultivar, but none for nitrogen rate. While significant interactions were found, all results were in the same direction, with differences
being in the magnitude of the reactions. Overall, Atlantic, Marcy and Snowden had TGA levels of 20.95, 25.96 and 34.75 mg
100g-1, respectively. Averaged over cultivars and treatments, the earlier harvest had higher TGA levels (35.49) than
the later harvest (18.95). The bruising treatment was severe, visual assessment would place it at two to four times commercial
bruising levels, resulting in a 33.03 average compared to the non-damaged control average of 21.42.
Hamm, PB, DA Inglis, R Finn and G Olaya. "Resistance to mefenoxam in isolates of Pythium
ultimum from potato in Oregon." [Vol. 81, No. 1, Pg. 64]
During the 2002 growing season, a 125-acre potato field planted on 23 April to Russet Norkotah in eastern Oregon had losses of
approximately 36 % due to tuber rot. Symptoms resembled, but were not typical, of leak. Isolates obtained on either amended corn
meal or potato dextrose media yielded colonies typical of Pythium, and were identified as P. ultimum. A total of 19 isolates were
tested for mefenoxam sensitivity at Vero Beach, FL; 4 additional isolates were tested at both Mount Vernon, WA, and Hermiston, OR. At
Vero Beach, 16 isolates were found to have an intermediate resistance response to mefenoxam while 3 isolates were insensitive. At Mount
Vernon and Hermiston, all 4 isolates grew similarly on media amended with 100 ppm mefenoxam and on non-amended controls. The field
had been planted to potato in 1996 using a single Russet Norkotah seed lot, to winter wheat in 1997, and to alfalfa from 1998 to 2001.
Potato seed used in 2002 came from three different seed lots. Mefenoxam (Ridomil Gold at 6.5 oz/a) was applied in-furrow at planting and
to foliage (Ridomil Gold/Bravo at 2 lb/a) on 26 June according to label directions. High levels of disease could not be explained by improper
water application nor could the origin of mefenoxam-resistant isolates be explained by the planting of contaminated seed.
Hannapel, David J, Hao Chen, Faye M Rosin, Anjan Banerjee and Peter J Davies. "Molecular
controls of tuberization." [Vol. 81, No. 1, Pg. 64]
Tuber formation in potatoes (Solanum tuberosum L.) is a complex developmental process involving important biological
processes like carbon partitioning, signal transduction, and meristem determination. Under conditions of a short-day photoperiod and
cool temperature, a transmissible signal is activated that initiates cell division and expansion and a change in the orientation of cell growth
in the subapical region of the stolon tip. In this signal transduction pathway, perception of the appropriate environmental cues occurs in
leaves and is mediated by phytochrome and gibberellins (GA). Phytohormones also play a prominent role in regulating the morphological
events of tuberization activated in the stolon apex. GA, cytokinins, and jasmonate-like compounds have all been implicated in regulating
tuber development. High levels of GA are correlated with the inhibition of tuberization, whereas low levels are associated with induction.
Transcription factors are proteins that bind to DNA to regulate gene activity and, in some cases, to mediate hormone levels. Several of
these DNA-binding proteins are involved in regulating plant growth and meristem development in potato, including tuber formation. One
type, designated POTM1, regulates cytokinin levels in potato meristems and controls branching of axillary shoots. Two other types that
physically interact, the BEL and KNOX proteins, mediate vegetative development. Transgenic plants that overexpressed BEL and KNOX
proteins exhibited enhanced tuber formation even under long-day conditions. KNOX overexpressers exhibited abnormal leaf architecture
and dwarfism. These transgenic lines exhibited a decrease in the levels of GA and an increase in cytokinin levels. In addition, the BEL
transgenic lines grew more rapidly than wild-type plants. Our results indicate that DNA-binding proteins of potato mediate tuberization
by enhancing or repressing the activity of specific target genes.
Hannapel, David J, Hao Chen, Faye M Rosin, Anjan Banerjee and Peter J Davies. "Molecular
controls of tuberization." [Vol. 81, No. 1, Pg. 64]
Tuber formation in potatoes (Solanum tuberosum L.) is a complex developmental process involving
a number of important biological systems. Under conditions of a short-day photoperiod and
cool temperature, a transmissible signal is activated that initiates cell division and expansion and a change in the orientation of cell growth
in the subapical region of the stolon tip. In this signal transduction pathway, perception of the appropriate environmental cues occurs in
leaves and is mediated by phytochrome and gibberellins (GA). Phytohormones also play a prominent role in regulating the morphological
events of tuberization activated in the stolon apex. GA, cytokinins, and
jasmonate-like compounds have all been implicated in regulating
tuber development. High levels of GA are correlated with the inhibition of tuberization, whereas low levels are associated with induction.
Transcription factors are proteins that bind to DNA to regulate gene activity and, in some cases, to mediate hormone levels. Several of
these DNA-binding proteins are involved in regulating plant growth and meristem development in potato, including tuber formation. One
type, designated POTM1, regulates cytokinin levels in potato meristems and controls branching of axillary shoots. Two other types that
physically interact, the BEL and KNOX proteins, mediate vegetative development. Transgenic plants that overexpressed BEL and KNOX
proteins exhibited enhanced tuber formation even under long-day conditions. KNOX overexpressers exhibited abnormal leaf architecture
and dwarfism. These transgenic lines exhibited a decrease in the levels of GA and an increase in cytokinin levels. In addition, the BEL
transgenic lines grew more rapidly than wild-type plants. Our results indicate that DNA-binding proteins of potato mediate tuberization
by enhancing or repressing the activity of specific target genes.
Hayes, Ryan J and CA Thill. "Selection for late blight tuber resistance within foliar resistant
genotypes." [Vol. 81, No. 1, Pgs. 64-65]
Late blight caused by P. infestans destroys potato foliage and tubers. Early generation selection (EGS) can increase genetic
foliar resistance, but may alter a population’s tuber resistance since genetic correlations between tuber and foliar resistance are
reported as positive, negative, or uncorrelated. The objectives of this research were to determine if 1) tuber resistance differs in clones
selected for foliar resistance (FR) or single-hill (SH) tuber quality, 2) if tuber resistance differs in clones from resistant (R) x susceptible
(S) or S x S crosses, and 3) if FR genotypes have variation for tuber resistance. Four disease free tubers from 69 FR and 24 SH genotypes
(87 R x S, 6 S x S) were wounded and inoculated with approx. 700,000 sporangia (US8 strain). The R parents were MN96080-2, Atzimba,
Bertita, Bzura, Greta, Libertas, Jacqueline lee, NY121, Tollocan, and Zarewo. Red Pontiac and Silverton Russet were inoculated with
sporangia (12 tubers) and water (16 tubers). Tubers were incubated 3 days at 22C 100%RH then 11 days at 13C 90%RH. Lesion volume
was estimated as 1/2 an ellipsoid volume. No genotypes completely resisted infection, but clones differed significantly for lesion volume.
Mean lesion volume of FR (30.2cm3) and SH (29.6cm3) was not significantly different, indicating no genetic
correlation. Variation was sufficient for further selection of tuber resistance, identifying 69% of FR genotypes and 67% of SH that were not
significantly different from water inoculations (0cm3). Genotypes from R x S had significantly smaller lesions
(29.1cm3) than S x S (43.3cm3). Selection for tuber resistance was combined with EGS for foliar resistance
within R x S crosses, identifying 8 FR genotypes with lesion volumes <10cm3 2 years after making the cross.
Haynes, KG, RW Goth, DH Lambert and BJ Christ. "Late blight resistance in a tetraploid potato
population with horizontal resistance." [Vol. 81, No. 1, Pg. 65]
A population of tetraploid potatoes with horizontal resistance to late blight was developed at the International Potato Center in Lima,
Peru. True seed from this population was obtained from the NRSP-6 Project at Sturgeon Bay, WI for the purpose of evaluating its potential to
contribute to the breeding effort for late blight resistance in the United States. In 1996, 552 single hills were planted on Chapman Farm,
Presque Isle, ME; only 448 tuberized.. In 1997 these clones were planted on Chapman Farm for increase; 129 were saved, 53 failed to
tuberize, and 266 were discarded because they were sprouting at harvest. In 1998 and 1999, 69 of these clones were evaluated for their
reaction to the US-8 strain of late blight in replicated plots on Aroostook Farm. Percent infected foliage was estimated three times towards
the end of the season and used to compute area under the disease progress curve (AUDPC). There were significant differences among the
clones for the square root of AUDPC (sAUDPC): 55 of them were significantly more resistant than ‘Atlantic’. There was also a
significant clone x year interaction for sAUDPC. Broad-sense heritability for horizontal resistance to late blight was estimated as 0.78 with
a 95% confidence interval of 0.64 to 0.86. Using detached leaf assays, these clones were inoculated with US-8 strains of P. infestans
and the diameter of the lesion was measured 7, 8, 9, 10, and 11 days after inoculation. The correlation's between field resistance and
the detached leaf assay were very low (0.18<r<0.24). Based on field tests, this population is an excellent source of genetic resistance
to late blight.
Haynes, Kathleen G and D Peter Weingartner. "The Use of Area Under the Disease Progress
Curve to Assess Resistance to Late Blight in Potato Germplasm." [Vol. 81, No. 2, Pgs. 137-141]
The multiple evaluation of potato cultivars and breeding selections (clones) for disease during the season can be costly and may not
be necessary for accurate assessments of disease resistance or susceptiblity. For diseases whose progression can be described by
sigmoid curves, an estimate of the area under the disease progress curve from two data points may provide as much information as
from repeated assessments. Twenty-three clones were planted in a randomized complete block design in Hastings, FL, in 1997 and
evaluated for percent diseased foliage 14 times during a 31-day period after late blight was first noticed in the plots. The area under the
disease progress curve (AUDPC) was calculated for all 14 assessments. The AUDPC was also calculated for nine sub-sets of the original
data set. There was a high correlation between all the methods in the calculation of the AUDPC. The AUDPC calculated based on two dates
(representing the beginning of the epidemic and the time until two of the clones were dead from late blight) was as informative as the
AUDPC calculated on the entire data set. The AUDPC could be calculated based on any two dates from this time frame as long as one date
was shortly after the epidemic started and the other date was as the epidemic was reaching its peak. Much information was lost if AUDPC
was calculated based on dates involved only in the early part of the epidemic. A considerable savings in time and effort can be realized by
only a few assessments.
Higley, JS, Love SL, Price, WJ, Nelson, JE and Huber, KC. "The Rapid Visco Analyzer (RVA) as a tool
for differentiating potato cultivars on the basis of flour pasting profiles." [Vol. 81, No. 1, Pgs. 65-66]
Though the practice of selecting potato cultivars for favorable agronomic traits has led to improved production capacity, the ability to
screen developing cultivars for end-use potential is limited. A primary objective of this study was to investigate the potential for the Rapid
Visco Analyzer (RVA), a rheological instrument, to discriminate two potato cultivar extremes, Russet Burbank (mealy texture) and
IdaRose (waxy texture). Potatoes of the two cultivars were lyophilized and ground into whole-tissue flours in preparation for RVA analysis.
To identify RVA run parameter combinations that facilitated maximal discrimination of the two cultivar extremes, a factorial experiment
including multiple levels of heating rate (2, 3, 4, 6, or 8 C min-1), peak temperature (75, 80, 85, 90, or 95 C), and flour
concentration (2.5, 3.0, or 3.5 g) was employed. Pasting profiles resulted in unique functional fingerprints for each cultivar, and were
influenced by variable levels of heating rate, peak temperature, and flour concentration. Discrimination of the cultivar extremes according
to RVA viscosity attributes was maximized at moderate heating rates (4 to 6 C min-1), moderate to high levels of peak
temperature (85 to 90 C), and intermediate flour concentrations. Thus, differentiation of the cultivar extremes was possible based upon
their respective pasting profiles. Using the optimized RVA run parameters, future work will focus on an increased number of potato cultivars
known to possess a full range of textural attributes to investigate potential relationships between RVA pasting behavior and end-use potential.
Hopkins, BG. "Best management practices (BMP’s) for potato production: Putting university
recommendations to the test." [Vol. 81, No. 1, Pgs. 66]
The objectives of this project were to: 1) establish a field demonstration highlighting a potato grower that follows UI BMP’s;
2) establish plots within the field to compare BMP’s with a high input, maximum yield approach; and 3) enhance grower confidence
regarding UI BMP’s. The demonstration field was established by a grower identified as one that utilizes an approach consistent with
UI BMP’s. High input plots were established by applying additional fertilizer and pesticide treatments in an effort to achieve maximum
yield. These plots were compared to matching BMP plots receiving the same treatment as the rest of the field with five replications.
Surprisingly, the BMP plots yielded significantly more (6% or 30 cwt./acre) as compared to the high input plots. The yield differences
resulted in an increase of $159/acre. In addition, the high input plots used more fertilizer/chemical with a net cost of $205/acre, giving a
net increase of $364/acre for the BMP’s. Additionally, the yield average for the field was 428 cwt./acre, which is substantially higher than
the average for the region. These results suggest that following UI BMP’s not only saved this grower money, but also allowed for
superior yields. A field day was conducted with 50+ growers and media persons in attendance. A survey of the growers attending the field day
indicated an increased optimism regarding UI BMP’s. This project is being expanded to five Pacific Northwest locations annually for
the next three years to further instill confidence in growers regarding these practices.
Hopkins, BG, JW Ellsworth and S Funk. "Phosphorus-zinc interactions in potato
production." [Vol. 81, No. 1, Pg. 66]
Previous research indicates negative effects on potato when excess phosphorus (P) fertilizer is applied. The standard grower practice
is to uniformly apply P to an entire field, which results in 30-45% of the field receiving excess P fertilizer. The field scale impact of excess
P, as well as management options, has not been adequately defined. One possible approach is based on a physiological coupling of
excess P inducing a zinc (Zn) deficiency. A field study in Aberdeen, ID was initiated to determine the effects of excess fertilizer P. The
study consisted of five replications in a RCBD experimental design of all combinations of 4 rates of P (0, 224, 448, and 672 kg
ha-1) with and without added Zn (0 and 22 kg ha-1). Significant responses were observed both for P and Zn
fertilization, as well as a significant interaction between the two. Applying P at the recommended rate (224 kg ha-1)
resulted in significant increases in overall and US no. 1 grade yields; however, excessive application (two or three times the recommended
rate) decreased both tuber yield and quality. Applying Zn alleviated the negative effect of excess P, although only at the high rates of
P. It seems that the synergy between adding P and Zn together can substantially increase tuber yield and quality in situations where this
phenomenon occurs. Application of P without consideration of Zn nutrition is potentially a serious management problem for potatoes
grown in Zn limiting soils, particularly common in the western United States. Further research is needed to confirm this effect and to
explore rate and ratio effects of adding P and Zn fertilizers.
Hosaka, Kazuyoshi. "An Easy, Rapid and Inexpensive DNA Extraction Method, “One-Minute
DNA Extraction”, for PCR in Potato." {Short Communication} [Vol. 81, No. 1, Pgs. 17-19]
A simple DNA extraction method was developed by modification of the SDS-potassium-acetate method (Dellaporta et al. 1983). It
can be completed in one minute and produced sufficient DNA for 500 RAPD or other conventional PCR amplifications.
Hosaka, Kazuyoshi, "Evolutionary Pathway of T-type Chloroplast DNA in Potato."
[Vol. 81, No. 2, Pgs. 153-158]
Potato was domesticated in the Andes of South America. However, the presently worldwide-grown potato (Solanum tuberosum
L. ssp. tuberosum, 2n=4x=48) has characteristic T-type chloroplast DNA that was introduced after late blight epidemics in the
mid-19th century from the Chilean potato (2n=4x=48) grown in the southern coastal regions in Chile. Among many wild potato species, the
same chloroplast DNA was found only in some populations of a diploid species S. tarijense Hawkes (2n=2x=24), which ranges
from central Bolivia to northwest Argentina. To elucidate an evolutionary pathway of T-type chloroplast DNA from S. tarijense to Chilean
potato, 215 accessions of S. stenotomum Juz. et Buk., considered to be the most primitive, diploid cultivated potato species, from
which all the Andean cultivated species evolved, and 286 accessions of the most widely grown, Andean tetraploid cultivated species
S. tuberosum L. ssp. andigena Hawkes (2n=4x=48) were examined in this study. No accession of S. stenotomum had
T-type chloroplast DNA, while nine accessions, mostly from northwest Argentina, of S. tuberosum ssp. andigena had T-type
chloroplast DNA. Therefore, I conclude that some populations of S. tarijense having T-type chloroplast DNA were naturally crossed
as female with S. tuberosum ssp. andigena from which the Chilean potato was selected.
Hutchinson, Chad M. "Controlled release fertilizer use in northeast Florida potato
production." [Vol. 81, No. 1, Pgs. 66-67]
Potato (Solanum tuberosum L.) production best management practices (BMPs) are under development for the Tri-County
Agricultural Area (TCAA; St. Johns, Putnam, and Flagler counties) near Hastings, Florida. BMPs are designed to reduce nitrate non-point
pollution in the St. Johns River from the approximately 8000 ha in potato production in the TCAA. Research to develop a controlled
release fertilizer (CRF) program to help growers meet the current nitrogen rate BMPs was conducted during the 2002 season.
A randomized complete block experiment with three replications was conducted on a local grower’s farm to compare standard BMP
and alternative fertilizer systems. The treatments were a CRF program (168 kg N ha-1; The Scotts Company, Marysville,
OH) and the grower standard BMP program (224 kg N ha-1) using soluble fertilizer sources. Total tuber yields were 40.8
and 38.4 MT ha-1 for the CRF and grower program, respectively and were significantly different. The CRF program produced
approximately 6% more tubers using 25% less nitrogen compared to the BMP nitrogen program. Tuber size distribution, specific gravity,
and chip quality were not significantly different. Currently, the cost of the CRF nitrogen program is 2.7 times higher than a standard
BMP nitrogen program. Nitrogen expense represents 2.4 and 6.3% of total production costs for the BMP and CRF nitrogen programs,
respectively. Although cost is higher, the CRF program improves time management and provides insurance against nitrogen leaching
in inclement weather compared to a soluble fertilizer program.
Hutchinson, Pamela JS, BR Beutler, RA Boydston, CV Ransom and FE Fletcher.
"Dimethenamid-p, sulfentrazone and flumioxazin: three new preemergence herbicides for weed control in
potato." [Vol. 81, No. 1, Pg. 67]
Dimethenamid-p, sulfentrazone, and flumioxazin are three preemergence herbicides being developed for use in potato. Efficacy
and potato variety tolerance trials were conducted over a multi-year period in Idaho, Oregon, and Washington. All three herbicides improved
season-long hairy nightshade control when combined in two-way tank mixtures with standard preemergence herbicides, such as EPTC,
metribuzin, pendimethalin, rimsulfuron, or s-metolachlor, compared to those standard herbicides applied alone. Depending on year and
location, common lambsquarters, kochia, and grass control also was improved with two-way mixtures including one of these developmental
herbicides compared to standard herbicides applied alone.
Russet Burbank potato variety was tolerant to one and two times the proposed dimethenamid-p label rate in trials conducted
in Idaho and Oregon. Russet Burbank, Russet Norkotah, Ranger Russet, Shepody, Alturas, and Bannock Russet potato varieties were
tolerant to one and two times the proposed dimethenamid-p, sulfentrazone, or flumioxazin label rates in Idaho and Washington trials,
depending on year and location. When grown during heat stress conditions, most varieties were less tolerant to sulfentrazone or flumioxazin,
compared to varieties grown during average growing conditions.
Ingham, Russ, NL David, DA Horneck, GH Clough and PB Hamm. "Effect of cover crops, metam
sodium and Vydate C-LV® on Columbia root-knot nematode." [Vol. 81, No. 1, Pg. 67]
Fall cover crops of clover (used as a control), mustard cv Martigena, and oil seed radish cv Colonel were compared to 38 gpa of metam
sodium (MS) applied in ¾ in. water for control of Columbia root-knot nematode (Meloidogyne chitwoodi). Cover crops were planted
17 August 2001 and incorporated on 25 October. MS was applied on 8 November. Potato cv Russet Norkotah was planted on 19 April 2002
and harvested on 5 September. Half of each plot received Vydate C-LV® (oxamyl) at 1 lb. a.i./a. applied in furrow at planting,
banded at hilling (29 May) and by chemigation in ½ in. water at 950 soil degree-days base 5C after planting (5 July). Nematode populations
across the plot area averaged 128/250 g soil when cover crops were planted, 9/250 g soil at incorporation and 6/250 g soil when potato was
planted. There was no difference between treatments as populations declined dramatically in all plots, even wet fallow. At potato harvest,
populations were lower than in control plots in MS only, MS + Vydate, mustard + Vydate, and radish + Vydate treatments. Tuber damage
from nematode infection was less with MS alone, but not with cover crops alone. However, damage in mustard + Vydate plots was less
than in the control or the Vydate only treatment, and equal to that in the MS + Vydate treatment. Damage in MS + Vydate or Mustard + Vydate
treatments was near to being acceptable and one more application of Vydate may have been sufficient. Yield of number ones was higher
with MS than in other treatments, but while total yield was higher in the MS treatment than in the control, it was not different from that in
mustard or radish treatments.
Inglis, Debra, B Gundersen, D Johnson, G Newberry and R Thornton. "Using improved host resistance
to control late blight on potato." [Vol. 81, No. 1, Pgs. 67-68]
Organic, conventional, reduced and no fungicide application programs were compared on A90586-11 and Russet Burbank
(RB) in the field at Mount Vernon, WA. A90586-11 is a late blight resistant potato clone from the Tri-State Potato Variety Development
Program. Area under the disease progress curve (AUDPC) values calculated from weekly late blight ratings were used to express disease
severity over time. The interaction between spray program and cultivar was significant for AUDPC: The mean values did not differ significantly
for programs among the two cultivars, but were nearly six-fold lower (263 vs. 1542) for no fungicide program on A90586-11 compared to
RB. Total yield on A90586-11 ranged from 695 to 723 cwt/a among the treatment programs. In contrast, total yield on RB (524 cwt/a) was
significantly lower for no fungicide program compared to the organic, conventional and reduced fungicide programs (661, 646 and 604
cwt/A, respectively). Gross returns minus fungicide costs on A90586-11 ranged from $1850 to $2106 for the organic and reduced fungicide
programs, respectively. However, on RB returns ranged from $1038 for the no-fungicide program to $1621 for the organic program. Advanced
potato clones such as A90586-11 with improved resistance to late blight can be managed successfully under organic and reduced spray
programs, offering economical control of late blight.
Jansky, Shelley, PJ Kauth and DI Rouse. "Inheritance of resistance to potato early dying disease in
diploid interspecific hybrids." [Vol. 81, No. 1, Pg. 68]
Verticillium dahliae is a soil-borne fungal pathogen and the primary causal agent of potato early dying disease (PED). Genetic
resistance offers effective disease control, but is not present in major commercial cultivars. This study was carried out to evaluate resistance
to PED in progeny of a cross between the diploid interspecific resistant clones C287 and C545. The two parents and 95 of their
progeny were evaluated in a PED screening field at Hancock, Wisconsin in 2001 and 2002. Apical and basal stem sections from mature
plants were collected, air-dried, ground in a Wiley mill, and plated on Sorensen’s medium. After a two-week incubation period, the
number of V. dahliae colonies per plate was recorded as a measure of stem colonization. An Analysis of Variance was performed on
both the apical and basal stem data using the General Linear Model in SAS. Means were separated using the Least Significant Difference
(LSD) test at P=0.05. Progeny clones that were significantly more susceptible than both parents were considered to be susceptible.
The ratios of resistant to susceptible clones were 73:22 and 70:25 for the apical and basal data, respectively. These ratios support a
single gene hypothesis, with resistance due to a dominant allele. It is proposed that both resistant parents are heterozygous, producing
an offspring population with 75% resistant plants. We have used the two resistant parents in 4x x 2x and 2x x 4x crosses and are currently
evaluating the ability to transfer resistance to the tetraploid level.
Jung, Chun Suk and WS De Jong. "The potato I locus, required for expression of red and purple
pigments in tuber skin, appears to encode a MYB domain transcriptional regulator of the anthocyanin biosynthetic pathway."
[Vol. 81, No. 1, Pg. 68]
The potato I locus is required for the synthesis of red and purple anthocyanin pigments in tuber skin. The results of several
experiments, outlined below, collectively suggest that I encodes a MYB domain transcription factor. 1) Petunia AN2 encodes
a MYB factor and is required for the expression of anthocyanin pigments in the floral limb. It has previously been reported that potato I
is located on the lower arm of chromosome 10. The tomato homolog of Petunia AN2 maps to the same region. 2) A potato gene with
sequence similarity to AN2 was isolated from a cDNA library prepared from pigmented tuber skin. Two alleles were observed when
part of this gene was sequenced from a purple diploid clone known to be heterozygous Ii. One of these alleles co-segregated with
pigmented skin in a diploid population created by crossing the purple clone with a white clone: the allele was present in all 73 progeny
with colored skin and absent in all 63 progeny with white skin. 3) Using RT-PCR the potato MYB domain gene was found to be expressed
in the epidermis of colored tubers but not in white tubers. RT-PCR also revealed that genes encoding two known anthocyanin pathway
enzymes, dihydroflavonol 4-reductase and flavonoid 3', 5'-hydroxylase, are expressed in colored but not in white tuber skin. Thus, like
Petunia AN2, I coordinately regulates the expression of multiple structural genes involved in anthocyanin biosynthesis.
Kelling, K, M Jordan, F Arriaga, B Lowery and P Speth. "Evaluation of hill shape for improving nitrogen
use efficiency." [Vol. 81, No. 1, Pgs. 68-69]
This experiment evaluates if using a hill shaper to form flat-topped hills with a small ridge on each shoulder can improve use efficiency
of applied fertilizer N compared to more standard, rounded hills or extremely pointed hills. The experiment, on very sandy irrigated soil,
used a split-plot design with hill shape (shaped, pointed, or standard) as the main plots and N rate (0, 134, 202, or 269 kg N
ha-1) as the splits with four replications in randomized complete blocks. Results show that in 2002 tuber yield and quality
were affected by hill shape with the shaped hills generally out-performing both standard and pointed hill. Shaped hills also resulted in
a larger proportion of larger (>170 g) and appeared to improve N use efficiency since on these plots yields responded to only 134 kg
N ha-1, with the same top yield, but responded to a higher N rate with the two other hill shapes. Differences between hill
shapes in the yield of US#1 (170-370 g) tubers were especially noticeable. Results of petiole analyses also show that there was more
NO3-N present in the petioles with the shaped hills at a given rate of N. Surprisingly, measured water content at 15 and
45 cm below the top of the hill for the periods of 11-23 June and 29 July-8 Aug. was consistently greater in the standard hill, followed by
the pointed and the shaped hill. This trend may have resulted because of increased runoff from the steeper hill sides when compared
to the standard hill shape, and possibly greater ET from the improved plant growth with this geometry. Although these data are from only
one site year, they strongly suggest that improvements in N use efficiency are possible by manipulating hill shape on very sandy soils.
Khu, Dongman, Stephen L Love and Jim Lorenzen. "Evaluation of corky ringspot disease resistance of
three different tetraploid populations for genetic map construction." [Vol. 81, No, 1, Pg. 69]
Corky ringspot (CRS) disease in potatoes is caused by tobacco rattle virus (TRV), which is vectored by stubby root nematode
species (Paratrichondorus, Tricondorus spp.). Screening as part of resistance breeding is difficult because the disease
distribution within the field varies depending on the environmental factors or the presence or absence of the vector or virus. Genetic
mapping of resistance loci should provide useful information to enable marker-assisted selection for CRS. One-hundred genotypes from
each of three tetraploid families developed from the crosses PA95A33-1 (R) x A9446-7 (unknown), PA95A11-14 (R) x A9014-2
(MR), and A8259-5 (R) x A7816-14 (S) were tested for field resistance. A9014-2 has a degree of resistance that although it does not have
identifiably resistant ancestry. The resistant parents all produce long, russet type tubers and are derived from Aberdeen, Idaho
germplasm. Resistance genes come from the European varieties Bintje, Multa, and Record. Each plot had a susceptible check cultivar
flanking the test genotype. The complex spatial patterns of CRS symptoms on check plants were mapped in 2001 and 2002, and resistance
of segregating genotypes was determined. Resistance levels in two families that were developed by crossing resistant x susceptible
parents appeared to be normally distributed. However, the phenotypic distribution of the family developed from a resistant x resistance cross
had a bimodal appearance.
King, BA, JC Stark and RW Wall. "Site-specific water management for potatoes under center pivot
irrigation." [Vol. 81, No, 1, Pg. 69]
Center pivot irrigation is the most common type of irrigation system used for potato production in the Pacific Northwest and
Intermountain West of the U.S. Conventional water management with center pivots treats the field as a homogeneous unit. In practice
though, differences in water requirements often develop throughout the season within center pivot irrigated fields that can reduce field
scale tuber yield and quality. Studies to equip center pivot irrigation systems for site-specific water management have been undertaken.
Most of these studies have focused on equipment development and evaluation and not potential economic benefit. This study investigated
the potential economic benefit from increased tuber yield and quality under site-specific versus conventional uniform irrigation management
with center pivot irrigation. In 2001 and 2002, one quadrant of an 11.5 ha center pivot irrigated field was divided into eighteen arbitrary
irrigation management zones. One-half of the management zones received site-specific irrigation management and the remainder received
equal irrigation based on the average irrigation requirement for the nine zones. The difference between mean seasonal irrigation amounts
for the treatments was less than 13 mm for both years. Both total and marketable tuber yields were not significantly different (p<0.05) for
both years. However, based on a tuber quality adjusted price structure for processing potatoes, gross receipts were approximately $160/ha
greater under site-specific water management compared to conventional uniform irrigation management for the field site.
Klimes, John, Gale Kleinkopf, Nora Olsen and Jeffrey Miller. "Hydrogen peroxide based products for
potato tuber disinfestation." [Vol. 81, No. 1, Pgs. 69-70]
A hydrogen peroxide/peroxyacetic acid (HPPA) mixture was evaluated for antimicrobial activity against potato pathogens Erwinia
carotovora, Phytophthora infestans, Fusarium sambucinum and Helminthosporium solani, which cause rot and
disfigurement in storage, reducing marketability and useable product. In vitro experiments indicated that HPPA was highly effective
against potato tuber pathogens at all current label concentrations (900, 2,700, 5,400, and 10,800 mg/kg, OxiDate™ label). In general,
significant reductions in pathogen viability on tuber surfaces were observed following HPPA applications to washed and unwashed tuber
surfaces, but these reductions varied with HPPA concentration. Applications to inoculated tubers followed by standard storage conditions
showed no significant reduction in disease development at any label concentration. Application into the ventilation air to stored potatoes
did not successfully move HPPA through the pile. While HPPA is effective in reducing pathogen viability on ‘Russet Burbank’ tuber surfaces,
it fails to meet the expectations for disease reduction or control of potato disease in storage.
Knowles, N Richard, LO Knowles and GNM Kumar. "Predicting the yield potentials of northern and
southern seed lots in the Columbia Basin." [Vol. 81, No. 1, Pg. 70]
Markers of seed-tuber age were identified for predicting the relative productivities of northern- and southern-grown Russet Burbank
(RB) and Ranger Russet (RR) seed in the Columbia Basin. Seed-tubers with a broad range in growth and yield potentials were produced
by varying storage temperature. Production environment (as reflected by seed from different regions) affected how seed aged in storage
to influence subsequent growth and yield potentials. Seed that had accumulated a particular number of storage degree-days (DD) at
12oC was physiologically different than seed that had accumulated the same number of DD at 22 and 32oC,
s indicated by the basal respiration rates of tubers at the end of storage. Aging affected the productivity of RB, RR and Umatilla
Russet seed-tubers primarily by altering stem number/tuber set relationships and tuber size distribution, with less impact on total,
U.S. #1 and marketable yields. Tuber set and size distribution were predicted with great precision from aboveground mainstem number
for northern- and southern-grown RR and RB seed. Furthermore, 2-methyl-1-butanol content of seed at planting correlated with the
number of above ground mainstems over 3 years of field trials, providing a consistent biochemical marker of seed age and relative
productivity. While total and U.S. #1 yields were comparable for northern- and southern-grown RR and RB seed, southern seed
consistently produced more tubers of smaller average size than northern seed. This knowledge provides an opportunity to ‘
customize’ management practices to the seed-source, to achieve maximum productivity with respect to market requirements.
The potential productivities for northern- and southern-grown seed can be estimated from seed butanol/stem number/tuber set
relationships.
Kumar, GNM, LO Knowles and NR Knowles. "Physiological basis for the loss of wound-healing
ability with advancing tuber age." [Vol. 81, No. 1, Pgs. 70-71]
The development of a suberized periderm in response to wounding is critical to protect potato tubers from desiccation and invasion
by pathogens. Suberization entails the synthesis and integration of polyphenolic and polyaliphatic compounds into the wall matrix of phellem
cells. Wound healing ability and resistance to pathogens decline with tuber age. Aging reduces the ability of tubers to produce superoxide
radicals and to increase phenylalanine ammonia lyase (PAL) activity in response to wounding. PAL synthesizes t-cinnamic acid, while
superoxide radical production at the wound site facilitates oxidative polymerization of the hydroxy-cinnamic acid residues into suberin through
a coupled reaction involving superoxide dismutase (SOD) and peroxidase (POX). Aging effected an increase in SOD and POX activities, which
normally would favor the incorporation of cinnamic acid into suberin. Suberin synthesis, however, is apparently limited in older tubers by reduced
ability of the wounded tissue to produce superoxide via membrane-bound NADPH oxidase. In intact tubers, NADPH oxidase activity was low
and unaffected by tuber age. Activity increased rapidly over a 16-h interval in response to wounding, and the increase was several-fold
greater in younger as compared with older tubers. Thus, the ability to increase NADPH oxidase activity in response to wounding decreased
with advancing tuber age. Furthermore, older tubers had lost the capacity to synthesize microsomal membrane proteins in response to
wounding. Inhibition of NADPH oxidase activity in young tubers effectively suppressed superoxide formation on the wound surface, reduced
wound healing ability and enhanced the susceptibility of wounded tissue to fungal infection. The age-induced loss in wound-healing ability is
mediated by reduced ability to produce superoxide radicals at the wound site, synthesize t-cinnamic acid and sustain its incorporation
into suberin.
Lara-Cabrera, Sabina and David M Spooner. "Taxonomy of North and Central American diploid
wild potato (Solanum sect. Petota, Solanaceae) species: AFLP data." [Vol. 81, No. 1, Pg. 71]
Solanum section Petota, the potato and its wild relatives, contains about 200 wild species distributed from the
southwestern United States to central Argentina and adjacent Chile. Most species grow in the Andes, but North and Central America
contain about 25 species. Ploidy levels of wild potatoes in North and Central America, as in South America, include diploids, tetraploids
and hexaploids. Chloroplast DNA restriction enzyme data from a prior study showed that 13 of these 30 species formed a clade containing
only diploids, but there was low resolution within the clade. This Amplified Fragment Length Polymorphism (AFLP) study complements
chloroplast and morphological and microsatellite studies to examine the species boundaries and relationships of the North and Central
American diploids. Wagner parsimony and phenetic analyses mostly agreed with the morphological data in supporting currently
recognized species except suggest that S. brachistotrichium and stenophyllidium are conspecific. Our new AFLP data,
in combination with the cpDNA and morphological data, supported sister taxon relationships for 1) S. cardiophyllum subsp.
ehrenbergii and S. stenophyllidium, 2) S. tarnii and S. trifidum, 3) S. jamesii and S. pinnatisectum,
4) S. lesteri and S. polyadenium, and 5) S. clarum and S. morelliforme.
Lebecka, R and E Zimnoch-Guzowska. "The Inheritance of Resistance to Soft Rot (Erwinia
carotovora subsp. atroseptica) in Diploid Potato Families." [Vol. ]
Soft rot of potato tubers, caused by Erwinia (Pectobacterium), is a serious disease affecting potato crops during storage.. Studies
on the inheritance of resistance to tuber soft rot were undertaken on diploid potato hybrids. A total of 480 clones, derived from 12 families,
were examined for resistance to soft rot in laboratory tests over 3 years and for basic agronomic traits in field experiments over 2 years.
General (GCA) and specific (SCA) combining abilities were significant in the inheritance of resistance to soft rot; however, GCA for female
parents were significant in 1 or 2 years during 3 years of evaluation and SCA was significant for eight, two, and six families out of 10 tested
in 1994, 1995, and 1996, respectively. There were also significant differences between years. Moreover, marked interactions for GCA
(females) x year and SCA x year in the variation of soft rot resistance were found. Broad-sense and narrow-sense heritability of resistance,
measured as diameter of rotten tissue, was estimated as 0.92 and 0.89, respectively. The maternal effect, evaluated in two sets of reciprocal
crosses, was not significant for the genetic determination of resistance to soft rot. No significant relationships were found between resistance
to soft rot and the main agronomic traits in the tested diploid families. These results suggest that diploid potato clones with resistance to
soft rot can be selected after being evaluated over a few seasons. It is also possible to select clones combining good resistance to soft rot
with high yield, superior tuber characteristics, and acceptable starch content. These resistant diploids can be used as male parents in
4x-2x crosses in breeding tetraploid potato resistant to soft rot.
Leite, Daniela Lopes, Margaret Dibble and James Lorenzen. "Development of Solanum berthaultii
cDNA libraries for identification of insect resistance factors." [Vol. 81, No. 1, Pg. 71]
The presence of glandular trichomes on the foliage of the wild Bolivian species, S. berthaultii, is associated with an important
type of insect resistance. Some of this resistance has been introgressed into the cultivated potato. Major incentives for this work include
the cost of alternative control measures, the development of insecticide resistance in target pests, and the health and environmental
impacts of chemical applications. The BCB/BCT populations from Cornell University were derived from S. berthaultii and have
been useful in mapping trichome-related insect resistance factors. These populations were produced from a cross between a
dihaploid S. tuberosum clone with an accession of S. berthaultii, and subsequent backcrosses to S. berthaultii
or S. tuberosum, respectively. The insect resistance factors are based on expressed genes, and quantitative trait loci for the
trichome traits have been identified. Although the initial research with these populations focused on trichomes and foliar factors,
collaborators in Chile and at Cornell University have shown that tubers of related breeding lines are also resistant to the potato tuber
moth. The diverse effects of this resistance source on several pests imply that trichome-mediated host plant resistance is likely to be a
stable source of crop resistance. We are cloning and sequencing cDNA libraries from leaves, trichomes, and tuber periderm of the
S. berthaultii parent of BCB population to identify novel ESTs to test for association with insect-resistance factors.
Lightbourn, Gordon, John Jelesko and Richard E Veilleux. "Retrotansposon based polymorphism
between parental monoploid potatos and electrofusion derived somatic hybrids to evaluation stability of retroelements Tst1."
[Vol. 81, No. 1, Pgs. 71-72]
The activation of transposable elements during both protoplast fusion and the in vitro regeneration process has been shown
to occur in rice and is thought to be a causal agent of somaclonal variation. Potato somatic hybrids derived from electrofusion of
monoploids were analysed using S-SAP (sequence specific amplified polymorphism or, in this case, retrotransposon display), a
modification of the AFLP technique. Primer pairs were designed to target MseI adapter sites, as produced during the AFLP
procedure, and the potato retrotransposon element Tst1. We used both automated and manual sequencing apparati with Cy5
fluorescently labeled primers to score polymorphism. Little polymorphism (15 of 120 bands scored) was observed between
monoploids derived from genetically distinct source plants. Bands were extracted from the 8% polyacrylamide gel, reamplified using
non-fluorescent primers and cloned. The cloned fragments were selected and sequenced. Preliminary sequence analysis revealed
that Tst1 had inserted into distinct sites that had no obvious simple sequence repeats or match in the GenBank. The paucity of
polymorphism among different genotypes suggests that Tst1 is an ancient retrotransposon and the influence of tissue culture
manipulations is little and/or masked by the genome.
Lim, Hak-Tae, Mei A Zhao and Yong Z Zhu. "Genetic stability analyses of cryopreserved potato
(Solanum tuberosum L.) using vitrification method." [Vol. 81, No. 1, Pg. 72]
Shoot tips of potato (Solanum tuberosum. L) isolated from in vitro grown shoot cultures were successfully cryopreserved
using the vitrification technique. From the genetic stability analyses of cryopreserved potatoes, there was no significant difference on the
morphological characteristics. The analysis of ploidy stability and mineral contents revealed that there was a little difference, but the
degree didn’t affect the heredity of plant characteristics. Molecular biological analyses with RAPD and SSR showed there was a little
difference about the quantity of DNA content, but there was no significant difference in quality. In conclusion, the method used in this
paper was a stable method to conserve the potato germplasm, and it maybe applied to other potato species or other germplasm for
long-term conservation.
Lim, Hak-Tae, Mei A Zhao, Yong Z Zhu, Dhital, Shambhu Prasad and Ik J. Chun. "Development
of rapid and stable cryopreservation method for the application of potato (Solanum tuberosum L.) germplasm."
[Vol. 81, No. 1, Pg. 72]
Dormant and axillary buds from in vitro grown buds of potato (Solanum tuberosum L.) cultivars in Korea were
successfully cryopreserved by a modified vitrification technique. Excised shoot tips from nodal segments cold-hardened at 10?
for 3 weeks were precultured on solidified MS medium supplemented with high concentrated sucrose for 1 day. After osmoprotected
by a mixture of 2 M glycerol plus 0.6 M sucrose for 90 min, they were dehydrated with a cryoprotectant adding ice blocking agent for 1 h
at 0? prior to a plunge into liquid nitrogen. Successfully vitrified shoot tips resumed growth within a week in a modified medium
plus low concentrated Pluronic F-68 and developed shoots directly. The average survival rates of all tested cultivars were about 70%.
This procedure was successfully applied to other cultivars. So, it appeared to be promising for the cryopreservation of various
potato germplasm. In addition, the stability of vitrified plants was confirmed based on biochemical and molecular analysis.
López-Delgado, H, ME Mora-Herrera, HA Zavaleta-Mancera, M Cadena-Hinojosa and
IM Scott. "Salicylic Acid Enhances Heat Tolerance and Potato Virus X (PVX) Elimination during Thermotherapy of Potato
Microplants." [Vol. 81, No. 3, Pgs. 171-176]
A modification of the standard thermotherapy was used to eliminate virus from potato virus X (PVX)-infected Solanum tuberosum
microplants of the Mexican National Potato Program is described here. Microplants were cultured with or without 10-5 M salicylic acid (SA)
for 4 wk, then subcultured without SA and exposed to 42 C for 30 days. Survival was more consistent in SA-treated microplants: among
seven genotypes, 40% to 100% of SA-treated microplants and 0% to 96% of controls survived at the end of thermotherapy. SA also improved
survival of the post-thermotherapy subculture. Among surviving microplants, SA increased the virus-free yield to 100% from 40% to 65% in
the controls. In an additional 30 PVX(+) genotypes, 98% of surviving SA-treated microplants were virus-free after thermotherapy, compared
to 75% of controls. SA-treated microplants had lower catalase activity and higher H2O2 levels.
Love, SL and JC Stark. "Potato Production Systems: A comprehensive guide for potato production
published by the University of Idaho." [Vol. 81, No. 1, Pg. 72]
Potato Production Systems is a new book written by 32 potato scientists and specialists at the University of Idaho. It is one of the
most comprehensive potato production manuals ever published, and is designed for use by potato producers, crop managers, consultants,
crop advisors, researchers, extension educators, and students of potato science. It was written for two specific purposes: 1) to provide
information on the scientific basis of potato production, and 2) to give specific recommendations to assist with daily management
decisions. Content of the book will allow the reader to recognize, diagnose, and solve most potato production problems. There are
individual chapters on Growth and Development; Variety Selection and Management; Seed Production and Certification; Field Selection,
Crop Rotations, and Soil Management; Green Manures; Seed and Planting Management; Potato Nutrient Management; Integrated Pest
Management; Disease Management; Nematode Management; Insect Pests and Their Management; Weed Management; Irrigation
Management; Physiological Disorders; Tuber Quality; Harvest Management; Storage Management; Economics and Marketing; and
Cost of Production. Potato Production Systems is useful as a practical production manual, but is also ideal for use as a textbook
for college courses in potato science. Publication is scheduled for summer 2003 and the book will be available from the Agricultural
Communications Department at the University of Idaho.
Lozoya-Saldaña Hector and Claudia Belmar-Díaz. "Behavior of USDA potato clones in the Toluca
valley in 2002 and characterization of their Phytophthora infestans isolates." [Vol. 81, No. 1, Pgs. 72-73]
Field resistance to late blight was assessed to 3,216 USDA potato clones. From Aberdeen, IO, forty or more clones each from
the families A00386, A00393, and A00375 showed no more than 10 % infection. Parental lines A95053-55 and A95053-61 as females,
and P1583331 and 750660 (37946A) as males, produced the most resistant clones. From Prosser, WA, family LB7 generated more
than 40 clones with less than 30 % of final foliage infection, followed by LB9 with 21 and 18 clones within such infection level in two
replicates, LB8 with 22 and 16 clones, and LB4, with 17 and 16. The families from Sturgeon Bay, WI included Solanum microdontum,
S. okadae, and S. berthaultii-derived clones. Families 473170 and TF produced 39 out of 50 clones each with less than
10% lesions, followed by 458367 and F2 with 21 clones each in this category. However, most genotypes had a wild-type appearance
and did not tuberize. The materials from Madison, WI, showed less than 20 % infection most of the season, but ended up with 40 % or
less damage. The most frequent P. infestans genotypes from the LB families (Prosser) and the J101 series (Madison) were
(mating type, Pep, Gpi) A1, 100/100, 100/100; A2, 100/100, 100/122; and A2, 100/100, 100/100, which are common. No host specificity
was detected.
Lulai, Edward C. "Proceedings from the Symposium: Recent Advances in the Physiology of Tuberization and Tuber
Dormancy." [Vol. 81, No. 4, Pgs. 251-252]
Symposium Introduction. The physiology of tuberization and dormancy is of great economic importance. The initiation and regulation of
tuberization impact costly issues including yield, maturity for harvest, and the development of related diseases and defects. The regulation
of dormancy is significant for maintaining tubers in sprout-free condition during sotrage and marketing, as well as for proper sprout initiation
in seed potatoes.
The process of tuberization and dormancy are biologically linked (see cover photograph). Environmental cues, i.e. shortened photoperiod
and accompanying cooler temperatures, promote tuberization. Upon tuber intiation, the orientation of cell division within the sub-apical
portion of the stolon changes to produce radial expansion rather than longitudinal growth. The resulting nascent tuber is dormant and
remains so during growth and until sometime after harvest. After dormancy is broken, signals initiating sprouting induce cell division and
elongation similar to that occurring in stolons prior to tuber intiation. Both tuberization and dormancy are known to be under hormonal control.
However, important questions concerning these processes arise. Specifically what hormones, signals, genes and other mechanisms are
involved in regulating tuberization and dormancy. A better understanding of the physiology and regulation of these processes will bring us
newarer to the development of new technologies that can be used to control tuberization and dormancy.
The four papers that comprise these proceedings describe recent cutting edge advances from research on tuberization and dormancy
and integrate our current knowledge of these processes. Questions are addressed concerning hormonal regulation and signalling
products, signal transduction pathway(s), genetic factors and gene regulation association with tuberization and dormancy.
Recent Advances In the Physiology of Tuberization and Dormancy.
- Molecular Controls of Tuberization
- Physiological Regulation of Tuber Dormancy
- Comparing Potato Tuberization and Sprouting: Opposite Phenomena?
- Polygene Mapping as aTool to Study the Physiology of Tuberization and Dormancy.
aThis symposium was organized by the Physiology Section of The Potato Association of America and presented on
August 11, 2003 at the 87th annual meeting of The Potato Association of America in Spokane, WA. Symposia sponsors were: AgriNorthwest,
Black Gold, J.R. Simplot Co., McCain Foods USA, Pinnacle Farms, Red River Valley Potato Marketing Association, and The Potato
Association of America.
bMention of company trade name does not imply endorsement by the United States Department of Agriculture over others
not named.
Lund, Anne, David Douches, Glenn Bryan, Karen McClean and Lynn Frank. "Genetic mapping of
resistance to Phytophthora infestans in cultivated tetraploid potato (Solanum tuberosum subsp. tuberosum)."
[Vol. 81, No. 1, Pg. 73]
One strategy for controlling foliar Phytophthora infestans in potato is to develop resistant cultivars. The identification of markers
for P. infestans resistance will enable the introgression of multiple sources of resistance through marker assisted selection.
The pyramiding of resistance genes in commercial potato cultivars would provide more durable resistance. A tetraploid (2n=4x=48)
mapping population (MSL603) was developed using the MSU breeding lines Jacqueline Lee (MSG274-3) and MSG227-2. The source of
foliar resistance to P. infestans in MSG274-3 originates from the wild diploid species Solanum demissum. With cooperation
from SCRI (Scottish Crops Research Institute), 205 AFLP and 27 SSR markers were generated using 210 individuals from mapping
population MSL603. In 2001 and 2002 the population was screened for foliar resistance to the US8 genotype of P. infestans at the
Muck Soils Research Farm in Bath, Michigan. Preliminary analysis indicates that 12 AFLP markers present in MSG227-2 are associated
with a significant increase in RAUDPC (Relative Area Under the Disease Progress Curve). Eight markers present in Jacqueline Lee were
associated with a significant decrease in RAUDPC. Software developed at SCRI for mapping tetraploid potatoes will be used to develop
a linkage map and identify any QTL associated with foliar resistance to P. infestans.
Lynch, DR, LM Kawchuk, Q Chen, M Konschuh, J Holley, DK Fujimoto, D Driedger, H Wolfe, L Dunbar, D
Waterer, P Bains, J Wahab and P McAllister. "Alta Russet: An Early-Maturing, High-Quality Russet Cultivar for Wedge-Cut French Fry
Production." [Vol. 81, No. 3, Pgs. 195-201]
Alta Russet (Russet Nugget x Ranger Russet) is an early-maturing cultivar, with high yield and excellent processing quality (fry color and
dry matter) coupled with a tuber size and shape profile ideal for the manufacture of wedge-cut french fries. In the western Canadian regional
trials harvested 110 days after planting, the yield of the new cultivar was similar and the specific gravity superior to that of Russet Burbank.
In multi-harvest date trials conducted under irrigated conditions in southern Alberta (Canada) the yield of Alta Russet was superior to Russet
Burbank and Shepody and similar to Ranger Russet (Amisk) when harvested at 95 and 110 days after planting. The tuber specific gravity of
the new cultivar was superior to Russet Burbank, Shepody, and Ranger Russet (Amisk) at 95 days after planting. At 110 days after planting
tuber specific gravity was similar to Ranger Russet (Amisk), but superior to Russet Burbank and Shepody. Fry color was generally superior to
Russet Burbank in the western Canadian regional trials and in the multi-harvest trials was generally similar to Russet Burbank, Shepody, and Ranger Russet (Amisk). Alta Russet produces excellent fry color out of long-term storage at 8 C and
acceptable color at 6 C. External and internal defects occurred at very low levels in all trials. Alta Russet is resistant to common scab and
Verticillium wilt, moderately resistant to early blight and Fusarium wilt and susceptible to Fusarium dry rot and late blight. The new
cultivar shows clear symptoms when infected with bacterial ring rot.
Lynch, DR, LM Kawchuk, Q Chen, J Wahab, M Konschuh, D Waterer, J Holley, DK Fujimoto, D Driedger, H Wolfe, L Dunbar, P Bains
and P McAllister. "Pacific Russet: An Early Maturing, Attractive Russet Cultivar with Excellent Culinary Quality."
[Vol. 81, No. 4, Pgs. 235-241]
Pacific Russet is a high-yielding, early maturing, oblong russet fresh market cultivar with excellent tuber appearance and culinary quality.
In trials conducted in western Canada the yield of the new cultivar was generally superior to Russet Burbank, Ranger Russet, and Atlantic at
80, 90, and 110 days after planting. In the North Central Regional Variety Trial the yield of Pacific Russet exceeded that of Russet Norkotah in
four of the eight sites in 2000 and three of the eight sites in 2001. In trials conducted in Ontario (Canada) Pacific Russet exceeded the yield
of Goldrush at both sites in 2001 and in 2002 at two of the three sites that included both cultivars. External and internal defects occur at very
low levels. The new cultivar is resistant to common scab and moderately resistant to Verticillium and Fusarium wilt, but susceptible to
Fusarium dry rot and late blight (foliar). Pacific Russet shows clear foliar but not tuber symptoms when infected with bacterial ring rot.
Lynch, DR, Q Chen, LM Kawchuk and D Driedger. "Verticillium Wilt Resistant Germplasm- Release of Clone LRC18-21
and Derivatives." [Vol. 81, No. 2, Pgs. 295-297] [Short Communication]
Verticillium wilt is an important disease affecting potato tuber yield and quality. In North America the major commercial cultivars are
susceptible, and management strategies for control rely mainly on soil fumigation and crop rotation. We describe a Solanum chacoense
clone (LRC18-21) with single gene (Vc) for resistance to Verticillium wilt as well as germplasm derived from the original clone.
LRC18-21 (diploid S. chacoense), LRC418-21 (tetraploid S. chacoense) and LRC373-5 (diploid S. tuberosum/chacoense
hybrid) and LRC4373-5 (tetraploid S. tuberosum/chacoense hybrid) have been released to Potato Introduction Station (NRSP-6,
Sturgeon Bay, WI) for distribution to interested parties. Transfer of the Vc gene to commercial cultivars could provide effective and economical
control of verticillium wilt.
McCue, Kent F, Louise VT Shepherd, Paul V Allen, M Malendia Maccree, David R Rockhold, Howard V Davies
and William R Belknap. "Modified steroidal alkaloid biosynthesis in transgenic tubers containing an antisense sterol glyco transferase
(Sgt) gene encoding a novel steroidal alkaloid diglycoside rhamnosyl transferase." [Vol. 81, No. 1, Pgs. 73-74]
Steroidal Glyco Alkaloids (SGAs) are undesirable naturally occurring secondary metabolites in potatoes. SGA levels are dependent
upon both variety and growth/storage conditions. In an effort to control accumulation of SGAs we have introduced antisense transgene
constructs encoding enzymes of the biosynthetic pathway. Transcription of transgenes is directed from the Granule Bound Starch Synthase
promoter, to alter accumulation in the tuber without affecting levels in the aerial portions of the plant. We report here the isolation and effects
of a gene encoding an enzyme for the final step in the production of the two major SGAs of potato, a-solanine and a-chaconine, the addition
of the 2-a-D rhamnosyl moiety of the triose sidechain. We have designated this gene SOLtu:Sgt3 and the enzyme is a novel E.C. 2.4.1.X Sterol
Glycosyl Transferase (SGT) catalyzing ß-solanine/ß-chaconine :UDP-rhamnose 1®2 rhamnosyltransferase. Examination by HPLC and MS
of alkaloids extracted from dried tuber slices identified transgenic lines with modified SGA profiles. In selected lines a severe reduction in
the accumulation of a-solanine and a-chaconine was observed with a subsequent accumulation of ß-chaconine the immediate precursors.
These data provide evidence that a single or highly conserved enzyme is responsible for addition of the final rhamnosyl unit to the triose
side chain of both of the major potato SGAs. Although the antisense transgene did not lower total SGA levels the data has helped us
characterize new genes in the biosynthetic pathway. Studies with additional Sgt transgenes are currently in progress.
Miller, J Creighton, Jr., George CC Tai, Bernard Ouellette and Jeannie P Miller.
"Discriminating Russet Norkotah Intraclonal selections using canonical and cluster analysis." [Vol. 81, No. 3,
Pgs. 203-207]
Intraclonal selection has been used to develop improved versions of existing popular potato cultivars. The approach is usually
undertaken to overcome trait deficiencies that limit production/acceptance of the cultivar. Because of close genetic relationshps,
discriminating between strains and the original cultivar is more difficult than discriminating between conventionally derived hybrid cultivars.
The objective of this investigation was to determine the genetic relationship between several Russet Norkotah intraclonal selections (strains)
using statistical analysis. Russet Norkotah and seven Russet Norkotah strains (TXNS102, TXNS112, TXNS223, TXNS278, CORN3 and
CORN8) were grown in 2000 and 2001 in New Brunswick, Canada, and several plant and tuber traits were measured. Hierarchical cluster
analysis and canonical discriminant analysis demonstrated that the Russet Norkotah strains differ in a significant manner from the original
cultivar and are therefore distinct and unique cultivars.
Miller, Jeff, MK Hubbard, BD Geary and AT Schneider. "Effect of irrigation method and fungicide
application interval on late blight tuber blight." [Vol. 81, No. 1, Pg. 74]
Trials were established in 2001-2002 to evaluate the effect of irrigation method on tuber blight caused by Phytophthora
infestans. The trial was arranged as a split block, randomized complete block design with irrigation method (solid set vs. simulated pivot)
as the whole plot factor and fungicide interval as the sub-plot factor. In 2001, solid set sprinklers applied 5 cm of water once each week and
a traveling gun applied 2.5 cm of water twice each week. In 2002, solid set sprinklers applied 3.8 cm of water twice each week and a linear
irrigation system applied 1.3 cm of water daily. Fungicide treatments (Dithane RS NT, 2 lbs/acre) included an untreated control and
applications made on 7, 14, and 21 day intervals. Tubers were evaluated for tuber blight incidence on two dates prior to harvest and two
months after harvest. In both years, tuber blight was detected when foliar blight was minimal (less than 3%). In 2001, sprinkler irrigated plots
had more tuber blight on the first evaluation, but differences between treatments were not significant by the final evaluation. In 2002, the
opposite was observed with pivot irrigation having more tuber blight at the early evaluation. Fungicide application interval did not affect the
overall incidence of tuber blight, but all fungicide treatments had less than the untreated control in 2002. Few differences were observed
for foliar blight severity. These data indicate that irrigation method does not significantly influence tuber blight incidence and that fungicide
intervals may be lengthened in semiarid environments.
Miller, Jeff, PB Hamm, SR James, BD Geary, DA Johnson and K Rykbost. "Influence of soil, seed
source, and fludioxonil seed treatment on incidence and severity of silver scurf on daughter tubers."
[Vol. 81, No. 1, Pg. 74]
A study was conducted from 1999-2002 to examine the influence of soil, seed source, and fludioxonil seed treatment on daughter tuber
silver scurf (caused by Helminthosporium solani). The experiments were designed as two-way factorial randomized complete blocks
with four replications, with seed source (pre-nuclear and generation 3 seed) and seed treatment (Maxim MZ and untreated) as the two factors.
Experiments were conducted in the lower Columbia Basin (OR), northern Columbia Basin (WA), central OR, southern OR, western ID, and
eastern ID. Tubers were stored for three months then evaluated for silver scurf incidence and severity. Significant differences were observed
among years and locations with disease incidence being highest in central Oregon and highest in 2000. Daughter tubers from generation 3
(G3) seed had significantly higher silver scurf incidence (18.4%) and severity (1.3) compared to daughter tubers from pre-nuclear seed
(1.2% and 0.04 for incidence and severity, respectively). Treatment with Maxim MZ seed treatment reduced incidence (3.8%) and severity
(0.2) significantly compared to the untreated control (15.8% and 1.1 for incidence and severity, respectively). These data indicate that seed,
not soil, is the primary source of daughter tuber infection in the field. For long term storage, purchase of clean seed is essential.
Miller, Jeff, TD Miller, AT Schneider and R Poteet. "Influence of mefenoxam application method
on pink rot incidence as determined by laboratory assays." [Vol. 81, No. 1, Pgs. 74-75]
Pink rot, caused by Phytophthora erythroseptica, can cause significant losses in storage. Mefenoxam application is one method
for reducing tuber infection. In 2000, many potato producers in eastern Idaho applied mefenoxam in-furrow and still experienced significant
losses due to pink rot. In 2001 and 2002 plots were established in a sandy soil to evaluate the efficacy of different application methods in
reducing pink rot, and to determine if mefenoxam could be leached from the root zone. Mefenoxam was applied in-furrow at planting
(IFAP) as a spray, IFAP dribble, at hilling, by ground sprayer twice, and by simulated chemigation twice. Twenty tubers from each plot were
inoculated with a zoospore suspension of a mefenoxam-sensitive isolate of P. erythroseptica (10,000 zoospores/ml) and stored
in a humid environment for 10 days. In 1999, pink rot incidence was reduced in all treatments compared to the untreated control.
Disease incidence was lowest for the at-hilling application (11%), followed by the foliar ground application treatment (25%). In 2002,
disease incidence in all treatments was similar to the untreated control. In the second trial, mefenoxam was applied in-furrow for
two treatments. One treatment was irrigated two days after planting (7.5 cm in 2001, 5.0 cm in 2002). In both years, the treatment
receiving water after planting had disease incidence similar to the untreated control, while the treatment without irrigation significantly
reduced disease incidence. These results indicate mefenoxam may be leached from soil with early season precipitation.
Mollov, Dimitre S and CA Thill. "Heritability of asymptomatic expression to potato virus Y."
[Vol. 81, No. 1, Pg. 75]
Potato virus Y (PVY) is spread in all areas where potatoes are grown and is one of the most economically important tuber-borne
viruses. The main strategies to limit spread of PVY are use of virus free seed and control of aphid vectors. Disease can occur undetected
in certain cultivars due to PVY asymptomatic expression (ASM), which can counter the benefits of potato seed certification programs. The
research objective was to determine if PVY ASM is heritable. Two breeding populations were planted in an aphid-vectored PVY disease
transmission nursery. The first population was exposed to PVY inoculum for 2 years having 94 clones from 5 half-sib families using
Russet Norkotah as a male, while the second population was exposed to PVY in 2002 having 248 clones from 15 families (13 4x-4x, 1
2x-4x, and 1 2x-2x). Genotypes were harvested and labeled clonally. Then, harvested clones were planted in a winter testing location.
Clones were visually evaluated for PVY symptom expression and tested for PVYOC and PVYN by ELISA
monoclonal antibodies. ANOVA indicated that families contributed significant sources of variation for both ELISA and visual evaluation
(p<0.0001). A moderate correlation r = 0.49, p<0.0001 was found between visual and ELISA PVY readings emphasizing the
inability to always detect PVY visually. Based on parental ploidy and symptom expression, progeny were grouped into six categories.
The frequency of ASM progenies were as follow: Group 1) 2x ASM – 2x ASM 33%, 2) 2x ASM – 4x ASM 15%, 3) 4x ASM - 4x SYM 42%, 4)
4x SYM – 4x ASM 49%, 5) 4x Resistant - 4x SYM 38%, and 6) 4x SYM - 4x Resistant 43%. Among all families 42% of the clones were
PVY ASM, indicating that regardless of ploidy, resistance, or virus expression ASM can segregate from multiple cross combinations.
Mollov, Dimitre S and CA Thill. "Identifying resistant PVY and PLRV progenies among
various parental matings." [Vol. 81, No. 1, Pgs. 75-76]
Potato virus Y (PVY) and potato leafroll virus (PLRV) are the most economically important viruses for the potato industry. Yield losses
caused by both viruses can exceed 50%. PVY necrotic strains and PLRV cause internal net necrosis on tubers which severely reduces
the quality of processed potato products. The research objectives were to identify clones 1) resistant to PVY, and 2) resistant to PLRV
among different mating types. Hybrid crosses produced 342 progeny from 20 families that were exposed to PVY and PLRV in an
aphid-vectored virus transmission nursery. Progeny were grouped by matings based on parental ploidy, and susceptibility (S) or
resistance (R) to PVY and PLRV. Mating groups were 1= 10 clones 2x PVY/PLRV SS – 2x SS, 2= 18 clones 2x SS – 4x SS,
3= 19 clones 4x SS – 4x RR, 4= 160 clones 4x RR – 4x SS, 5= 27 clones 4x SS – 4x RS, and 6= 108 clones 4x
SS – 4x SS. Genotypes were harvested and labeled clonally. Then, harvested clones were planted in a winter testing nursery
and evaluated for PVY using monoclonal antibodies for OC and N isolates, and for PLRV. ANOVA for PVYN determined that
replications and families were significant source of variation, emphasizing the uneven distribution of infected genotypes having
PVYN. Families contributed significant variation for PVYOC indicating that favorable parental crosses resulted
in genetic improvement for virus resistance. Susceptible genotypes for PLRV accounted for 329 of 342 clones and families did not contribute
significantly to variation. Among all progeny, clones negative for PVY (49.7%) and negative for PLRV (3.8%) in ELISA readings were identified
among the six mating types. One family had 84.2% of the progeny that lacked PVY detection despite high aphid pressure and virus inoculum
during growth.
Moreyra, Rocio, John Bamberg and Alfonso del Rio. "Genetic consequence of collecting tubers
vs seeds of wild potato species indigenous to the USA." [Vol. 81, No. 1, Pg. 76]
Wild potatoes reproduce in the wild clonally by tubers or sexually by seeds. This study was conducted to determine the genetic
consequences of sampling in situ clones or in situ seeds for two indigenous potato species of the USA, Solanum
fendleriand Solanum jamesii. Solanum fendleriis a selfing disomic tetraploid while S. jamesii is an outcrossing
diploid. Genetic diversity of in situ clonal collections and in situ seed collections of these species were compared with
RAPDs. More genetic diversity (i.e., RAPD polymorphism) was found within tuber collections than seed collections for S. fendleri
but, in contrast, similar (slightly more) diversity was found in seeds than tubers of S. jamesii. It has generally been assumed that
collecting in situ seeds captures more genetic diversity and is also more desirable for technical reasons. But in the case of an
in situ colony composed of mixed inbreds, many genes may be linked with genetic factors that influence which tuber genotypes
are collected, making the potential difference in diversity collected as tubers versus seeds greater than in outcrossers. Thus, for
inbreeders like S. fendleri, the capture of maximum diversity would be made more likely by collecting and combining both
tuber and seed samples whenever possible.
Navarre, Roy, Pete Thomas, Jim Crosslin and David Mayo. "Analysis of the effect of SAR on
potato viruses." [Vol. 81, No. 1, Pg. 76]
Systemic Acquired Resistance (SAR) is a process whereby a plant that successfully resists a pathogen becomes highly resistant to
subsequent infection not only by the original pathogen, but a variety of unrelated pathogens. Potato can have severe virus problems, as
many varieties have poor resistance. Chemical approaches to virus control usually target the viral vector and have no effect on the virus.
The expense and efficacy of anti-viral compounds precludes their use in the field. On the other hand, SAR is known to be an effective plant
defense mechanism against viruses. Indeed, the classic model system for analysis of SAR has been the tobacco-TMV interaction. We are
examining whether SAR can give effective virus control in potato. SAR was induced in Russet Burbank and Norkotah plants of various ages
grown in growth chambers or the greenhouse. Plants were then challenged with PVY or PLRV. Disease development was monitored
and compared to non-induced plants to assess whether SAR was effective in virus control.
Navarre, Roy and David Mayo. "Analysis of systemic acquired resistance in potato."
[Vol. 81, No. 1, Pg. 76]
We are interested in using Systemic Acquired Resistance (SAR) for disease control in potato. In order to optimize its utilization we are
studying SAR regulation in potato. Salicylic acid-mediated defense signaling in potato has significant differences relative to the tobacco
and Arabidopsis model systems. Potato has high constitutive levels of salicylates in all tissues examined. SA levels were the highest in
leaves and flowers, with concentrations of up to 15 mg/gram fresh weight. Relative to Arabidopsis or tobacco, high SA levels were also
found in stems, roots and tubers. Potato leaves have a constitutive level of PR-1 expression and may exhibit a differential competence for
SAR induction. In some cases, little or no increase in PR-1 gene expression was seen after treatment with SAR inducers Interestingly, potato
can also exhibit a dramatically increased sensitivity to BTH (Actigard). Extensive cell death is induced by BTH concentrations as low as 1
uM, whereas concentrations of 500 uM BTH had no such effect on tobacco treated in a similar manner. Thus, in some ways, potato
SA-signaling resembles certain Arabidopsis SA-signaling mutants more than it does wild-type Arabidopsis. This raises interesting
questions about the consequences of high basal levels of SA in some crops on defense signaling.
Nelson, JE and Huber, KC. "Influence of variable processing parameters on the freeze-thaw
stability of a mashed potato product." [Vol. 81, No. 1, Pgs. 76-77]
Frozen potato products represent a significant volume of all potatoes consumed in the US. Conditions under which potatoes are
processed impact the textural quality and stability of their frozen products. A high degree of cellular disruption (pasty texture) and loss
of water-holding capacity (syneresis) upon thawing are detrimental to the quality of frozen potato products. A primary objective was to
investigate the effects of processing parameters (length of cook, refrigerated hold, and mash) on the cellular integrity and syneresis
tendency of mashed potato tissue. A factorial experiment with varied levels of cook (boiling) (15, 20, or 25 min), refrigerated hold
(4 C storage) (0, 2, 4, 8, 16, or 24 hr), and mash time (2.0 or 7.5 min) were used to generate mashed products for two cultivars
(Nordonna, Russet Burbank). Cellular integrity and syneresis tendency were tracked by Blue Value (BV) and freeze-thaw stability
(FT) methods, respectively. Mash BV varied significantly with cook, mash, and 4 C hold time, with higher levels of cook and mash
promoting a greater degree of cellular disruption (elevated BV). Over 24 hr of 4 C storage, BV decreased to near zero levels due to
starch retrogradation. However, a higher degree of cellular disruption (longer lengths of cook) tended to increase the time for BV to
reach near zero levels during 4 C storage. Within FT experiments, the degree of syneresis for potato mash decreased with conditions
that promoted increased cellular disruption (highest cook and mash times), but increased with increasing length of 4 C storage.
A mashed potato product with optimum texture (low level of cellular disruption) and frozen stability (high degree of cellular disruption)
may require the balance of opposing phenomena.
Newberry, GD and RE Thornton. "Influence of post harvest tillage and rotation crop selection
on volunteer potato survival." [Vol. 81, No. 1, Pg. 77]
Volunteer potato plants in rotation crops can reduce yield and quality of those crops and can increase potato disease and insect
problems. Experiments to ascertain if post harvest tillage and cereal crop competition would reduce volunteer potato numbers were
conducted. In 1998, tubers were planted 0-, 5-, 10-, 15-, and 20-cm and fall tilled with a rotary disk, paraplow, rod weeder or not tilled.
In 1999 and 2000 tillage treatments were rotary disk, paraplow, moldboard plow or not tilled. In the cropping systems trial, tubers were
planted 10- or 20-cm deep and 1) fall tilled/seeded to winter wheat, 2) fall tilled/fallow, 3) spring tilled/seeded to spring wheat or 4) spring
tilled/fallow. In 1998 tillage had no effect on plant number the following spring, but tubers planted 20 cm deep produced more plants than
the other depths. In 1999, depth had no effect, however, the moldboard plow treatment had more volunteer plants than the other tillage
treatments. In 2000, tubers 0- and 5-cm deep produced fewer plants than tubers 10 cm deep. Tubers planted 15- and 20-cm deep
produced the most plants. Moldboard plow tillage produced the highest number of plants and the paraplow the lowest. Plant number
was lower in the 10 cm plots planted to wheat than those in fallow. In 2001, few volunteer plants grew from tubers planted 10 cm deep.
The 1999 and 2000 the fall treatments reduced plant number compared to the spring treatments from tubers 20 cm deep. Wheat
reduced the plant number produced from 20 cm planted tubers. These results indicate that both after harvest tillage and the presence
of a competitive cereal crop affect the number of volunteer potato plants produced by tubers left in the field following harvest.
Noronha, Christine and Donna Giberson. "Comparison between in-furrow and foliar
insecticide treatments on carabid beetle populations in potato fields." [Vol. 81, No. 1, Pg. 77]
The effect of insecticide application technique on carabid beetle populations in four commercial potato fields on Prince Edward Island
was studied. One half of each potato field received an in-furrow insecticide treatment and the other foliar sprays. Pitfall traps were
used to collect beetles. Four carabid genera (Coleoptera: Carabidae) were common: Harpalus, Pterostichus, Poecilus, and Bembidion.
Beetles numbers were higher within the in-furrow treatment section. Populations decreased following a foliar spray however, at the same
time, numbers increased in the adjacent in-furrow section indicating possible movement. The dominating genera differed in each field.
Harpalus (83%) in field one; Pterostichus (95%) in field two; in field three Harpalus (23%), Pterostichus (27%), and Poecilus (19%)
and Bembidion (19%); Populations in field four were the highest overall, with Harpalus (24%), Pterostichus (42%), Poecilus(19%), and
Bembidion (10%) dominating. Thus, potato fields treated with an in-furrow insecticide harbor higher numbers of carabid beetles. Foliar
sprays may induce movement into non spray areas.
Novy, Richard G, DL Corsini, A Nasruddin, EB Radcliffe and DW Ragsdale. "Resistance to PVY, PLRV,
PVX, green peach aphid, Colorado potato beetle, and wireworm in the progeny of a tri-species somatic hybrid."
[Vol. 81, No. 1, Pgs. 77-78]
Solanum etuberosum Lindl., a non-tuber-bearing, 1 EBN potato species native to Chile, is notable its high levels of resistance
to potato leafroll virus (PLRV), potato virus X and Y (PVX, PVY), and green peach (Myzus persicae) and potato (Macrosiphum
euphorbiae) aphids. A clone of this species was somatically hybridized with a haploid Gp. Tuberosum x S. berthaultii hybrid;
the somatic hybrid was successfully crossed to potato cultivars to generate 1st and 2nd generation progeny.
Evaluation of progeny in greenhouse, cage, and field trials in Minnesota showed the PVY, PLRV, and green peach aphid resistance of
S. etuberosum was transmissible to its progeny (Amer. J. of Potato Res. 2002. 79:9-18). Subsequent field evaluations in Idaho
also have confirmed the results from MN and additionally have identified resistances to PVX, Colorado potato beetle (Leptinotarsa
decemlineata), and wireworm (Limonius spp.) in the progeny. S. berthautii is notable for its resistance to Colorado
potato beetle and is the likely source of the resistance observed in the somatic hybrid progeny. It is unclear which of the two wild potato
species is contributing to the observed wireworm resistance; such resistance may involve additive contributions from both species.
Analysis of the classes and levels of glycoalkaloids present in the progeny is being conducted to determine their role in the observed
insect resistances. This germplasm, with its multiple genetic resistances, should prove useful for potato variety development and
molecular analyses.
Oberg, NA and GE Kleinkopf. "Evaluation of an automated variable airflow ventilation
system." [Vol. 81, No. 1, Pg. 78]
Ventilation system operation and management are key effecters of stored potato quality. Modern potato storage ventilation systems
are often designed to provide high airflow rates in order to deal with undesirable harvest conditions, damaged or diseased potatoes, and
disease spread within storage. In many cases, these high airflow rates are not required throughout the entire storage season. The ability
to precisely control airflow rates throughout the storage season may be beneficial. A novel variable airflow ventilation (VAV) system was
evaluated over three successive years, with Shepody or Russet Burbank potatoes, in paired 5,000 Mg commercial storage bays. Each
bay was designed to provide maximum airflow rates of 38.2 m3 h-1 Mg-1. One bay employed
the VAV system while a grower-cooperator managed the other bay. The VAV system was integrated with computer control circuitry and
a variable frequency drive to control airflow volume. Volumetric airflow rates delivered to the bulk pile were varied by the control system to
maintain a defined temperature differential from the bottom to the top of the potato pile. Temperature and relative humidity sensors were
placed within each pile and throughout the storage structures to assess the impact of reduced airflow rates on the physical storage
environment. Seasonal airflow rates in the VAV system varied from 11.5 to 38.2 m3 h-1 Mg-1.
Tuber quality following storage, as defined by glucose and sucrose content, specific gravity and fry color, was not impacted by reduced
airflow rates. Over the first two years VAV reduced average mass loss by 0.45% and electrical energy consumption by 42% relative to the
cooperator-managed bay. VAV systems can effectively maintain potato quality while reducing mass loss and energy use.
Olsen, Nora, T Brandt and J Robbins. "Production and tuber size manipulation of specialty potatoes
in Southern Idaho." [Vol. 81, No. 1, Pgs. 78-79]
Consumer demand for specialty potatoes has increased in the last several years. Preliminary studies and analysis in Southern
Idaho indicated market acceptance and good production yields for Caribe (lavender skin/white flesh), NorDonna (red skin/white flesh) and
Yukon Gold (yellow skin/yellow flesh) in Southern Idaho. Consumer tuber size preference differs by cultivar, therefore attempts were made to
alter yield and size profile by physiologically aging the seed in elevated storage temperature treatments. Seed tubers were stored at a) 3.3°C
until planting (no aging), b) 3.3°C and 30 days at 7.2°C prior to planting, c) 3.3°C and 15 days at 15.5°C prior to planting. Seed pieces (71 g)
were planted in field trials, grown for ~110 days, and evaluated for performance in two years. Cultivar response to storage treatments varied
between years. In 2002, all three cultivars had earlier emergence with the two aging treatments. Caribe average stem number per plant was
not affected by seed storage treatments. Although the combined-years total yield (37.8 t/ha) was not significantly impacted by aging
treatments for Caribe, the 2002 total yield was significantly higher with the aging treatments. NorDonna responded to both aging treatments
with increased stem numbers, higher total (38.4 t/ha) and US1 yields and greater yield in the 170 to 283 g size range. Although seed aging
significantly increased stem numbers for Yukon Gold, there was no impact on total yield (42.4 t/ha) or size distribution. In general, seed aging
using these elevated storage temperatures did not substantially impact size distribution. Other means to alter size such as seed piece size,
plant spacing and earlier harvests may need to be utilized in conjunction with warmer seed storage temperatures.
Olsen, Nora, LK Woodell, GE Kleinkopf and A Hornbacher. "Seed storage temperature and
performance." [Vol. 81, No. 1, Pg. 79]
Optimal seed storage temperatures and physiological age varies with cultivar and market use. This study altered seed storage
temperatures to produce different levels of physiological age of five cultivars and evaluated the affects on early performance, yield and size
distribution. Russet Burbank, Ranger Russet, Russet Norkotah, Umatilla Russet and Shepody seed tubers were stored at a) 3.3°C
until planting (no aging), b) 3.3°C and 30 days at 7.2°C prior to planting, c) 3.3°C and 15 days at 15.5°C prior to planting. Seed was planted
in Kimberly, ID and the study was repeated over three years. Shepody and Norkotah were grown for ~127 days and Russet Burbank, Ranger
Russet and Umatilla Russet were grown for ~150 days. Cultivar response to storage treatments varied between years. Combining all years,
Shepody and Norkotah, had significantly earlier emergence with the two aging treatments. Norkotah had greater stem number per plant with
both aging treatments whereas Shepody had greater stem numbers with only the highest storage temperature treatment. Seed storage
treatments did not impact Norkotah final yield or size profile. On average, storing Shepody for 15 days at 15.5°C significantly increased
yield of 170 to 283 g size (9.6 t/ha) compared to no aging (8.4 t/ha). Russet Burbank and Russet Umatilla showed earlier emergence with
elevated storage temperatures. Although the highest storage temperature treatment significantly increased stem numbers of Russet
Burbank and Umatilla, it did not influence yield or size distribution. Storage treatments had a limited affect on Ranger Russet emergence
and no affect on stem numbers. In general, seed storage temperatures impacted early performance, but had limited influence on final yield
and yield profile, and varied with cultivar.
Ozgen, Senay; and Jiwan P Palta. "Root zone calcium has a dramatic influence on growth of potato
apical meristem and maintenance of apical dominance." [Vol. 81, No. 1, Pg. 79]
It is well known that Ca plays an important role on plant growth and development including cell division and cell elongation. The
purpose of the present study was to determine the impact of root zone Ca on the growth and health of potato apical meristem and
maintenance of apical dominance. For this purpose 4 weeks old 2nd and 3rd nodes of micropropagated potato
(Solanum tuberosum L. cv Dark Red Norland) plantlets were grown in sterilized MS media with varying amount of Ca (using
CaCl2) concentration (from 0.2 to 440 ppm). After 4 weeks in the MS media plantlets were harvested and data for number
and height of shoot was collected. Plantlets were ashed and tissue calcium concentration was determined. Shoot growth (measured
from the agar surface) decreased with decreasing concentration of Ca. For example shoot length was about 15, 15, 13, 11, 10, 6, 5 cm
at 440, 220,100, 25, 5, 2.5 and 1 ppm Ca concentration in the media. As Ca concentration decreased the apical dominance was not
maintained resulting in axillary shoot growth. The number of shoots increased from 1 to 21 as Ca concentration in the media decreased
from 440 to 0.2 ppm. At Ca concentration of 220 ppm or higher there was a single main shoot with no axillary shoots.
These experiments were repeated in the presence of 5 mM EGTA in the media. In the presence of EGTA the shoot growthwas further
inhibited and apical dominance was not maintained even at 440 ppm Ca in the media. Consistent with visual observation the Ca
concentration in the shoot tissue decreased from about 3000 to 500 mg.kg-1 (dry weight) with decreasing Ca in the root zone.
These results provide evidence that amount of root zone Ca can dramatically influence growth of apical meristem and maintenance of
apical dominance in potato.
Palumbo, Rose and Richard Veilleux. "The potential for green fluorescent protein as a screening
tool in the production of haploid potato plants." [Vol. 81, No. 1, Pgs. 79-80]
A hybrid between a highly regenerative diploid clone (BARD 1-3) of Solanum phureja and haploid inducer IVP 101 was
transformed with Agrobacterium tumefaciens strain 4404 containing plasmid pHB2892 with genes for green
florescent protein (GFP) and kanamycin resistance. Hemizygous primary transformants were produced from three leaf discs. One leaf
disk produced 17 diploid plants, whereas the other two leaf disks produced three and nine plants, which spontaneously doubled to
tetraploids. Diploid plants were self-pollinated to obtain plants homozygous for GFP expression as well as haploid induction capacity.
Anther culture was used on the tetraploid plants to reach similar homozygosity, as well as to reduce their ploidy level. GFP expression
was observed qualitatively under a fluorescence microscope and quantitatively with a portable GFP meter. GFP expression was greatest
in the guard cells, the trichomes and along vascular traces. GFP could also be observed faintly in most other tissues with the exception of
dry seed, which has too much interfering autoflorescence for the microscopes to filter out. The GFP meter revealed variable expression
among primary transformants, and based on that variation the progeny of those plants that expressed the highest levels of GFP were
selected. Unfortunately, these selections also segregated for a dwarfed phenotype resembling that of the topiary gene, thus precluding
their utility as haploid extractors. Progeny with normal phenotype will be evaluated for GFP expression, homozygosity of GFP and the
embryo spot marker, and potential for haploid induction.
Pavek, JJ and DL Corsini. "Inheritance of Vitamin C content in several 4x potato crosses."
[Vol. 81, No. 1, Pg. 80]
Potato is an important, dietary source of Vitamin C. A high degree of variation in Vitamin C content exists in our parental germplasm,
the content varying from 10mg to over 30 mg/100g FWB. From 1991-97 we tested the progeny of 8 crosses: low x high, low x medium, and
medium-high x high, plus a medium-high self. In most crosses, vitamin content of progeny was uniformly distributed between the two
parents with the mean about halfway between, suggesting additive gene action. Two crosses of low x medium deviated from this observed
distribution, with the Vitamin C content of the medium parent and of the progeny mean located in the center of the progeny distribution. In
two crosses of medium-high x high, transgression was observed with 8-12% of the progeny exceeding the Vitamin C content of the high parent,
while 28-39% were lower than the value observed for the medium-high parent. Progeny from self-pollination of a medium-high parent had a
uniform distribution (14 to 33 mg) of Vitamin C content; the parent and the progeny mean were midway between the two extremes.
Testing progeny selections over years showed that the Vitamin C content is highly heritable.
Pavek, MJ and RE Thornton. "Economic impact of missing and irregularly spaced potato
plants." [Vol. 81, No. 1, Pg. 80]
Missing and irregularly spaced potato plants compromise commercial grower revenue. To estimate value of non-uniform plant
spacing in Washington (WA) State potato fields, seed and plant spacing was measured during 2000-02. Russet Burbank (RB) and
Russet Norkotah (RN) were grown in 4 small plot experiments designed to mimic spacing errors common to WA potato fields. Yield
and economic values of uniform (optimum) spacing were compared to treatments containing planter skips, rotten or blind seed, and
seed clumps (doubles) in 2001 and 2002. A 3-plant-unit area design was used to allow yield compensation measurements from in-row
and adjacent-row plants next to errors. For each treatment, economic value was derived using regional-average market prices.
Coefficient of variation for grower in-row spacing ranged from 18 to 69% compared with a hand-planted check average of 13%. Missing
plants averaged 2970 ha-1. When plants were missing, 92% of the time no seed was planted, 4% rotted, and 4% failed
to sprout. For both cultivars in the small plot experiment, in-row plants next to a skip collectively compensated for 55% or more of the
missing plants economic value. Plants in adjacent rows failed to compensate for their missing neighbor. Doubles reduced average
tuber size of both cultivars compared with the optimum spacing. Using process market values, 2970 missing RB plants
ha-1 reduced seed-cost-adjusted gross income 3% or $205 ha-1. Using fresh market values, 2970 missing
and 1980 double-clumped RN plants ha-1 reduced seed-cost-adjusted gross income 4.8% or $270 ha-1.
Seed preparation and planting operations benefited from intensive management, but new planter technology is needed. Growers should
use this information to guide management decisions.
Pavek, MJ and RE Thornton. "Understanding the influence of planting depth and post-planting
tillage on potato production." [Vol. 81, No. 1, Pgs. 80-81]
Little is known about the effects of planting depth and hill drag-off on cultivars grown in the Columbia Basin of Washington State.
Depth and drag-off research was conducted on cultivars ‘Russet Burbank’ (RB), ‘Russet Norkotah’, ‘Gem
Russet’, ‘Umatilla Russet’, ‘Shepody’, and ‘Ranger Russet’ during 2000, 2001, and 2002.
The objective was to determine if planting depth and drag-off have an effect on soil temperature, vine, node, stolon, stem, and tuber
development, tuber greening and yield. Ten and 20 cm planting depths were used all 3 years, 15 and 25 cm depths were added in 2002.
Drag-off from 20 to 10 cm (2001) and 25 to 15 cm (2002) was compared to similar planting depths without the drag-off treatment. Umatilla
and RB were included in each experiment all years; the other cultivars were included in the depth trial for 1 or 2 years. Soil temperature
extremes and heat-unit accumulation increased as seed pieces were planted closer to the soil surface. Plant emergence was delayed with
an increase in planting depth for all cultivars, especially Umatilla and Gem. For most cultivars, Rhizoctonia solani severity, node,
stolon, and tuber number increased as planting depth increased, stems per plant tended to decrease. Green tuber yield was reduced as
seed pieces were planted deeper or hills were dragged off. Other than losses from green tubers, market yield and tuber size were relatively
unaffected by planting depth or drag-off. Commercial growers should match planting depth with soil-type, growing region, and cultivar.
Cultivars that produce large tubers or have early-senescing vines should be planted deep enough, or have their hills dragged-off, to reduce
tuber greening.
Peters, RD, HW (Bud) Platt, IK Macdonald, R Coffin, Y Leclerc, T Kloepfer-Dawes, L Letkeman, D Martin,
K MacCallum, KA MacIsaac, R Reddin and C Baker. "Use of foliar and in-furrow applications of mefenoxam for control of potato tuber
rots." [Vol. 81, No. 1, Pg. 81]
Potato tuber rots, caused by Phytophthora erythroseptica (pink rot) and Pythium ultimum (leak), reduce yields at harvest
and in storage annually. In Canada, chemical control of pink rot and leak has relied on foliar applications of mefenoxam (Ridomil Gold).
However, variations in the efficacy of foliar applications of mefenoxam have been reported. Field trials were established at several locations
in 2001 and 2002 and post-harvest tuber inoculations were conducted to compare the efficacy of foliar with in-furrow applications of
mefenoxam for control of potato tuber rots. In both years of study, tubers from plots receiving in-furrow applications of mefenoxam were
significantly (P=0.05) less diseased than tubers from plots receiving foliar applications of mefenoxam or chlorothalonil alone
(control). Foliar applications of mefenoxam provided suppression of tuber rots in some locations in a particular year but not in others.
In-furrow applications of mefenoxam provided excellent disease suppression in New Brunswick and Prince Edward Island, but were
somewhat less effective in Ontario and Manitoba, indicating that soil type may play a role in the efficacy of this method. Applications of
mefenoxam at planting may be more appropriate than timed foliar applications to circumvent early infection of underground plant tissues
by P. erythroseptica and consequent tuber infection via diseased stolons.
Peters, RD, AV Sturz, WJ Arsenault, IK Macdonald, KA MacIsaac, A Malone and R Reddin. "Pink rot
development in potato cultivars following inoculation of tubers with Phytophthora erythroseptica."
[Vol. 81, No. 1, Pgs. 81-82]
The causal agent of pink rot, Phytophthora erythroseptica, can infect potato tubers via growth of mycelium from diseased
stolons or by zoospore infection of tuber eyes. Differences in the tolerance of various potato cultivars to pink rot have been reported. Tuber
inoculation studies were conducted during a three year period (2000-2002) with six potato cultivars (Russet Burbank, Shepody, Norland,
Yukon Gold, Butte, and Goldrush) and four different pathogen isolates to test for the susceptibility of tuber tissues to infection and the
pathogenicity of isolates. Although no cultivars were immune to pink rot, significant (P<0.001) differences in disease incidence
and severity among cultivars were noted. The cultivars Norland and Shepody were significantly (P=0.05) more susceptible to disease
than the other cultivars according to measurements of surface necrosis, internal pinking and disease incidence. Year × cultivar interactions
for trials conducted in 2001 and 2002 were significant (P<0.001). All isolates used in the studies were highly pathogenic and
no significant differences in pathogenicity among isolates were noted. A comparison of the response of tuber tissues to infection by
P. erythroseptica with previous work on non-tuber (roots, stems, stolons) tissues revealed that disease severity of the two tissue
types was similar for some cultivars but different for others. Information on differences in the tolerance of potato cultivars to pink
rot may influence the choice of cultivars grown in fields that are poorly-drained or with a history of the disease.
Platt, HW (Bud) and IK Macdonald. "Tuber rot resistance in potato cultivars and breeding program
clones to A1 and A2 mating type isolates of Phytophthora infestans." [Vol. 81, No. 1, Pg. 82]
Late blight of potatoes has its greatest impact on the potato industry in terms of the incidence and severity of late blight tuber rot which
frequently occurs after the majority of crop production expenses have been incurred. Often a 'hidden' disease prior to and at harvest,
late blight tuber rot can lead to severe crop losses during and after potato storage. It also affects the occurrence of disease in
subsequent crops and growing seasons as the pathogen survives in tubers and initiates new disease when favorable conditions occur.
Therefore, management of late blight tuber rot is vital to ensure cost-effective potato production and to limit disease potential in seed and
potato growing areas due to the occurrence of infected, 'overwintering' tubers and subsequently volunteer plants. While late blight resistance
in plant foliage is very important, the most effective late blight tuber rot management option is host resistance. With the changing nature
of pathogen populations worldwide, knowledge of late blight tuber rot responses is vital to successful development of late blight resistant
cultivars and to proper crop management determinations. Results of tuber rot responses of potato cultivars and breeding program lines
to two of the new and more aggressive genotypes of the late blight pathogen are presented. Several lines demonstrated significant
levels of resistance to one or both of the pathogen populations. Implications of these results will be discussed regarding the development
of late blight management and of potato breeding programs.
Platt, HW (Bud), AAS Mills, A MacPhail and RAR Hurta. "Post-harvest tuber disease management
with organic and inorganic salt compounds." [Vol. 81, No. 1, Pg. 82]
The potato industry has identified a serious problem involving the control of post-harvest tuber diseases. Tuber damage incurred by
mechanical harvest, infected soil and stem end or lenticel infection contributes to post-harvest diseases in potatoes. The use of
commercial fungicides for post-harvest disease control is limited by harvest intervals restrictions and on use of certain compounds on
human foodstuffs. Research was conducted on the effect of salt compounds on bacterial and fungal pathogens of potatoes that cause
post-harvest tuber diseases. Both organic and inorganic salt compounds and commercial fungicides were tested for efficacy on control
of mycelial growth, sporulation and spore germination in vitro. Disease prevention and curative effects of the compounds were
measured in vivo using fresh harvested tubers as well as tubers from cold storage. Two treatments, sodium metabisulfate
and propyl-paraben, were very effective for controlling mycelial growth, sporulation, and spore germination for all fungal pathogens
at all concentrations. Alum (aluminium potassium sulfate, dodecahydrate) and potassium sorbate provided effective control at high
concentrations. Sodium bicarbonate was very effective at controlling sporulation in most pathogens. Most salt compounds effectively
inhibited growth of bacterial pathogens at all concentrations although there were indications some compounds were beneficial to
microbial growth rather than inhibitory. This project is funded by Patates Dolbec Inc. and Agriculture and Agri-Food Canada.
Porter, GA, A Siver and P Ocaya. "Potash fertilization affects fry color, internal defect incidence,
blackspot bruise susceptibility, and tuber calcium concentration." [Vol. 81, No. 1, Pgs. 82-83]
Potassium, most commonly potassium chloride, can have strong effects on yield, tuber size, and specific gravity. From 2000 to 2002,
we studied current-season (0, 224, or 448 kg/ha K2O) potash and long-term potash fertility programs effects on non-irrigated
Atlantic potatoes. Soil-test K levels ranged from 130 to 225 kg/ha (2.4 to 4.4 % base saturation) depending on the long-term fertility
program (medium-low to medium soil-test potassium based on University of Maine criteria). Current-season potash had a much stronger
effect on tuber quality than did soil potassium. Chip color improved dramatically as the potash rate increased from 0 to 224 kg/ha and
more slowly as the rate was increased to 448 kg/ha. Internal defects incidence (hollow heart, brown center, and black spot bruise) declined
dramatically as potash rate increased. Increased potash rates resulted in higher tuber potassium, calcium, and magnesium
concentrations. Additional studies were conducted with Russet Burbank, Shepody, and Snowden from 1999 to 2002. Fry color generally
improved in response to increasing potash rates, while blackspot bruise susceptibility declined. Tuber tyrosine concentration, a key
biochemical ingredient in blackspot bruise development, declined as potash rate increased. These studies show that increasing potash
rates can improve most tuber quality attributes; however, over the 11 experiments, each 32 kg/ha of potash decreased specific gravity by
about 1 point. Despite this negative effect, the specific gravity of Atlantic and Snowden remained very high at all potash rates.
Porter, GA, DH Lambert, AA Bushway, RL Plaisted, KM Paddock, WS DeJong and DE Halseth. "Monticello: A Mid-season
Variety with Good Tuber Appearance and Chipping Potential from Mid- to Long-term Storage."
[Vol. 81, No. 2, Pgs. 143-152]
Monticello (NY102), a new medium-maturing, round-white chipping variety was released in 2003 by the University of Maine and Cornell
University. It is primarily intended for use in the chipping industry, especially from mid- to long-term storage. Its ability to chip from relatively
long-term storage, low storage weight loss, and relatively long tuber dormancy should be particularly valuable. Tubers have shown a good
ability to recondition and regain good chip color after periods of stress in storage. Monticellos specific gravity typically averages only a few
points lower than Atlantic, a variety that is widely used for out-of-field chipping in the eastern U.S. Chip color of Monticello has been very good
from short-, mid-, and long-term storage. It has been grown successfully in commercial-scale tests in Maine since 1999 with combined
seed and chipping production of more than 37 and 60 ha during 2001 and 2002, respectively. Research and commercial-scale trials in
Maine have generally produced favorable yield and quality results relative to other storage chippers like Snowden. The tubers are bright and
attractive with relatively few external defects. Tuber size tends to be fairly small and is ideal for chipping. Sensory panel tests have also
shown that Monticello is good for boiling and baking. Although ideally suited for chipping, the fresh market may serve as a secondary
market for this variety because of its typically good external appearance and cooking quality scores. Monticello has moderate to good
common scab resistance and is resistant to golden nematode. It is moderately susceptible to blackspot bruise, powdery scab, and typical
foliar diseases of potato. Although tubers can develop hollow heart and internal heat necrosis, Monticello is typically much less
susceptible than Atlantic.
Porter, LD and DA Johnson. "Effects of tuber depth and soil moisture on infection of potato tubers
in soil by Phytophthora infestans." [Vol. 81, No. 1, Pg. 83]
Effects of tuber depth, soil type and soil moisture on potato tuber infection due to Phytophthora infestans were quantified under
greenhouse conditions in soil contained in 35-cm-dia. by 25-cm-deep pots. Healthy tubers were either hand-buried in soil at specific
depths or naturally formed from potato plants grown in the soil to assess infection at varying soil depths. A spore suspension of P.
infestans at a concentration of 10,000 sporangia/ml water was chilled at 4°C for two hours to induce zoospore formation and 100
ml of the spore suspension was applied to the soil surface within a pot. Tuber infection significantly decreased with increasing soil
depth. Most infected tubers were found at the soil surface; infection was rare on tubers at 5 cm or deeper. Significantly less tuber
infection occurred in a Shano silt loam than in medium and fine sands. Only tubers on the soil surface were infected in the Shano silt
loam. Depth in soil at which tubers became infected did not differ significantly among Quincy fine sand, Quincy loamy fine sand and
Quincy medium sand. Increased soil moisture did not significantly increase depth at which tubers became infected for any of the soil
types.
Porter, LD, DA Johnson and DA Inglis. "Identification and characterization of resistance to
Phytophthora infestans in commercial potato cultivars and advanced breeding lines." [Vol. 81, No. 1, Pg. 83]
Resistance to Phytophthora infestans in tubers, stems, leaflets, and flowers of commercial cultivars grown in the Columbia
Basin and advanced potato breeding lines from the Tri-State Variety Development Program was quantified. Foliage of eight commercial
cultivars was highly susceptible in field and greenhouse tests. Advanced breeding lines J138-A12, A9583-56, A95020-70, PI583331,
A95053-61, A9512-3 and A9553-68 had high levels of resistance in stems and leaves in the field; but, only lines J138-A12 and
A95020-70 had high levels of resistance in stems and leaves in the greenhouse. Level of foliar resistance varied among lines depending
on the clonal lineage of P. infestans (US-8 or US-11). Percentage of tubers infected in the field at Mount Vernon, WA was
significantly higher for Russet Norkotah, Ranger Russet, and Bannock Russet than for Russet Burbank and A90586-11. Tubers of
Umatilla Russet, Russet Legend, Gem Russet, A90586-11, AWN86524-5, A9514-8, A9553-68, A9588-18, PI583331, A95053-61 and
A95020-70 had high levels of resistance in laboratory tests. Level of tuber resistance varied little depending on clonal lineage.
Flowers of plants with high to moderate levels of foliar resistance became severely infected in the field and greenhouse. Potato
plant parts differed in level of resistance within and between breeding lines. Plant parts were ranked from most to least susceptible
to P. infestans based on late blight severities in the field and greenhouse, in the following order: flowers, lower leaflets,
upper leaflets, tubers and stems.
Pruski, Kris. "Seed tuber storage conditions affect the tuber size in field production of two
commercial potato cultivars." [Vol. 81, No. 1, Pgs. 83-84]
Tuber size control is one of the major problems in potato varieties for processing. Processors are looking for large and uniform
tubers that could be easily utilized for chips and French fries production. The growers are also interested in relatively small, uniform
tubers for seed production. Each of the studied varieties has weaknesses related to tuber size and yield. Russet Burbank produces
a large number of tubers, often too small for processing. Shepody tends to produce a small number of large sized tubers, giving poor
yield of seed tubers. Understanding the physiological processes that control tuber number and size would allow development of
treatments/management practices to optimize tuber size in these varieties (seed use vs. processing use), thus increasing the value
of the crop to both, the grower and the processor. Also, multimillion savings in reducing unnecessary extra weight of seed tubers
associated with grading categories can be expected. Providing processors with large, uniform tubers will significantly reduce time
on sorting. This presentation provides an overview of the research work on tuber size control in Russet Burbank and Shepody
conducted at NSAC, Truro between 2000 and 2002. Detailed research data include the treatments in storage (November-May)
that were then superimposed on planting density in the field during each growing season. Emergence, stem count, total yield and yield in
size categories will be presented.
Qu, Xinshun & Barbara J. Christ. "Genetic Variation and Phylogeny of Spongospora subterranea f. sp. subterranea
Based on Ribosomal DNA Sequence Analysis." [Vol. ]
The nuclear rDNA regions of the two internal transcribed spacers (ITS1 and ITS2) and 5.8S rRNA gene from 52 field isolates of
Spongospora subterranea f. sp. subterranea obtained from the British Isles and North America were polymerase chain
reaction-amplified, sequenced, and assessed for genetic variation. Two genetically distinct groups (I and II) were identified based on the
ITS sequence diversity among the isolates, representing 34.6% and 65.4% of the isolates, respectively. British Isles isolates occurred in
groups I and II, whereas North American isolates belonged only to group II. The British Isles groups of S. subterranea were associated
with particular potato cultivars. The full-length small-subunit rRNA gene of S.subterranea was sequenced and analyzed by both
neighbor-joining and parsimony methods to clarify the taxonomic position of this pathogen. The results of phylogenetic analysis showed that
S. subterranea grouped together with other species of plasmodiphorids, and this group clustered with the phylum Cercozoa, an
assemblage of filose and reticulose amoebae and phylogenetically related zooflagellates. The recognition of the existence of different genetic
groups within S. subterranea will be important for the design of plant-breeding programs and in testing for plant resistance.
Reis, Anne H and JP Palta. "Calcium improves skin health and color of ‘Dark Red
Norland’ potato (Solanum tuberosum L.): Localization of color in intact cells." [Vol. 81, No. 1, Pg. 84]
Calcium is known to be deficient in potato tubers and research has shown that tuber quality can be improved by changing tuber
calcium levels. In season calcium applications were made to ‘Dark Red Norland’ potatoes (Solanum tuberosum L.) to
determine the effect of calcium application on color, anthocyanin concentration and visual appearance of buckskinning. In addition,
tuber periderm sections were viewed under a microscope to determine the location of anthocyanins in the periderm. Application of
calcium increased the tuber periderm calcium concentration by 10% over the control. Calcium application also increased visual color and
increased anthocyanin concentration in the periderm by 22 %. Paired measures of calcium and anthocyanin concentration were made on
individual tubers from calcium treated and control tubers to determine the relationship between tuber calcium and anthocyanins. Linear
regression analyses showed that calcium and anthocyanin concentration were positively correlated and that calcium application increased
the regression line slope by 35 %. Buckskinning was significantly reduced in calcium treated tubers after three months of storage.
Magnified periderm sections showed that anthocyanins were located in the cell sap and cell walls of healthy periderm, whereas
anthocyanins were absent and cells appeared dead in unhealthy (buckskinned) periderm. These data suggest that calcium
concentration of the periderm influences the anthocyanin concentration and visual color of ‘Dark Red Norland’ tubers; application
of supplemental calcium increases the anthocyanin content of red tuber skin; and, there is a potential for reducing the incidence
of buckskinning in red tubers by in season application of calcium.
Reyes, LF, JC Miller, Jr. and L Cisneros-Zevallos. "Environmental Conditions Influence the Content
and Yield of Anthocyanins and Total Phenolics in Purple- and Red-flesh Potatoes during Tuber Development."
[Vol. 81, No. 3, Pgs. 187-193]
Changes in content and yield of anthocyanins (ACY) and total phenolics (PHEN) during development of purple- and red-flesh potato
(Solanum tuberosum L.) were studied in cultivars grown in Texas and Colorado. In both locations, the ACY and PHEN
content (mg/100 g tissue) decreased with tuber growth and maturity, while tuber weight (kg), total yield (Ton ha-1) and compound yields
(kg ha-1) increased. Longer days and cooler temperatures in Colorado favored about a 2.5- and 1.4-fold higher ACY and PHEN content,
respectively, than in Texas-grown tubers. Harvesting potatoes at later maturity stages maximized compound yields while minimizing the
glycoalkaloid content. This information can be useful to potato breeders and producers in selecting appropriate growing conditions for the
enhancement of natural colorant and antioxidant yields in purple- and red-flesh potatoes for the nutraceutical and food industry.
Riga, E, H Mojtahedi, H Collins and J. Wilson. "Edaphic and biological factors impacting metham
sodium efficacy to control root-knot nematodes in the Pacific Northwest." [Vol. 81, No. 1, Pg. 84]
Metam sodium products including Vapam® are important tools are effective nematicides for potato growers of the Pacific Northwest
to control root-knot nematodes, Meloidogyne chitwoodi and M. hapla, and early die disease organisms, Verticillium dahliae. However,
several fields throughout the State of Washington have been identified where metham sodium products fail to control root-knot nematodes.
Extensive laboratory, greenhouse, and field studies indicated that certain edaphic factors like low soil moisture levels prior to fumigation and
high silt content may impede the performance of the metham sodium products to control root-knot nematodes population in soil profile.
Recently, we have obtained data to suggest that biological factors may also render metham sodium ineffective in soil from a ‘problem’
field. In these studies 100% M. chitwoodi survived in the ‘problem’ soil treated with Vapam. However, 100% of M. chitwoodi were
controlled when the soil ‘problem’ soil was autoclaved or pasteurized prior to Vapam application. The performance of Vapam
improved in soil samples that were previously irradiated or treated with methyl bromide. However, the residual population in these samples
was higher than the known damage threshold of M. chitwoodi. Bacterial populations were determined following each soil treatment. Total
culturable bacteria, Pseudomonas, and fluorescent Psuedomonas declined in response to autoclaving and pasteurization and showed
a significant increase following the methyl bromide treatment. The thermo-deactivation of Vapam blocking agent in this field soil suggests a
living component which is not known at this time.
Riga, E and H Collins. "The effect of combining synthetic nematicides and organic nematicides on
plant parasitic nematodes of potatoes." [Vol. 81, No. 1, Pg. 85]
The majority of nematodes in the soil are free-living, and benefit plants and soil health by contributing to decomposition and release
of nutrients. However, frequent use of nematicides can create biological voids in soil ecosystems by removing, or preventing the
establishment of beneficial free-living nematodes and other soil microorganisms that are competitors and predators of plant parasitic
nematodes. It was hypothesized that application of either organic nematicides or organic amendments preceding synthetic nematicides
may lower populations of plant parasitic nematodes, making lower rates of synthetic nematicides a viable option. The effect of Neem
Cake, DiTera, Dominator and Liquid Compost Factor (LCF) on the root knot nematodes, Meloidogyne chitwoodi, M. hapla and
the free-living beneficial nematode, Caenorhabditis elegans was evaluated in laboratory and greenhouse studies. Neem Cake,
DiTera, Dominator and LCF reduced M. chitwoodi and M. hapla, both in the laboratory and greenhouse assays while at the same time
they enhanced the free-living nematode populations. Bacterial populations were determined following each soil treatment. Total culturable
bacteria and Pseudomonas populations showed a slight increase in numbers with the addition of the biopesticides. The effect of the
organic nematicides in combination with low rates of synthetic nematicides is in progress.
Rivera-Peña, Antonio and Adolfo López Mateos. "Advances on late blight resistance factors
transference of wild species of Solanum to Solanum tuberosum L." [Vol. 81, No. 1, Pg. 85]
As the Potato is host to late blight (LB) disease, new resistance factors to counteract the pathogen damage are required.
Mexico is regarded as the center of origin of both Phytophthora infestans (Mont.)de Bary the fungus that causes
LB disease; and of wild species of Solanum (WSS) with resistance factors to LB. The work was carried out in the Toluca
Valley station-INIFAP in 2001. The modern use of WSS in Mexico as a source of resistance factors started in 1987 with Solanum
iopetalum (iop).In 1998, samples of Solanum brachycarpum (bcp) and S. hougasii (hou) were exposed
to late blight. In 1999 F1´s hybrids Alpha and Lopez (susceptible varieties)x WSS were obtained. In this study, 16 to 25 clones of
7 families of hybrids F1 with factors of bcp and hou and 8 families BC-4 and BC-5 with iop, and parents Alpha, hou and bcp
were exposed to late blight in the field. Weekly readings of LB damage were recorded. AUDPC were calculated. Statistical analysis of the
results included ANOVA and multiple range test Tukey at 0.05. Differences of AUDPC among the treatments were significant
(F test of 17.78**).This provides evidence that there were real differences among the treatment means which can be explained by
the genotype effect. Tukey test showed that means treatment of groups 6,4, and 5 performed almost similar to the wild parent
bcp, This results support the hypothesis that factors derived from hou in F1 are relatively different to those derived from
iop and bcp. Both bcp and hou showed the lowest figures determined by several genes, probably. The Transference of late
blight resistance factors from the wild species to the cultivated ones; and the use of the parameter AUDPC for screening potatoes
are discussed.
Rosen, Carl and M McNearney. "Potato yield and tuber set as affected by phosphorus
fertilization." [Vol. 81, No. 1, Pg. 85]
Relatively high rates of P fertilizer are often applied to potato even on high P testing soils. While potato yield response to P fertilizer
has been documented in the literature, specific effects on tuber set are less defined. A 2-year field study on a Hubbard loamy sand with
25-35 mg kg-1 P (Bray P1) was conducted to evaluate the effect of P fertilizer source (diammonium phosphate vs.
monoammonium phosphate) and rate (0, 35, 70 kg ha-1 P) on potato (cv. Russet Burbank) yield and quality. Phosphorus
fertilizer rate and source did not consistently affect marketable tuber yield (tubers greater than 85 g). However, P fertilizer application
regardless of source tended to increase total tuber yield and yield of tubers less than 85 g. As a consequence, the proportion of tubers
greater than 170 g decreased with P fertilizer application. Tuber number per plant in July and at harvest was higher when P was applied
compared to when P was not applied. These results suggest that under the conditions of this study, P nutrition played a role in
regulating tuber set.
Sabba, Robert P and Edward C Lulai. "Immunocytological determination of rhamnogalacturonan
and extensin cell wall polymers associated with skin-set." [Vol. 81, No. 1, Pgs. 85-86]
The susceptibility of potato tubers to excoriation (skinning injury) during harvest and handling into storage is a widespread problem
that results in costly disease, defects and shrinkage. Little is known about the processes responsible for the development of
resistance to excoriation. Recently, we identified the specific type of periderm cells and the cell wall fractures responsible for excoriation.
We are now determining the biochemical processes within these cell walls that are responsible for the development of resistance to
excoriation. Potato periderm consists of three different cell types: phellem, phellogen, and phelloderm. Changes in the phellogen cell
walls upon cessation of meristematic activity and periderm maturation are directly responsible for the development of resistance to
excoriation. Here we compare immunolabeling of the cell walls of immature and mature periderm for epitopes of the pectin
rhamnogalacturonan-I (RG-I) and the structural protein extensin. Immunolabeling with the monoclonal antibody LM5 (reactive with a
(1,4)-ß-galactan epitope found in RG-I) increases dramatically in phellogen walls upon maturation of the periderm. Labeling with
the monoclonal antibody LM6 (reactive with a (1,5)-a-L-arabinan epitope found in RG-I) does not change in phellogen walls upon
maturation of the periderm. In addition, immunolabeling with the monoclonal antibody LM1 indicates that extensin increases in these
cell walls during periderm maturation. These results identify deposition of a specific type of RG-I and extensin in phellogen cell walls
as key biochemical processes involved in the inactivation of the phellogen layer as a lateral meristem and in the development of
resistance to excoriation in potato tuber.
Sabba, Robert P and Edward C Lulai*. "Immunocytological Comparison of Native and Wound
Periderm Maturation in Potato Tuber." [Vol. 81, No. 2, Pgs. 119-124]
The maturation of potato (Solanum tuberosum L.) tuber native periderm and wound periderm, which develops to replace the
native periderm when it is damaged, are agriculturally important processes that are poorly understood. While both types of periderm form
from a phellogen layer that serves as a lateral meristem, there has been little research done on comparing the biochemical processes
and steps involved in the maturation of the two types of periderm. Here, we use immunological techniques to compare some of the cell
wall changes during wound and native periderm maturation. Consistent with our recent work on native periderm, we demonstrate that
toluidine blue O is also useful for distinguishing between suberized and non-suberized cells in wound periderm. More importantly, we
use the immunological probes JIM5 and JIM7 to show that there is no increase in either un-esterified or esterified homogalacturonan
pectin epitopes in phellogen walls accompanying wound periderm maturation. In contrast, as we previously described, native periderm
maturation and resistance to excoriation (skinning) is accompanied by an increase in relatively un-esterified and esterified
homogalacturonan pectin epitopes in the walls of phellogen cells. These results demonstrate that the biochemical processes
responsible for maturation and resistance to excoriation differ between native and wound periderm. This dissimilarity between wound
and native periderm maturation demonstrates the potential limitations in applying the wound periderm model to research on native
periderm.
Salaiz, TA and SL Love. "Seed warming and ambient temperature effects on Umatilla Russet
little-tuber syndrome." [Vol. 81, No. 1, Pg. 86]
Umatilla Russet is susceptible to little-tuber syndrome: lack of sprout formation, stolons growing from eyes, and mini-tubers growing
directly from the seed piece. This study was conducted to evaluate factors associated with incidence of little-tuber, such as seed age.
Seed warming treatments were imposed to induce aging conditions, and consisted of 35o or 40o F until
planting or 50o F for 6 weeks or 12 weeks prior to planting. Seed from each treatment was divided into 2 groups, those
with sprouts removed or those with sprouts left on the seed piece. Part of the seed was planted in the field in a RCBD with 4 replications.
Emergence was evaluated 40 days after planting (DAP), and no little-tuber symptoms were observed. Emergence was delayed by
removal of sprouts in the 50o F – 12 week treatment. After harvest, total and US No. 1 yield were evaluated. A significant
year by treatment interaction was observed for % emergence at 40 DAP and total yield. Total and US No. 1 yield were highest for the
50o F – 6 week treatment, and lowest for the 50o F – 12 week treatment. Removal of sprouts reduced
yields for the 50o F – 12 week treatment. The remainder of the seed was used in a growth chamber study that was planted
under 55o or 75o F constant ambient temperature, with 4 replications and 2 seed pieces per rep arranged
in a CRD. Emergence was evaluated daily and days to emergence calculated. At harvest, little-tuber severity was observed. A significant
year by treatment interaction was observed for days to emergence. Removing sprouts delayed emergence for both 50o
F treatments regardless of ambient temperature. Little-tuber occurred only at 55 o and severity was highest for the
50o F - 6 weeks with sprouts removed, and 50o F - 12 weeks with or without sprouts removed.
Salas, E, E Mihovilovich, W Amorós and M Bonierbale. "Estimation of variability for PLRV resistance in
tropically adapted potatoes." [Vol. 81, No. 1, Pgs. 86-87]
Potato Leaf Roll Virus (PLRV) is one of the most important diseases worldwide. The use of healthy seed may be the most
appropriate method for controlling viruses where efficient certification programs are in place, but for many developing countries the use
of resistant varieties would provide a more dependable alternative. Knowledge of heritability and genetic variances is key to the success
of population improvement. Efficient screening is crucial, and understanding of the relationships among resistance sources is important
for maintaining an adequate genetic base. An NCDII of 50 families was assembled to estimate genetic parameters of CIP’s advanced
population for the lowland tropics. Tuber families were inoculated by natural field exposure (FE) and by tuber sprout inoculation (TSI).
Secondary infection was measured by ELISA. Experiments using a RCBD with three reps were evaluated in two locations in Peru.
Genetic diversity among the progenitors was estimated with microsatellite markers. The infection rates obtained by the two exposure
methods were highly correlated, but higher percentages were achieved by TSI than FE, without sacrificing the ability to distinguish
resistant families and clones from susceptible ones. Variance components calculated in the TSI trials showed a high proportion of
additive variance and high narrow sense heritability (h2=0.69) for resistance to infection. The progenitors C93.154,
C93.156, LR93.156, LR93.160, C91.640, 92.187 and C92.140 transmitted resistance to between 40 and 80% of their progenies.
The latter two also transmitted high yield and good agronomical characteristics, having high selection indexes. Similarity
coefficients of 0.3-0.7 indicated considerable genetic diversity among the progenitors
Scott, Greg. "Back to the future? Models, maps, and global prospects for the potato."
[Vol. 81, No. 1, Pg. 87]
Recent publications have suggested that future prospects for potato production and use in such countries as India, China, and Peru
are likely to parallel historical trends for consumption of starchy staples in Europe and the United States. According to the associated
descriptive model, a country’s utilization of potato is likely to shift with economic development and changes in per capita income. As
incomes rise, consumers and countries shift away from consumption of potato toward more preferred foods. Similar parallels have
been suggested as regards the so-called “specialization” of potato production, combining descriptive analysis with detailed,
GIS-based dot maps of global and regional potato production. Drawing on historical data and a synthesis of country-level case studies, this
presentation contends that future prospects for the global potato economy are more complex than these recent publications suggest.
Seabrook, Janet EA*, L Katheryn Douglass and Deborah A Arnold. "Effect of Leaves on Microtubers
Produced from Potato Single-node Cuttings In Vitro." [Vol. 81, No. 1, Pgs. 1-5]
Microtubers are used to propagate, to store, and to transport potato clones. Culturing single-node explants from potato plantlets in
vitro without subtending leaves was reported to result in plantlets with lower vigor and a higher coefficient of variation. The effect on
microtuber production in vitro of leaf area and the presence or absence of leaves on potato single-node cuttings was investigated as
an extension of the above study. Stock plantlets of potato cvs Atlantic, Kennebec, Russet Burbank, and Shepody were cultured under
a 16-h photoperiod. Single-node cuttings were excised and grown in a high-sucrose tuberization medium in darkness. Leaf area did
not affect the frequency, size, or weight of microtubers of cvs Katahdin and Russet Burbank. The absence of leaves reduced microtuber
diameter for Russet Burbank; whereas Atlantic, Kennebec, and Shepody were unaffected. Mean fresh weight of microtubers was
reduced when leaves were removed for all cvs except Atlantic. No effect of the removal of the leaf was observed for mean dry weights
of microtubers from all cvs, although microtubers from single-node cuttings without leaves accumulated significantly more percent
dry matter than those with leaves. Rapid multiplication facilities may therefore wish to consider conserving resources such as media,
vessels, and growth room space by culturing explants without leaves for the production of microtubers.
Seabrook, Janet (Jane) EA, L Katheryn, Douglass and Deborah A Arnold. "Effect of
single-node cutting leaves on potato microtuberization." [Vol. 81, No. 1, Pg. 87]
Microtubers are an efficient way to propagate, store and transport valuable potato germplasm or clones. In a previous study, we reported
that culturing single-node explants from potato plantlets in vitro without subtending leaves resulted in plantlets with lower vigor
and a higher coefficient of variation. Plantlets derived from leafless potato cuttings in vitro were of poor quality for rapid multiplication.
The question was therefore asked – what is the effect of the leaf of a potato single-node cutting on microtuberization? Leaf area and the
presence or absence of the leaf on single-node cuttings, and subsequent effect on microtuberization were studied. Stock plantlets of
potato cvs. Atlantic, Kennebec, Russet Burbank and Shepody were cultured under in 16 h photoperiod. Single-node cuttings were excised
from the plantlets and grown in a high sucrose tuberization medium in darkness. Leaf area did not affect the number or fresh weight of
microtubers of cvs. Katahdin and Russet Burbank. The presence or absence of the leaf did not generally influence the diameter, fresh
weight or dry weight of microtubers from all cvs. Microtubers from single-node cuttings without leaves accumulated significantly more dry
matter than those with leaves. The results confirm the concept that several metabolic pathways can influence tuberization in potato, and
provided nutrient salts and a high level of sucrose are available in vitro, leaves are not necessary for microtuberization. Rapid
multiplication facilities can therefore consider saving on culture room space and resources by removing the leaves from potato single-node
cuttings in vitro when producing microtubers.
Secor, Gary A, Neil C Gudmestad and Robert Suranyi. "Fungicide compatibility with Aphoil for late
blight control." [Vol. 81, No. 1, Pgs. 87-88]
Two of the most serious diseases of potato in recent years have been late blight, caused by Phytophthora infestans, and
mosaic, caused by potato virus Y (PVY). Both of these diseases have been difficult to control. In-field control of late blight requires repeated
application of fungicides. Insecticide applications are not effective for PVY control because transmission of this stylet-borne virus occurs
before the insecticide can act against the vector. Crop oils have been shown to be effective in reducing spread of stylet-borne viruses such
as PVY by 40-60%. Most fungicides are applied as water soluble suspensions, in contrast with crop oils applied as aphicides. Because
both of these applications frequently occur at the same time during the growing season, and producers often combine fungicides and
insecticide application to save money, it was of interest to us to determine the compatibility of these products. Eight fungicides commonly
used for late blight control were applied full season alone or tank-mixed with Aphoil, a crop oil commonly used in our area. The trial was
conducted in 2001 and 2002 using the cultivar Norvalley inoculated with late blight prior to the first treatment application. Treatments
were applied eight times during the growing season. Combined results showed that the RAUDPC of all fungicide treatments for late
blight was not significantly reduced or enhanced by the addition of Aphoil. The efficacy of Dithane was numerically reduced, and the
efficacy of Acrobat was numerically enhanced, by the addition of Aphoil. It is concluded that Aphoil can be tank-mixed with commonly
used fungicides for late blight control without adversely affecting efficacy of the fungicide.
Shepherd, C, N McKinley, J Harbour, M Holm, M Martin, D Ganske and C Kral. "Potato disease
control with a new premix fungicide containing famoxadone and cymoxanil." [Vol. 81, No. 1, Pg. 88]
Tanos™, a mixture of Famoxate™ (famoxadone) and cymoxanil, is a new fungicide for U. S. potato growers. Tanos™
controls both potato early blight (Alternaria solani) and late blight (Phytophthora infestans). It effectively controls strains of
A. solani with reduced sensitivity to chlorothalonil and strains of P. infestans resistant to phenylamide fungicides.
Tanos™ has long-lasting preventive activity with outstanding resistance to washoff. Tanos™ also provides post-infection, local
systemic control of late blight and excellent control of both foliar blight and stem blight. The wettable granule formulation is convenient and
effective when applied by ground, air or chemigation equipment. A disease management program including Tanos™ in combination
or alternation with other contact fungicides increases the range of useful fungicide attributes and reduces the risk of resistance development.
Shock, Cedric A Clinton, C Shock, Lamont D Saunders, Lynn B Jensen, Kerry Locke, Steven R James,
Harry L Carlson, Donald W Kirby and Brian A Charlton. "Evaluation of the Wallin model for regional predictions of potato late blight
in semi-arid regions of Oregon." [Vol. 81, No. 1, Pg. 88]
Potato late blight (Phytophthora infestans) epidemics have occurred during the last decade in arid parts of eastern Oregon where
it was previously unknown. Weather data were collected at regional stations in the potato (Solanum tuberosum L.) canopy of selected
fields and off-site weather stations from 1995 to 2002. The data was used to evaluate the Wallin model for predicting the spread of potato
late blight in the arid environments in Oregon. The model was tested against both in-field and off-site data for regional late blight predictions.
The Wallin model used with in-field, in-canopy weather observations successfully provided advanced warning of potato late blight outbreaks.
Off-site, out of field weather data did not mirror the conditions in the potato canopy, and when off site weather data was used, the Wallin model
failed to predict late blight outbreaks.
Silva, Erin M, AJ Hamernik and PW Simon. "Evaluation of the Maillard-reaction related compounds in wild
X cultivated species crosses at harvest, after storage, and after reconditioning." [Vol. 81, No. 1, Pg. 88]
The potato processing industry uses a significant portion of the potatoes grown in the US. The ability of the tubers to fry to a light color
and the ability to recondition (metabolize reducing sugars upon warming) are among the most important considerations in the breeding
for chipping potato and French fries. Breeding projects have also focused on selection of tubers that can be stored at low temperatures
(less than 7°C) with minimal reconditioning which would ultimately lead to less disease and shrinkage of the crop in storage. Hanneman
and Hamernik have crossed wild species including Solanum raphanifolium, S. chacoense, S. tarijense, S. phureja,
and S. sparsipilum to cultivated potato and selected progeny that exhibit light chip color directly out of cold storage. We evaluated the
reducing sugar, sucrose, amino acid, starch, and phytate content of these 2X progeny to determine the relationship of these variables to
chip color. We will identify unique alleles using a candidate gene approach in these species that modify the carbohydrate and/or amino \
acid pathways thus leading to better chipping characteristics.
Simko, Ivan, S Costanzo, KG Haynes, BJ Christ and RW Jones. "Linkage disequilibrium mapping of a
Verticillium dahliae resistance QTL in tetraploid potato (Solanum tuberosum) through a candidate gene approach."
[Vol. 81, No. 1, Pgs. 88-89]
We have used the linkage disequilibrium mapping method combined with a candidate gene approach to detect a QTL for resistance
to Verticillium dahliae in tetraploid potato. The tomato Verticillium resistance gene (Ve1) was selected to develop an RFLP
probe that identified homologous sequences (StVe1) in potato. In a diploid mapping population all the StVe1 homologues
map to a single location on chromosome 9, at a position analogous with that of the tomato Ve1 resistance gene. Microsatellite
STM1051 that is closely linked (1.5 cM) to the StVe1 at the diploid level served as a candidate gene marker to screen 139 tetraploid
potato genotypes. A highly significant association (p < 0.001) between the microsatellite marker and the resistant potato phenotype
was observed. The amount of phenotypic variance in resistance explained by the STM1051-193 allele was greater than 25% in
one of two subpopulations inferred from a coancestry data matrix. Cloning of the StVe1 homologues from highly resistant cv. Reddale
indicates that the resistance QTL is part of at least an eleven-member family that encodes plant-specific leucine-rich repeat proteins, highly
similar to the tomato Ve genes. All sequenced StVe1 homologues were found to be uninterrupted open reading frames and
thus represent putative functional resistance genes. This is the first time that the linkage disequilibrium method has been used to
detect a functional gene in tetraploid species. We have shown that it is possible to map QTL directly on already available potato cultivars
without developing a new mapping population.
Skoneczka, Jeff and RE Veilleux. "Effects of gametogenesis on transgenic Cry3Aa expression in
F1 generations of cultivated potato hybrids." [Vol. 81, No. 1, Pg. 89]
Transgenic resistance to plant pathogens and insect pests, although temporarily on hold for potato for political reasons, offers promise
for the future of both asexually and sexually propagated potato. If a system incorporating true potato seed (TPS) and transgenic resistance is
to be employed, we need to understand the influences imposed on transgene expression during and after gametogenesis. Gene silencing
is an epigenetic phenomenon affecting transgene expression that may be influenced by the parent-of-origin of a transgene. Using ELISA to
determine transgene expression in reciprocal crosses of tetraploid potato lines, one of which carried the Cry3Aa gene as a single insert, we
found that overall expression levels of progeny bearing the transgene did not dramatically differ. However, in crosses between transgenic
Atlantic and wild type Katahdin, the ratio of expressors to nonexpressors varied significantly between reciprocals and differed significantly
from the expected 1:1 segregation expected. Furthermore, an overabundance of transgenic progeny when the Cry3Aa gene was
maternally inherited suggests differential gametic selection or an epigenic effect on transgene expression during megagametogenesis
and/or pollination and fertilization.
Sowokinos, Joe, Irene Shea, Vladimir Vigdorovich and Mitch Abrahamsen. "Sequence anomalies
of UDP-glucose pyrophosphorylase cDNAs between potatoes sensitive or resistant to cold-induced sweetening (CIS)."
[Vol. 81, No. 1, Pgs. 89-90]
Previous investigations have identified two UGPase-cDNAs in potatoes designated UgpA and UgpB. Both cDNAs contained
1,431 bp and coded for polypeptides of 477 amino acids. UGPase is a single copy gene per haploid genome of potato and most tetraploid
potatoes examined have demonstrated distinct allelic ratios of UgpA/UgpB (i.e., 4:0, 3:1, 2:2, 1:3, 0:4). An attempt was made to
isolate new UGPase-alleles from a number of potato cultivars (i.e., Snowden, ND-860-2, Russet Burbank, Norchip, Redsen and Belrus) that
demonstrate either cold-resistance (CR) or cold-sensitivity (CS) to sweetening and to compare their sequences and restriction maps to those
cDNA’s previously described. Primers were designed so that the entire ORF of the UGPase-cDNA could be cloned. TOPO-TA cloning
was used to ligate all PCR products into the thymidinated vector pCR-2.1. Sequencing was conducted on a ABI 377 machine using Lasergene
software (DNAstar, Inc.). Primer walking was done from both sides of the insert (i.e., both directions) to check that the proper base sequence
was obtained. At least six new cDNAs were identified and registered in GenBank. Of the 26 bp differences between the CS and CR cDNAs,
only five led to an amino acid (aa) changes in the encoded polypeptide. These five bp changes co-segregated along with the BamH1
site that was present only in the CS potato cultivars. Examination of the deduced aa sequence of each polypeptide revealed the presence
of glucosyl and 14-3-3 protein binding sites.
Sterrett, SB, GC Yencho, MR Henninger and KG Haynes. "Internal heat necrosis resistant potato
clones have higher tuber concentrations of magnesium, sulfur, manganese, and calcium, and lower tuber concentrations of potassium than
susceptible clones in the mid-Atlantic states." [Vol. 81, No. 1, Pg. 90]
Internal heat necrosis (IHN) is a physiological disorder that results in necrotic tissue forming in the pith of potato tubers. Low levels of
tuber calcium are thought to play a role in susceptibility to IHN. Studies were conducted in VA, NC, and NJ in 2001 and 2002 to determine
the influence of soil-applied calcium on the expression of IHN and on tuber calcium concentration. Interspecific 4x-2x S. tuberosum x
S. phureja-S. stenotomum hybrids, previously identified as resistant or susceptible to IHN, were planted with and without calcium
sulfate (448 kg ha-1 Ca) applied in furrow over the seed-pieces. Yield, size distribution, specific gravity (sg), susceptibility to
IHN (% ihn), severity of IHN (hnrate), and tuber concentrations of S, P, K, Mg, Ca, Na, Zn, Mn, Fe, Cu, and Al were determined from all
site-years. There were significant differences among the clones for yield, sg, % ihn, hnrate, P, and Mg at all six site-years; for S, K, and
Zn at five site-years; and, for Mn and Ca at four site-years. In those site-years with significant differences among clones, the IHN resistant
clones had significantly higher tuber concentrations of Mg, S, Mn, and Ca and lower concentrations of P than the susceptible clones.
These results suggest that there may be factors in addition to Ca that are important in the expression of IHN.
Sun, Mike, Susan Siemsen, William Campbell, Bob Simas, Robert Davidson, Jonathan L Whitworth, Terry
Bourgoin, Jeff Axford, Willem Schrage, Gary Leever, Alan Westra, Steve Marquardt, Hossien El-Nashaar, Jeff McMorran, Oscar Gutbrod,
Tom Wessels and Robert Coltman. "Survey of Potato Spindle Tuber Viroid in Seed Potato Growing Areas of the United States."
[Vol. 81, No. 3, Pgs. 227-231] [Short Communication]
Fourteen United States (U.S.) seed potato certification agencies surveyed all U.S. seed potato growing areas for presence of the potato
spindle tuber viroid (PSTVd). The survey included general surveillance, which involved searching for the occurrence of PSTVd in state seed
potato certification records from 1990 through 2000, and a field survey, which involved testing selected crops for PSTVd infection by nucleic
acid dot blot hybridization during 1999 through 2001. No PSTVd incident was documented in any of the state certification records, nor was
PSTVd detected in the field surveys. All U.S. seed-growing areas were determined to be free of PSTVd. It is concluded that PSTVd has been
eradicated and freedom from potato spindle tuber viroid has been successfully maintained in all of the seed potato growing areas in the
United States.
Suttle, Jeffrey C. "Regulation of tuber dormancy." [Vol. 81, No. 1, Pg. 90]
At harvest and for an indeterminate time thereafter, potato tubers are dormant and will not sprout. The length of dormancy is dependent
on both tuber genotype and environmental conditions during tuber development and storage. Uncontrolled postharvest sprouting results
in numerous physiological changes that adversely affect tuber quality and market value. Improvements in postharvest sprout control
technology is hindered by ignorance of the biological bases of tuber dormancy. Tuber dormancy is characterized by low rates of many
metabolic processes and by the near-complete absence of bud or eye meristematic activity. Non-dividing cells in tuber bud meristems
are arrested in the G-1 phase of the cell cycle prior to DNA replication. The resumption of cell division at the end of dormancy is
accompanied by numerous changes in chromatin composition, gene expression and increased DNA synthesis. Although widely
believed to play a role in tuber dormancy, the exact roles of endogenous plant hormones in tuber dormancy control are only now
being experimentally verified. The sustained synthesis and action of abscisic acid (ABA) are required for both the initiation and
maintenance of tuber dormancy. In addition, ethylene action is required during the earliest stages of dormancy inception. Although
both ABA levels and ethylene production decline during storage, these declines are not essential for dormancy termination. Increases
in both cytokinins and gibberellins occur as dormancy weakens and sprouting commences. Recent evidence suggests that only the
increase in cytokinin content is required for the termination of tuber dormancy; while the increase in gibberellin content is important
in subsequent sprout growth. Manipulation of plant hormone systems offers unique possibilities for postharvest sprout control.
For example, treatment of dormant tubers with stable cytokinin analogs rapidly terminates tuber dormancy and may be of use in the
seed industry. Conversely, manipulation of ABA and other dormancy-inducing hormones may offer novel methods to prevent
postharvest sprouting.
Suttle, Jeffrey C. "Physiological Regulation of Potato Tuber Dormancy." [Vol. 81, No. 4, Pgs 263-274]
This paper was originally presented as part of a symposium entitled “Recent Advances in the Physiology of Tuberization and Tuber
Dormancy.” The symposium was held on 11 August 2003, by the Potato Association of America, in Spokane, WA.
At harvest, potato (Solanum tuberosum L.) tubers are dormant and will not sprout. As the period of postharvest storage is extended,
tuber dormancy is broken and sprout growth commences. The loss of tuber dormancy and onset of sprout growth is accompanied by
numerous biochemical changes, many of which are detrimental to the nutritional and processing qualities of potatoes. Endogenous
hormones have been proposed to play a significant role in tuber dormancy regulation. The involvement of all major classes of endogenous
hormones in tuber dormancy is reviewed. Based on available evidence, it is concluded that both ABA and ethylene are required for dormancy
induction, but only ABA is needed to maintain bud dormancy. An increase in cytokinin sensitivity and content appear to be the principal factors
leading to the loss of dormancy. Changes in endogenous IAA and GA content appear to be more closely related to the regulation of
subsequent sprout growth.
Taylor, Raymond J and Neil C Gudmestad. "Influence of tillage and method of metam sodium
application on distribution and survival of Verticillium dahliae in soil." [Vol. 81, No. 1, Pgs. 90-91]
The effect of plowing and deep-rip tillage, in combination with chemigation or shank fumigation of metam sodium, on V. dahliae
populations was assessed. Soil samples (0-10 cm; 10-20 cm depths) were collected before tillage, after tillage and after chemical
application. Propagules of V. dahliae were detected at 142 of 143 sites sampled prior to tillage. Most (76.9% in heavy, sandy
loam; 63.1% in light, loamy sand) were concentrated in upper 10 cm. In the heavy soil, the propagule ratio (upper : lower strata) decreased
from 3.3 : 1 to 1.2 : 1 after plowing, but remained essentially unchanged (2.9 : 1 vs. 2.5 : 1) following deep-rip tillage. Plowing also
redistributed inoculum into the subsurface strata (10-20 cm depth) in the lighter soil, reducing the ratio from 1.7 : 1 to 0.78 : 1. Vertical
redistribution was not observed with deep-ripping, as pre- and post-tillage ratios were 1.7 : 1 and 1.8 : 1, respectively. Plowing, followed
by chemigation, reduced the V. dahliae population in the upper strata of heavy soil by 20% but was ineffective at the lower depth.
Chemigation after deep-rip tillage reduced the inoculum load in the upper 10 cm of soil by 36% and the lower 10 cm by 60% in the heavy
soil. Neither of the previous two treatments was effective in the lighter soil. Fumigation had the greatest impact in the lower soil layer.
Shanking at 10 cm and 25 cm reduced inoculum by 57% in the heavy soil and 67% in the lighter soil. Inoculum was reduced by 81% and
75% at these sites when fumigated at 15 cm and 30 cm. Fumigation at 10 cm and 25 cm after deep-rip tillage reduced the level of
inoculum in the upper strata but the magnitude was not as great as at the plowed sites whereas fumigation at 15 cm and 30 cm was
ineffective.
Thomas, PE, Kiyoko Richards and Stacy Oberding. "Endemic survival of potato viruses in the
Columbia Basin." [Vol. 81, No. 1, Pg. 91]
Potential strategies for control and eradication of viruses in a region are often dependent on the overwintering sources of inoculum.
We conducted numerous studies to determine whether potato viruses A, M, S, Y, or leafroll overwinter in weeds or winter crops in the
Columbia Basin of Northwest USA. Overwintering weed and crop species in the region were assessed for susceptibility to the viruses
a greenhouse. Winter weeds and crops found growing in the proximity of virus-infected grower plantings or in experimental field plots
were assessed for virus infection. Green peach aphids (Myzus persicae) overwintering on winter weeds were assessed for virus
infectivity. Hosts of potato viruses were exposed to natural infection in areas that once produced potatoes but are now remote from potato
production. Summer annual weed hosts of potato viruses found growing in the same remote regions were assessed for virus infection
in the fall. Only potato leafroll virus infected any winter surviving weed or crop species. It infected Capsella bursa-pastoris and
Sisymbrium altissimum in the greenhouse but was not found overwintering in these species except rarely in field plots where that
had undergone severe field exposure late in the fall. In one instance, PLRV was transmitted by aphids collected from overwintering,
virus-free Malva neglecta in December. However, neither leafroll or any other potato virus ever infected any plant exposed in
regions remote from potato production. These results indicate that survival of potato viruses in the Columbia Basin may be entirely
dependent on the potato crop. Thus, eradication and control of the viruses studied may be possible by elimination of volunteers
and of viruses from potato seed.
Thomas, PE., BC Kirkpatrick, GL Reed and JM Crosslin. "Association of the beet
leafhopper-transmitted viresence agent with the potato yellows disease epidemic of 2002." [Vol. 81, No. 1,
Pgs. 91-92]
A serious epidemic of a yellows type disease of potato occurred in the Columbia Basin in 2002. The symptoms resembled those
caused by the beet leafhopper-transmitted viresence agent (BLTVA) and those of psyllid yellows. Plants in affected fields either
expressed distinct symptoms or expressed no symptoms. Among 20 symptomatic field plants started as cuttings in a greenhouse,
17 survived, and none assayed positively for phytoplasmas using PCR primers that detect a broad spectrum of phytoplasmas.
Asymptomatic plants from the same field also assayed negative. However, using a nested PCR procedure specific for BLTVA, 12 of
the 17 original DNA samples assayed positively. By this time only three of the five cuttings that assayed negatively by nested PCR
remained alive in the greenhouse. A second set of DNA extracts from these were all PCR-positive by the nested procedure. Plants
generated in the greenhouse from tubers of the 20 symptomatic and 20 asymptomatic plants were all free of the yellows symptoms,
and all assayed negatively for BLTVA. Three of the plants assayed positively for potato leafroll virus and one was positive for PVY strain N.
All assayed negatively for beet curly top virus (BCTV) and for potato viruses A, M, S, and X. Transmission studies are underway to further
confirm a BLTVA etiology of the disease using the beet leafhopper (Circulifer tennelus). A high incidence of beet curly top
virus (BCTV), also vectored by the beet leafhopper, occurred in the region concurrent with the potato yellows disease. This fact
confirms that high BLTVA vector populations were present in this region during 2002.
Thompson, Asunta, B Farnsworth, H Hatterman-Valenti and P. Mayland. "Screening potato
genotypes for resistance to the sugar end disorder." [Vol. 81, No. 1, Pg. 92]
The complexion of the potato industry in North Dakota and Minnesota has changed in the last 10-15 years; about 60% of production
is now processed for french fries and frozen processed products. Recently, producers have been plagued with sugar ends, a serious
defect to french fry quality. Tubers with the physiological disorder exhibit one end with relatively low starch and high sugar content,
compared to carbohydrate distribution within non-stressed tubers. A superior cultivar, resistant to sugar end formation, may be the
best solution to the problem. In 2002, an investigation was initiated to assess resistance in genotypes utilized in the breeding program
at NDSU. Forty-six advanced selections and cultivars were grown in a replicated trial at Tappen, ND. A stress treatment was applied by
withholding irrigation during early tuber bulking to simulate heat and water stress, attributing factors associated with the disorder. Tubers
from stressed and non-stressed treatments were stored at 7.2C for 8 weeks, fried, and rated for fry color, percent sugar ends, and sugar
end color, based on the 000 to 4 rating scale. Mean fry color was 1.92 across treatments, not statistically different for treatments.
Percent sugar ends ranged from 0 to 100 for clones, with a mean of 26.8% across treatments. Stressed and non-stressed treatments
were significantly different, 19.2 and 34.4%, respectively. Sugar end fry color was significantly different for stressed (2.7) and
non-stressed (2.3) treatments. Umatilla Russet and five advanced selections exhibited no sugar ends in the trial. Eight selections and
Russet Burbank averaged 50% or more sugar ends across treatments. Results are being utilized in parental selection and breeding
for resistance.
Thornton, MK and JC Wallace. "Influence of fumigation with Vapam on chipping potato yield,
size and internal quality in Nebraska." [Vol. 81, No. 1, Pg. 92]
Previous research has shown that fumigation with metam sodium products such as Vapam generally increases potato tuber yield
and quality. Most of this research has been conducted on late-maturing varieties such as Russet Burbank in Idaho, Washington or
Wisconsin. Very little is known about the impact of fumigation on chipping potato varieties grown outside of these regions. A replicated trial
to evaluate the affect of Vapam rate on yield and quality of two chipping potato varieties was conducted on a commercial farm in Nebraska.
The field had been previously cropped to potatoes 3 times, but had a relatively high population of Verticillium (20 ppg) and moderate root
lesion nematode levels. Vapam was applied by chemigation to the top 12 inches of soil at rates of 0, 20, 30 and 40 gal/ac. Fumigation
with Vapam significantly increased total and marketable tuber yields, with optimum yields occurring at the 30 gal/ac rate. Averaged across
both varieties, marketable yields were 90 cwt/ac higher after fumigation at 30 gal/ac compared to the non-treated check. Tuber solids and
tuber number per plant also increased following fumigation. Internal tuber defects due to vascular discoloration were significantly reduced
at all Vapam rates for one of the varieties, but only at the 20 gal/ac rate in the other variety. These results were compared to those measured
from split fields on the same farm where a section was treated at 38 to 40 gal/ac and a section was not treated. Averaged across three
locations and three chipping varieties, Vapam increased marketable yield by108 cwt/ac, increased solids by 0.7% and reduced tuber
defects by 5%.
Tombolato, Denise and DP Weingartner. "Historical perspectives on late blight in Florida."
[Vol. 81, No. 1, Pgs. 92-93]
Late blight caused by Phytophthora infestans has been a problem in Florida potatoes since the late 1800’s when the crop
was first grown in the state. Severity of the disease was greatly diminished in the 1940’s with the use of ethylenebisdithiocarbamate
fungicides (EBDC’s); and, following the introduction of metalaxyl in the early 1980’s, was essentially a nonproblem until the
arrival of new metalaxyl resistant genotypes of P. infestans in1993. The disease has occurred in either potato or tomato each year
since 1993. Infected seed potatoes were long considered as the most important primary inoculum source for late blight in Florida. Recent
anecdotal observations suggest that over seasoning inoculum can also survive in home gardens, fall potato crops, and potato and tomato
volunteers, and over summering cull piles. Bell pepper (Capsicum annum), petunia (Petunia hybrida), egg plant
(Solanum melongena), cutleaf ground cherry (Physalis angulata)(CLGC), American black nightshade (S. americanum)
(ABNS), tropical soda apple (S. varium), jimsonweed (Datura stramonium), morning glory (Ipomea sp.), potato
(Solanum tuberosum), and tomato (Lycopersicon esculentum) were investigated as potential alternative and/or over seasoning
hosts in excised leaf tests using isolates of P. infestans US-1, 8, 11, and 17. Isolates sporulated on potato, tomato, eggplant, pepper,
CLGC, ABNS, petunia, and jimson weed, but most consistently on ABNS. Transfers of US-1, 8, and 11 from ABNS sporulated on petunia,
ABNS, and to a lesser degree on jimson weed. The potential of petunia and ABNS as alternative hosts of P. infestans in Florida merits
further study.
Topley, HL, G Wang-Pruski and G Sun. "Identification of genes and gene-markers related to
after-cooking darkening in French-fry potatoes using cDNA-AFLP." [Vol. 81, No. 1, Pg. 93]
One of the most widespread undesirable traits affecting potato tuber quality (Solanum tuberosum L.) is after-cooking darkening
(ACD). The grayish darkening is caused by the oxidation of a ferrous chlorogenic acid complex, which forms during cooking. ACD has a
negative effect on the marketability of both processed and table stock potatoes. The degree of ACD is genetically controlled and strongly
influenced by environmental conditions. Some potato varieties are more resistant to ACD than others; however there have been no
varieties developed which have a low degree of ACD as well as the desired processing qualities. To date there are no genes or gene
markers which are known to be related to ACD. Our previous study has shown that the degree of ACD in potatoes is correlated with the
length of tuber storage. In this study we further identified genes that are differential expressed in potato tubers during eight months of
storage. Monthly evaluation of cooked tubers of Russet Burbank was carried out using digital-imaging analysis procedures.
Concurrently, the cDNA-amplified fragment length polymorphism (cDNA-AFLP) method of RNA fingerprinting was used to detect
differentially expressed transcripts during the storage period. Minimal cDNA-AFLP fingerprint variation was observed upon comparison
of the monthly samples. However, we have identified 20 transcript-derived fragments (TDFs) whose gene expression are activated or
inactivated, up-regulated or down-regulated. Transcriptional analyses using Northern hybridization confirmed the differential expression
profile of genes corresponding to the polymorphic TDFs.
Tsror (Lahkim), Leah and Itzahk Peretz-Alon. "Control of Silver Scurf on Potato by Dusting or Spraying Seed Tubers
with Fungicides Before Planting." [Vol. 81, No. 4, Pgs. 291-294]
[Short Communication]
Silver scurf of potato caused by Helminthosporium solani Dur. & Mont. is a blemish disease that has become economically
important in recent years and is considered primarily seedborne. The objective of the present study was to compare the effectiveness of
various fungicides, alone or in combination, applied to seed tubers prior to planting, in controlling silver scurf on the daughter tubers.
Disease incidence and severity were significantly reduced by all treatments in three experimental locations, with the exception of fluazinam,
which was not effective. Among the fungicides tested in these experiments, the most effective were fludioxonil and prochlorazn applied as
a LV spray (control efficiency of 88% and 82%, respectively) and propineb and mancidan applied as a dust treatment (control efficiency of
78% and 77%, respectively). Azoxystrobin and imazalil treatments were less effective with control efficiencies of 68% and 43%, respectively.
None of the various treatments affected crop yields in the three experimental sites.
Valluru, R, BJ Christ and KG Haynes. "Inheritance of resistance to Fusarium tuber rot in
potatoes." [Vol. 81, No. 1, Pg. 93]
Fusarium tuber rot of potato is one of the most economically important diseases of stored potatoes. The objective of this
study was to determine the inheritance of resistance to Fusarium tuber rot. A highly resistant (B0172-22) and a highly susceptible
(B0178-34) potato clone were crossed as female parents with two male parents. Tubers from varying numbers of progeny
(28-37) from these four crosses were inoculated with Fusarium sambucinum in the laboratory. Three tubers from each
progeny were inoculated at approximately monthly intervals six times in each of two years. The depth and the diameter of the lesion were
measured 40 days after inoculation. Estimates of broad-sense heritability for lesion depth and a 95% confidence interval about
these estimates were similar in 2000 and 2001: 0.84 (0.84, 0.91) and 0.77 (0.77, 0.87), respectively, as were the estimates for lesion
diameter: 0.83 (0.83, 0.90) and 0.80 (0.80, 0.89), respectively. General combining ability for lesion depth for the female parents was
significant in 2001, but not in 2000. General combining ability for lesion diameter for the female parents and the male parents was
significant both years. There was no specific combining ability for either lesion depth or lesion diameter. There were significant
differences among clones in each of these four families for both traits both years. These results indicate that resistance to
Fusarium dry rot is a heritable trait with a substantial additive genetic component. They also indicate lesion diameter is more
informative for evaluating resistance than lesion depth.
Vega, Sandra E, Alfonso H del Rio, John B Bamberg and Jiwan P Palta. "Evidence for the Up-regulation
of Stearoyl-ACP (^ 9) Desaturase Gene Expression during Cold Acclimation." [Vol. 81, No. 2, Pgs. 125-135]
Our previous studies demonstrated that an increase in 18:2 (linoleate) in the purified plasma membrane fraction during cold acclimation
is associated with genetic variations in cold acclimation capacity. This increase was found only in genotypes that are able to cold acclimate
and was reversible on deacclimation suggesting a link between the accumulation of 18:2 and acquisition of freezing tolerance. The present
study was aimed at understanding the association between the induction of stearoyl-ACP (acyl carrier protein) (^ 9) desaturase and
the ability to cold acclimate. Our approach was to study the induction of ^ 9 desaturase at the transcript level using potato ^
9 desaturase gene-specific primers and reverse transcription polymerase chain reaction (RT-PCR). For this purpose, total RNA from
Solanum tuberosum (cold sensitive, unable to acclimate) and Solanum commersonii (cold tolerant, able to cold acclimate)
was extracted before and after cold acclimation. RT-PCR produced a single band and sequence analysis confirmed that the amplified band
was ^ 9 desaturase. While the cold acclimating species, Solanum commersonii, exhibited an increase in ^ 9
desaturase transcript levels after cold acclimation, the cold non-acclimating species, Solanum tuberosum, exhibited no change.
Our results show that the increase in ^ 9 desaturase gene transcripts during cold acclimation is associated with the cold
acclimation response in potato.
Vreugdenhil, Dick. "Is tuber sprouting the reverse of tuber initiation?"
[Vol. 81, No. 1, Pgs. 93-94]
Tuber formation comprises a switch in the direction of growth of the stolon, viz., from longitudinal to radial. When a tuber
sprouts, an elongated structure (the sprout) forms from the swollen organ. This raises the question: is the regulation of tuber
sprouting (partly or completely) the reverse of the regulation of tuber initiation? A positive answer to this question is suggested by
observations that environmental factors unfavorable for tuber initiation, such as high temperatures, often lead to premature sprouting.
To examine other possible parallels, we decided to compare in more detail physiological processes occurring during tuber initiation
and sprouting. All classes of hormones have been studied in relation to both tuber initiation and sprouting, although by different research
groups with different experimental systems. It is clear that gibberellins play important roles during both tuber formation and sprouting:
their levels decrease under tuber-inducing conditions and increase before or during sprouting. For the other classes of hormones,
the picture is less clear. Several studies have shown that the expression of a range of genes changes upon tuber initiation,
e.g., patatin, AGPase, sucrose synthase, and lipoxygenase. Much less research has been done on gene expression during tuber
sprouting. We have analyzed expression of several classes of genes using a non-destructive in vivo method, viz., transgenic
plants carrying the promoter of the gene of interest fused to fire-fly luciferase. Overall expression of AGPase (a key gene in starch
biosynthesis) and cycB1;1 (a cell cycle related gene) was induced upon tuber initiation, and reduced during sprouting, supporting the
‘reversion hypothesis’. However, more detailed analysis revealed that both cycB1;1 and AGPase expression increased in/around the
apical bud during sprouting. Other evidence also pointed towards differential gene expression in storage tissue as compared to the buds.
Carbohydrate metabolism changes during tuber initiation, concomitant with the massive accumulation of starch. Levels of glucose
and fructose decrease, invertase activity decreases, and sucrose synthase and AGPase activities increase. During the dormant period,
activities of most enzymes are relatively low. Before sprouting, not many changes in enzyme activities were observed, except for
AGPase—which surprisingly increased around the apical bud before visible sprouting. The simultaneous presence of amylases
and starch synthesizing enzymes points towards the existence of futile metabolic cycles, i.e., the simultaneous synthesis
and degradation of metabolites. From this and other evidence, we concluded that during tuber initiation and tuber sprouting
similar metabolic pathways are used, but with net fluxes in opposite direction. The regulation of the fluxes through these
pathways is only partly understood. It is concluded that the question, asked in the title, should only partly be answered by ‘yes.’
Vreugdenhil, Dick. "Comparing Potato Tuberization and Sprouting: Opposite Phenomena?"
[Vol. 81, No. 4, Pgs. 275-280]
This paper was originally presented as part of a symposium entitled “Recent Advances in the Physiology of Tuberization and Tuber
Dormancy.” The symposium was held on 11 August 2003, by the Potato Association of America, in Spokane, WA.
The regulation of tuber formation and tuber sprouting are compared. As a starting point it is hypothesized that these two phenomena are
opposite to each other. This idea is tested from three points of view: hormonal regulation, gene expression, and carbohydrate metabolism.
It is concluded that there is only limited evidence to support the hypothesis. On the contrary, several examples are given indicating that
similar mechanisms might be operative during tuber formation and tuber sprouting.
Wang, Qingbin and Wei Zhang. "China’s Potato Industry and Potential Impacts on the Global
Market." [Vol. 81, No. 2, Pgs. 101-109]
While China has been the world’s largest potato producer since 1993 and accounted for more than 80% of the increase in global potato
production from 1990 to 2002, few studies have analyzed the remarkable growth in China’s potato industry and its potential impacts on the
global market. This paper reviews the development and growth of China’s potato industry since 1961, especially since the economic reforms
started in 1978, identifies major factors that have contributed to the dramatic growth in China’s potato production in the past two decades,
examines the trends of China’s potato production and consumption, and discusses the potential impacts of China’s potato industry on the
global market. Results suggest that China’s ongoing transitions in economic system and food-consumption patterns will contribute to
further growth in its potato market and China’s potato output may reach 71 mmt in 2006 and 81 mmt in 2010. Furthermore, China as the
world’s largest potato producer and a new member of the World Trade Organization (WTO) will play an increasing role in the global market
of potatoes and potato products.
Wang-Pruski, Gefu and Jerzy Nowak. "Potato After-Cooking Darkening."
[Vol. 81, No. 1, Pgs. 7-16]
After-cooking darkening (ACD) is one of the most widespread, undesirable characteristics of cultivated potato. With the current
expansion of the potato-processing industry around the world, there is a renewed interest in the development of new ways to prevent
ACD. After-cooking darkening is caused by the oxidation of the ferri-chlorogenic acid in the boiled or fried potatoes. The severity of the
darkening is dependent on the ratio of chlorogenic acid to citric acid concentrations in the potato tubers. Higher ratio normally results in
darker tubers. The concentration of the chlorogenic and citric acids is genetically controlled and influenced by environmental conditions.
This paper outlines the history of ACD and current status of knowledge of the chemistry of the dark pigment formation and its genetic
and environmental determinants. Also discussed are the methods of chemical prevention of ACD presently used by the potato-processing
industry and potential strategies for reducing tuber after cooking darkening using molecular approaches.
Wang-Pruski, Gefu "Potato after-cooking darkening and its genetic and environmental
controls." [Vol. 81, No. 1, Pg. 94]
After-cooking darkening is one of the most widespread, undesirable characteristics of cultivated potato. It occurs after the tubers are
cooked, including boiling, steaming and frying. The color development is dependent on the oxidation of the chlorogenic acid-iron complex.
During cooking, a ferrous-chlorogenic acid complex is formed. When the cooked tubers are exposed to air, this complex is oxidized,
resulting in the formation of ferri-dichlorogenic acid, a bluish-gray compound. After-cooking darkening reaction is a non-enzymatic
oxidation reaction. Its genetic control and environmental response is independent from other tuber quality defects, such as browning,
bruising, and blackspot formation. It is generally accepted that after-cooking darkening is genetically controlled and influenced by
environmental factors. However, little is known about its controlled mechanisms. This presentation provides an overview of the
investigation of after-cooking darkening at genetic, physiological, and agronomic levels. Detailed research data include the development
of the diploid clones for genetic mapping; cloning of genes related to after-cooking darkening; and environmental effects on
after-cooking darkening.
Weingartner, DP and Denise Tombolato. "Temporal, geographic and host distribution of
Phytophthora infestans genotypes in Florida." [Vol. 81, No. 1, Pgs. 94-95]
A total of 892 Phytophthora infestans isolates from Florida potato (778) andtomato (114) crops were analyzed for Gpi allozyme
banding, mating type, and metalaxyl sensitivity between 1993 and 2002. Prior to 1991, the only P. infestans genotype known to
exist in Florida was US-1. A single isolate of US-6 was detected in Florida tomatoes in 1991. Coincident with the discovery of new P.
infestans genotypes in other regions of the US, multiple (US- 1,6, 7, 8, 10, 11, and 17) genotypes have been found in either Florida
potatoes or tomatoes since 1993. The last detections in Florida of, respectively, US-1, US-6, and US-7 were in 1997, 1993, and 1996.
US-8 has been the predominant (>90%) genotype in potato each year since 1994, whereas, since 1997, depending on the year,
US-11 (51%) and US-17 (34%) have been the most prevalent genotypes in tomato. A wider diversity of genotypes occurs in south
Florida where both potato and tomato are grown. With the exception of a single unconfirmed US-10 detection in north Florida potatoes
in 2000, all P. infestans from north Florida potatoes since 1995 have been US-8. On the other hand, US-8, 11, and 17 have been
found in south Florida. US-8 and 10 were equally aggressive on potato and tomato in growth room studies whereas US-17 was more
aggressive on tomato. Distinct potato and tomato late blight pathosystems are hypothesized for Florida. The genotypes predominating
in each crop are for the most part unique to the particular crop. The two pathosystems in south Florida apparently overlap resulting in
“potato genotypes” infecting tomato and “tomato genotypes” occurring in potato.
Woodell, Lynn K, N Olsen and GE Kleinkopf. "Vine kill effects on Ranger Russet quality."
[Vol. 81, No. 1, Pg. 95]
High yields, good recovery, and fry quality make Ranger Russet an advantageous cultivar for growers and processors, but unacceptable
fry quality with time in storage can be problematic and limiting. Maturity at harvest may influence storability. This study was conducted to
determine the effect of vine kill on Ranger Russet yields and processing quality. Ranger Russet potatoes were grown three years in
Kimberly, ID. Treatments included a) no vine kill (NVK) b) two week vine kill (2WVK) c) four week vine kill (4WVK) and d) two week vine kill
with maleic hydrazide (MH30). Vines were removed mechanically. Yield and quality measurements at harvest and monthly storage quality
evaluations were collected. Tubers were cured at 12.8°C for 14 days and decreased by 0.3°C/day to 8.9°C. Chlorpropham was applied 52
days after harvest. There was no significant difference in yield due to vine kill treatment for 2000 and 2001. In 2002, 4WVK plots had higher
yields in the 114-283g size category and lower yields in the >397g category. The three-year average of 4WVK specific gravity was lower
(1.0827) than the other treatments (1.0891). The NVK treatment had a lower incidence of blackspot bruise and the MH30 treatment reduced
bruise severity. At-harvest glucose levels in 2002 (0.073%FW) were higher than 2000 and 2001 (0.026%FW). Average initial glucose levels
were lowest with NVK (0.03%FW) and highest with 4WVK (0.05%FW). No significant differences were seen in initial and in-storage
glucose levels or fry color between MH30 and 2WVK. NVK tubers maintained lower glucose levels and lighter fry color and 4WVK had
higher glucose levels in storage. By five months in storage, 4WVK showed a higher severity of mottling. Tuber quality in storage was
maintained for a longer period when vines were not killed.
Yi-Lan, Fang and Hak-Tae Lim. "Eradication of potato virus (PLRV, PVY) by heat and chemical
treatments for the nodal segment of potato (Solanum tuberosum L.)" [Vol. 81, No. 1, Pg. 95]
F9-99 genotype infected with both potato viruses(PLRV and PVY) was evaluated for the establishment of in vitro virus eradication
using heat and chemical treatments and combinations of two methods. The effect of explant size on virus eradication after treatments was
also evaluated. Infected plantlets were cultured in the media added with Acetylsalicylic acid (ASA) (10-6, 10-5, 10-4M) and Ribavirin (10,
15, 20mg/ml) alone and combination of ASA+Ribavirin. The plantlets grown in each medium was kept at 25C, and heat treatment (35C/30C
1-hr, 4-hr, 8-hr) or 42C/25C 4-hr of nodal segments (0.5-1.0cm). Following these treatments, plantlets were tested quantitatively
(OD at A405) for virus detection based on enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain
reaction (RT-PCR). After 4-8 weeks, the potato genotype F9-99 showed 56%, 50%, 80%, 82%, and 0% survival rates when cultured on
MS media at 25C ASA + Ribavirin (25C), MS (35C/30C) and ASA + Ribavirin (35C/30C), all (42C/25C), respectively. Among the tested
treatments, the heat treatment (35C/30C) showed 92% or more PVY eradication, In other cases, the combined treatments eliminated PLRV
sporadically. From this study, it was concluded that heat treatment was the most effective method for PVY elimination, and both heat and
chemical treatments (ASA+Ribavirin) at the same time were effective for PLRV elimination when nodal segments were used instead of
meristem culture.
Zink, RT, RD Davidson and A Houser. "Control strategies for powdery scab of potato."
[Vol. 81, No. 1, Pgs. 95-96]
Powdery scab of potato, caused by Spongospora f. sp. subterranea, has become increasingly more relevant to potato
production among western states in recent years. At this time no reliable or economic controls are available. Furthermore, resistance
among established potato cultivars is not well characterized. Field trials were initiated to screen compounds for efficacy in control, cultivars
for resistance and to elucidate soil conditions that support disease. Trials were conducted in commercial potato fields under center pivot
irrigation on naturally infested soils. Russet skin cultivars notwithstanding, moderate levels of resistance to tuber symptoms have been
observed in Satina, Calred and AC87340-2W. Tuber resistance is not correlated to root resistance. Data on soil moisture have shown that,
even under ideal water management, conditions in the root zone are adequate to foster extensive disease on roots and tubers. At high
elevations in coarse-textured soils, as plant canopy increases and irrigation becomes more frequent, soil temperatures at the root zone
decrease to a range highly favorable for infection. In trials where planting date was delayed and tuber development concomitantly postponed,
significantly higher incidences of disease were recorded. In efficacy trials with the cultivar DT6063-1R, in-furrow applications at planting of
Omega (3-7 pt./A) have typically increased the percent of healthy tubers by 27% over the untreated control. Likewise, in-furrow applications
of Quadris (4-12 pt./A) have controlled disease on tubers by up to 18%. Equal levels of control have also been achieved using combination
treatments of Evolve applied to seed tubers followed by in-furrow applications of Omega and/or Quadris, at lower more economical rates.
Zlesak, David C & Christian A Thill. "Foliar Resistance to Phytophthora infestans (Mont.) de Bary (US-8) in 13
Mexican and South American Solanum sp. Having EBNs of 1, 2, and 4 and Implications for
Breeding," [Vol. 81, No. 6, Pgs. 421-429]
The recent US-8 clonal lineage of Phytophthora infestans, the pathogen causing late blight (LB) disease, is one of the most
widespread and difficult to control. Sources of foliar resistance to US-8 were evaluated in 1927 seedling genotypes by sampling 49 plant
introductions (PIs) representing 13 Mexican and South American Solanum species having an Endosperm Balance Number
(EBN) of
1, 2, or 4, and one species with an unknown EBN. Species evaluated were 2x(1EBN) S. bulbocastanum, S. cardiophyllum, S. commersonii,
S. pinnatisectum, and S. trifidum; 2x(2EBN) S. berthaultii, S. megistacrolobum, S. microdontum, and S. verrucosum;
4x(2EBN) S. fendleri and S. stoloniferum; 6x(4EBN) S. guerreroense; 2x unknown EBN S. polyadenium; as
well as 4x S. tuberosum families as controls. Foliar resistance in the field was monitored in 1998 and 1999. Resistance differed
relative to species geographic origin, EBN, species themselves, PIs within a species, and genotypes within a PI. In 1998 Mexican
germplasm had a lower area under the disease progress curve (AUDPC, 1140) and greater resistance than South American germplasm
(1601), while the 1EBN (1119) and unknown EBN (1075) species had greater resistance than 2EBN (1470) and 4EBN (1888) species.
AUDPC ranged among species from 555 (S. cardiophyllum) to 1932 (S. megistacrolobum) and among PIs within a species
most widely for S. bulbocastanum (267-1007) and least widely for S. polyadenium (1019-1179). In 1999 LB symptoms were
not observed on the species before an early freeze; however, all 1999 S. tuberosum families showed LB symptoms and segregated
for resistance, pointing to greater resistance in the species than in cultivated germplasm. Resistance found in diploid 2EBN germplasm is
more accessible due to greater crossability with cultivated germplasm; however, though more difficult to
introgress, resistance found in
some of the more reproductively isolated 1EBN germplasm is worth pursuing.