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 lesi