AbdelGadir, AH*, MA Errebhi, HM Al-Sarhan and M Ibrahim. "
The effect of different levels of additional potassium on yield and industrial qualities of potato (Solanum tuberosum L.) in an irrigated
arid region." E-mail: abdelgadir@sabic.com
[Vol. 80: No. 3, 219-222]
(Short Communication)
Soils and irrigation waters in Saudi Arabia are naturally rich in potassium (K). In spite of this, farmers and
large-scale agricultural companies usually add K fertilizers to various crops without soil and water testing and whether or not the crop
requires high amount of K. The objective of these experiments was to study the response of fresh tuber yield, specific gravity, and frying
quality of processed potato to different levels of additional K under farmer conditions. Two field experiments were conducted
during the 2000-2001 and 2001-2002 growing seasons in Wadi Addawasir (latitude 20-21 N, longitude 45-46 E), Kingdom of Saudi
Arabia. The experimental layout was a randomized complete block design with five K levels (0-100 kg K
2O ha-1) and four replicates. Water and soils in this region contained
more than 10 and 200 ppm K, respectively. Results indicated that there were no statistical differences (P<0.05) between the levels of K
on fresh tuber yield, specific gravity, or frying quality. Similarly, K content of leaves at 45 or 60 days after emergency and of tubers at harvest
was not significantly affected (P<0.05) by K rates. Potassium content in leaves was above optimum levels. Results of this study indicated
that current application rates of K are higher than the potato crop requirement for optimum yield obtained in this region. Results also
indicated that farmers' basic application of 215 kg, K2O ha
-1 along with soil native K and irrigation water K were sufficient to produce economic yield and high-quality
potatoes.
Andrivon, Didier*, Roselyne Corbière, Jean-Marie Lucas, Claudine Pasco, Jean-Michel Gravoueille,
Roland Pellé, Jean-Paul Dantec, and Daniel Ellissèche. "Resistance to Late Blight and Soft Rot in Six Potato Progenies and
Glycoalkaloid Contents in the Tubers."
E-mail: didier.andrivon@rennes.inra.fr
[Vol. 80: No. 2, 125-134]
Glycoalkaloids are anti-nutritional compounds commonly found in wild Solanum species used as resistance sources to
major potato pathogens. It is therefore important for breeding purposes to know whether selecting for resistance using such species
necessarily selects also for high glycoalkaloid contents in the tubers. To test this hypothesis, we used six partial progenies from crosses
between Solanum tuberosum and accessions of S. andigena, S. berthaultii, S. phureja, and S. vernei to investigate
the possible correlation between resistance to Phytophthora infestans and/or to Erwinia carotovora subsp.
atroseptica and the concentration of glycoalkaloids in tubers. Concentrations of solanine and chaconine in the tubers
segregated in each progeny, as did resistance to each pathogen. Some, but not all, clones from each progeny showed hypersensitive
reactions to the isolate of P. infestans used. Furthermore, clones within each progeny also differed for components of partial
resistance to P. infestans, suggesting that all four wild species could be used as sources of both race-specific and partial
resistance to late blight. With the exception of low, but statistically significant, correlations between concentration of solanine and two
late blight resistance components (incubation period and spore production per unit lesion area) in progenies derived from
S. vernei, and despite a trend towards higher glycoalkaloid concentrations in the tubers of the clones most resistant to
soft rot within progenies derived from S. berthaultii and S. vernei, no consistent relationship between resistance to
either disease and concentrations of solanine and/or chaconine was observed. These results indicate that neither race-specific
nor partial resistance to late blight and soft rot in the accessions used as progenitors of resistance depend on high solanine or
chaconine concentrations. These resistance sources could thus prove useful in breeding programs for improved behavior
against P. infestans and/or E. carotovora.
Arregui, LM, J Veramendi, and AM Mingo-Castel*. "Effect of Gelling Agents on in vitro
Tuberization of Six Potato Cultivars." E-mail:
angelma@unavarra.es {Vol. 80: No. 2, 141-144]
(Short Communication)
The gelling agent PhytagelTM was compared with Difco Bacto-agar for in vitro tuberization of six potato
cultivars (Jaerla, Blanka, Claustar, Kennebec, Désirée, and Baraka). On a culture medium with 6% sucrose but lacking growth
regulators, tuberization was higher when PhytagelTM was used rather than Difco Bacto-agar, regardless of the
photoperiodic regime used. Chemical analyses of the gelling agents revealed a higher mineral content and organic impurities
in Bacto-agar than in PhytagelTM, which is therefore recommended for microtuber production. The same gelling agent
should be used in all treatments of microtuberization experiments in order to draw meaningful physiological conclusions.
Bamberg, JB* and AH del Rio. "Vulnerability of Alleles in the US Potato Genebank
Extrapolated from RAPDs." E-mail: nr6jb@ars-grin.gov
[Vol. 80: No. 2, 79-85]
Crop genebank managers must be concerned with preserving low-frequency alleles that are vulnerable to being lost from the
genebank because they are not sampled as seed increase parents. Traits conferred by such alleles are also vulnerable to being
overlooked because they are not sampled in plants evaluated for breeding traits. Mathematical models and recommendations that follow
from hypothetical vulnerable alleles within single populations have been made by various researchers. This work was undertaken to
empirically detect the prevalence of such alleles in the US Potato Genebank by extrapolation from RAPD markers. Two outcrossing
species known to be very heterogeneous were selected, Solanum jamesii Torr. (2n=2x=24) and Solanum sucrense
Hawkes (2n=4x=48). RAPD band frequencies at a total of 83 marker loci within each of 15 populations were assessed using 24 plants per
population. For both species, about 10% of within-population loci had vulnerable alleles (banded plant frequency <40%), considering
just the particular population in question. However, about half of these were fixed in at least one other population (making that marker
invulnerable to loss). The highest within-population banded plant frequency for loci not fixed in any population was, with one exception,
always >40%. So, while several alleles may be vulnerable within a given population, these were nearly always fixed or nearly fixed
(invulnerable) in another population. This suggests that the safest strategy for maximizing conservation of alleles is to apportion available
resources over many separate populations, rather than adopt a preservation protocol so rigorous that it can only be practically applied
to a limited number of populations.
Bamberg, J*. A Del Rio, Z Huaman, S Vega, M Martin, A Salas, J Pavek, S Kiru, C Fermandez and D
Spooner. "A Decade of collecting and research on wild potatoes of the Southwest USA." E-mail:
nr6jb@ars-grin.gov [Vol. 80: No. 3, 159-172]
Potato is an important world crop with an abundant diversity of wild relatives for research and breeding. About 200 tuber-bearing
Solanum relatives of the cultivated potato are distributed from southern Chile to the southwest USA. Only five of these have been
reported in the USA, and only two exist with certainty (S. fendleri and S. jamesii). This paper reviews the procedures and
outcome of 12 expeditions by the authors to the Southwest USA from 1992 to 2001 that resulted in 132 new germplasm accessions.
Previously published information allowed successful collection from many documented sites, and many new sites were discovered
and sampled. Incomplete or inaccurate records were improved and refined, making it possible for others to easily find these sites.
When assessed for genetic diversity, re-collections from the same site were found to be nearly as genetically different as samples
from different sites, and genetic differences between sites could not be linked with any ecogeographic parameter, even physical
distance of separation. In conclusion, wild potato germplasm from the USA and associated knowledge was greatly expanded, but
reaching the goal of obtaining and keeping the most complete sample possible of the genetic diversity will involve additional
collecting and continued research on the reproductive behavior of these plants.
Beaver, R Gary, Mary L Devoy, Ronald Schafer, and Bruce D Riggle*. "CIPC and
2,6-DIPN sprout suppression of stored potatoes." E-mail Bruce Riggle (CA):
bruceriggle@aol.com [Vol. 80: No. 5, 311-316]
A five-year storage season study using small-scale bins was undertaken to determine the effectiveness of 2,6-diisopropylnaphthlene
(2,6-DIPN) in combination with isopropyl-N-(3-chlorophenyl)carbamate (CIPC) for sprout suppression of stored potatoes
(Solanum tuberosum L.). The study environment simulated a commercial operation and the storage bins held up to 4,500 kg of tubers.
Russet Burbank potatoes were tested for five storage seasons, and for one season the bin space was split between Ranger Russet and
Snowden potatoes. Sprout suppression was measured as percent acceptable for fresh pack (%AFP), defined as sprouts = 3 mm in
length. When 2,6-DIPN was used alone at 8.3 mg kg-1 fw, it only provided short-term sprout suppression. Sprout suppression
responses for the two chemicals were similar for Russet Burbank, Snowden and Ranger Russet. When 2,6-DIPN was used in combination
with CIPC, a significant increase in sprout suppression was observed. In addition, when the two chemicals were used in combination, the
amount of CIPC could be reduced by as much as 50% while still maintaining equal or better sprout suppression as compared to CIPC
alone. For overall long-term sprout suppression, the best treatment was a combination of CIPC and 2,6-DIPN, each at 16.6 mg kg-1.
Belanger, G*, JR Walsh, JE Richards, PH Milburn, and N Ziadi. "Critical petiole Nitrate
Concentration of two processing potato cultivars in Eastern Canada."
E-mail: belangergf@agr.gc.ca [Vol. 80: No. 4, 251-262]
Plant-based diagnostic methods of nitrogen (N) nutrition such as petiole nitrate (NO3-
N) concentration can be used to improve the efficiency of N utilization, and hence decrease the risks of
N losses to the environment. Our first objective was to determine the effect of N fertilization and supplemental irrigation on the
petiole NO3-N concentration during tuber growth of two potato cultivars, Russet Burbank
and Shepody, widely grown for processing in Eastern Canada. Our second objective was to establish the critical petiole
NO3-N concentration and the N nutrition index (NNI), and index based on the N
concentration of shoots and tubers. This on-farm study was conducted at two sites in each of three years, 1995 to 1997. The NO
3-N concentration of petioles from the most recently mature leaves was measured on
three sampling dates in 1995 and four sampling dates in 1996 and 1997. The petiole NO3-
N concentration generally decreased with time. At all sites and on all sampling dates, the petiole NO
3-N concentration increased with increasing N fertilization and was significantly greater for Shepody than
for Russet Burbank. Irrigation had no consistent effect on petiole NO3-
N concentration. Petiole NO3-N concentration was related to NNI (0.29<R
2<0.62). Critical petiole NO3-N
concentrations required to reach an NNI of 1.0, indicating a situation where N is not limiting growth, where greater for Shepody than for
Russet Burbank, and they decreased with time. Critical petiole NO3-N concentration (Y)
expressed as a function of the number of days after planting (X) are Y = 4.80 - 0.055X for Russet Burbank and Y = 5.03 - 0.054X for
Shepody.
Brodie, BB "The Loss of Expression of the H1 Gene in βt Transgenic Potatoes"
E-mail: bbb2@cornell.edu [Vol. 80: No. 2, 135-139]
During evaluation of potato clones and cultivars from the Cornell seed production program to confirm their resistance to
Globodera rostochiensis (Wollenweber) Behrens (golden nematode) pathotype Ro1, several cysts developed on the transgenic
cultivar Atlantic NewLeaf. This transformed cultivar resulted from the insertion of a t endotoxin gene into the golden-nematode-resistant
cultivar Atlantic. In subsequent bioassay tests, golden nematode cysts developed freely on the transgenic cultivar that originated from
Atlantic NewLeaf clone 6, but not on Atlantic NewLeaf clones 31 and 36. Clones 31 and 36 were from different t transformation
events of the cultivar Atlantic that were never commercialized. RFLP analysis of Atlantic used in the transformations and the Atlantic
NewLeaf clones 6, 31, and 36 showed that they possessed the marker for the H1 gene hat confers resistance to golden
nematode pathotype Ro1. These data indicate that the t transformation process adversely affected the expression of the
H1 gene in the transgenic cultivar Atlantic NewLeaf. This finding highlights the importance of pre-release evaluation of
transgenic plants for any previously known major traits such as pest and disease resistance before they are commercialized.
Brown, CR*, R Wrolstad, R Durst, C-P Yank, and B Clevidence. "Breeding studies in potatoes
containing high concentration of anthocyanins."
E-mail: cbrown@pars.ars.usda.gov
[Vol. 80: No. 4, 241-250]
Studies of the breeding behavior of clones containing high levels of anthocyanins were conducted. Red-fleshed clones appeared in
proportions suggesting multigenic control of degree of pigmentation. Red-fleshed and purple-fleshed clones were always accompanied
by red and purple skin, respectively. Red flesh ranged from partial pigmentation to complete pigmentation represented by pigment
present in all tuber tissues. Percentage of completely red-fleshed progeny was 14.5% and 4.1% in red x red crosses vs red x
white (or the reciprocal), respectively. Purple-fleshed progeny were obtained from red x white crosses where the white-fleshed parent
harbored the P pigment gene in juxtaposition with the nulliplex recessive state of the I gene (i.e., iiii), which
suppressed expression. Total anthocyanin ranged from 6.9 to 35 mg per 100 g fresh weight in the red-fleshed and 5.5 to 17.1 in
the purple-fleshed clones. Red-fleshed clones contained predominantly acylated glycosides of pelargonidin while the purple-fleshed
clones contained predominantly acylated flycosides of petunidin and peonidin. Oxygen Radical Absorbance Capacity and Ferrous
Reducing Ability of Plasma revealed that the antioxidant levels in the red or purple-fleshed potatoes were two to three times
higher than white-fleshed potato.
Carputo, D*, M Parisi, F Consiglio, M Iovene, G Caruso, L Monti and L Frusciante. "Aneuploid
Hybrids from 5X - 4X Crosses in Potato: Chromosome Number, Fertility, Morphology and Yield."
E-mail: carputo@unina.it [Vol. 80: No. 2, 83-101]
The objective of this study was to characterize six S. commersonii - S. tuberosum progenies deriving from 5x - 4x
crosses to provide evidence that they can be used in potato breeding. Hybrids analyzed (coded PTH) had a chromosome number
between the 4x and the 5x level. In particular, progeny means for chromosome number ranged from 50±0.5 to 54±0.7, with most (70%)
genotypes exhibiting a low aneuploid level of 48 to 53 chromosomes. Despite being aneuploid, the hybrids did not generally show
phenotypic aberrations or vigor reduction common to aneuploids of other species. Most genotypes resembled S. tuberosum in
growth habit, whereas corolla type, eye depth, and stolon length varied between and within progenies. Aneuploid hybrids produced tubers
under long-day conditions. However, tuber yields were not as high as expected, probably due to lack of adaptation of the S.
commersonii genome to long-day conditions. Although aneuploidy has often been associated with reduced male and female fertility,
many 5x - 4x hybrids were fertile in crosses with S. tuberosum. The average berry set and number of seeds/berry were 33% and
34.7, respectively, following PTH x S. tuberosum crosses, and 40% and 51.7, respectively, for S. tuberosum x PTH crosses.
The useful variation for fertility and tuber traits found in this material is being used for further breeding efforts.
Chen, Q*, LM Kawchuk, DR Lynch, MS Goettel and DK Fujimoto. "Identification of Late Blight,
Colorado Potato Beetle and Blackleg Resistance in Three Mexican and Two South American Wild 2x (1EBN) Solanum Species."
E-mail: chenqi@agr.gc.ca
[Vol. 80: No. 1, 9-19]
Wild potatoes are important sources of genes for resistance to disease and insect pests. A collection of wild Mexican and South
American Solanum species from the US potato Genebank was evaluated under laboratory and/or field conditions for their reaction
to late blight (Phytophthora infestans), Colorado potato beetle (CPB, Leptinotarsa decemlineata Say), and blackleg
(Erwinia carotovora subsp. atroseptica (van Hall) Dye) in order to identify individual genotypes with multiple resistance
genes. Late blight inoculations using aggressive isolates (US-8/A2 and US-11/A1mating types) of P. infestans revealed a wide
range of variation for resistance between and within the accessions of the wild species tested. For late blight, susceptible as well as
moderately to highly resistant genotypes were observed in all the species tested. However, at least one accession from the three Mexican
and one South American wild diploid species tested showed a relatively uniform high level of resistance to P. infestans. These
included S. bulbocastanum, S. pinnatisectum, S. cardiophyllum, and S. circaeifolium. Two accessions from South American
species S. commersonii were highly susceptible to late blight. For the Colorado potato beetle test, only one species, S.
pinnatisectum appeared uniformly resistant to CPB under field conditions. Results of screening for blackleg resistance showed
that there were major differences between genotypes in the wild species. Accessions of S. circaeifolium PI 498119 and S.
bulbocastanum PI 243504 were identified as having significantly higher blackleg resistance than cultivated potato and the other wild
species tested. However, genotypes from these two accessions were more susceptible to late blight and CPB. Characterization of the
P. infestans isolate P1801C.16 used for late blight evaluation and multi-locus isolate tests using US-8/A2 and US-11/A1 races
revealed that the resistance in S. pinnatisectum genotypes tested corresponded to a race-non-specific genetic system, which was
different from any existing R genes. Solanum pinnatisectum genotypes with both high levels of late blight and CPB resistance as
well as blackleg resistance genotypes identified in the present study represent a diverse gene pool that may be useful for development
of new potato cultivars with multiple disease and insect resistance. The potential utilization of these valuable sources for improvement of
cultivated potato is discussed.
Costanzo, Stefano*, BJ Christ and KG Haynes. "Construction of a Molecular Linkage Map of
Diploid Potato Hybrid (Solanum phureja x S. stenotomum) for Identification of QTLs Involved in Late Blight Resistance."
(GSC, 86th Annual Mtg.) [Vol. 80: No. 1, 73)
Late blight, caused by Phytophthora infestans, is the most destructive fungal disease of potato worldwide. Since this fungus
can rapidly overcome major race-specific resistance genes, identifying the basis for quantitative resistance has become a crucial
element for implementing advanced breeding strategies. For this purpose a population of 240 F1 progenies derived from
a cross between two diploid hybrid Solanum phureja × S. stenotomum clones were utilized to develop a genetic linkage
map of potato and to detect late blight resistance quantitative trait loci (QTLs). To date, 130 restriction fragment length polymorphism
(RFLP) markers have been mapped in a subset of 132 clones and 12 linkage groups have been identified covering approximately 600
cM. Genome coverage by the map is estimated to be at least 50% with an average distance of 4.9 cM between two markers. The RFLP
map contains 118 markers based on random genomic and cDNA sequences of potato. Two markers from tomato random genomic
DNA clones and ten resistance gene analogs (RGAs) of various origins have also been included in this mapping project.. By comparing
map positions of these common potato markers with those previously reported, it was determined that these markers were essentially
co-linear in all published maps. Based on this map, an initial QTL analysis will be performed for mapping and characterizing resistance
loci acting against Phytophthora infestans. Our focus will then be directed, in particular, on identified QTL loci that have not been
reported in previous studies. These QTLs could potentially represent a specific contribution of the two diploid potato species used in this
study. We plan to obtain more comprehensive molecular marker coverage of these regions for future analysis.
Daayf, Fouad and Harold W (Bud) Platt*. "US-8 and US-11 genotypes of Phytophthora
infestans from potato and tomato respond differently to commercial fungicides." E-mail:
platth@agr.gc.ca [Vol. 80: No. 5, 329-334] (Short Communication)
Isolates of Phytophthora infestans collected in Canada in 1997 from both potatoes and tomatoes, were tested on potato leaf
discs for their response to an equal active ingredient concentration (10 µg a.i./mL) of the following commercial fungicides: Acrobat MZ
(Dimethomorph and Mancozeb), Ridomil Gold (metalaxyl-m), Dithane (Mancozeb), Curzate (Cymoxanil), Bravo (Chlorothalonil),
and Tattoo C (Propamocarb and Chlorothalonil). Relative percent leaf infection values, estimated on fungicide-treated vs fungicide-free
leaf discs, were compared among isolates from the US-8 and US-11 genotypes isolated from the two hosts plants. Based on an equal
concentration of each fungicide's active ingredients, variations in relative percent leaf infection were recorded between US-8 and US-11
genotypes, and between potato and tomato isolates within each genotype. Bravo and Tattoo C used with similar active ingredients
concentrations were the most similar inhibitory to all groups of isolates. Dithane and Ridomil Gold provided uniform low inhibition
against P. infestans when tested on potato leaf discs. The different behavior of P. infestans isolates from potato vs tomato
suggests that management of late blight in these two important crops must take such differences into consideration. In particular, the
nature and concentration of the fungicides to be applied must take into account any information available about genotypes present on each crop.
Deffo, V*, D Njualem, J Koi and P Demo. "Socioeconomic Impact of Two Potato Varieties (Cipara
and Tubira) Released in Cameroon."
E-mail: vdeffo@yahoo.fr [Vol. 80: No. 3, 151-158]
In 1988, the IRA-CAP potato project was created in Bambui, Cameroon, with the major objective of improving potato production in
the country. In 1992, two potato cultivars, Cipira and Tubira, were released by the project. In 1998, a socioeconomic impact study of
Cipira and Tubira was carried out in the main potato-producing region of Cameroon to determine the reaction of the farmers,
the effect of the new potato cultivars on the farmers' standard of living, and the level of achievement of the project's objectives. Data
were collected on-farm using questionnaires and direct observations. An impact survey was carried out in the region with a sample of
297 farmers selected among the potato farmers using stratified random sampling. The survey indicated that 98.6% of the potato farmers
were aware of the new potato cultivars. Their main source of information was other farmers (51.5% of farmers informed). Seventy-eight
percent of the farmers were using Cipira and 62% had adopted it as part of their production system. These farmers (62.6%) reported
that the resistance of Cipira to late blight was higher than that of local and European cultivars used in their production system. More
than 44% of the farmers believed that their standard of living had improved due to Cipira and Tubira, since they had generated more
revenue to improved their family education and nutrition, build more houses, buy more farms, purchase more farm inputs, and open
new businesses. In addition, the farmers' average yearly potato production increased from 1.6 to 3.1 tons during the period when
these varieties were being adopted.
Deffo, V* and P Demo. "Adoption of two new potato varieties in Cameroon: progress and
constraints." E-mail: vdeffo@yahoo.fr
[Vol. 80: No. 4, 263-270]
In 1992, two potato varieties, Cipira and Tubira, were released in Cameroon by IRAD-CIP, a cooperative project between Cameroon
and the International Potato Center. From 1993 to 1997, more than 31 tons of sprouted potato basic seed from these varieties were
distributed to farmers. In 1998, a study was carried out in the main potato-producing region of Cameroon to characterize the progress and
constraints faced by potato farmers in adopting the new potato varieties. Data were collected through a survey of 297 farmers using
stratified random sampling. These data, analyzed using descriptive and student statistics, indicated that 98.6% of the potato farmers
were aware of the new cultivars. Their main source of information was other farmers (51.5% of farmers informed). Seventy-eight
percent of the farmers were still using Cipira and 62% had adopted it as part of their production system. These farmers (62.6%)
reported that the resistance of Cipira to late blight was higher than that of local and European cultivars. The farmers' average yearly
potato production increased from 1.6 to 3.1 tons during the period when these varieties were being adopted. The main constraint to the
adoption of Cipira and Tubira was bacterial wilt susceptibility. About 59% of the potato farmers complained of this constraint. Another
major problem was the lack of technical guidance for potato farmers from the Cameroon Agricultural Extension Service, from which
only 27.3% of the farmers received information. Because of these constraints, 3% and 7.4% of the farmers had already abandoned
Cipira and Tubira, respectively.
del Rio, AH and JB Bamberg*. "The effect of genebank seed increase on the genetics of recently
collected potato (Solanum) germplasm. E-mail: nr6jb@ars-grin.gov
[Vol. 80: No. 3, 215-218] (Short Communication)
In previous work at the US Potato Genebank, RAPDs were used to detect large differences between genebank-conserved samples
and their corresponding in situ populations re-collected from the wild. This work investigates one possible explanation for these
differences: a large genetic change in the sample when it undergoes "domestication" by a forced sexual seed increase and
subsequent adaptation to cultivation in the genebank. However, when 11 Solanum fendleri and 17 S. Jamesii populations
were collected from the wild and compared to their sexual progeny generated at the genebank, no significant differences in RAPD
fingerprints were detected. These results showed that theory of "genebank domestication" is not supported. However, when
plants of one pair of populations were tested individually, the seed increase population was significantly more heterogeneous than its
clonally collected in situ parents. Thus, while genebank populations have the same genes as their wild counterparts, they may
contain genotypes not present in the wild.
Dinu, Ioana* and CA Thill. "Cytological Analysis of a Solanum pinnatisectum - S. tuberosum
Bridging Genotype Developed by EBN Manipulation and Sexual Crosses."
(GSC, 86th Annual Mtg.)
[Vol. 80: No. 1, 73]
Introgression of desirable traits from the reproductively isolated wild Solanum species into cultivated potato is valuable for
potato improvement. However, interspecific incompatibility barriers can limit gene transfer. Post-zygotic endosperm failure, a barrier due
to Endosperm Balance Number (EBN) can be overcome using polyploidization via somatic doubling of wild species
genomes, haploids, embryo rescue and 2n gametes. Breeding schemes manipulating EBN are of interest due to transferring late blight
(LB) resistance from exotic 1EBN Mexican Solanum species. Our goals are developing 3x bridging-hybrids to introgress
LB resistance to cultivated potato and the monitoring of chromosome transfer using cytogenetic techniques. The clone MNDZ-1
was produced in our program from a cross between S. pinnatisectum P.I. 275233 (in vitro chromosomally doubled
4x(2EBN)) x S. tuberosum 2x(2EBN) haploid-species hybrid. The objectives of this research were to cytologically analyze MNDZ-1
for: 1) mitotic chromosomal constitution, 2) meiotic chromosome behavior, and 3) viability and size variation in pollen population. The
evidenced somatic chromosome number was 2n=3x=36, but tetraploid metaphase cells were also observed. Meiotic abnormalities at
tetrad stage of microsporogenesis involved dyads (low frequency), triads, and tetrads with 1 – 2 micronuclei. Percent stainable pollen was
above average (68.4%) with a large variation in diameter, between 18.7m m – 37.4m m, whereby 3% exceeded 30m m.
Trends toward lower values of pollen diameter indicate the predominance of lower ploidy levels. MNDZ-1 had a lower AUDPC for LB
compared to moderately resistant S. tuberosum controls. The authors thank Drs. R. Phillips and R. Kynast for their assistance with
cytological study.
Donnelly, Danielle J*, Warren K Coleman and Shirlyn E Coleman. "Potato Microtuber Production
and Performance: A Review." E-mail: donnelly@nrs.mcgill.ca
[Vol. 80: No. 2, 103-115]
Almost half a century has passed since in vitro tubers (microtubers) were first described in potato, but their adoption as a seed
propagule has been uneven globally. Consensus is lacking regarding optimal production practices for microtubers and their relative
productivity in relation to other propagules for minituber production. There is significant; uncertainty regarding the utility of microtubers
for evaluation of agronomic characters. However, the application of microtubers in germplasm conservation is widely accepted.
Microtubers are produced in vitro in a plethora of different growing systems with varying environment, media constituents, and
storage intervals. Many of the interactions between growth parameters in vitro and subsequent productivity appear to be
genotype-specific. Accordingly, microtubers come in different sizes, have different dormancy requirements, and differ widely in relative
growth potential and productivity. Despite these differences, there is evidence for strong analogies in growth responses between
field-grown tubers and microtubers. The use of microtuber technology in seed tuber production, breeding programs, germplasm
conservation, and research appears to have enormous potential. This review discusses microtuber production, yield and performance,
in vitro screening, and germplasm storage and exchange.
Douches, DS*, J Coombs, K Kastrzebski, R Hammerschmidt, WW Kirk, C Long, RW Chase and
S Snapp. "Boulder: A Round White Multipurpose Potato Variety." E-mail:
douchesd@pilot.msu.edu [Vol. 80: No. 6, 345-352]
Boulder is a round white selection with medium specific gravity that can be used in both the tablestock and chip-processing markets.
The tubers will chip process out-of-the-field and from 10 C storage. The tubers of Boulder are large in size with a low incidence of internal
defects. Boulder was tested in Michigan State University trials, the North Central Regional trials, on-farm trials in Michigan and other
out-of-state replicated agronomic trials. Under irrigated conditions in Michigan, the yield is similar to or better than Atlantic, but specific
gravity is less. Boulder has a full-season vine maturity that is similar to Snowden, but the tubers size early. Based upon our trials, an in-row
spacing of less than 25.4 cm to reduce the percentage of oversize tubers is recommended. In simulated bruise tests, Boulder had less
blacksport bruising than Atlantic, but was more blackspot susceptible than Onaway. Based upon five years of trials, Boulder has resistance
to scab that is greater than Atlantic, but less than Onaway.
Gruszewski, Hope A*, Harsh Pal Bais, and Jorge M Vivanco. "Rosmarinic Acid: A Plant Compound
with Potent Antifungal Activity Against Phytophthora infestans US-8."
(GSC, 86th Annual Mtg.) [Vol. 80: No. 1, 74]
The impact and severity of late blight epidemics caused by Phytophthora infestans (Mont.) de Bary has been revisited in the
United States and Canada in the past two decades. Migration of metalaxyl-insensitive P. infestans biotypes (US-6,US-7,US-8, US11)
combined with increased fitness and pathogenicity of the fungus caused earlier application of protectant fungicides at more frequent
intervals. These strategies are costly to both producers and the environment while increasing selection pressure for pathogen resistance.
Accordingly, new environmentally friendly fungicides are required to control this pathogen. Our recent studies have shown that rosmarinic
acid (RA), an antioxidant compound present in many species of the Lamiaceae, has strong antimicrobial activity against a broad range of
soil borne pathogens. In this study a series of assays were performed to test the inhibitory effect of RA against P. infestans US-8.
Strong inhibition of P. infestans hyphal growth and spore germination was observed. RA damaged P. infestans sporangia
and hyphae and thus prevented germination and growth as observed by scanning, confocal and light microscopy. Future experiments
will address the effect of RA applications on late-blight infected potato plants growing under greenhouse conditions. Additionally, we
plan to monitor the effect of RA on P. infestans at the genomic level. Our studies highlight that RA is a potent antifungal agent
against Phytophthora infestans US-8.
Halbert, Susan E*, Dennis L Corsini and Monica A Wiebe. "Potato Virus Y Transmission Efficiency
for some common aphids in Idaho." E-mail: halbers@doacs.state.fl.us
[Vol. 80: No. 2, 87-91]
Green tile pan trap counts during the potato-growing season showed that Capitophorus elaeagni (32%), Diuraphis noxia
(27.7%), and Metopolophium dirhodum (15%) were the most abundant aphid species in potato fields at Aberdeen, Idaho.
Acyrthosiphon pisum (22%), C. elaeagni (19%), and Metopolophium dirhodum (19%) were the most abundant species
in potato fields at Tetonia, Idaho potato seed production areas. Eight species of aphids found to visit potato fields (C. elaeagni, D. noxia,
M dirhodum, Myzus persicae, Rhopalosiphum maidis, Rhopalosiphum padi, Schizaphis graminum, and Sitobion avenae) were
tested for Potato Virus Y (PVY) transmission efficiency by timed probe experiments. Four of these species (D. Noxia, M. dirhodum, M.
persicae, and S. avenae) and an additional three (Diuraphis frequens, Diuraphis mexicana, and Diuraphis tritici)
were tested using mass inoculations. Capitophorus elaeagni, M. persicae, R. maidis, R. padi, and S. graminum all
transmitted PVY in the timed probe experiments. Myzus persicae and D. noxia transmitted PVY in the mass inoculation
experiments.
Hane, DC*, AR Mosley, SR James, KA Rykbost, CC Shock, SL Love, DL Corsini, JJ Pavek, RE
Thornton, BA Charlton, EP Eldredge and S Yilma. "Wallowa Russet: A Full Season Long Russet for Processing and Fresh Market.
" E-mail: dan.hane@oregonstate.edu
[Vol. 80: No. 4, 289-294]
The Agricultural Experiment Stations of Oregon, Idaho, and Washington and the U.S. Department of Agriculture jointly released
Wallowa Russet in 2002. This late maturing variety is most suitable for frozen french fry use, but may find limited fresh market potential
because of outstanding flavor and texture when baked. Wallowa Russet was evaluated as AO87277-6 in Oregon irrigated trials from
1993 through 1999, and in western regional trials from 1997 through 1999. Averaged over 13 locations in seven states, Wallowa Russet
produced total yields of 55.6 mt/ha compared to 53.5 and 45.7 mt/ha for Russet Burbank and Russet Norkotah, respectively, and U.S.
No.1 yields of 44.4 mt/ha compared to 30.7 and 36.0 mt/ha for Russet Burbank and Russet Norkotah. Specific gravity is consistently
higher for Wallowa Russet than for Russet Burbank and fry color is as light or lighter; sugar end development is less than that
observed in Russet Burbank. Wallowa Russet is similar to Russet Burbank in susceptibility to Verticillium wilt, foliar early blight
(Alternaria solani), and potato leafroll virus (PLRV). However, Wallowa Russet develops less net necrosis than Russet Burbank
from PLRV infection. Wallowa Russet is more susceptible to common scab (Streptomyces scabies) than Russet Burbank.
It has moderate resistance to potato virus Y (PVY). Tubers of Wallowa Russet are less susceptible to tuber infection and decay caused
by potato late blight (Phytophthora infestans) than Russet Norkotah and Ranger Russet. Wallowa Russet has less hollow heart,
brown center, blackspot bruise, and fewer growth cracks than Russet Burbank but is more susceptible to shatter bruise. Vitamin C is
higher for Wallowa Russet (30.4 mg/100 g fresh weight) than for Russet Burbank (21.9) or Russet Norkotah (22.0), and protein content
averaged 5.6% compared to 4.7% and 4.9% for Russet Burbank and Russet Norkotah, respectively.
Hayes, Ryan J* and CA Thill, "Early Generation Selection to Rapidly Develop Cold Chipping
Germplasm." (GSC, 86th Annual Mtg.) [Vol. 80: No. 1, 74]
Early generation selection (EGS) can identify cold chipping (CC) genotypes earlier in the breeding cycle. Immediate use of CC
genotypes as breeding parents may increase favorable alleles in breeding populations, thus accelerating genetic gain. The research
objective was to determine if CC genotypes identified by EGS have increased value as parents. Twelve 4x progeny from 2x haploid-species
(HS) x (HS) crosses were selected as single-hills and retained following evaluation for CC after 9 mo. storage at 3C. Ten clones
having acceptable chipping (AC) incorporating S. sparsipilum, S. berthaultii, S. gourlayi, and S. bukasovii, and
2 having unacceptable chipping (UC) were crossed to 30 4x tuberosum clones grouped in CC performance classes of good (G-tub),
intermediate (I-tub), and poor (P-tub). This resulted in 35 4x x 4x families. Up to 20 progeny per family were grown, harvested clonally and
chipped after 3 and 6 mo. storage at 4C. Chip color was evaluated 1-10, scores < 4 were acceptable. Progeny from AC had better
chip color means (3 mo: 7.1 / 6 mo: 7.2) than UC (3 mo: 7.8 / 6 mo: 8.1). High percentages of acceptably chipping progeny were observed
in AC x G-tub (3 mo: 15% / 6 mo: 18%) and AC x I-tub (3 mo: 10% / 6 mo: 17%) compared to UC x G- or I-tub (ranged from 0-9%). Four AC
parents C20, C55, C182, and C332 resulted in families with 20-60% acceptably chipping progeny. Acceptably chipping progeny were found
in AC x P-tub (5-9%) but rare in UC x P-tub (<2%). The value of good x good crosses is apparent, but depends on the availability of good
chipping parents. Using EGS, new parents are rapidly identified and selected. High performance of AC parents may result from sexual
polyploidization used in their development, since CC alleles from wild species are easily introgressed.
Higley, JS, SL Love, WJ Price, JE Nelson and KC Huber*. "The Rapid Visco Analyzer (RVA) as a tool
for differentiating potato cultivars on the basis of flour pasting properties.
E-mail: huberk@uidaho.edu [Vol. 80: No. 3, 195-206]
Potatoes of two cultivars representing extremes in potato texture, Russet Burbank (mealy) and IdaRose (waxy), were lyophilized,
ground into flour, and analyzed with a Rapid Visco Analyzer (RVA) to identify flour pasting characteristics unique to each cultivar. A factorial
experiment, which included multiple levels of heating rate, peak temperature, and flour concentration, was employed to assess RVA run
parameter association with flour pasting behaviors and the potential to differentiate cultivars according to the responses. Pasting
profiles of the potato flour provided a unique functional fingerprint for each cultivar flour, which embodies structural and molecular
components of the native potato tissue. Pasting profile viscosity attributes were influenced by variable levels of heating rate, peak
temperature, and flour concentration. At increasing flour concentrations, RVA viscosity attributes increased in magnitude, but
possessed similar pasting curves. A variable heating rate primarily affected events occurring early within the pasting profile (time to
gelatinization, time to peak viscosity, peak viscosity), while changes in peak temperature influenced viscosity attributes (trough viscosity,
breakdown, final viscosity, total setback) associated with the latter portion of the viscosity curve. A high peak temperature generally
resulted in increased breakdown and total setback and decreased trough and final viscosities. RVA viscosity attributes, time to
gelatinization, peak viscosity, breakdown, and final viscosity were identified as potential characteristics for cultivar differentiation.
Discrimination of the cultivar extremes was affected by RVA run parameters, and was maximized at moderate heating rates (4 to
6 min4, moderate to high levels of peak temperature (85 to 90 C), and intermediate flour
concentrations.
Hijmans, Robert J "The effect of climate change on global potato production."
E-mail: rhijmans@uclink.berkeley.edu
[Vol. 80: No. 4, 271-280]
The effect of climate change on global potato production was assessed. Potato yields were calculated with a simulation model
and a grid with monthly climate data for current (1961-1990) and projected (2010 -2039) and 2040-2069) conditions. The results were
mapped and summarized for countries. Between 1961-1990 and 2040-2069 the global (terrestrial excluding Antarctica) average
temperature is predicted to increase between 2.1 and 3.2 C; depending on the climate scenario. The temperature increase is small when
changes are weighted by the potato area and particularly when adaptation of planting time and cultivars is considered (a predicted
temperature increase between 1 and 1.4 C). For this period, global potential potato yield decreases by 18% to 32% (without adaptation)
and 9% to 18% (with adaptation). At high latitudes, global warming will likely lead to changes in the time of planting, the use of later-
maturing cultivars, and a shift of the location of potato production. In many of these regions, changes in potato yield are likely to be
relatively small, and sometimes positive. Shifting planting time or location is less feasible at lower latitudes, and in these regions
global warming could have a strong negative effect on potato production. It is shown that heat-tolerant potato cultivars could be used
to mitigate effects of global warming in (sub) tropical regions.
Holm, Amy L, Viviana V Rivera, Gary A Secor and Neil C Gudmestad*. "Temporal Sensitivity of
Alternaria solani to Foliar Fungicides." E-Mail:
neil.gudmestad@ndsu.nodak.edu
[Vol. 80: No. 1, 33-40] (Short Communication)
Alternaria solani Sorauer (Ellis) is a causal agent of early blight of potato (Solanum tuberosum L.). Sensitivity to
chlorothalonil, triphenyl tin hydroxide (TPTH), and mancozeb was determined for field isolates of A. solani in 1998 and 1999.
Specifically, the relative sensitivity of A. solani to foliar fungicides in field populations collected from several commercial fields
was evaluated over the course of two growing seasons. Sensitivity to these foliar fungicides was determined with an in vitro
spore-germination assay method. The fungicide concentration that inhibited conidial germination by 50% (EC50) was
estimated for each isolate. Sensitivity of A. solani isolates to TPTH and mancozeb varied little during the growing season, possibly
because there were few TPTH and mancozeb applications made to the fields studied. At several locations, however, repeated exposure
of A. solani populations to chlorothalonil resulted in considerable variability in sensitivity, frequently causing isolates to have
decreased sensitivity to this fungicide at the end of the growing season. In five of seven fields, isolates of A. solani collected at the
end of the season were significantly less sensitive to chlorothalonil than isolates collected at the beginning of the season.
Hosaka, Kazuyoshi. "T-type Chloroplast DNA in Solanum tuberosum L. ssp. tuberosum
Was Conferred from Some Populations of S. tarijense Hawkes." E-mail:
hosaka@kobe-u.ac.jp
[Vol. 80: No. 1, 21-32]
The highly heterozygous and tetraploid nature of potato (Solanum tuberosum L. ssp. tuberosum) has hampered discovery of its wild
ancestral species. Chloroplast DNA is a very reliable indicator to trace maternal ancestry of crops. Most of the common potato (grown
worldwide) has unique, T-type chloroplast DNA derived from Chilean cultivated potato (both are S. tuberosum ssp.
tuberosum). Analyzing seven different chloroplast DNA markers, I found all the T-type accessions of cultivated potatoes shared the
same chloroplast DNA haplotype only with some accessions of S. tarijense Hawkes and its derived hybrids. Thus, I conclude that
some populations of S. tarijense acted as the maternal ancestor of potato.
Kawakami, Jackson, Kazuto Iwama*, Toshihiro Hasegawa and Yutaka Jitsuyama. "Growth and
Yield of Potato Plants Grown from Microtubers in Fields." E-mail: iwama@res.agr.hokudai.ac.jp [Vol. 80: No. 6, 371-378]
Despite many reports of the in vitro production of microtubers, little is known about plant growth and yield from microtubers planted in
the field. This study clarified differences in growth and yields between potato plants grown in the field from,microtubers and from
conventional seed tubers. The experiments were performed at Hokkaido University, Japan, over four years. Conventional seed tubers
of about 50 g and microtubers of two sizes (0.5-1.0 g and 1.0-3.0 g) of the late-maturity cultivar Norin 1 were planted, and plant growth and
tuber yields were analyzed. The microtuber plants had a lower initial increase in root and leaf area index than conventional seed tuber
plants, but had the same leaf area index after about 40 days from emergence. The first tuber formation in microtuber plants was about
7 days later than in conventional seed tuber plants, while tuber bulking occurred about 14 days later in microtuber plants. Consequently,
the onset of tuber weight increase was later in microtuber plants, but the rate of increase thereafter was similar between conventional
seed tuber and microtuber plants. At harvest the tuber fresh weight of microtuber plants was 82% that of conventional tuber plants,
suggesting a potential for using microtubers for field planting.
Kirk, William M "Thermal Properties of Overwintered Piles of Cull Potatoes."
E-mail: kirkw@msu.edu [Vol. 80: No. 2, 145-149]
Annual epidemics of late blight of potato have lead to debate as to the relative importance of overwintering sources of inoculum. Host
availability is a key factor for overwinter survival of Phytophthora infestans and the initiation of epidemics of potato late blight.
Temperature within discarded piles of cull potatoes may influence tuber tissue temperature and therefore affect survival of meristematic
tissue. Consequently the risk of initiation of an epidemic of late blight from cull piles is closely related to the thermal experience of
overwintered potato culls. Temperature monitoring of cull piles over two years indicated that temperature was stable in the interior of the
piles regardless of cull pile size (1-15 ton) or year. The possible use of ambient temperature information gathered during winter months
in potato-growing regions may not help estimate the risk of an epidemic of late blight initiated from cull piles as, although highly
correlated with the surface temperature of cull piles, ambient temperature was not correlated with the temperature within the cull piles.
The presence of cull piles in excess of 1 ton may enhance the survival of the host and thus the development of P. infestans from
infected tubers.
Kleinkopf, Gale E*, Nathan A Oberg, and Nora L Olsen. "Sprout inhibition in storage:
Current status, new chemistries and natural compounds." E-mail:
kleinkop@kimberly.uidaho.edu [Vol. 80: No. 5, 317-327]
A major component of managing potato quality in storage is effective sprout inhibition. Sprouting causes increased weight loss,
reduced tuber quality and impedes air movement through the potato pile. The primary method to control sprouting in storage is with
postharvest applications of isopropyl N-(3-chlorophenyl) carbamate (chlorpropham; CIPC), CIPC inhibits sprout development by interfering
with cell division. However, a recent Environmental Protection Agency mandate, from the requirements of the Food Quality Protection
Act (FQPA) of 1996, resulted in a reduction in allowable CIPC residue on fresh potatoes in the United States from 50 ppm to 30 ppm.
This mandate coincides with tolerate reductions or restrictions for use of CIPC in other parts of the world. CIPC is an effective sprout
inhibitor although factors such as storage conditions, application technology, and cultivar can impact that effectiveness. Alternative sprout
inhibitors to CIPC continue to be evaluated. Essentials oils (e.g., caraway, peppermint, spearmint, clove) or their components (e.g.,
s-carvone, eugenol), and hydrogen peroxide-based materials, physically damage materials, physically damage the developing sprout
and suppress sprout elongation. However, repeated or continuous application of these compounds may be necessary for efficacy.
Substituted naphthalenes (e.g., dimethyl naphthalene, diisopropyl naphthalene) may help reduce the amount of CIPC applied and/or our
dependency on CIPC for sprout suppression in storage. The objective of this review is to summarize the current use of CIPC for potato
sprout inhibition in storage and to review the status of current research on other postharvest applied compounds or materials that may
be used as alternatives for CIPC.
Love, SL,* AR Mosley, R Novy, DL Corsini, RE Thornton, SR James and DC Hane. "Ivory Crisp:
A potato variety with high tuber solids and cold chipping ability." E-mail:
slove@uidaho.edu
[Vol. 80: No. 3, 207-213]
Ivory Crisp was released in 2002 by the experiment stations of Idaho, Oregon, Washington, and North Dakota, and by the USDA/ARS.
It resulted from a 1980 cross of ND292-1 and A77268-4. Ivory Crisp is suited for use in both the direct delivery and storage chipping
markets. Ivory Crisp is a medium-maturing potato variety with round, white tubers and excellent chipping quality. It has medium
to high yield potential, high tuber solids, resistance to most internal and external tuber defects, and the ability to chip from cold storage. In
trials in Idaho, Oregon and Washington, total and U.S. No. 1 tuber yield of Ivory Crisp was similar to Atlantic but lower than Chipeta.
Yield of tubers in the size range 113-336 g for Ivory Crisp is higher than for either Atlantic of Chipeta. Ivory Crisp is resistant to growth
cracks. secondary growth, hollow heart, and stem-end necrosis, but susceptible to shatter bruise. Tuber sugar content has
consistently remained low following cold storage and near acceptable chip color retained at 4.4 C. Ivory Crisp is susceptible or moderately
susceptible to most common field diseases of potato. It is highly susceptible to common scab, powdery scab, and pink rot. Tubers of Ivory
Crisp have dry matter content (22.4%) lower than those Atlantic, but higher than those of Chipeta. Glycoalkaloid content of Ivory Crisp
tubers if very low (4.3 mg 100 g4. An application for Plant Variety Protection has been filed
for Ivory Crisp. Seed is available from potato seed growers in Idaho, North Dakota, and Canada. Small amounts of seed, for research
purposes, can be obtained by contacting the corresponding author.
Lynch, DR*, LM Kawchuk, R Yada and JD Armstrong. "Inheritance of the
response of fry color to low temperature storage." E-mail:
drlynch@telus.net [Vol. 80: No. 5, 341-344] (Short Communication)
Most commercial potato processing cultivars rapidly accumulate reducing sugars at storage temperatures below 10 C, producing an
unacceptably dark fried product. Development of cultivars with the ability to process with a light color out of 4 to 6 C storage is a major
breeding objective worldwide. Low temperature storage reduces the need for chemical sprout inhibitors and pesticides used to
control storage pathogens. The genetic control of the ability to fry out of cold storage temperature was studied in a diploid population and
in tetraploid breeding populations of the Western Canadian Potato Breeding Program. Based on the segregation ratios observed in the
study, a two-independent-loci genetic model is proposed with either homozygous recessive alleles or at least one dominant allele at both
loci required to ensure acceptable fry color out of low temperature storage.
Lynch, DR*, LM, Kawchuk, Q Chen and M Kokko. "Resistance to Fusarium sambucinum
in Wild and Cultivated Solanum Species." E-mail:
drlynch@telus.net [Vol. 80: No. 6, 353-358]
Several species of Fusarium cause both dry rot in storage and seedpiece decay in the field, which results in severe losses in
all major potato-growing regions. In temperate climates two Fusarium species are the principle causes of tuber dry rot–F.
sambucinum and F. coeruleum. Resistance to F. sambucinum was identified in cultivated and wild Solanum
species. Relatively high levels of resistance exist in the following 2EBN species: S. boliviense (PI#’s 265860, 310975, 310974,
545853, 545889, 545964), S. gourlayi ssp. gourlayi (PI#’s 473344, 545865), S. microdontum (PI#’s 310979,
473171), S. sancta-rosae (PI# 498392), S. kurtzianum (PI# 472930), S. fendleri ssp. fendleri (PI# 262895),
S. gandarillasii (PI#’s 265866, 283076), S. oplocense (PI# 498281) and S. vidaurrei (PI# 498332). The resistance
is highly heritable but appears, at least in some of the species, to be associated with recessive alleles.
Mauromicale, Giovanni*, Paolo Signorelli, Anita Ierna and Salvatore Foti. "Effects of intraspecific
competition on yield of early potato grown in Mediterranean environment."
E-mail:gmauromicale@yahoo.it [Vol. 80: No. 4, 281-288]
Since the environment of the Mediterranean regions allows offseason production, potatoes are planted in autumn-winter and
harvested in spring. During this period, potatoes are subjected to low temperatures and short day lengths which modify the grown
characteristics of plants. For this reason, our analysis of competition response was conducted to better clarify the biological relationship
between yield and plant density. Field trials were conducted in Sicily (south Italy), a highly representative area of early potato crop in the
Mediterranean Basin, with the aim of studying effects of intraspecific competition on tuber yield and yield components. Ten
planting densities (ranging from 3.0 to 8.0 plants m-2 were studied on cv. Spunta using
"tuber-pieces" with a different number of eyes (one eye or all the eyes in 1996; one eye, two eyes, or all the eyes in 1997).
Intraspecific competition reduced the tuber yield of individual plants, which became gradually less evident with increasing plant density.
Competition affected the number of tubers per plant in the lower plant populations only (from 3.0 to 5.8 plants m
-2, whereas effects on average tuber weight were at times more marked in the higher populations
(from 5.8 to 8.0 plants m-2 and at other times in the lower densities (from 3.0 to
5.8 plants m-2. As a consequence of increased plant density, and not withstanding
the higher intraspecific competition, the yield of tubers per unit area increased linearly. Regardless of the number of eyes per tuber-piece,
when passing from the lower to the higher plant density, yield increased from 34.0 to 54.1 t ha-1
in 1996 and from 39.9 to 56.7 ha-1in 1997.
Mills, Dallice* and Brian W Russell. "Parameters for specific detection of Clavibacter
michiganensis subsp. sepedonicus in potato stems and tubers by multiplexed PCR-ELISA.
E-mail: millsd@science.oregonstate.edu
[Vol. 80: No. 4, 223-234]
A multiplex PCR-ELISA protocol for detection of Clavibacter michiganensis subsp. sepedonicus (Cms) was
developed that is based on primers for amplification of three single-copy, unique DNA sequences, Cms50, Cms72, and Cms85. The
three sequences were simultaneously amplified from the genomes of all 42 strains of Cms that were tested including variant mucoid
forms, but not from strains representing five related subspecies, and Rathayibacter rathayi and Rhodococcus faciens.
The lowest limit of detection by gel electrophoresis was estimated to be approximately 300 CFU per mL when cells were spiked into
potato core fluid, but sensitivity increases approximately 10-fold using PCR-ELISA. Inclusion of a sea anemone DNA fragment
engineered so it would be amplified from the Cms72 primer set provided the simultaneous signal that the system functioned properly
when any sample was free of the pathogen. The addition of hydrolyzed casein to the reaction mix was demonstrated to markedly
reduce or eliminate inhibition of PCR by plant cell components or contaminants. Multiplex PCR-ELISA detection of Cms was determined to be
verifiable for analysis of both stems and tubers based on the amplification of multiple sites in its genome, it provides absolute
specificity, and it was more sensitive than detection based on gel electrophoresis of PCR products and serological approaches.
Mojtahedi, H*, RA Boydston, PE Thomas, JM Crosslin, GS Santo, E Riga, and TL Anderson. "Weed
Hosts of Paratrichodorus allius and Tobacco Rattle Virus in the Pacific Northwest." Email:
mojtahed@tricity.wsu.edu [Vol. 80: No. 6, 379-385 ]
The ability of several weed species to serve as hosts for tobacco rattle virus (TRV), the causal agent of corky ringspot disease of
potato (CRS), and its nematode vector, Paratrichodorus allius, was investigated in greenhouse studies. Viruliferous
P. allius multiplied on 24 out of 37 weed species tested, indicating they were suitable hosts of the vector. However, only 11
of these weeds were infected with TRV, as determined by ELISA. The nonhost status of a given weed species was not changed
whether the viruliferous vector population originated from CRS problem fields in WA, OR, or ID. Several weeds served as
hosts for the vector and virus including kochia, prickly lettuce, henbit, nightshade species(black, hairy, and cutleaf), common
chickweed, and annual sowthistle. Virus-free P. allius acquired TRV from the three nightshade species, volunteer potato
grown from TRV-infected tubers, and prickly lettuce, and subsequently transmitted the virus to Samsun NN tobacco indicator
plants. Thus, some weeds may play a role in the epidemiology of CRS by perpetuating TRV and its vector in a problem field.
Mollov, Dimitre S* and CA Thill. "Identifying PVY Asymptomatic Clones in 4x and 2x Breeding
Populations." (GSC, 86th Annual Mtg.) E-mail: moll0073@umn.edu [Vol. 80: No. 1, 74-75]
Seed potatoes having potato virus Y (PVY) exhibit reduced plant productivity and quality. It is required that a certified seed-potato crop
be rejected for exceeding virus thresholds. PVY can occur without detection during certification due to asymptomatic (PVYasym)
expression. The cultivars Shepody and Russet Norkotah (RN) are PVYasym and account for 20% of the seed acreage in the
US and Canada. This research focuses on PVYasym expression to determine: (1) if PVYasym clones could be
identified in 4x and 2x breeding populations, and (2) the utility of having PVYasym clones as parents in breeding. Four hundred
sixty four 2x and 4x clones were planted in an aphid-transmitted PVY disease nursery. Five populations, the first and second (C-Series)
having 96 2x and 91 4x-clones from 2x haploid species (HS) x (HS) crosses; the third and fourth (E and S-Series) having 81 and 80
4x-clones (cultivars x (multiple interspecific hybrids)); and the fifth 116 RN progeny (five half-sib families with RN as male), were screened
visually and by ELISA for disease expression and detection. Aphids were observed on all plants. Chi square indicated dependence
between ploidy (C-Series 2x vs. 4x) and PVYasym. Among the 90 2x and 75 4x clones having PVY 60% and 37.3% lacked
symptoms, respectively. Dependence was not found between disease expression and 4x progeny having similar pedigrees. ELISA tests
confirmed that 39 E and 15 S clones were PVY+ with 17.9% and 7% being PVYasym, respectively. As a breeding
parent RN contributed attractive tuber appearance and shape to its progeny. However, among the 69 RN progeny infected with PVY 27%
were PVYasym and had a range among the 5 families of 11 to 50%; no dependence between PVYasym
and RN families was found. These results provoke examining the inheritance of PVYasym expression and the breeding
behavior of this trait.
Nitzan, N and L Tsror (Lahkim)*. "Effect of temperature and pH on In Vitro growth
rate and sclerotial density of Colletotrichu coccodes isolates from different VCGs." E-mail:
tsror@volcani.agri.gov.il [Vol.
80: No. 5, 335-339]
(Short Communication)
The radical growth rate and sclerotial density of Colletotrichum coccodes isolates representing four major vegetative
compatibility groups (VCGs) were determined at three temperatures (21, 25, and 30 C) and three pH levels (pH 5, 6, and 7). This is the first
report indicating that C. coccodes isolates characterized to the same VCG share common physiological traits. The optimal
temperature for growth of isolates from all four VCGs was 25 C, except for VCG1 isolates, for which growth at 21 and 25 C was equivalent.
The growth rate of all isolates, of all VCG groups was deceased at 30 C, whereas sclerotia development was enhanced. The optimal pH
level for growth of all isolates was pH 6 and pH 7. Interactions between CGs and temperature or pH were observed in relation to
radial growth rate and sclerotia density. At 25 C, isolates from VCG1 and 2 demonstrated the most rapid growth rate. At 21 and 30 C, VCG1
isolates demonstrated the fastest growth compared with all over VCGs. In response to pH, VCG1 and 2 demonstrated the fastest growth
rates at all pH levels. VCG3 and 4 demonstrated the highest sclerotial density at 25 C and at pH 6; and VCG2 and 4 demonstrated the
highest sclerotial density at 30 C.
Nolte, P*, M Bertram, M Bateman and CS McIntosh. "Comparative Effects of Cut and Treated Seed
Tubers vs Untreated Whole Seed Tubers on Seed Decay, Rhizoctonia Stem Canker, Growth, and Yield of Russet Burbank
Potatoes." E-mail: pnolte@uidaho.edu
[Vol. 80: No. 1, 1-8]
Whole seed tubers have been reported to have performance advantages over seed tubers that have been cut, even if the cut tuber
pieces are treated with a fungicide dust. For this study, whole seed tubers were compared to cut seedpieces and to cut seedpieces
treated with four different commercial fungicide dusts for five consecutive seasons. A new field generation 3 Russet Burbank seed lot
was used for each of the five years of this study. Both whole tubers and cut seedpieces were inoculated with Fusarium spp., and
the seedpieces were then treated with a fungicide dust. Inoculated and uninnoculated untreated controls were also included. Emergence,
Fusarium seed decay, Rhizoctonia stem canker, stem numbers, and vigor, as well as yield and grade data were obtained.
Rhizoctonia stem canker in stems grown from whole seed tubers was significantly higher than in stems from seedpieces receiving
fungicide treatment in several of the study years. Predicting whole seed tuber performance is difficult because performance varies more
from year to year than performance of cut and treated seedpieces. Yield performance of whole seed tubers was not significantly better
than cut and fungicide-treated seedpieces in any experimental year, and yield of large (over 280 g) tubers was significantly less than
that recorded for two of the treatments when data from all five years were combined. This study demonstrated that untreated whole
seed did not outperform cut and treated seedpieces for vigor, stem numbers, disease ratings, or yield in small plot comparisons for
five consecutive seasons.
Novy, RG*, DL Corsini, SL Love, JJ Pavek, AR Mosley, SR James, DC Hane, CC Shock,
KA Rykbost, CR Brown and RE Thornton. "Alturas: A Multi-Purpose, Russet Potato Cultivar with High Yield and Tuber Specific
Gravity." E-mail: rnovy@uidaho.edu
[Vol. 80: No. 5, 295-301]
‘Alturas’, a late-maturing, high-yielding, russet potato cultivar with high tuber specific gravity, was released in 2002 by the USDA-ARS
and the Agricultural Experiment Stations of Idaho, Oregon, and Washington. Originally selected for dehydration processing, its
cold-sweetening resistance also makes it suitable for processing out of storage into french fries and other frozen potato products.
Culinary quality is high, with larger tubers suitable for fresh market if heavily russeted skin is not essential. Alturas consistently produced
greater total and U.S. No. 1 yields than ‘Russet Burbank’ and ‘Ranger Russet’ in southern Idaho trials. Across other western trial sites,
total yields of Alturas have on average been 29% and 14% greater than Russet Burbank and Ranger Russet, respectively. Alturas is
resistant to Verticillium wilt (Verticillium dahliae) and early blight (Alternaria solani). Compared with Russet Burbank
and Ranger Russet, Alturas is less susceptible to corky ringspot and foliar and tuber infection by late blight (Phytophthora infestans).
It also is less susceptible to tuber net necrosis and Fusarium dry rot than Russet Burbank, and is more resistant to common
scab (Streptomyces scabies) than Ranger Russet. However, Alturas is more susceptible to infection by PVY and PVX than Ranger
Russet. Total nitrogen application recommendations for Alturas are approximately 40% less than those for Russet Burbank. Alturas
requires 15% to 20% more water during the growing season than does Russet Burbank.
Olsen, Nora L*, Gale E Kleinkopf, and Lynn K Woodell. "Efficacy of Chlorine Dioxide for Disease
Control on Stored Potatoes." E-mail: norao@uidaho.edu
[Vol. 80: No. 6, 387-395 ]
The post-harvest application of chlorine dioxide (ClO2) was evaluated as a disease suppressant for stored potatoes.
Chlorine dioxide was prepared by acidifying a buffered sodium chlorite solution with a food grade acid. In vitro studies verified the
effectiveness of ClO2 at low concentrations (ED50 = 2 to 122 ppm) against Erwinia carotovora (soft rot),
Fusarium spp. (dry rot) and Helminthosporium solani (silver scurf). Evaluations of tubers inoculated with Phytophthora
infestans (late blight) and Fusarium spp. or infected with H. solani and then treated with ClO2 either
going into storage or through the humidification system resulted in a lack of disease suppression. Inconsistent performance of
ClO2 in storage appeared to be a result of several contributing factors. Chlorine dioxide concentrations varied greatly (up to
six-fold), depending upon the method of activating and diluting sodium chlorite solutions. Chlorine dioxide is a gas soluble in water and,
therefore, is easily released from solution (25%-75% loss) into the air when applied as an aqueous spray. Chlorine dioxide reacts
quickly with the tuber and associated organic matter, thereby reducing the effectiveness. Applying higher than currently registered
rates may be necessary to achieve measurable disease suppression.
Pérez, EE*, DP Weingartner, R McSorley and R Littell. "Estimates of Sample Size for Detection and
Estimation of Incidence and Severity of Corky Ringspot of Potato." E-mail: eperez@vt.edu
[Vol. 80: No. 1, 117-124]
A computer program was developed to simulate the random collection of tuber samples from potato fields with corky ringspot (CRS).
Tubers were harvested from 16 plots in the 1993-94 and 1994-95 seasons, and the incidence and severity of CRS symptoms were
assessed. Inputs for the program were number of healthy and CRS-affected tubers and severity tuber symptoms from each plot. The
output was the mean and the standard error of the mean of disease incidence and severity for 12 different sample sizes. Accuracy and
precision for each sample size were estimated to determine sample size. The sample size of 20 tubers was required to detect the
presence of CRS in research plots. The binomial distribution was used. With sample sizes greater than 20, the increase in accuracy and
precision leveled off regardless of disease incidence and severity values; therefore sample sizes greater than 20 may be unwarranted for
evaluation of chemical control tests.
Petersen, Mikael Agerlin*, Leif Poll and Lone Melchior Larsen. "Changes in Flavor-affecting Aroma
Compounds during Potato Storage Are Not Associated with Lipoxygenase Activity." E-mail:
map@kvl.dk [Vol. 80: No. 6, 397-402]
When potatoes are boiled and then chill-stored they rapidly develop off-flavor. This is a result of lipoxygenase activity, and is a serious
problem in food-service systems. Lipoxygenase activity may vary during winter-storage of potatoes. Raw potatoes of the variety ‘Bintje’ were
therefore analyzed for lipoxygenase activity during winter storage. Furthermore, content of potential off-flavors and typical potato aroma
compounds were determined in raw, boiled, and in boiled/chill-stored potatoes. Four months after harvest the lipoxygenase activity
started to increase, both when linoleic and linolenic acid were used as substrates. Production of typical oxidation products (aldehydes)
of these fatty acids that earlier have been shown to cause off-flavor in boiled/chill-stored potatoes did, however, decrease. It is therefore
concluded that this was not due to changes in lipoxygenase activity.
Posch, Danielle M* and CA Thill. "Yield and Quality of Clones Selected for Late Blight Resistance
Early in Breeding." (GSC, 86th Annual Mtg.)E-mail: posch006@umn.edu
[Vol. 80: No. 1, 75]
Traditionally (T) in breeding, single-hill progeny (SH) are advanced following visual selection in the 1st field generation
and disease evaluations are done later in cultivar development. Potato late blight (LB) disease is caused by the pathogen Phytophthora
infestans, which is attracting worldwide breeding attention due to its pathogenicity. If SH selection was performed in a LB nursery
greater progress for resistance may result. Nevertheless, selected clones must also have favorable yield and quality for acceptance as a
cultivar. Previous selection at 2 Minnesota field locations resulted in 114 clones (87-LB/SH and 27-T/SH). The objectives of this research
were to determine (1) the yield and quality performance, and (2) levels of LB resistance among clones selected in 2000 in comparison
to 14 variety standards. Clones were planted as 2-hill plots in a RCBD with 2 replications. The cultivar Norchip was planted adjacent to
each plot and inoculated with US-8 strain of P. infestans 60 DAP. Foliar disease was assessed biweekly using the CIP scale
(1=0% infection to 9=100%). At harvest, 95 DAP, tubers were weighed and counted and yield was calculated as gm/tuber (g/t). Overall,
T/SH clones had significantly higher total tuber weight and number than LB/SH clones at harvest and after 4 mo. storage. Fifteen clones
(10 LB/SH and 5 T/SH) exceeded a yield cull level of 157g/t (Russet Burbank). The LB/SH clones had a significantly lower area under the
disease progress curve (AUDPC) than T/SH. Sixty-eight LB/SH and 8 T/SH clones had a lower AUDPC than Atzimba (700, partially resistant).
A selection index was developed to identify clones having acceptable yield and AUDPC. Using previously established cull levels 46 clones
performed favorably.
Pruski, K*, T Astatkie, P Duplessis, L Stewart, J Nowak and PC Struik. "Manipulation of microtubers
for direct field utilization in seed production." E-mail:
kpruski@nsac.ns.ca
[Vol. 80: No. 3, 173-181]
A two-year field study was conducted to determine the effects of jasmonic acid (JA), light (during in vitro explant production and
in vitro tuberization phases), and dormancy-bearing treatment on performance of microtubers in the production of seed tubers
(pre-elite) in five potato cultivars. Microtubers were produced under short day (8-h) conditions and in darkness, from stock plantlets
pre-treated with JA. Microtuber performance was compared to in vitro plantlets transplanted directly to the field. Yields
of tubers from microtubers were 30% to 40% of those from plantlets. Microtubers of cultivars Amisk and Russet Burbank produced the
highest yields of pre-elite tubers. Atlantic microtubers performed poorly in the field. JA pre-treatment of stock plantlets, prior to
in vitro tuberization, enhanced seeds tuber production from microtubers in Russet Burbank and lowered in Shepody. JA
presence in media during in vitro tuberization significantly lowered production of tubers while exposed to 8-h light resulted in
microtubers performing significantly better in the field than microtubers produced in the dark. Dormancy release was the key factor
influencing microtuber performance. Unlike greenhouse studies, gibberellic acid (GA3 was
more effective than Rindite. A further refinement of the production and handling methods is required before microtubers can be
recommended for field production of seed tubers.
Pruski, K*, T Astatkie, P Duplessis, T Lewis, J Nowak and PC Struik. "Use of Jasmonate for
conditioning of potato plantlets and microtubers in greenhouse production of minitubers."
E-mail: kpruski@nsac.ns.ca [Vol. 80: No. 3, 183-193]
A two-year study was conducted to determine the effects of (1) jasmonic cid (JA) pre-treatment, (2) JA supplement in culture
media, (3) cultivar (Amisk, Atlantic, Russet Burbank, Shepody, and Umatilla Russet), (4) light (0 h, 8 h), and (5) dormancy breaking
treatment (Rindite, gibberellic acid) on greenhouse production of minitubers from microtubers in in vitro plantlets. The microtubers
were produced under short day (8 h) light conditions and in darkness, from stock plantlets pre-treated with JA and untreated, and on
tuberization media with or without JA. In vitro plantlets (the industry choice in nuclear seed potato production) of all five
cultivars performed well, meeting the standard criteria for greenhouse production of minitubers. Production of minitubers from
microtuber-derived plants of cvs Amisk, Russet Burbank, and Umatilla Russet was similar to that of plantlet-derived plants with regard to
number of minitubers. Yields (weight), however; were lower than those from plantlets. Microtuber responses to JA varied with cultivar.
Amisk produced the highest number of minitubers per plow from microtubers derived from JA pre-treated plantlets. Jasmonic
acid-pretreated microtubers also gave significantly more minitubers in Russet Burbank and Umatilla Russet than the microtubers from
other treatments. Shepody did not benefit from JA treatments and JA pre-treated Atlantic microtubers performed poorly, producing
significantly lower yields of minitubers than other cultivars. Independently of cultivar, microtubers produced under 8-h photoperiod gave
significantly higher yields of minitubers than microtubers produced in the dark. Dormancy release was the key factor influencing
microtuber performance. Rindite proved to be a much more effective dormancy breaking treatment than gibberellin. JA conditioning of
stock plants prior to tuberization is being proposed as a treatment in production of microtubers for greenhouse production of minitubers.
Reyes, Luis Fernando*, Luis Cisneros-Zevallos, J Creighton Miller, Jr. "Red/Purple-Flesh Potatoes:
A Potential Source of Natural Colorants and Antioxidants for the Food Industry."
(GSC, 86th Annual Mtg.) E-mail: luisfer_reyes@yahoo.com
[Vol. 80: No. 1, 75]
Anthocyanins are natural pigments responsible for red and blue colors observed in plants. The inherent antioxidant activity of
anthocyanins enhances the nutritional and commercial value of red/purple potatoes by offering a source of natural colorants with added
functional properties. The overall objective of this study was to assess the potential use of red/purple potatoes as a source of natural
colorants by determining the influence of several factors on the yield and stability of anthocyanin extracts from potato tubers.
Spectrophotometric methods were used to quantify anthocyanins, phenolic compounds and changes in antioxidant activity during tuber
development. The color stability of the anthocyanin extracts during storage was also determined. A two-year study with several
red/purple potato cultivars grown in Texas and Colorado showed decreased phytochemical content with increased tuber mass, but
this increase in tuber mass resulted in higher phytochemical yields per tuber. Seed source, planting site and year influenced phytochemical
accumulation. Anthocyanin yields from Colorado-grown tubers averaged 26 kg/ha, which was 2.5 times that of the same cultivars harvested
in Texas. Red potato extracts were more stable than purple potato extracts. Data on the yield and color attributes of tuber extracts
suggest that red/purple potatoes could be used by the food industry as a colorant source that is natural and alleviates concerns of
health-conscious consumers on the consumption of synthetic colorants and antioxidants.
Rykbost, KA*, SR James, AR Mosley, BA Charlton, DC Hane, CC Shock, E Eldredge, R Voss, RH Johansen,
SL Love and RE Thornton. "Modoc: a potato variety with bright red skin and early maturity for fresh market." E-mail:
kenneth.rykbost@oregonstate.edu [Vol. 80: No. 4, 235-240]
Modoc is an early maturing, red-skinned, white-fleshed potato cultivar for fresh market use. The Agricultural Experiment Stations of
Oregon, North Dakota, California, Idaho, and Washington jointly released Modoc in 2003. Modoc was derived from a 1989 cross of
ND1196-2R and ND2225-1R performed at North Dakota State University. Modoc retains bright skin color in storage and is suited for
marketing directly from the field or storage. It produces slightly lower total yield than Red LaSoda or Dark Red Norland, but higher marketable
yield and more desirable tuber size and shape. Modoc tubers seldom exhibit growth cracks, secondary growth, hollow heart or other
external or internal defects. Dry matter content of Modoc tubers is similar to Dark Red Norland and Red LaSoda (18.9% compared to
18.8% and 17.7%, respectively). Culinary quality of Modoc was rated equal to Dark Red Norland and Red LaSoda for boiling and
microwaving preparation methods. Modoc tubers are similar to standard varieties in sugar, vitamin C, and glycoalkaloid (4.5 mg/100 g)
concentration. Modoc foliage clearly expresses PVY symptoms and has not demonstrated high susceptibility to viral or fungal diseases
during a decade of seed production and evaluation.
Suttle, Jeffrey C. "Auxin-induced sprout growth inhibition: Role of endogenous
ethylene." E-mail: suttlej@fargo.ars.usda.gov [Vol.
80: No. 5, 303-309]
The role of endogenous ethylene in auxin-medicated tuber sprout growth inhibition was determined in potato (Solanum
tuberosum L. cv. Russet Burbank) minitubers. Treatment of tubers with biologically active auxins resulted in a transient,
dose-dependent increase in ethylene production and inhibition of sprout growth. Biologically inactive auxin analogs elicited neither
response. Continuous exposure to > 0.001 µL L-1 exogenous ethylene inhibited sprout growth in a dose-dependent
manner with complete inhibition occurring at ethylene concentrations >/- 1 µL L-1. In further studies with the active
auxin (a-naphthalene acetic acid (NAA), the role of ethylene in auxin-induced sprout growth inhibition was determined using ethylene
biosynthesis and action inhibitors. The ethylene biosynthesis inhibitor amino-ethoxyvinylglycine reduced NAA-induced ethylene
biosynthesis by over 80% but had no effect on sprout growth inhibition. The non-competitive ethylene action inhibitor silver thiosulfate
had no effect on NAA-induced sprout inhibition. Similarly, both the competitive ethylene action inhibitor 2,5-norbornadiene and the
irreversible action inhibitor 1-methylcyclopropene were ineffective in reduce NAA-mediated sprout growth inhibition. Collectively,
these results do not support the proposal that, in the case of potato tuber sprouts, auxin-induced growth inhibition is mediated by
endogenous ethylene action.
Vega, Sandra E, Alfonso H. del Rio, Geunhwa Jung, John B. Bamberg and Jiwan P. Palta*.
"Marker-assisted Genetic Analysis of Non-acclimated Freezing Tolerance and Cold Acclimation Capacity in a Backcross
Solanum Population." E-mail: jppalta@wisc.edu
[Vol. 80: No. 6, 359-369 ]
Random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers were used to construct a partial
genetic linkage map in a potato backcross population. The population, derived from two diploid wild Solanum species (frost tolerant,
able to cold acclimate S. commersonii; frost sensitive, unable to cold acclimate S. cardiophyllum), was used to map
quantitative trait loci (QTL) of non-acclimated relative freezing tolerance (NARFT) and cold acclimation capacity (CAC). Precise
assessment of these traits allowed distinction of small but significant differences among 35 backcross genotypes. NARFT and CAC were
not correlated in the segregating population, suggesting independent genetic control for these two major components of freezing tolerance.
The linkage map spanned 479.4 cM and included 77 RAPD markers and two SSR markers, with 38 RAPD and 10 SSR unassigned
markers. Two QTLs for NARFT were detected in two different linkage groups, accounting for 44.0% of the phenotypic variation for this trait.
Two QTLs for CAC were detected, accounting for 24.9% of the phenotypic variation for this trait. QTLs for NARFT and CAC were detected
at separate genomic regions, in support of the independent genetic control of these two traits. QTLs for NARFT and CAC were detected
in a linkage group identified as part of chromosome V, suggesting that such chromosome constitutes a prime candidate for fine-mapping.
Due to the relatively small progeny size evaluated in this study, additional QTLs for NARFT and CAC could have been involved but not
identified. Therefore, the conclusions derived from this study should be considered preliminary.
Young, Robin L* and Martin G Scanlon. " Effect of Blanching Conditions and Starch Swelling
Properties on Textural Changes in Processed Potatoes." (GSC, 86th Annual Mtg.)
[Vol. 80: No. 1, 75-76]
Understanding the relationships between raw material properties and how those raw materials should be optimally processed is
vital for enhanced utilization of potatoes. Our objective was to investigate the effect of starch swelling properties on the textural response
of processed potatoes. Potatoes of high and low solids content (starch) were selected from a batch of tubers. Excoriated and whole potato
cylinders were prepared and half were subjected to hypertonic mannitol treatment (to remove water form potato cells). Three blanching
conditions were selected: standard, low temperature long time (LTLT) and high temperature short time (HTST). After blanching the textural
response modulus of the cylinders was measured in compression. Hunterlab L (lightness) value of the resulting french fries was also
monitored. French fries blanched under standard conditions had large L values, while those blanched under LTLT and HTST conditions
had similar L values. Modulus values of excoriated cylinders were substantially lower than would be expected form a simple reduction
in the cylinders’ cross-sectional area. For fresh potatoes, the moduli for whole potato cylinders blanched by LTLT conditions were
smaller than those blanched by HTST and standard conditions, while the moduli for cylinders excised from potatoes with lower starch
contents were larger than those of a higher starch content. In contrast, removing water with mannitol prior to processing essentially
eliminated textural differences between processing treatments and starch contents. The interaction between free water, starch content
and the chosen processing regime and its effect on measured texture illustrates that starch swelling pressure plays a significant role in
french fry texture. Blanching conditions should be adjusted for tuber solids content in order to optimize texture as well as to improve fry
colour.
Zhang, R*, BJ Christ and KG Haynes. "Mapping Early Blight Resistance in a Diploid Hybrid Potato
Population of Solanum phureja X S. stenotomum." (GSC, 86th Annual Mtg.)
E-mail: rxz124@psu.edu
[Vol. 80: No. 1, 76]
Early blight, caused by Alternaria solani is an important potato disease worldwide. Currently, fungicides are used to manage
early blight since no commercial cultivar has high levels of resistance. A diploid hybrid F1 population from S. phureja X
S. stenotomum was evaluated for early blight resistance over three years. The field experiments were in a randomized complete
block design with either 2 or 3 replications. Disease severities were assessed for each plot throughout the development of the epidemic,
and area under disease progress curve (AUDPC) values were calculated. The data were analyzed using PROC MIX in SAS®.
There were significant differences among the F1 clones for AUDPC. Based on the distribution of AUDPC values, resistance to early blight
appears to be inherited quantitatively. There were significant clone X year X interactions. Further partitioning of the clone X year interaction
revealed that 74 out of 219 clones made significant contributions to this interaction. Broad-sense heritability in this population was
estimated as 0.77 with a 95% confidence interval of 0.71 to 0.82. Amplified fragment length polymorphism (AFLP) and restriction fragment
length polymorphisms (RFLP) markers were used to construct the linkage groups which are being aligned to the 12 potato chromosomes.
Quantitative trait loci (QTL) associated with the early blight resistance will be mapped on these two parental chromosomes. This will
improve our understanding of the disease resistance and facilitate our breeding program for the durable resistance against early blight
through marker-assisted selection (MAS).