Showing papers in "American Journal of Potato Research in 2012"
TL;DR: All commercial potato cultivars appear to be susceptible to ZC, and management tactics targeted against the potato psyllid are currently the only means to effectively manage the disease.
Abstract: Zebra chip (ZC), a new and economically important disease of potato (Solanum tuberosum L.), has been documented to occur in commercial potato fields in the United States, Mexico, Central America, and New Zealand. This disease has caused millions of dollars in losses to the potato industry. Whole crops might be rejected because of ZC, often leading to abandonment of entire fields. Plant growth and yield are severely affected by the disease. Additionally, chips or fries processed from ZC-infected tubers exhibit dark stripes that become markedly more visible with frying, and hence are commercially unacceptable. The disease causes serious losses to the fresh market, tablestock and export potato industry as well. ZC-infected tubers usually do not sprout and if they do, produce hair sprouts or weak plants. Finally, there are indications that ZC symptoms might develop in tubers during storage. ZC has been associated with a previously undescribed species of liberibacter, tentatively named “Candidatus Liberibacter solanacearum”, also known as “Ca. L. psyllaurous”. The bacterium is transmitted to potato by the potato psyllid, Bactericera cockerelli (Sulc). All commercial potato cultivars appear to be susceptible to ZC, and management tactics targeted against the potato psyllid are currently the only means to effectively manage the disease. Furthermore, there are concerns about quarantine and trade issues in psyllid-affected regions because some countries may require that shipments of potatoes from certain growing regions be tested for the disease before the shipments are allowed entry. ZC history, geographic distribution, biology, epidemiology, and management are discussed herein.
232 citations
TL;DR: It is concluded that positive selection can benefit all smallholder potato producers who at some stage select seed potatoes from their own fields, and should thus be incorporated routinely in agricultural extension efforts.
Abstract: Selecting seed potatoes from healthy-looking mother plants (positive selection) was compared with common Kenyan farmer practice of selection from the harvested bulk of potatoes (farmer selection) in 23 farmer-managed trials. Positive selection assured lower incidences of PLRV (39%), PVY (35%) and PVX (35%). Positive selection out-yielded farmer selection irrespective of the agro-ecology, crop management, soil fertility, variety and quality of the starter seed, with an overall average of 30%. Regression analysis showed a relation between lower virus incidence and higher yield for the varieties. The paper discusses the consequences for seed system management in African countries. Furthermore possible additional effects of positive selection are discussed and further research is suggested. The paper concludes that positive selection can benefit all smallholder potato producers who at some stage select seed potatoes from their own fields, and should thus be incorporated routinely in agricultural extension efforts.
58 citations
TL;DR: A high proportion of accessions combining low drought susceptibility and high irrigated yield were found in Andean landraces, and particularly in the species Solanum curtilobum Juz, which exhibited the lowest average values and highest variation for drought susceptibility.
Abstract: Potato production worldwide is strongly affected by water stress, either because of insufficient rainfall or due to inadequate irrigation. Improving drought tolerance is consequently becoming a priority for potato breeders, particularly in the perspective of climate change. In the present study, a set of 918 accessions from CIP world potato collection was evaluated under field conditions with full irrigation and deficit irrigation, on the desertic coast of Peru. The set included improved varieties, genetic stocks and landraces. The subset of landraces comprised accessions from the species Solanum ajanhuiri Juz. & Bukasov, Solanum curtilobum Juz. & Bukasov, Solanum juzepczukii Bukasov and Solanum tuberosum L. S. tuberosum L. included non Andean accessions of the ssp. Chilotanum as well as accessions belonging to the Andean cultivar groups Andigenum, Chaucha, Goniocalyx, Phureja and Stenotomum. Under both drought and irrigated treatments, significant differences were found for tuber yield, tuber number and tuber weight among subsets, cultivar groups and accessions. On average, improved varieties and advanced bred lines yielded more under both deficit and well-irrigated conditions than did landraces, while variation for drought susceptibility was greater in landraces and genetic stocks than in improved varieties. Within the subset of landraces, the species Solanum juzepczukii Bukasov exhibited the lowest average values and highest variation for drought susceptibility. A high proportion of accessions combining low drought susceptibility and high irrigated yield were found in Andean landraces, and particularly in the species Solanum curtilobum Juz. & Bukasov in the S. tuberosum L. cultivar groups Stenotomum, Andigenum and Chaucha. The differences observed among species and cultivar groups were not directly related to their eco-geographic distribution. The polyploid species and cultivars groups appeared more drought tolerant than the diploid ones. The study evidenced the interest of Andean landraces as potential sources of drought tolerance in potato breeding programs.
52 citations
TL;DR: How rapidly ZC symptoms develop in potato tubers following plant exposure to liberibacter-infective potato psyllids and how the disease affects the overall potato yield and tuber processing quality over time will assist potato producers make harvest timing decisions following infestations of potatoPsyllids in their fields to minimize damage caused by ZC.
Abstract: Zebra chip (ZC), a new and serious disease of potatoes, has caused millions of dollars in losses to the potato industry in the United States, Mexico, Central America, and New Zealand. The disease has been associated with the bacterium “Candidatus Liberibacter solanacearum” transmitted to potato by the potato psyllid, Bactericera cockerelli (Sulc). The most characteristic symptoms of ZC develop in potato tubers and include browning of vascular tissue concomitant with necrotic flecking of internal tissues and streaking of the medullary ray tissues, all of which can affect the entire tuber. Upon tuber frying, these symptoms become more pronounced and potato chips or fries processed from ZC-affected tubers show very dark blotches, stripes, or streaks, rendering them commercially unacceptable. Field experiments were conducted to determine how rapidly ZC symptoms develop in potato tubers following plant exposure to liberibacter-infective potato psyllids and to assess how the disease affects the overall potato yield and tuber processing quality over time. Results indicated that ZC symptoms developed in potato tubers 3 weeks following plant exposure to psyllids. Tuber development ceased upon the onset of ZC symptoms, resulting in substantial yield loss. Levels of tuber solids decreased as soon as initial disease symptoms were observed. In contrast, reducing sugar levels in tubers increased dramatically upon the onset of ZC symptoms, significantly affecting potato processing quality. This information, in combination with effective psyllid monitoring and control, will assist potato producers make harvest timing decisions following infestations of potato psyllids in their fields to minimize damage caused by ZC.
45 citations
TL;DR: The amount of genetic variation for micronutrient content in potato germplasm is large, suggesting that the micronUTrient content of potatoes can be improved through breeding, and biofortification of potato production in developing countries may be feasible.
Abstract: Micronutrients are crucial to healthy growth and development, yet a large proportion of the world’s population suffers from micronutrient deficiencies. Biofortification of staple foods has tremendous potential to alleviate these deficiencies. Potato production in developing countries is increasing rapidly, and therefore, biofortification of potatoes for essential micronutrients may be feasible. The purpose of this study was to determine the amount of genetic variation for micronutrient content in potato germplasm. Eighteen potato clones, consisting of ‘Atlantic’ and 17 4x-2x hybrids between S. tuberosum and diploid hybrids of S. phureja-S. stenotomum, were grown in three locations (NC, VA, NJ) 2 years (2001, 2002). Samples of tuber tissue were analyzed for copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn). There were significant differences among clones for Cu, Fe, Mn and Zn. Clone x environment interactions were significant for Cu and Zn. Broad-sense heritability and its 95 % confidence interval for Cu was 0.65 (0.50–0.89); Fe was 0.49 (0.27–0.84); Mn was 0.84 (0.82–0.96); and Zn was 0.82 (0.73–0.94). Genetic variation for these four micronutrients is large, suggesting that the micronutrient content of potatoes can be improved through breeding.
45 citations
TL;DR: Saikai 35 is being released as a breeding line, which can confer efficiently PCN and PVY resistance genes, and is particularly useful for having Solanum phureja-derived cytoplasm (S/ε), which resulted in high male and female fertility.
Abstract: Saikai 35 was bred from a cross between TD0101 as the female, which was created by chromosome-doubling of a good-tasting and bacterial wilt resistant diploid variety, Inca-no-mezame, and Sakurafubuki as the male, the latter of which has H1 and Rychc genes showing resistance to potato cyst nematode (PCN) and Potato virus Y (PVY), respectively. All favorable traits were combined into Saikai 35, although marketable yield in the spring cropping was 20.4–21.0% lower than those of major double-cropping varieties. Saikai 35 is particularly useful for having Solanum phureja-derived cytoplasm (S/e), which resulted in high male and female fertility. In addition, sets of very tightly linked DNA markers sandwiching H1 and Rychc are available. Therefore, Saikai 35 is being released as a breeding line, which can confer efficiently PCN and PVY resistance genes.
39 citations
TL;DR: It is estimated that the production of cultivar Criolla Colombia will be reduced by ~130 g/plant when 10 % of the plants show PYVD symptoms in a plot, and called for urgent action to improve the number of growers that use certified potato tubers in Colombia.
Abstract: Potato vein yellow virus (PYVV) causes vein yellowing in Solanum tuberosum (PYVD). Yield reduction due to PYVV has been studied for Andigena but not for Phureja varieties. Cultivar Criolla Colombia is important as a native gourmet potato and corresponds to 11 % of the national potato production. The objective of this work was to assess the effect of PYVV on the potato production of cultivar Criolla Colombia (Group Phureja), in Cundinamarca-Colombia. The yield of 12 plots of 120 plants each, comprising 6 % to 27 % symptomatic (S) plants, was compared to 4 plots with symptomless plants (NS). At the end of the planting season the yield per plot was measured. A linear relationship was found between the number of S plants per plot and its yield (average weight of tubers per plant). It is estimated that the production will be reduced by ~130 g/plant when 10 % of the plants show PYVD symptoms in a plot. When the potato production per plant (g) of S versus NS plants was compared in two different consecutive trials, reductions of 33 % and 48 % were found in plants with PYVD, where the average production of NS plants was 1,095 +/−225 g/plant and 628 +/−169 g/plant in first and second trials respectively. The average number of tubers per plant was also reduced in S versus NS plants, in 48 % and 57 %, where the average number of tubers produced by NS plants was 38 and 33 in the two experiments. The yield differences between the two trials are attributed to changes in environmental conditions. Only those plants that expressed PYVD presented reduction in the number of tubers. We call for urgent action to improve the number of growers that use certified potato tubers in Colombia.
33 citations
TL;DR: In this paper, a new algorithm has been developed to determine nitrogen requirement (NR) applying critical N dilution curve (Nc) for processing potato under the growing conditions of the Argentinean Humid Pampas.
Abstract: For processing potato, a new algorithm has been developed to determine nitrogen (N) requirement (NR) applying critical N dilution curve (Nc). The objectives of this work were i) to determine the Nc for processing potato under the growing conditions of the Argentinean Humid Pampas; ii) to compare the parameters of the Nc with those of the Nc obtained by other authors, and iii) to establish the crop NR. The experiments were carried out during four growing seasons. The cultivar Innovator was planted in a randomized complete block design with four N treatments. Dry matter yield and N concentration of shoots and tubers were measured during the growing season. The Nc was determined by selecting data points for which the highest total biomass (W), comprised of shoots and tubers, was obtained and by expressing N concentration as function of W. The N nutrition index (NNI) was determined as the ratio between the actual N concentration (Na) and the Nc. The NR was determined as the difference between actual N uptake and the critical N uptake, divided the N utilization efficiency. A fitted Nc (Nc = 5.30 W–0.42, R2 = 0.92) presented similar values than a published reference Nc. The relation between relative tuber yield (RY) and NNI was expressed by a linear-plateau function and accounted for 69% of the variation. For a NNI ≥ 1 the RY was near 98.7%. With decreasing NNI below 1 the RY decreased. The relation between RY and NR was expressed by a linear-plateau function and accounted for 66% of the variation. For a NR ≥ 0 the RY was near 98%. With decreasing NR, below 0, the RY decreased. Furthermore, the NNI increased linearly with increasing NR, which indicates that the NNI was 0.99 when NR was zero. This study has shown that Nc can be applied in potato crop systems. The NNI calculated from that curve is a reliable indicator of the N stress level during potato’s growing season. The critical N uptake and the actual N uptake enable the calculation of crop NR.
30 citations
TL;DR: In total, 154 accessions of wild potato species from VIR’s potato collection were screened at IHAR-PIB Młochów Research Center (Poland) for resistance to Phytophthora infestans and, a part of them, for resistencia to Potato Virus X and Potato Virus Y (PVY).
Abstract: In total, 154 accessions of wild potato species from VIR’s potato collection were screened at IHAR-PIB Mlochow Research Center (Poland) for resistance to Phytophthora infestans and, a part of them, for resistance to Potato Virus X (PVX) and Potato Virus Y (PVY). High levels of leaf resistance to P. infestans were found in the accessions of Central American species S. antipovichii Buk., S. cardiophyllum Lindl., S. demissum Lindl., S. guerreroense Corr., S. neoantipovichii Buk., S. papita Rydb., S. pinnatisectum Dun., S. polytrichon Rydb., S. stoloniferum Schlechtd., and S. verrucosum Schlechtd., as well as South-American species S. berthaultii Haw., S. microdontum Bitt., S. ruiz-ceballosii Card., S. simplicifolium Bitt., and S. vernei Bitt. et Wittm. Tuber resistance was found in the accessions of Central American species S. cardiophyllum, S. neoantipovichii, S. papita, S. polytrichon, S. pinnatisectum, and S. trifidum Corr., and of South-American species S. acaule Bitt., S. berthaultii Hawk., S. kurtzianum Bitt. et Wittm. and S. ruiz-ceballosii Card. The majority of the accessions were characterized by within population variation of leaf and tuber resistance to late blight under laboratory testing conditions. A few accessions of S. demissum, S. guerreroense Corr., S. neoantipovichii and S. stoloniferum expressed combined resistance to late blight, PVX and two or three strains of PVY.
29 citations
TL;DR: The data obtained suggested that testing with more than one PVYN serotype-specific MAb could assure a reliable serological identification of a PVYN or PVYNTN isolate, and possible selection for substitutions in corresponding epitopes leading to the loss of reactivity towards these antibodies.
Abstract: Potato virus Y (PVY) is an important viral pathogen of potato responsible for reducing tuber yield and quality across the globe. The PVYN and PVYNTN strains, the latter of which induces potato tuber necrotic ringspot disease (PTNRD), are regulated for international potato trade, and have been routinely detected using monoclonal antibodies (MAbs) that discriminate between PVYN and PVYO serotypes. Here, we identify the distinct binding sites in the capsid protein of PVY for three of the four main PVYN-specific MAbs, Bioreba-N, SASA-N, and Neogen-N, available commercially. These binding domains were mapped through a combination of TAS-ELISA testing of MAbs on multiple reference isolates of PVY, sequence analysis, heterologous expression of capsid protein fragments, and synthetic peptide binding experiments. All three MAbs were found to bind linear epitopes located within the first 31 N-terminal amino acids of the capsid protein. Bioreba-N MAb epitope spanned aa 1-17 and included three positions, aa 1, aa 11, and aa 17, which differ between PVYN and PVYO serotypes. Both SASA-N and Neogen-N epitopes spanned aa 22-30, and included two positions, aa 24 and aa 29, which differ between PVYN and PVYO serotypes. Epitopes for SASA-N and Neogen-N MAbs are likely to be identical or overlapping. Examination of available sequences for tuber necrotic isolates of PVY that do not react with PVYN-specific MAbs SASA-N and Neogen-N indicated possible selection for substitutions in corresponding epitopes leading to the loss of reactivity towards these antibodies. The data obtained suggested that testing with more than one PVYN serotype-specific MAb could assure a reliable serological identification of a PVYN or PVYNTN isolate.
26 citations
TL;DR: In this paper, the authors used a value chain framework, FAO times-series data and a review of the literature to estimate and then interpret growth rates for the different uses of potatoes in China over the last five decades.
Abstract: China is not only the world’s largest producer of potatoes, but also its largest consumer. This article uses a value chain framework, FAO times-series data and a review of the literature to estimate and then interpret growth rates for the different uses of potatoes in China over the last five decades. It singles out changes in government policy, production, per capita incomes, and consumer tastes and preferences to explain the rise in consumption of potatoes as food and the decline in their use as feed. The paper also notes the negligible importance of imports as a percentage of the total volume of potatoes consumed and the emerging influence of various private sector initiatives before reassessing past projections of future utilization levels. It concludes by highlighting opportunities for industry and identifying some key topics for future research.
TL;DR: The objective of this study was to isolate and characterize genera of bacteria that had been identified as being the most common residents in the rhizosphere of potato using cpn60 pyrosequencing analysis and gain a better understanding of the biological activities of the most abundant bacterial species in therhizosphere and rhizoplane of a cultivated crop.
Abstract: The objective of this study was to isolate and characterize genera of bacteria that had been identified as being the most common residents in the rhizosphere of potato using cpn60 pyrosequencing analysis. Using various semi-selective media targeted to specific genera of interest, 200 isolates of bacteria were collected from rhizosphere soil and the rhizoplane of potatoes grown in soils obtained from a potato farm in Prince Edward Island and Ontario. The procedures employed were successful in selecting out representative bacteria suggested by pyrosequencing to be common in the potato rhizoplane. Results of 16S rRNA sequencing showed that 44 % of the isolates represented new species. All isolates were tested for biological and biochemical activities including phosphate solubilization, phytohormone metabolism, nitrogen fixation, antibiosis, exoenzyme production, and production of acyl-homoserine lactones. Massilia spp. and Chryseobacterium spp. showed the strongest exoenzyme activities. A greater proportion of Agrobacterium tumefaciens rhizosphere strains produced acyl-homoserine lactones compared to rhizoplane strains. Pseudomonas spp. and Lysobacter capsici had the greatest antagonistic activity on laboratory media towards six potato pathogens, and also significantly decreased disease in plants grown in pathogen-infested soil. Four isolates significantly increased growth of potato nodal explants in tissue culture. By using preliminary results derived from next generation sequencing technology and a targeted cultural technique, we were able to gain a better understanding of the biological activities of the most abundant bacterial species in the rhizosphere and rhizoplane of a cultivated crop.
TL;DR: To determine if genetic variation exists among advanced potato breeding clones for tuber calcium and magnesium content and the extent of genotype x environment interactions on these two traits, trials were evaluated in the Tri-State, Western Regional, and Western Regional Red/Specialty Trials.
Abstract: Calcium and magnesium are two minerals that play prominent roles in animal and plant metabolism. The purpose of this study was to determine if genetic variation exists among advanced potato breeding clones for tuber calcium and magnesium content and the extent of genotype x environment interactions on these two traits. Ten, 13, and 13 clones were evaluated in the Tri-State, Western Regional, and Western Regional Red/Specialty Trials, respectively. Tuber calcium content ranged from 266 to 944 μg-g−1 DW; magnesium from 787 to 1,089 μg-g−1 DW. Genotype x environment interactions were significant in all trials. However, only the Tri-State for calcium and the Western Regional Red/Specialty trials for both minerals displayed a significant source of variation for genotypes. Broad-sense heritabilities for tuber calcium content were 0.65, 0.37 and 0 in the Tri-State, Western Regional, and Western Regional Red/Specialty Trials, respectively. Broad-sense heritabilities for tuber magnesium content were 0.57, 0, and 0.72 in the Tri-State, Western Regional, and Western Regional Red/Specialty Trials, respectively. Potato is not a rich source of either calcium or magnesium for the human diet, but genetic variation exists among potato clones that might be useful for plant health.
TL;DR: In this article, the expression of genes in leaf tissue of greenhouse-grown potatoes to the form of N supplied in the context of development of a diagnostic tool for detection of N status was examined.
Abstract: This study examined the expression of genes in leaf tissue of greenhouse-grown potatoes to the form of N supplied in the context of development of a diagnostic tool for detection of N status. Potato cultivar ‘Shepody’ was grown over a two-week period at three stages of growth (tuber initiation, flowering and early tuber bulking) with three forms of N (NO3− only, NH4+ only, or 1:1 NO3−:NH4+) at two levels of N supply (0.75 or 7.5 mM). Leaf disks were collected and extracted for RNA, and 28 genes examined for expression using nCounter. Expression of ammonium transporter AT1 was increased when the N supply was reduced, regardless of N form, and was generally independent of growth stage. Expression of AT1 was less influenced by N form than currently used chemical or optical measures of plant N status. Expression of AT1 can be used as a quantitative indicator for plant N status of potato regardless of nitrogen form and crop growth stage.
TL;DR: Identification of quantitative trait loci responsible for stress tolerance could help to develop new tolerant potato cultivars through markers-assisted selection and ayudar a desarrollar nuevas variedades of papa tolerantes mediante selección asistida by marcadores.
Abstract: Identification of quantitative trait loci (QTL) responsible for stress tolerance could help to develop new tolerant potato cultivars through markers-assisted selection. The objective of the research was to identify and map loci that may play major role in the control of osmotic stress tolerance in potato under in vitro vegetative growth conditions. Mannitol-induced osmotic stress response of cv. White Lady and breeding line S440 as well as their 85F1 progeny for root number and root length under in vitro conditions was investigated. Interval mapping based on 200 informative markers produced a molecular marker map comprising 13 linkage groups for White Lady and 14 for S440. In total, 14 QTLs with LOD > 2 were identified from which 6 were confirmed as major QTLs. Of those six, three were associated with root length and three with root number. For root length, one major QTL was identified on chromosome XII (LOD = 4.8), which explained 52.3 % of the phenotypic variance. Two other major QTLs from an unidentified chromosome explained 64.9 and 51 % of the phenotypic variance with LODs of 5.34 and 4.8, respectively. For root number, one QTL with 19.2 % of the phenotypic variance (LOD of 2.9) was tentatively identified on chromosome IX, while another was putatively identified on chromosome XII (LOD of 2.4), together explaining 26.8 % of the phenotypic variance.
TL;DR: In this paper, the effects of various processes used during the laboratory production of dehydrated cooked potato on the concentration of glycoalkaloids (α-chaconine and α-solanine) and nitrates in the raw material, intermediate and final product were investigated.
Abstract: The aim of this study was to investigate the effects of various processes used during the laboratory production of dehydrated cooked potato on the concentration of glycoalkaloids (α-chaconine and α-solanine) and nitrates in the raw material, intermediate and final product. In the raw material, half-products and in the final products there were determined glycoalkaloids contents (α-chaconine and α-solanine) with the use of HPLC method and nitrates contents colorimetrically by RQflex apparatus. During the laboratory production of dehydrated potato, glycoalkaloid and nitrate content in processed potatoes decreased. TGA decreased most after peeling (30 %), blanching (28 %) and pre-drying (25 %). Nitrate content decreased significantly after blanching (21 %) and after pre-drying (18 %).
TL;DR: The strain diversity and variant population of Potato virus Y (PVY) was investigated in potato lots with high PVY incidence in 2009 in New Brunswick, Canada, using reverse transcription (RT)-PCR, enzyme-linked immunosorbent assay (ELISA) and biological assays.
Abstract: The strain diversity and variant population of Potato virus Y (PVY) was investigated in potato lots with high PVY incidence in 2009 in New Brunswick, Canada, using reverse transcription (RT)-PCR, enzyme-linked immunosorbent assay (ELISA) and biological assays. Twenty lots with PVY infection rates >3 % were chosen following post-harvest testing for further investigation. Assays using multiplex RT-PCR revealed the existence of the common (PVYO), the recombinant N:O (PVYN:O) and the recombinant (European) potato tuber necrosis (Eu-PVYNTN) strains. PVYO was the predominant strain while PVYN:O and Eu-PVYNTN were widespread in these potato lots. PVYN:O and Eu-PVYNTN, either present alone or mixed with PVYO, were found in 19 and 13 of the 20 lots, respectively. Neither the tobacco veinal necrosis strain (PVYN) nor the non-recombinant (North American) PVYNTN was detected in the potatoes. Among the PVYO strain group, PVYO-Oz/-FL variant type was the predominant followed by the uncharacterized PVYO and the PVYO-139/-RB types. Biological assays of representative PVY positive-samples using tobacco and Yukon Gold were consistent with the findings of RT-PCR and serological assays.
TL;DR: In this paper, a distinctive russeting disorder was observed in the Negev area of Israel and was named Magen Russeting after one of the repeatedly affected plots, which appeared as protruding dark-brown patches on the surface of the tubers.
Abstract: Russeting of smooth-skinned potato varieties affect the protective characteristics of the skin against water loss and pathogens invasion. A distinctive russeting disorder, differs from previously reported tuber blemishes, has been observed in the Negev area of Israel and was named ‘Magen russeting’ after one of the repeatedly affected plots. The russeted skin appears as protruding dark-brown patches on the surface of the tubers. Histological studies identified the russet as old skin cells that remain adhered to the newly formed skin layers below them. Phytopathological tests and rDNA pyrosequencing analysis for whole bacterial community suggested that ‘Magen russeting’ is a physiological disorder. Mineral analysis of isolated pure skin samples indicated that russeted skin areas have higher concentrations of Ca and lower concentrations of K than the smooth skin of normal tubers, irrespective of CaCl2 or KCl fertilization of the soil prior to sowing, or of the irrigation regime during the growing season. Nevertheless, application of CaCl2 prior to tuber-seed sowing reduces the rate of affected mature tubers and the severity of the russeting.
TL;DR: The sensitivity tests conducted indicate that the immunocapture reverse transcriptase PCR was more sensitive in detecting PVY in infected plant sap than multiplex RT-PCR or ELISA alone while retaining the ability to differentiate strains of PVY that can infect potato in the United States.
Abstract: Potato virus Y (PVY) is a serious problem for the seed potato industry in the United States. The maximum allowable infection level of PVY in certified seed potatoes is 2 % and is substantially lower in early generations of seed production. Moreover, recent emergence of genetically recombinant and serologically different strains of Potato virus Y has led to the development of diagnostic procedures to determine strain identity and to detect mixed strain infections more easily, sensitively and accurately. In the studies reported here a protocol for the detection of single or mixed PVY infections in potato incorporates the advantages of enzyme-linked immunoassay (ELISA) and multiplex reverse transcriptase PCR (RT-PCR). The viral particles from plant sap were enriched by ELISA and then lysed by heating to release the viral RNA for the reverse transcriptase. The cDNA product was used as template for the detection of infection by multiplex PCR eliminating the need for RNA extraction and handling. The sensitivity tests conducted indicate that the immunocapture reverse transcriptase PCR was more sensitive in detecting PVY in infected plant sap than multiplex RT-PCR or ELISA alone while retaining the ability to differentiate strains of PVY that can infect potato in the United States. The immunocapture multiplex RT-PCR described will be particularly useful for seed certification and diagnostic laboratories as a confirmatory test in conjunction with ELISA.
TL;DR: In this paper, geospatial integration of remotely-sensed cropland (2008-2010) and soil datasets for Maine indicate an estimated 61,900ha in potato production with 62% and 27% on prime farmland (PF) and farmland of statewide importance (FSI), respectively.
Abstract: Maine consistently ranks in the top ten potato (Solanum tuberosum L.) production areas though yields are substantially lower than the mid- and western USA. Geospatial frameworks help resolve patterns and trends in production environments (at multiple scales) that may enable improvements in adaptive management strategies which enhance yield, increase whole-farm profitability, and foster sustainable land use. Results from geospatial integration of remotely-sensed cropland (2008–2010) and soil datasets for Maine indicate an estimated 61,900 ha in potato production with 62 % and 27 % on prime farmland (PF) and farmland of statewide importance (FSI), respectively. Geospatial analyses of other agri-environmental indicators indicate close to 85 % of these potato production soils are classified as either “potentially highly erodible” (PHEL) or “highly erodible” (HEL). Therefore, at least 52,300 ha require the highest standards in soil conservation practices. Crop rotation patterns for potato, derived from the time-series geo-referenced datasets, help resolve actual cropping practices and facilitated evaluation of the benefits and economic impacts for select alternate crops.
TL;DR: High throughput sequencing can generate large data sets of sRNA sequences which can be analyzed to recognize the abundant sRNAs that result from transcript degradation and to identify the regulatory micro RNAs involved in gene regulation and small inhibitory RNAs (siRNA) that confer virus resistance.
Abstract: Global climate change has the potential to quickly alter the distribution and profile of crop pests and pathogens. Ready tools for mobilization of resistance into elite crops will be part of an integrated strategy to maintain agricultural productivity. Engineered virus resistance through expression of coat protein is well established. The mechanisms of virus suppression by small RNAs (sRNAs) have only recently been elucidated. Understanding the role of sRNAs in gene regulation and development is rapidly evolving. High throughput sequencing (HTS) can generate large data sets of sRNA sequences which can be analyzed to recognize the abundant sRNAs that result from transcript degradation and to identify the regulatory micro RNAs (miRNA) involved in gene regulation and small inhibitory RNAs (siRNA) that confer virus resistance. Transgenic Solanum tuberosum that are glass house or field grown and that express the potato virus Y coat protein (PVY-CP) inverted hairpin RNA (ihRNA) from the 409s promoter with GBSS6 intron as a spacer exhibited resistance to PVY. Southern blots of genomic DNA indicated one or two copies of the transgene and analysis of HTS data of the small RNA population indicated high levels of siRNA production from the transgenic hairpin construct. Up to 47 of the top 200 most frequent sRNA reads were attributable to the PVY-CP transgenic construct in Ranger Russet line #5. This combination of transgene and transcription strength is functional for constructing efficient resistance cassettes for crop protection. Up to 95 of the top 200 sRNA sequences were 21 nucleotides in length with as many as 19 sequences corresponding to known miRNA transcripts. Additional endogenous sRNAs with homology to resistance gene analogs may be indicative of additional or complimentary resistance mechanisms produced in concert with the PVY siRNAs arising from PVY-CP RNA transcription.
TL;DR: A significant amount of variation in total carotenoids was observed within all Zep1 dosage classes, reinforcing the evidence that additional loci are important for high total carOTenoids in potato.
Abstract: Zeaxanthin epoxidase (Zep) is one of at least two genes important for the incidence and amount of carotenoids in yellow-fleshed potato. The recessive allele of the gene encoding zeaxanthin epoxidase (Zep1) has previously been shown to inhibit the conversion of the xanthophyll zeaxanthin to other, more polar carotenoids. We examined the effect of the dosage of Zep1 on total carotenoids in yellow-fleshed tetraploid potato germplasm. The dosage of heterozygous individuals was determined using high-resolution DNA melting. We also surveyed a wide range of germplasm available in the USDA-ARS potato breeding program in Washington for the presence and dosage of Zep1. Genotypes with zero, one, or two copies of Zep1 had statistically similar levels of total tuber carotenoids. Triplex individuals showed a small but significant increase in total carotenoids over the previous three classes. In turn, individuals that were homozygous for Zep1 had much higher levels of total carotenoids than all other dosage classes. This suggests that a slight dosage effect is present, but that the effect of Zep1 is indeed largely recessive. A significant amount of variation in total carotenoids was observed within all Zep1 dosage classes, reinforcing the evidence that additional loci are important for high total carotenoids in potato. Our survey of breeding germplasm supported earlier research that Zep1 is uncommon in tetraploid potato germplasm. The use of high-resolution DNA melting again allowed us to identify the dosage of Zep1 in heterozygous individuals. This is important for breeding high-carotenoid potatoes at the tetraploid level, since recovery of homozygous Zep1 individuals is very rare. Identification of agronomically desirable parents with two or more copies of Zep1 would allow for higher recovery of homozygous Zep1 progeny, permitting additional selection for other desirable traits.
TL;DR: Palisade Russet is a medium-late maturing, lightly russeted potato cultivar notable for its resistance to late blight (Phytophthora infestans) infection of foliage and tuber that has potential as a processing cultivar in potato production regions with inherently low specific gravities.
Abstract: Palisade Russet is a medium-late maturing, lightly russeted potato cultivar notable for its resistance to late blight (Phytophthora infestans) infection of foliage and tuber Palisade Russet is suitable for processing with low tuber glucose concentrations observed following long-term storage at a temperature as low as 56°C with consistently acceptable fry color scores (USDA value ≤20) following storage at temperatures of 56 to 89°C Reducing sugars are also maintained uniformly throughout the tuber, resulting in a low incidence of sugar ends in French fries relative to standard processing cultivars such as Russet Burbank and Ranger Russet Palisade Russet has shown high specific gravities in western production regions of the US which may limit its acceptance by the western processing industry However, in potato production regions with inherently low specific gravities, Palisade Russet could have potential as a processing cultivar In full-season trials conducted in Idaho, Oregon, and Washington over a 5 year period, the average total yield of Palisade Russet across all three states was very similar to yields observed for Ranger Russet and Russet Burbank However, the US No 1 yield of Palisade Russet was 3% and 31% higher relative to Ranger Russet and Russet Burbank, respectively In addition to late blight, Palisade Russet is also resistant to Verticillium wilt, black dot, and pink rot, and has a moderate level of resistance to net necrosis, PVY, and early blight of both the foliage and tuber The disease resistances of Palisade Russet make it a good candidate for organic production, or for use by growers seeking reduced pesticide inputs Palisade Russet displays a low incidence of second growth and growth cracks, especially relative to Russet Burbank, and is intermediate between Ranger Russet and Russet Burbank for incidence of hollow heart/brown center Blackspot bruise expression for Palisade Russet is less pronounced than for either Ranger Russet or Russet Burbank, however it is slightly more susceptible to shatter bruise Palisade Russet was released in 2011 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program
TL;DR: The applying multidimensional statistical methods revealed that the most stable resistance is expressed by highly resistant cultivars Bzura, Wawrzyn, Meduza and moderately resistant ones Klepa, Jasia, Nimfy, Ania, Hinga, Vistula.
Abstract: In this study, genotype by environment (G × E) interaction and biological stability of resistance to Phytophthora infestans were analyzed for 22 potato cultivars, using multidimensional statistical methods. Sergen 3 computer program, based on multiplicative model was applied to analyze the G × E interaction and regression analysis. The potato cultivars were tested in four experiments in Central and South-eastern Poland over a 4 year period. The analysis of variance of rAUDPC values indicated significant (P < 0.01) influence of genotype (=cultivar) (G), year (Y), environment (E) and G × E interaction. The applying multidimensional statistical methods revealed that the most stable resistance is expressed by highly resistant cultivars Bzura, Wawrzyn, Meduza and moderately resistant ones Klepa, Jasia, Nimfy, Ania, Hinga, Vistula. For these cultivars all tested interactions (with year, location and environment) were insignificant. Such cultivars can be recommended for cultivation across all environments in Poland. In the group of unstable cultivars, two subgroups were separated: unstable and unpredictable (12 cvs.) and unstable and regular (1 cv). A different response of potato cultivars to environmental factors suggests that there is a need to select potato cultivars which are stable in terms of late blight resistance expression at various locations and years.
TL;DR: In this article, the authors evaluate processor preferences regarding potato product attributes such as price and country of origin attributes are selected according to their influence on the buying decision of the processors and quantify the relative importance of product attributes for the main market segments chips, fries, and flakes.
Abstract: Managing the transition from a commodity to a differentiated good in an increasingly liberalized, price-driven world is a challenge for Swiss producers of potatoes To facilitate this process at the production level, knowledge about preferences in terms of product attributes is needed We evaluate processor preferences regarding potato product attributes such as price and country of origin Attributes are selected according to their influence on the buying decision of the processors Additionally, we quantify the relative importance of product attributes for the main market segments chips, fries, and flakes By applying a discreet-choice experiment with Bayesian estimation of individual part-worth utilities and randomized first-choice models for scenario analysis, we find that color, size and producer price determine 46 % of the buying decision However, while price is an important decision criterion, product and supplier criteria can be used to segment the market if the price premium is held within limits and size and color requirements are met
TL;DR: This study has shown that somatic hybridization can be used to introgress aphid resistance from wild potato species that are sexually incompatible with S. tuberosum, PVY and late blight resistance into one clone, which can now be used as a breeding source for multiple resistance factors.
Abstract: Solanum bulbocastanum Dun. is a wild potato species resistant to late blight, Phytophthora infestans (Mont.) de Bary, green peach aphid, Myzus persicae (Sulzer), and potato aphid, Macrosiphum euphorbiae (Thomas). Because of its reproductive incompatibility with S. tuberosum, S. bulbocastanum aphid resistance has been under-realized in potato breeding. Solanum tuberosum + S. bulbocastanum somatic fusions created for introgression of late blight resistance and subsequently backcrossed to cultivated potato were screened to determine if aphid resistance, virus resistance, and late blight resistance could be concurrently incorporated. Among the 63 lines screened, nine expressed resistance to green peach aphid and five lines expressed resistance to potato aphid. Virus resistance field screenings over 4 years indicated 29 lines were resistant to PVY and five were resistant to PLRV. Of those, two were resistant to both PVY and PLRV. Lines were tested with markers linked to R genes for resistance to PVY as well as the marker for late blight resistance. Line K7G-319 has pyramided M. persicae, M. euphorbiae, and PVY resistance and line K7G-329 has pyramided M. persicae, M. euphorbiae, PVY and late blight resistance into one clone, which can now be used as a breeding source for multiple resistance factors. This study has shown that somatic hybridization can be used to introgress aphid resistance from wild potato species that are sexually incompatible with S. tuberosum.
TL;DR: The purpose of this paper is to describe a new potato variety in the Fingerling Class with red skin and red flesh with high antioxidant activity and potential healthful benefits from these pigments or other antioxidant compounds.
Abstract: The diversity of traits in varieties of potato outside of its South American birthplace is a small subset of that available in the Andean center of origin. Among the traits that evoke most interest are skin and flesh pigments. Recent studies have pointed to the high antioxidant activity and potential healthful benefits from these pigments or other antioxidant compounds. The market for potatoes with unusual color patterns has been supplied largely by heirloom varieties of uncertain origin and the highly successful Yukon Gold. Interest has intensified and been transformed into a focused effort in the breeding of specialty varieties, remarkable for their unusual colors. The purpose of this paper is to describe a new potato variety in the Fingerling Class with red skin and red flesh.
TL;DR: Results show that protocols for PVY post-harvest testing used by state seed certification agencies should be written to specify the amount of time needed before sampling and that specific protocols may be needed based on cultivar in order to accurately detect PVY in tuber samples.
Abstract: Russet Burbank, Russet Norkotah, and Shepody tubers infected with Potato virus Y strains (PVYO, PVYN:O, PVYNTN) were tested from storage at 4°C at the initiation of sprouting and then the same tubers were tested again from storage at 4°C seventy eight days later. Samples were taken from eyes in the stem, middle, and bud (distal end) areas of the tubers. Testing of the samples was done with an enzyme-linked immunosorbent assay (ELISA) and negative samples were retested using reverse transcription-polymerase chain reactions (RT-PCR). The ELISA alone and the ELISA+PCR combined results were evaluated for each of the strains, sample locations, sample time, and cultivar. Results show that ELISA underestimated the actual percentage of tubers with virus. When test results were combined to show a more accurate percentage, PVYN:O was unevenly distributed in some cultivars, but PVYO and PVYNTN were evenly distributed 78 days after initial sprouting. Results show that protocols for PVY post-harvest testing used by state seed certification agencies should be written to specify the amount of time needed before sampling and that specific protocols may be needed based on cultivar in order to accurately detect PVY in tuber samples.
TL;DR: It is concluded that moderate environmental stresses and maturity of tubers at harvest are not sufficient to consistently cause stem-end chip defect, and more severe defects with larger areas of dark color on the stem end of chips were associated with increased amounts of tuberstem-end glucose and increased stem- end acid invertase activity.
Abstract: Global consumption of potato (Solanum tuberosum L.) continues to shift from fresh potatoes to value-added processed food products such as potato chips. One serious tuber quality defect of chipping potatoes is stem-end chip defect, which results in chips with dark-colored vasculature and adjacent tissues at the tuber stem end after frying. In this study, treatments of moderate water deficit for 14 days, alone or in combination with moderate daytime heat stress at 30 °C, as well as varied chemical maturity of tubers at harvest were imposed in controlled-environment greenhouses. Only temperature stress for 14 days in 1 of 2 years significantly changed the occurrence of stem-end chip defects. Water deficit for 14 days and chemical maturity of tubers harvested at four time points from early tuber bulking to after vine senescence did not have significant impacts on defect incidence or severity. Biochemical analyses showed that more severe defects with larger areas of dark color on the stem end of chips were associated with increased amounts of tuber stem-end glucose and increased stem-end acid invertase activity. We conclude that moderate environmental stresses and maturity of tubers at harvest are not sufficient to consistently cause stem-end chip defect.
TL;DR: H2O2-mediated symptoms and antioxidant responses were examined in phytoplasma-infected potato plants under drought conditions and a signal role for H2O1 in lessening symptoms is suggested.
Abstract: H2O2-mediated symptoms and antioxidant responses were examined in phytoplasma-infected potato plants under drought conditions. In vitro phytoplasma-infected or uninfected plants were transferred to a greenhouse and sprayed twice a week with H2O2. Phytoplasma decreased water potential, catalase (CAT) activity and increased H2O2 content significantly. H2O2 significantly enhanced minitubers weight and starch content in phytoplasma-infected plants. Under drought conditions, minitubers produced by H2O2-sprayed phytoplasma-infected plants had significantly more starch than the controls. Minitubers weight was reduced in both uninfected and infected plants, but H2O2 in the presence of phytoplasma significantly enhanced minitubers weight, CAT activity, and H2O2 content. H2O2 treatment induced higher internal H2O2 concentration, which was associated with positive effects on infected minitubers, such as weight, reduction of number, starch content, sprouting, and tolerance to drought a signal role for H2O2 in lessening symptoms is suggested.