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1.
Changes in the fungal pathogenPhytophthora infestans in the United States pose a significant threat to potato production. Sources of resistance to these new genotypes of P.infestans need to be identified for potato breeders to have parental materials for crossing, and the phenotypic stability of late blight resistance in these potato clones needs to be determined. Sixteen potato clones which reportedly have some resistance to late blight were evaluated at eight locations: Florida (FL), Maine (ME), Michigan (MI), Minnesota (MN), North Dakota (ND), New York (NY), Pennsylvania (PA) and Wisconsin (WI) in 1996. Percent infected foliage was recorded at approximately weekly intervals following the onset of the disease at each location. Area under the disease progress curve (AUDPC) was calculated. Clones were ranked for mean AUDPC within location and the nonparametric stability statistics, mean absolute rank differences and variance of the ranks, were analyzed for phenotypic stability. Neither of these statistics was significant, indicating a lack of genotype x environment interaction on the rankings of these clones across locations in 1996. The four clones with lowest AUDPC scores were U.S. clones AWN86514-2, B0692-4, B0718-3 and B0767-2. These clones should be useful parental materials for breeders seeking to incorporate genes for late blight resistance into potatoes.  相似文献   

2.
Late blight, caused byPhytophthora infestans, is the most important disease of potato worldwide and foliar resistance is an important component of managing late blight in the field. The objective of this research was to identify germplasm for use in breeding cultivars with foliar resistance toP. infestans. More than 500 clones were tested from 1997 to 2002 in inoculated (US8 genotype) field experiments conducted at the Michigan State University Muck Soils Research Farm in Bath, Michigan. All of the current commercial cultivars tested were classified as susceptible toP. infestans. The most resistant clones were A90586-11, AWN86514-2, B0718-3, Jacqueline Lee (MSG274-3), MSI152-A, MSJ307-2, MSJ317-1, MSJ453-4Y, MSJ456-2, MSJ456-4, MSJ461-1, MSK101-2, MSK128-1, NY121, LBR8, LBR9, Tollocan, and Torridon. Some of these resistant selections were from crosses with B0718-3, Jacqueline Lee, and Tollocan suggesting that the resistance toP. infestans was transmissible. These resistant clones will provide the opportunity to breed late-blight-resistant cultivars from a diverse pool of cultivated germplasm. Consistent foliar reaction toP. infestans over years suggested that the Michigan State University Muck Soils Research Farm is a valuable location for North American breeders to assess the reaction of potato germplasm to the US8 genotype of late blight.  相似文献   

3.
Foliar late blight, caused byPhytophthora infestans, is a devastating disease of potatoes worldwide. In 1996 we initiated a breeding strategy to improve the levels of resistance to late blight in a diploid hybrid population ofSolanum phureja-Solanum stenotomum. The purpose of this study was to determine if resistance to late blight in this diploid potato population could be improved by recurrent maternal half-sib selection. Four clones from each of 72 maternal half-sib families were evaluated for late blight resistance in replicated field trials in Pennsylvania in 1996 and 1997 (cycle 1) and in 2003 and 2004 (cycle 2). ‘Atlantic’ was included as a check cultivar at all sites. Percentage of infected foliage was recorded three times towards the end of the growing season each year and was used to compute area under the disease progress curve (AUDPC). Mean AUDPC for Atlantic in cycle 1 and 2 was 863 and 854, respectively. Mean AUDPC of the cycle 1 and cycle 2 diploid clones was 652 and 556, respectively. Narrowsense heritability for resistance in cycle 1 and cycle 2 was estimated as 0.78 and 0.77, respectively; additive genetic variance was estimated as 10960 and 12636, respectively; phenotypic variance was estimated as 14088 and 16375, respectively. Predicted and realized genetic gain from cycle 1 to cycle 2 was ?80 and ?96, respectively. Recurrent maternal half-sib selection is an effective way to improve resistance to late blight in this population and to maintain adequate genetic diversity for further enhancement efforts.  相似文献   

4.
Summary Increased virulence associated with fungicide resistance and variablePhytophthora infestans populations has been recorded in many potato growing regions with enormous economic effects. The current emphasis on disease management in East Africa includes the use of potato varieties with durable resistance to late blight. Seven promising clones from Population B with quantitative resistance (no R-genes), two advanced clones from Population A (with Rgenes) and three control varieties were grown for three cropping seasons in order to determine their reaction and stability of late blight resistance. Late blight occurrence was detected in all cropping seasons. The analysis of variance of disease data (AUDPC) for genotypes, locations x seasons was highly significant (P<0.001) indicating the differential response of the geno-types and the need for stability analysis. The Additive Main Effects and Multiplicative Interaction (AMMI) statistical model, showed that the most stable genotypes were 392127.256, 381471.18, 387121.4 (resistant) and 391049.255 (susceptible to late blight). Within environments, the ranking of genotypes was not consistent. The variety Kabale was ranked as the most susceptible genotype while clone 381471.18 and Rutuku were ranked the most resistant. Selective deployment of resistant and stable varieties is critical in minimizing economic loss and damage attributed to late blight in low input farming systems.  相似文献   

5.
Foliar late blight, caused by Phytophthora infestans, is an important disease problem worldwide. Foliar resistance to late blight was found in a hybrid population of the cultivated diploid species Solanum phureja-S. stenotomum (phu-stn). The objective of this study was to determine if resistance to late blight could be improved by recurrent maternal half-sib selection in the phu-stn population. Four clones from each of 72 maternal half-sib families plus the check cultivar ‘Atlantic’ were evaluated for late blight resistance in replicated field trials in Pennsylvania. The most late blight resistant clone from each of the 72 families was randomly intermated to advance the population. The cycle 1, 2, and 3 populations were evaluated in 1996–1997, 2003–2004, and 2009–2010, respectively. Percent infected foliage was recorded several times towards the end of the growing season and used to compute area under the disease progress curve (AUDPC). Mean AUDPC was 652 (cycle 1), 556 (cycle 2), and 276 (cycle 3), whereas the mean AUDPC of ‘Atlantic’ ranged from 775 to 863 each cycle. Narrow-sense heritability for resistance was estimated as 0.78, 0.77, and 0.80 in cycles 1, 2, and 3, respectively. Recurrent maternal half-sib selection continues to improve the levels of resistance to late blight in this diploid population with no adverse effect on the amount of additive genetic variance. Additional improvements for late blight resistance are likely to occur if this approach is continued.  相似文献   

6.
Several quantitative trait loci (QTL) for resistance to late blight have been reported in diploid potatoes. The diploid wild potato species Solanum chacoense possesses a high degree of horizontal resistance to late blight. In the present study, we report on QTL mapping for late blight resistance in a diploid mapping population of 126 F1 of Solanum spegazzinii (susceptible) × S. chacoense (resistant). The area under the disease progress curve (AUDPC) values for late blight resistance using the “whole plant in vitro assay” and the “detached leaf assay” on the mapping population displayed quantitative variation. Out of 64 AFLP primer-pairs combinations and SSR markers, a total of 209 significant AFLP loci were placed onto the 12 linkage group of potato covering a total map length of 6548.1 cM. QTL analysis based on the AUDPC dataset of the “whole plant in vitro assay” using the interval-mapping option identified two QTL (LOD?>?2.5) located on linkage groups IX and X, which explained 14.70 and 3.40% variation, respectively. The present study revealed the presence of potential new genetic loci in the diploid potato family contributing to quantitative resistance against late blight.  相似文献   

7.
Summary Host plant resistance is an important component to the management of potato late blight,Phytophthora infestans (Mont.) de Bary. Assessment of potato lines (Solanum tuberosum L.) with various levels of resistance toP. infestans (US8, A2 genotype) were evaluated in field trials, greenhouse controlled environment chambers and inoculated tuber reactions. Five lines (AWN86514-2, B0692-4, B0718-3, Jacqueline Lee, and B0288-17) with strong foliar resistance to late blight were identified in these inoculated field trials. Greenhouse controlled environment chamber studies allowed resistant and susceptible lines to be distinguished, but the 1998 greenhouse results did not correlate well with field data. Four lines (A084275-3, Bzura, MSG007-1, and MSG297-4RD) evaluated by a digital image analysis technique demonstrated tuber resistance based upon average reflective index values in the inoculated tuber studies. Tuber resistance did not correlate with field foliar resistance. Based upon these results, field assessment of foliar reaction toP. infestans provides the best measure for assessing late blight resistance in potato. Tuber resistance to late blight can be identified among lines with varying levels of foliar resistance.  相似文献   

8.
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9.
Wild potatoes are important sources of genes for resistance to disease and insect pests. A collection of wild Mexican and South AmericanSolarium 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/A1 mating 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 toP. infestans. These includedS. bulbocastanum, S. pinnatisectum, S. cardiophyllum, andS. circaeifolium. Two accessions from South American speciesS. 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 ofS. circaeifolium PI 498119 andS. 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 theP. 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 inS. pinnatisectum genotypes tested corresponded to a race-non-specific genetic system, which was different from any existing R genes.Solanum pin-natisectum 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.  相似文献   

10.
Late blight, caused by Phytophthora infestans, is a devastating disease on potato worldwide and new lineages of the pathogen continue to develop in the U.S. Breeding for resistance is important for economic and environmental purposes. The Solanaceae Coordinated Agricultural Project (SolCAP) focuses on linking allelic variation in genes to valuable traits in elite cultivated potato germplasm. This research assessed the SolCAP diversity panel (206 clones in Washington and 213 clones in Wisconsin) for tuber resistance to the US-24 clonal lineage of P. infestans after potatoes were harvested from fields in Washington and Wisconsin in 2011. This is the first time this germplasm has been evaluated for tuber resistance to P. infestans using a non-intrusive zoospore inoculation technique. Clones with a percent incidence of 30% or less were considered resistant and only eight clones (Palisade Russet, AWN86514–2, MSL268-D, MSM171-A, MSM182–1, MSN230-1RY, Patagonia and Yukon Gem) were characterized as resistant at both locations. These clones have previously demonstrated high to moderate partial foliar resistance to isolates of P.infestans and therefore represent germplasm with both foliar and tuber resistance. Nine clones (AWN86514–2, F66041, MN 18747, MSM 182–1, MSN230-1RY, Modoc, Ama-Rosa, Patagonia and Purple Majesty), were characterized as slow-rotting at both locations with a mean percent internal rot of 75% or less after 33 days of storage. Two clones, MN 18747 and Modoc, are considered to have the highest risk of being a carrier for P. infestans of all the clones evaluated in the SolCAP collection. Not a single clone demonstrated complete tuber resistance to the US-24 strain at both locations.  相似文献   

11.
Glycoalkaloids are anti-nutritional compounds commonly found in wildSolanum 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 betweenSolanum tuberosum and accessions ofS. andigena, S. berthaultii, S. phureja, andS. vernei to investigate the possible correlation between resistance toPhytophthora infestans and/or toErwinia carotovora subsp.atroseptica and the concentration of glycoalkaloids in tubers. Concentrations of α-solanine and α-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 ofP. infestans used. Furthermore, clones within each progeny also differed for components of partial resistance toP. 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 α-solanine and two late blight resistance components (incubation period and spore production per unit lesion area) in progenies derived fromS. vernei, and despite a trend towards higher glycoalkaloid concentrations in the tubers of the clones most resistant to soft rot within progenies derived fromS. berthaultii andS. vernei, no consistent relationship between resistance to either disease and concentrations of α-solanine and/or α-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 behaviour againstP. infestans and/orE. carotovora.  相似文献   

12.
The relationship between active oxygen metabolism and resistance to late blight (Phytophthora infestans) in potato (Solanum tuberosum L.) was studied for 72 h post-inoculation by comparing three resistant cultivars (low disease index) with three susceptible ones (high disease index). Activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), and the content of ascorbic acid (ASA), were higher in the resistant cultivars than in the susceptible ones. The production rate of the superoxide anion radical (O2?) was lower in the resistant cultivars than in the susceptible ones. These changes, which were associated with the potato plant’s response to infection with P. infestans, provide some insight into the physiological basis of resistance and may also provide a screening tool for resistance to late blight.  相似文献   

13.
Marker-assisted Breeding for Disease Resistance in Potato   总被引：1，自引：1，他引：0  
Sub-project 5 of BIOEXPLOIT aims to design durable disease resistance through marker-assisted breeding by converting existing markers for high-throughput application, developing and validating high-throughput marker technologies and pyramiding major R genes and/or quantitative trait loci into elite material. Activities include (1) the fine mapping of the quantitative trait locus PiXspg which accounts for a large proportion of the variation in late blight resistance, (2) converting SNP-based markers and an AFLP marker to easy-to-use-markers, (3) testing of progenies with combined sources of late blight resistance for presence of R genes and agronomic features, (4) backcrossing new sources of resistance to S. tuberosum and molecular screening of breeding materials with marker GP94 linked with gene Rpi-phu1 conferring late blight resistance, (5) evaluating potato clones with enhanced resistance against Phytophthora infestans under field conditions of Toluca (México), and (6) developing populations and marker-assisted breeding for disease resistance.  相似文献   

14.
Thirty progeny from each of fourSolanum crosses were evaluated in the field at Mount Vernon, WA, in 1996 and 1997 for partial resistance toPhytophthora infestans. Of the four parents, three have high levels of partial resistance toP. infestans; one derived from somatic hybridization ofS. bulbocastanum, the other two from traditional breeding efforts for multiple disease resistance. Data were collected from each cross to estimate area under the disease progress curve (AUDPC), days to 5% disease severity threshold (DT5), and sporangia production (SP). All of these variables differed significantly among the progeny within each cross in each year. Correlation analysis indicated that DT5 was highly correlated with AUDPC for all four populations for both years. Log-transformed SP was significantly (P>0.001) correlated to AUDPC values for one population in both years, but the significance of the correlation was variable between years for the remaining three crosses. The variable DT5, which is composed of three components (infection efficiency, latent period, and lesion growth rate), was the most important in identifying progeny with partial resistance to late blight in all four crosses in this study.  相似文献   

15.
Late blight is an important disease of potato(Solanum tuberosum L.) worldwide, and therefore, many potato-breeding programs have prioritized the development of late blight-resistant potato cultivars. Although the emphasis has been to enhance foliar resistance, it is also necessary to evaluate tuber late blight resistance in new breeding lines and new sources of late blight resistance. We report here on the assessment of foliar and tuber resistance and the correlation between these aspects of resistance in a sample of Michigan State University potato breeding lines. Two MSU breeding lines had significantly less infected foliage than the susceptible check cultivars. Tuber susceptibility was significantly different (P < 0.05) only between the most susceptible and the least susceptible breeding lines/cultivars. Foliar and tuber susceptibility to potato late blight were not correlated as low tuber susceptibility was associated both with extremely low (e.g., MSG274-3) and high (e.g., MSE202-3Rus) foliar susceptibility.  相似文献   

16.
The 1:1 ratio of the Phytophthora infestans A1 and A2 mating types favors the sexually derived genetic diversity of the late blight pathogen of potatoes, which is widespread in the central highlands of México. This ratio guarantees the successful infection of this pathogen, even in resistant potato hosts. However, wild Solanum species present in the region serve as alternative hosts to the pathogen. Knowledge about the external factors that influence the dynamics of this disease facilitates the assessment and selection for genetically resistant potato cultivars to late blight, in addition to providing the capacity to predict epidemics. This work aimed to assess the expected, observed, and simulated progress of natural P. infestans infection of potatoes during two epiphytotic field seasons (2009 and 2010) at Chapingo, México. Using 8-years of weather datasets, six ideal situations were predicted with four to eight infection cycles of 6 to 12 h each. In comparison to the predictions, the observed effect of the area under the disease progress curve, and its components (AUDPC, RAUDPC, RaRAUDPC), was highly significant, with a low coefficient of variation among the potato cultivars used in the study. In conclusion, we confirm that the LATEBLIGHT-LB2004 model is useful for simulating and predicting late blight epidemics based on the weather conditions of Chapingo, except for the magnitude of the relative humidity threshold variable (RH_threshold), which requires calibration for each cultivar.  相似文献   

17.
Summary Morphological and biochemical parameters that could be involved in resistance to late blight were studied in non-infected and in infected potato hybrids resulting from a cross betweenSolanum phureja, resistant toPhytophthora infestans, and a susceptibleSolanum tuberosum. Some morphological differences between resistant and susceptible hybrids, indicating a positive correlation between stem diameter and phloem thickness in the stem and resistance toP. infestans, were observed. The lignin content in the leaves of the resistant hybrid rose upon infection byP. infestans. In the leaves of the susceptible hybrid, a diminution of the lignin content could be observed upon infection byP. infestans. In the same context, peroxidasic activity raised upon infection byP. infestans in both resistant and susceptible hybrids. Further characterization of the hybrid clones based on the polymorphism of peroxidases was attempted using isoelectric focusing.  相似文献   

18.
Greenhouse assays were carried out to characterizeSolanum accessions previously reported to be late blight resistant and to identify individuals within the accessions with high levels of resistance to late blight. Foliage of wildSolanum species accessions or hybrid cultivated potato x wild species (diploid or tetraploid) from Mexico, Russia, or South America was inoculated withPhytophthora infestans (US-8) and was scored for severity of foliar symptoms at 7 and 14 days after inoculation (DAI). Mexican accessions (S. brachycarpum,S. pinnatisectum,S. guerreroense, andS.fendleri) were significantly more resistant (1.1% infection at 14 DAI) than either Russian (59.1% infection at 14 DAI) or South American (53.4% infection at 14 DAI) accessions. Moreover, the genotypes within the Mexican accessions tended to be more uniformly resistant whereas genotypes within the Russian and South American accessions tended to segregate for resistance. The more resistant genotypes of Russian and South American accessions (176/546) were retested, and 56 genotypes were identified as having potential for use in potato breeding programs for resistance to late blight. Fifty percent of the selected genotypes were fromS. microdontum accessions PI498124, PI595510, and PI595511. The potential of these species for incorporation into breeding programs for late blight resistance is discussed.  相似文献   

19.
Cultivated potato is susceptible to many pests and pathogens, none of which is more of a threat to potato agriculture than the late blight disease, caused by the oomycete Phytophthora infestans (Mont.) de Bary. To date all efforts to thwart this most adaptive of pathogens have failed, and early attempts to deploy ‘R genes’ introgressed from the wild Mexican hexaploid Solanum demissum ended in abject failure. With the advent of facile gene mapping and cloning, allied to knowledge of plant resistance gene structure, renewed efforts are leading to mapping and isolation of new sources of late blight resistance in potato wild species, many of which are being performed under the auspices of the BIOEXPLOIT project (Sub-project 2). We document recent advances in late blight resistance gene mapping and isolation, and postulate how these genes, allied to knowledge of pathogen effectors and their recognition specificity, may greatly enhance our chances of halting the progress of late blight disease in potato crops worldwide.  相似文献   

20.
Two potato breeding selections were released by the United States Department of Agriculture, Agricultural Research Service on November 14, 1996, as germplasm that is highly resistant to current populations ofPhytophthora infestans (Mont.) deBary, the causal organism of potato late blight: B0718-3 and B0767-2. These two clones have been evaluated for their reaction toP. infestans in replicated plots at Presque Isle, Maine since 1990. B0718-3 is a netted white-skinned selection with good yields but low specific gravity. It is both male and female fertile and crosses readily with tetraploid Tuberosum. B0767-2 is a russet-skinned selection that is low yielding and low in specific gravity. It has not been successfully crossed; however, it may have some potential use in somatic hybridizations. Neither B0718-3 nor B0767-2 process into acceptable colored chips. Genetic material of this release has been deposited in the National Plant Germplasm System where it is available for research purposes, including development and commercialization of new cultivars.  相似文献   

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