scholarly journals Population structure and phenotypic variation of Sclerotinia sclerotiorum from dry bean in the United States

2017 ◽  
Author(s):  
Zhian N Kamvar ◽  
Bimal S Amaradasa ◽  
Rachana Jhala ◽  
Serena McCoy ◽  
James R Steadman ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Sclerotinia Sclerotiorum ◽  
Genotypic Variation ◽  
Natural Populations ◽  
The United States ◽  
White Mold ◽  
Bipartite Network ◽  
Necrotrophic Pathogen ◽  
Dry Bean ◽  
Field Source

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries a) reflect the genetic diversity of the populations in the surrounding region and b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns. We genotyped 366 isolates of S. sclerotiorum from producer fields and white mold screening nurseries surveyed over 10 years in 2003–2012 representing 11 states, Mexico, France, and Australia at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n=18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several white mold screening nurseries across the US to account for both the phenotypic and genotypic variation that exists across regions.

scholarly journals Population structure and phenotypic variation of Sclerotinia sclerotiorum from dry bean (Phaseolus vulgaris) in the United States

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4152 ◽  
Author(s):  
Zhian N. Kamvar ◽  
B. Sajeewa Amaradasa ◽  
Rachana Jhala ◽  
Serena McCoy ◽  
James R. Steadman ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Sclerotinia Sclerotiorum ◽  
Genotypic Variation ◽  
The United States ◽  
White Mold ◽  
Bipartite Network ◽  
Necrotrophic Pathogen ◽  
Dry Bean ◽  
Field Source

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries (wmn) with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries (a) reflect the genetic diversity of the populations in the surrounding region and (b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns. We genotyped 366 isolates of S. sclerotiorum from producer fields and wmn surveyed over 10 years in 2003–2012 representing 11 states in the United States of America, Australia, France, and Mexico at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n = 18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several wmn across the United States to account for both the phenotypic and genotypic variation that exists across regions.

scholarly journals Population structure and phenotypic variation of Sclerotinia sclerotiorum from dry bean (Phaseolus vulgaris) in the United States

2017 ◽  
Author(s):  
Zhian N Kamvar ◽  
Bimal S Amaradasa ◽  
Rachana Jhala ◽  
Serena McCoy ◽  
James R Steadman ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Sclerotinia Sclerotiorum ◽  
Genotypic Variation ◽  
The United States ◽  
White Mold ◽  
Bipartite Network ◽  
Necrotrophic Pathogen ◽  
Dry Bean ◽  
Field Source

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries a) reflect the genetic diversity of the populations in the surrounding region and b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns. We genotyped 366 isolates of S. sclerotiorum from producer fields and white mold screening nurseries surveyed over 10 years in 2003–2012 representing 11 states in the United States of America, Australia, France, and Mexico at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n=18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several white mold screening nurseries across the US to account for both the phenotypic and genotypic variation that exists across regions.

scholarly journals Population structure and phenotypic variation of Sclerotinia sclerotiorum from dry bean (Phaseolus vulgaris) in the United States

2017 ◽  
Author(s):  
Zhian N Kamvar ◽  
Bimal S Amaradasa ◽  
Rachana Jhala ◽  
Serena McCoy ◽  
James R Steadman ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Sclerotinia Sclerotiorum ◽  
Genotypic Variation ◽  
The United States ◽  
White Mold ◽  
Bipartite Network ◽  
Necrotrophic Pathogen ◽  
Dry Bean ◽  
Field Source

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries a) reflect the genetic diversity of the populations in the surrounding region and b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns. We genotyped 366 isolates of S. sclerotiorum from producer fields and white mold screening nurseries surveyed over 10 years in 2003–2012 representing 11 states in the United States of America, Australia, France, and Mexico at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n=18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several white mold screening nurseries across the US to account for both the phenotypic and genotypic variation that exists across regions.

scholarly journals Variation in Sclerotinia sclerotiorum Bean Isolates from Multisite Resistance Screening Locations

Plant Disease ◽  
2011 ◽  
Vol 95 (11) ◽  
pp. 1370-1377 ◽  
Author(s):  
Lindsey Otto-Hanson ◽  
James R. Steadman ◽  
Rebecca Higgins ◽  
Kent M. Eskridge
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
The United States ◽  
White Mold ◽  
Resistance Screening ◽  
Dry Bean ◽  
Mycelial Compatibility ◽  
Greenhouse Screening ◽  
Mold Resistance ◽  
Production Areas ◽  
Resistance Expression

There is no complete resistance to Sclerotinia sclerotiorum, cause of white mold in dry bean (Phaseolus vulgaris). Variable resistance expression is one problem in screening for improved white mold resistance. With no previous information in the literature, pathogen variation in multisite screening nurseries was evaluated as one cause of diverse resistance expression. In all, 10 isolates of S. sclerotiorum used in greenhouse screening and 146 isolates collected from nine white mold field screening nurseries in major bean production areas in the United States were compared using mycelial compatibility groupings (MCGs) and an aggressiveness test. These 10 greenhouse screening isolates formed six MCGs. Among 156 field and greenhouse isolates, 64 MCGs were identified and 36 of those were each composed of a single unique isolate. Significant differences in isolate aggressiveness were found between some isolates in different MCGs but the isolates within an MCG did not differ in aggressiveness. High isolate variation found within and between field locations could influence the disease phenotype of putative white mold resistant germplasm. We next compared genotype and phenotype of isolates from screening nurseries and those from producer fields. Variability found in and among screening locations did reflect variability found in the four producer fields sampled. White mold resistance screening can be improved by knowledge of isolate genotypic and phenotypic characteristics.

Efficacy of three greenhouse screening methods for the identification of physiological resistance to white mold in dry bean

2009 ◽  
Vol 89 (4) ◽  
pp. 755-762 ◽  
Author(s):  
H Terán ◽  
S P Singh
Keyword(s):  
Phaseolus Vulgaris ◽  
Common Bean ◽  
Sclerotinia Sclerotiorum ◽  
Screening Method ◽  
White Mold ◽  
Screening Methods ◽  
Post Inoculation ◽  
Dry Bean ◽  
Physiological Resistance ◽  
Nueva Granada

White mold (WM) caused by Sclerotinia sclerotiorum (Lib.) de Bary is the most devastating disease of common bean (dry and snap or garden bean) (Phaseolus vulgaris L.) in North America. The use of a reliable screening method (SM) in common bean is crucial to improve physiological resistance to WM. The objective of this study was to compare the efficacy of three SM to identify physiological resistance in dry bean genotypes with different evolutionary origins and levels of resistance. Screening methods tested were: (i) the modified straw test or cut–stem (CSM); (ii) infected bean flower (IFL); and (iii) infected oat seed (IOS). A 195, ICA Bunsi, Othello, and VCW 54 dry bean were tested with the three SM. The experimental design was a split plot in randomized complete blocks with three replications in 2007 and 2008. Two independent inoculations 1 wk apart for each SM were made. The WM reaction was scored at 16, 23, and 33 d post-inoculation (DPI) using a 1 to 9 scale. There were highly significant differences between SM and its interaction with years. The CSM and IFL were the most consistent and highly correlated (r > 0.70, P < 0.01). Interspecific breeding line VCW 54 consistently had the highest WM resistance across years, SM, and evaluation dates, followed by A 195. White mold scores increased with delayed evaluations. Thus, CSM or IFL with disease assessed 33 DPI should be used for identifying common bean genotypes with high levels of physiological resistance to WM.Key words: Common bean, growth habit, race Mesoamerica, race Nueva Granada, Phaseolus vulgaris, Sclerotinia sclerotiorum

scholarly journals Screening for Partial Physiological Resistance to White Mold in Dry Bean Using Excised Stems

1992 ◽  
Vol 117 (2) ◽  
pp. 321-327 ◽  
Author(s):  
P.N. Miklas ◽  
K.F. Grafton ◽  
B.D. Nelson
Keyword(s):  
Phaseolus Vulgaris ◽  
Sclerotinia Sclerotiorum ◽  
Field Resistance ◽  
White Mold ◽  
Lesion Length ◽  
Laboratory Procedure ◽  
Dry Bean ◽  
Snap Bean ◽  
Breeding Lines ◽  
Physiological Resistance

A laboratory procedure was tested to determine whether excised stems would allow a reliable indication of partial physiological resistance (PPR) to white mold [Sclerotinia sclerotiorum (Lib.) deBary] in dry bean (Phaseolus vulgaris L.). Excised stems from 11- and 28-day-old plants were inoculated with growing mycelium of S. sclerotiorum, incubated for 4 to 7 days (11- and 28-day assays, respectively), then assayed for lesion length (LL). A total of 15 bean genotypes were screened for PPR, as indicated by LL. Significant (P < 0.05) differences among LL means of small- and medium-seeded bean genotypes were detected in the 28-day assay, whereas only LL means among medium-seeded genotypes. differed significantly (P < 0.05) in the n-day assay. `Bunsi', `C-20', `Sierra', `Topaz', and snap bean breeding lines NY 5262, NY 5394, and NY 5403 had the highest PPR and `Upland', D76125, and `UI-114' the lowest. The results from both assays were repeatable. A moderately high correlation (r = 0.68, P < 0.02) was observed between PPR and field resistance. The 28-day assay has potential for evaluating dry bean germplasm for PPR to white mold disease caused by S. sclerotiorum. A 28-day assay also was used to measure virulence of 18 isolates of S. sclerotiorum. The 18 isolates did not differ (P < 0.05) for virulence when measured by LL. The lack of any genotype × isolate interaction for LL indicated lack of host-pathogen specificity.

scholarly journals Mycelial compatibility and aggressiveness of Sclerotinia sclerotiorum isolates from Brazil and the United States

2014 ◽  
Vol 49 (4) ◽  
pp. 265-272 ◽  
Author(s):  
Lucimara Junko Koga ◽  
Charles Roger Bowen ◽  
Claudia Vieira Godoy ◽  
Maria Cristina Neves de Oliveira ◽  
Glen Lee Hartman
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Sclerotinia Sclerotiorum ◽  
Country Of Origin ◽  
The United States ◽  
Soybean Field ◽  
Soybean Cultivars ◽  
Mycelial Compatibility ◽  
The Usa ◽  
Midwest Region

The objective of this work was to evaluate the genetic diversity among Sclerotinia sclerotiorum isolates from Brazil and the USA, assess their aggressiveness variability, and verify the existence of an isolate-cultivar interaction. Isolate variability was determined by mycelial compatibility grouping (MCG), and isolate aggressiveness by cut-stem inoculations of soybean cultivars. Two experiments for MCGs and two for aggressiveness were conducted with two sets of isolates. The first set included nine isolates from the same soybean field in Brazil and nine from the Midwest region of the USA. The second set included 16 isolates from several regions of Brazil and one from the USA. In the first set, 18 isolates formed 12 different MCGs. In the second set, 81% of the isolates from Brazil grouped into a single MCG. No common MCGs were observed among isolates from Brazil and the USA. The isolates showed aggressiveness differences in the first set, but not in the second. Although aggressiveness differed in the first set, soybean cultivars and isolates did not interact significantly. Cultivar rank remained the same, regardless of the genetic diversity, aggressiveness difference, and region or country of origin of the isolate. Results from screening of soybean cultivars, performed by the cut-stem method in the USA, can be used as reference for researchers in Brazil.

scholarly journals First Report of Sclerotium Production by Sclerotinia sclerotiorum in Soil on Infected Soybean Seeds

Plant Disease ◽  
1998 ◽  
Vol 82 (2) ◽  
pp. 264-264 ◽  
Author(s):  
X. B. Yang ◽  
F. Workneh ◽  
P. Lundeen
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Germination Rate ◽  
Soybean Seed ◽  
The United States ◽  
Poor Quality ◽  
Soybean Seeds ◽  
Dry Bean ◽  
The North ◽  
Temperature Regimes ◽  
Sclerotium Production

Stem rot of soybean caused by Sclerotinia sclerotiorum (Lib.) de Bary was not recognized as an important problem in the North Central Region of the United States until severe outbreaks occurred in 1992, 1994, and 1996 (2). Although sclerotia mixed with seeds are known to be important to the spread of this disease, the role of internally infested soybean seed in dissemination of the disease is unknown. Tu (1) demonstrated in dry bean, which differs from soybean in seed size and plant architecture, that internally infected seeds are important to the spread of the disease, by producing sclerotia in the soil after the seeds are planted. Experiments were conducted to determine if sclerotia are formed in soils from internally infected soybean seeds. Soybean seed from a field with 70% disease severity were collected and sorted into three classes: (i) normal quality seed, which included moderate or good seed; (ii) poor quality seed (shriveled and/or whitish); and (iii) seed of regular size with visible mycelial mats (S. sclerotiorum or Peronospora manshurica (Naumov) Syd. in Gäum) on the seed coat. Transfer of surface-disinfested seeds to potato dextrose agar and subsequent production of sclerotia showed that 2, 44, and 6% of the seed from each respective class were infested with S. sclerotiorum. One hundred seeds from each of these classes were planted into sterilized and nonsterilized soil at a rate of 5 seeds per pot. Toothpicks were placed to identify the location of each seed, and seeds were covered with 2 cm of soil. Pots were placed in growth chambers with a 14-h photoperiod under two temperature regimes: (i) at 20°C; and (ii) at 10°C for 10 days and then raised to 20°C. Soil was kept saturated by periodically top watering the pots for the first 10 days and bottom watering after that. Two weeks after planting, seeds were examined for formation of sclerotia and the percentages of seeds from which sclerotia were formed were calculated. The experiments were conducted four times. One to two (occasionally three) sclerotia were found in place of each seed that did not germinate. Sclerotia were mainly found from seeds of poor quality, with an average of 12% seeds that produced sclerotia. The frequency of sclerotia found in normal quality seeds was 0.4%, and no sclerotia were found from seeds with mycelial mats. The sclerotia were 2.36 ± 1.07 mm in width, 3.33 ± 1.11 mm in length, and 6.8 ± 3.7 mg in weight, with an averaged germination rate of 88% 8 months after production. Sclerotia production frequencies were 11.4 and 15.4% for temperature regimes (i) and (ii), respectively. Higher percentages of sclerotium production were found in sterilized soil (15.6%) than nonsterilized soil (7.5%). Our results indicate the possibility of internally infected soybean seeds as a means for field-to-field dissemination of S. sclerotiorum. References: (1) J. C. Tu. J. Phytopathol. 121:40, 1988. (2) X. B. Yang. ICM Newsl. 18, 1997.

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