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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Improvement of Cool Season Food Legumes

Location: Grain Legume Genetics Physiology Research

Title: Genetic diversity and population differentiation of Sclerotinia sclerotiorum collected from canola in China and in USA

Authors
item Attanayake, Renuke -
item Carter, Patrick -
item Jiang, Daohong -
item Del Rio Mendoza, Luis -
item Chen, Weidong

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 25, 2013
Publication Date: June 21, 2013
Citation: Kithul-Pelage, R.A., Carter, P.A., Jiang, D., Del Rio Mendoza, L., Chen, W. 2013. Genetic diversity and population differentiation of Sclerotinia sclerotiorum collected from canola in China and in USA. Phytopathology. 103:750-761.

Interpretive Summary: Sclerotinia sclerotiorum is an important disease of many economically important crops including grain legumes and canola in China and the United States. The research was carried out to assess the genetic structure and differentiation of S. sclerotiorum populations infecting canola. Genetic and phenotypic diversity and population differentiation of Sclerotinia sclerotiorum isolates infecting canola from China and the United States were investigated. Eight microsatellite markers and mycelial compatibility groups (MCGs) were used to assess genetic diversity. Phenotypic diversity was measured with sensitivity to three fungicides, production of oxalate and sclerotia, growth rate, and virulence on two canola cultivars. There were no shared MCGs or multilocus haplotypes between the two populations, and significant differences were found between the two populations. The two populations differed significantly for all of the phenotypic traits except for sensitivity to fungicide fluazinam and virulence. Despite the phenotypic differentiation, heritabilities of the phenotypic traits were similar for both populations. Significant correlations were found among five phenotypic traits. Cross resistance to benomyl and iprodione was detected. Virulence was not significantly correlated with any other phenotypic trait and had the least heritability. However, both populations were equally virulent on either a susceptible or a moderately resistant canola cultivars. Results showed that controlling the environment is critical in conducting pathogenicity assay because heritability values suggest that the significant portion of the virulence variation was due to the environment.

Technical Abstract: Genetic and phenotypic diversity and population differentiation of Sclerotinia sclerotiorum isolates infecting canola from China and the United States were investigated. Genetic diversity was assessed with eight microsatellite markers and mycelial compatibility groups (MCGs). Phenotypic diversity was assessed with sensitivity to three fungicides, production of oxalate and sclerotia, growth rate, and virulence on two canola cultivars. No shared MCGs or multilocus haplotypes were detected between the two populations, and populations differed significantly (P < 0.001). Recombination was detected in both populations but was greater in the Chinese population. A polymerase chain reaction detection assay showed that ~60% of the isolates were inversion-plus at the mating type locus. The two populations differed significantly (P < 0.05) for all of the phenotypic traits except for sensitivity to fungicide fluazinam and virulence. Isolates in the Chinese population were unique in several aspects. Despite the phenotypic differentiation, heritabilities of the phenotypic traits were similar for both populations. Significant correlations were found among five phenotypic traits. Cross resistance to benomyl and iprodione was detected. Virulence was not significantly correlated with any other phenotypic trait and had the least heritability. However, both populations were equally virulent on either a susceptible or a moderately resistant canola cultivars.

Last Modified: 8/29/2014
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