Submitted to: Fungal Genetics Reports
Publication Type: Abstract Only
Publication Acceptance Date: January 4, 2011
Publication Date: March 1, 2011
Citation: Attanyake, R., Porter, L., Johnson, D., Chen, W. 2011. Genetic and phenotypic diversity of Sclerotinia sclerotiorum on a small geographic scale. Fungal Genetics Reports. 58:214. Technical Abstract: Population structure, genetic and phenotypic diversity of Sclerotinia sclerotiorum were investigated on a small geographic scale. A collection of 40 Sclerotinia isolates from one square meter top layer of soil in a Washington alfalfa field was studied for colony color, Mycelial Compatibility Groupings (MCGs), oxalic acid production, DNA haplotypes of eight microsatellite loci, fungicide sensitivity and virulence. The 40 isolates exhibited three colony colors: beige (22 isolates), dark (11 isolates) and white (7 isolates). Fifteen MCGs and 16 microsatellite haplotypes were found among the 40 isolates. However, the haplotypes did not necessarily correspond with MCGs. There were several examples of isolates within a MCG belonging to different haplotypes and of isolates of the same haplotype belonging to different MCGs. The proportion of microsatellite haplotypes over sample size (40%) was high compared to other studies where populations obtained from wider geographic areas. STRUCTURE analyses indicated there were five clusters, suggesting likely five genetic populations. All isolates showed considerable oxalic acid production except that one isolate consistently produced significantly less amount of acid, on a pH-indicating medium. The isolates also exhibited significant differences in sensitivity to fungicides benomyl, fluzinam and iprodione, and in virulence as measured by colonization on detached pea leaves. This study documents high level of genetic and phenotypic diversity of S. sclerotiorum on a small geographic scale, presenting challenges in managing the diseases it causes.