Population genetic structure analysis of Sclerotinia sclerotio rum (Lib.) de Bary from different host plant species in northern Iran

The genetic structure of 65 Sclerotinia sclerotiorum isolates representing 52 field populations from three provinces in northern Iran were analyzed with Mycalial Compatibility Groupings (MCGs) and five polymorphic microsatellite loci. In total, 44 haplotypes were detected with 25 allele polymorphisms. A high level of genetic diversity was observed in about 67.6% (with clonal fraction = 0.077 to 0.20) of the regional populations studies, and the Shannon diversity index (Ho) for the whole region was found to be 0.86 (Htot). Partition of total diversity (Htot) showed that 64% corresponded to a variation in diversity within the S. sclerotiorum populations. By mycelial compatibility grouping (MCG) tests, the isolates were classified into 39 groups of which 26 MCGs were individual. Molecular and phenotypic analyses results of all of the isolates (except MCG4 and MCG23) were similar; however, the isolates in the MCG4 and MCG23 groups, with variable microsatellite haplotypes, were morphologically dissimilar. The results shown here were possibly due to high rates of outcrossing, as well as to the evolutionary potential within population of the pathogen in different locations in Iran. Nei’s genetic identity showed that populations from Golestan province and wild plants were the most diverse.