Sclerotinia sclerotiorum genetic diversity in Bulgaria

The mycelial compatibility of 154 isolates of Sclerotinia sclerotiorum, obtained from sunflower and rapeseed plant samples, collected from 2019 - 2021 from 17 locations in Northern and Southern Bulgaria, was studied. The studied isolates were grouped into 108 local MCGs, and 60.1% included only one isolate. The Shannon index (Ho) at the studied locations varied from 0.718 to 1.00. The total diversity in MCG resulting from variation among individuals in the population was 92.2%, and the proportion of total diversity in MCG due to variation among populations was 7.78%. The clonal index for all populations was 0.299. In two of the six compatibility tests between isolates from different locations, 10 additional groups were formed, and one of them (MCGs-1D5x2D4x1SH3x1Y8) included six isolates from four locations (Dropla – Tsaricheno - Rish 1-Straldzha) located in three regions of the country. The results show significant genetic diversity in S. sclerotiorum populations based on mycelial compatibility between isolates.