Morphological, cultural and genetic variability among Indian populations of Sclerotium rolfsii

Twenty isolates of Sclerotium rolfsii collected from different host plants and various geographical locations of the country during 2009–2012 were found varied in their mycelial growth rate, colony morphology, size and pattern and distribution, number and size of the sclerotia. Random Amplification Polymorphism-DNA (RAPD) analysis showed 95.9% average polymorphism. UPGMA analysis of RAPD data revealed that all the isolates formed 2 major clusters at 0.32 similarity index and further, one cluster was divided in to 2 sub-clusters at 0.45 similarity index. The highest similarity coefficient (0.82) was recorded between Sr06 (Groundnut) and Sr10 (Groundnut) and Sr25 (Sweet potato) and Sr19 (Capsicum). The isolates had no apparent grouping according to geographical areas or host origin in RAPD analysis, indicated wide host range of the pathogen.