Pathogenic and genetic variability among Brassica isolates of Sclerotinia sclerotiorum from India and UK

Seventeen oilseed Brassica representative isolates of Sclerotinia sclerotiorum from a collection of 53 from different Brassica growing geographical regions of India, United Kingdom were used to study variation in their pathogenicity on twelve differentials, detect genetic variability among them. All the isolates showed considerable variability and were divided separately into groups according to their pathogenicity in respect of two quantitative characters i.e., stem lesion length (mm) and % disease incidence (Prasad et al., 2009) for genetic variability among them using Random Amplified Polymorphic DNA molecular marker. Cluster analysis of pathogenic data revealed a close relationship between SR-11, SR-14 isolates while a close relationship was also observed between SR-16, SR-17 isolates, which was supported by cluster analysis of RAPD data. On the basis of cluster analysis of RAPD data, isolates from UK viz., SR-08 and SR-10 shared a single group, which matched the data on disease incidence on twelve differentials while other isolates did not group according to their geographical origin. Two isolates viz., SR-12 and SR-13 were very identical to each other according to analysis of RAPD data but it did not match conclusions from pathogenicity data of these isolates. This study showed existence of pathogenic and molecular variability among S. sclerotiorum isolates from different parts of India and UK, where oilseed Brassicas are grown.