Studies on Diversity of Sclerotium rolfsii Causing Collar Rot in Chickpea using Morphological and Molecular Markers

Sclerotium rolfsii is a soil borne fast spreading fungal pathogen that causes collar rot in chickpea. The variability among the pathogen isolates have made difficult to design efficient management practices and necessitates for a comprehensive study to know its diversity. The present study was planned to study the genetic diversity among the isolates of S. rolfsii collected from chickpea growing regions of Kurnool and Ananthapur districts of Andhra Pradesh at morphological and molecular level. The morphological characterization of isolates on PDA indicated that the isolates, CSR 14, CSR 18 and CSR 20, were fast growing and the overall growth i.e., sclerotia formation in terms of number, size and days to formation, was also faster. These isolates took only 4 days for production of sclerotial bodies. A total of 254 reproducible and scorable polymorphic bands ranging from 200 to 2000 bp were observed with twenty nine RAPD primers. The RAPD banding pattern reflected the presence of greater variability among the isolates and grouped the isolates into two clusters. The isolates, CSR 18 and 20, formed the cluster II revealing their distantness from other isolates at molecular level. The isolate, CSR 14, formed a separate sub cluster in the cluster I indicating its distant association with other isolates of this cluster.