Differentiation of isolates of cotton root rot pathogens Rhizoctonia solani and R. bataticola using pathogenicity and RAPD markers

Twelve isolates of Rhizoctonia solani and fifteen isolates of R. bataticola causing root rot of cotton were studied for their pathogenicity and genetic diversity using RAPD markers. Pathogenicity of these isolates varied when tested on Gossypium arboreum variety RG-8. The similarity value of RAPD profiles in R. solani isolates ranged from 0.35 to 1.00 with an average of 0.67 among all the isolates and in R. bataticola it ranged from 0.27 to 1.00 with an average of 0.63 among all the isolates. Eighteen primers were used to fingerprint the individual isolates. The cluster analysis using unweighted primer group method with arithmetic average could distinguish R. solani and R. bataticola isolates into two separate fingerprint groups.