Abstract: Thirty two rice sheath blight pathogen strains (Rhizoctonia solani) were isolated from the infected rice samples from seven distinctive areas of Anhui Province, and their pathogenicity and genetic diversity were analyzed. Pathogenic differentiation analysis indicated that the pathogenicity among the strains was significantly different. The pathogenicity of the majority isolates was moderate in Anhui province. The genetic diversity of 32 Rhizoctonia solani strains was analyzed by RAPD. The results showed that the pathogenic and genetic diversity among the tested isolates were high, the polymorphic rate was 98.2%, and the genetic similarity coefficients of the isolates were 0.62-0.84. All the strains could be classified into 4 groups at the similarity coefficient of 0.653, and most of the isolates from the same area were consistent, but the pathogenicity showed no significant correlation within the RAPD groups．

Key words: rice, Rhizoctonia solani, pathogenicity, genetic diversity, RAPD