Genetic diversity and pathogenicity variation of different Rhizoctonia solani isolates in Sichuan province

An analysis of hyphal fusion, pathogenicity variation and molecular genetic variation of 15 fungal isolates from different rice varieties and 7 isolates from maize in Sichuan province were presented. All the isolates were identified as Rhizoctonia solani AG-1IA and showed significant pathogenicity variation. The genetic variation of these isolates was assessed with RAPD (random amplification of polymorphic DNA)method. In the dendrogram derived from RAPD data by UPGMA, the isolates could be classed into 5 subgroups at 0.92 similarity level. The isolates from the same host plant showed similar RAPD marker patterns and were clustered into the same genetic group or subgroup. These results suggest that a certain degree of genetic similarity exists among isolates recovered from the same host, whereas the pathogenicity variation was not related to host origin of isolates and RAPD groups.