First Report of AG-A of Binucleate Rhizoctonia in China, Pathogenic to Soya Bean, Pea, Snap Bean and Pak Choy

Twenty binucleate Rhizoctonia (BNR) isolates were collected from roots of soya bean, pea, snap bean and pak choy with root rot symptoms in Yunnan Province, China. Chinese isolates anastomosed with the tester isolate of anastomosis group-A (AG-A; C-517) with a high C2 fusion rate (>70%). Chinese isolates were pathogenic to soya bean, pea, snap bean and pak choy and had 97% similarity sequence of 5.8S rDNA-internal transcribed spacer with AG-A tester isolates SN-2 and C-662. When compared with other groups, AG-Ba and AG-Bb, Chinese isolates showed 77% sequence similarity. These results show that Chinese isolates belong to AG-A of BNR. Growth rate, hyphal diameter, cultural characteristics and pathogenicity of the Chinese isolates differed significantly from the tester isolate of AG-A. This is the first report on AG-A in China