Screening of varieties and isolates for identifying interaction between host and pathogen of rice sheath blight.

Five rice cultivars(YSBR1,C418,Jasmine85,Wuyujing3 and Lemont) with different levels of resistance to Rhizoctonia solani identified and screened from worldwide rice collections were selected to identify the pathogenicity of different isolates.Several hundred strains of R.solani had been isolated and purified from Jiangsu,Guangdong,Guangxi,Hainan,Yunnan,Hunan and Fujian Province.Thirty isolates with different pathogenicity were selected to inoculate the five identification cultivars at the seedling stage in the greenhouse.Five isolates with obvious discrepancy of pathogenicity,C30,GD-118,E67,YN-7 and YN-3,were selected ultimately.The obtained cultivars and strains for identification were verified through field experiments at rice adult stage in Yangzhou of Jiangsu Province and Fuyang of Zhejiang Province.The results indicated that both the cultivars and isolates were divided significantly to five resistance grades and three pathogenicity grades respectively,so both of which could be used as identification materials.An identification system to the isolate pathogenity and the host resistance for rice sheath blight was preliminarily setup.The necessity and feasibility about the identification system,and the further work were also discussed in the paper.