Abstract: In order to understand the pathogenic differentiation and variation of Xanthomonas oryzae pv. oryzae in Hubei province,pathogenic isolates were collected from rice growing areas in Hubei province. Near isogenic lines IRBB2,IRBB3,IRBB5,IRBB13,IRBB14 and IR24 carrying different resistance genes were used to detect pathogenic differentiation. Leaf-clipping method was used to detect pathogenic differentiation of the pathogen according to the interaction between the host and the isolates. The results showed that the pathotype R9（SSSSSS） of rice bacterial blight was 46.2%,and the unknown strains were 38.5%. Compared with the results of previous studies,the pathotypes of bacterial blight in Hubei province had undergone considerable variations, and the main pathogenic form was changed from R4 to R9,with the emergence of R8 （SSRSSS） types which wasn’t detected and unknown types. At the same time,Xa7 and Xa23 mediated resistance were identified. A few strains of Xa7 gene could be overcome,while Xa23 could resist all strains. Therefore,these two genes could be used in rice breeding for resistance to bacterial blight in Hubei province.

Key words: rice, Xanthomonas oryzae pv. Oryzae, pathotype