Isolation and Characterization of the Field Resistance Related Gene ( xc20 ) against Bacterial Blight Disease from the Tos17 Retrotransposon Mutant Series of Rice

Abstract

Bacterial blight (Xanthomonas oryzae) is one of the most destructive pathogens to rice in south-west area of Japan and South East Asia. The rice cultivar Nipponbare shows the high field resistance against the disease. We inoculated bacterial blight pathogens to Nipponbare mutants which were induced by the insertion of the endogenous retrotransposon Tos17, and have screened mutants which lacked the field resistance. One of the mutants, XC20, had tightly related to a Tos17 insertion in the ninth chromosome. A translational region of about 430 bp (xc20) were found near the Tos17 insertion. This XC20 protein had a sequence similarity to calmodulin binding protein ZmSAUR2 of maize and pathogenesis induced protein upa5 of pepper. Because the field resistance against the disease was recovered in the transgenic XC20 mutants in which native xc20 gene were introduced, we concluded the xc20 was related to the field resistance against bacterial blight disease.