Resistance and Its Inheritance to Bacterial Blight of IR8 Rice Cultivar Group

Abstract

In order to identify the bacterlal blight resistance gene of rice cultivar IR8, one of the rice baceterial blight differentials, a research was carried out under a collaboration between Ministry of Agriculture, Forestry and Fisheries (MAFF), Japan and International Rice Research Institute (IRRI), Philippines. Inoculation test using Japanese and Indonesian races of bacterial blight pathogen, was first carried out with cultivars which are known to show the reaction pattern similar to that of IR8. The results indicated that cultivars of IR8 reaction pattern showed resistance to Japanese races IB, II, IIIA and V, and Indonesian races IV and V but susceptibility to Japanese races IA, IIIB and IV. It was found that Japanese race IV differs pathogenetically from Indonesian race IV. Moreover, there was no difference between the reaction pattern of Elwee and Heen Dikwee which were considered to belong to different reaction groups by YAMADA et al. (1979a). The results of gene identificatlon by F2 analysis showed that IR8, Elwee and RP9-3 have the same gene for resistance to Japanese races IB and IIIA. The allelic test between the resistance gene of IR8, Elwee, and RP9-3, and the resistance gene(s) of Peta and IR944-102-3-2 showed that Peta and IR944-102-3-2 also have the same gene with IR8 and have another dominant gene for resistance to Japanese races. This study showed that IR8, Elwee, RP9-3, Peta, and IR944-102-3-2 have the gene Xa-11 for reslstance originally identified by OGAWA and YAMAMOTO (1986).