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

Abstract

In order to identify the bacterial blight resistance gene of ricecultivar IR8, one of the rice baceterial blight differentials, aresearch was carried out under a collaboration between Ministry ofAgriculture, Forestry and Fisheries (MAFF), Japan and International RiceResearch Institute (IRRI), Philippines. Inoculation test using Japaneseand Indonesian races of bacterial blight pathogen, was first carried outwith cultivars which are known to show the reaction pattern similar tothat of IR8. The results indicated that cultivars of IR8 reactionpattern showed resistance to Japanese races IB, II, IIIA and V, andIndonesian races IV and V but susceptibility to Japanese races IA, IIIBand IV. It was found that Japanese race IV differs pathogeneticallyfrom Indonesian race IV. Moreover, there was no difference between thereaction pattern of Elwee and Heen Dikwee which were considered tobelong to different reaction groups by YAMADA et al. (1979a). Theresults of gene identification by F2 analysis showed that IR8, Elwee andRP9-3 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 Petaand IR944-102-3-2 also have the same gene with IR8 and have anotherdominant gene for resistance of Japanese races. This study showed thatIR8, Elwee, RP9-3, Peta, and IR944-102-3-2 have the gene Xa-11 forresistance originally identified by OGAWA and YAMAMOTO (1986).