Identification of the quantitative trait loci in japonica rice landrace Heikezijing responsible for broad-spectrum resistance to rice blast.

Rice blast is one of the most devastating diseases affecting rice production worldwide. One japonica landrace, Heikezijing, from the Taihu Lake area in China, has been reported to be highly resistant to most of the rice blast isolates collected from China and Japan. To effectively dissect the inheritance of its resistance, a population of recombinant inbred lines (RILs) (F(2:8)) was constructed from a cross between Heikezijing and Suyunuo, a blast-susceptible cultivar. Nineteen blast isolates from China and Japan were inoculated into 166 RILs and their parents, and 22 quantitative trait loci (QTLs) conferring resistance to these isolates were identified and mapped onto rice chromosomes 1, 7, 9, 11, and 12. Most of the QTLs conferred race-specific resistance to blast. Some QTLs, such as qtl11-5-5, conferred resistance to two or more isolates. One blast-resistant gene cluster, including qtl11-2-2, qtl11-3-1, qtl11-4-1, qtl11-5-5, qtl11-6-1, qtl11-7-5, qtl11-8-2, qtl11-9-2, qtl11-10-4, and qtl11-11-1, was found on the long arm of chromosome 11 in the japonica landrace. These loci offered effective resistance toward as many as 17 isolates, including 16 isolates from seven Chinese race groups and 1 isolate from Japan. The results from this study suggest that the Heikezijing landrace involves a number of genes that are associated with broad-spectrum resistance to rice blast.