Molecular mapping of QTL for rice black-streaked dwarf disease resistance in rice (Oryza sativa L.)

Rice black-streaked dwarf disease (RBSDD) is one of the most serious crop diseases in Asia, causing serious damage to rice production. Therefore, reducing the harmful effects of RBSDD is vital to the food security of China and other Asian countries. In this study, 248 rice varieties from different countries were screened for resistance to RBSDD, and 19 varieties with high resistance to RBSDD were found. Among them, H185, an indica variety, showed stable and high resistance to RBSDD. Using an F-2:3 population of H185 and Wuyujing 3 (WYJ3, a highly susceptible japonica rice variety), three QTL conferring resistance to RBSDD, namely qRBSDD2, qRBSDD7, and qRBSDD11 were identified, and they explained 53.6% of the total phenotypic variation. Among them, qRBSDD2 and qRBSDD7, with LOD scores of 4.26 and 4.25, respectively, were repeatedly detected in artificial inoculation conditions, accounting for 28.0% and 29.8% of the total phenotypic variation, respectively. Resistant alleles of the two QTL were all derived from H185, and several BC5F2 lines possessing single or two QTL of qRBSDD2 and qRBSDD7 exhibited higher resistance for RBSDD. The QTL detected in our study open new possibilities for breeding rice cultivars with RBSDD resistance through resistance gene pyramiding.