Mapping and validation of quantitative trait loci that confer resistance to rice black-streaked dwarf virus disease in rice (Oryza sativa)

Rice black-streaked dwarf virus (RBSDV) disease is one of the most destructive viral diseases that threatens rice production in China. Breeding of resistant cultivars through multi-gene pyramiding is considered to be an effective way to control the disease, but few resistance genes have been characterized to date. In the present study, we identified T1012, a BC2F6 line from a cross of the japonica variety 'Wuyujing3' (recipient) and the indica variety 'Dular' (donor), that had improved resistance to RBSDV disease in a field test, and 140 backcross inbred lines (BILs) derived from a cross between T1012 and 'Wuyujing3' were developed using marker-assisted selection. Genetic analysis showed that the resistance of T1012 to RBSDV disease was controlled by quantitative trait loci (QTLs). Two QTLs for RBSDV disease resistance located on chromosomes 1 and 4, qRBSDV-1 and qRBSDV-4, were identified, and qRBSDV-4 was repeatedly detected in two environments. Compared to 'Wuyujing3', the line containing only the substitution segment covering qRBSDV-4 exhibited significantly decreased disease incidence, indicating that qRBSDV-4 is a reliable resistance QTL with a high breeding value. Furthermore, two linked QTLs, qRBSDV-4-1 and qRBSDV-4-2, were identified within the interval containing qRBSDV-4. The QTLs identified here will provide a useful resource for breeding RBSDV-resistant rice cultivars through marker-assisted selection and establish a foundation for the cloning of RBSDV disease resistance genes.