Molecular mapping of a quantitative trait locus qSTV11^Z harbouring rice stripe virus resistance gene, Stv-b

Rice stripe virus (RSV) predominantly affects rice. In this study, we attempted to localize the quantitative trait locus (QTL) conferring RSV resistance in the ‘Zenith’ variety, which is known to harbour Stv-a and Stv-b. The resistant variety Zenith was crossed with the susceptible variety ‘Ilpum’ to generate a mapping population comprising 180 F_2:3 lines for QTL analysis. Contrary to previous findings, we could not detect Stv-a-specific QTLs on chromosome 6. Stv-b-specific QTL was detected on the long arm of chromosome 11; it was designated qSTV11^z. Six F_4:5 lines were selected from the F_3:4 population and fine-mapped using insertion/deletion (InDel) markers. qSTV11^z was mapped to a 520-kb region between the InDel markers Sid2 and Indel8. This region included OsSOT1 (candidate gene for STV11) and other previously reported RSV resistance QTLs. The OsSOT1 sequence in Ilpum and Zenith was identical to that of the susceptible variety ‘Koshihikari’, indicating that OsSOT1 is not the candidate gene of qSTV11^z. The localization of qSTV11^z should provide useful information for marker-assisted selection and determination of genetic resources in rice breeding.