Fine mapping of qBlsr3d, a quantitative trait locus conferring resistance to bacterial leaf streak in rice.

Bacterial leaf streak (BLS) is a destructive bacterial disease in rice (Oryza sativa L.). To date, at least 13 quantitative trait loci (QTL) conferring resistance to BLS have been identified in rice, while only one QTL, qBlsr5a, has been fine mapped and cloned. The present study focuses on fine mapping of qBlsr3d, a minor QTL conferring resistance to BLS. To fine map this QTL, 24 overlapping chromosome segment substitution lines (CSSLs) were developed from the F2 population derived from H359 × H359‐BLSR3D. Combining genotyping of molecular markers with resistant performance, qBlsr3d was delimited to an 81‐kb interval on chromosome 3, which included 12 annotated genes. Sequence alignment indicated that one of the candidate genes, LOC_Os03g03570, has three nucleotide substitutions in the CDS region between H359 and H359‐BLSR3D. In particular, LOC_Os03g03570 encodes a leucine‐rich repeat transmembrane protein, which has been reported to be associated with disease resistance, suggesting that LOC_Os03g03570 may be the target gene. Our research also suggests that CSSLs are suitable for mapping of minor QTL confering disease resistance. Furthermore, our finding has potential value in breeding rice varieties with resistance to BLS in rice. [ABSTRACT FROM AUTHOR]