Substitution Mapping of the Major Quantitative Trait Loci Controlling Stigma Exsertion Rate fromOryza glumaepatula

Background Stigma exsertion rate (SER) is a key determinant for the outcrossing ability of male sterility lines (MSLs) in hybrid rice seed production. In the process of domestication, the outcrossing ability of cultivated rice varieties decreased, while that of wildOryzaspecies kept strong. Here, we detected the quantitative trait loci (QTLs) controlling SER using a set of single-segment substitution lines (SSSLs) derived fromO. glumaepatula, a wildOryzaspecies. Results Seven QTLs for SER were located on 5 chromosomes.qSER-1aandqSER-1bwere located on chromosome 1.qSER-3aandqSER-3bwere mapped on chromosome 3, andqSER-3bwas further located at an estimated interval of 898.8 kb by secondary substitution mapping.qSER-5,qSER-9andqSER-10were identified on chromosomes 5, 9 and 10, respectively, andqSER-9was delimited to an estimated region of 551.9 kb by secondary substitution mapping. The additive effects of the 7 QTLs ranged from 10.6% to 14.8%, which were higher than those of most loci for SER reported previously. Conclusions qSER-1aandqSER-1bare novel loci for SER on chromosome 1. All of the 7 QTLs have major effects on SER. The major QTLs of SER will help to develop MSLs with strong outcrossing ability.