Abstract
Stigma exsertion ratio (SER) of rice male sterile line directly affects the hybrid rice F(1) seed production, while SER was directly affected by the total of stigma and style length (TSSL). To improve the F(1) seed production, it is necessary to identify the genes or quantitative trait loci (QTLs) controlling TSSL. In this study, we used the 7001 S with short TSSL, Zitai S with long TSSL and F(2) to preliminarily map the QTL controlling TSSL to a 2.71 Mb interval using BSA-seq method. Based on the known SSR marker and newly designed InDel markers, the target region was further narrowed down to a 58.2 kb interval between TSL25 and TSL128 on chromosome 3. Gene knockout experiment was used to confirm Os03g0407400 (GS3) as a candidate gene controlling TSSL. Furthermore, according to the sequence alignment difference in the coding region of GS3 between 7001 S and Zitai S, the marker M1 was developed and revealed to be closely linked to TSSL. Combining fertility identification and molecular marker-assisted selection, a fertility-stable near-isogenic line (NIL) of C815S with long TSSL was created. It was found through small-scale F(1) seed production combination trials that the outcrossing seed setting ratio of combination NIL-C815S × R919 was 39.31%, and the yield of the F(1) seeds harvested from the female parents in the unit area was 237.50 g, which were both higher than that of the combination C815S × R919. These results laid a foundation for further research on the TSSL trait in rice and enriched its molecular regulatory network.