QTL Mapping For Leaf Rolling And Yield Component Traits In A Set Of Reciprocal Introgression Lines And RILs In Rice(Oryza Sativa L.)

Rice is one of the most important crops and is grown on142million hectares of arable lands in Asia. Rice is central to the lives of billions of people around the world. The global demand for rice will be booming in the future. High yield potential still remains the major target of rice breeding. Improvement of plant type plays an important role in super-high yield breeding in rice (Oryza sativa L.). Moderate leaf rolling is of great importance for the improvement of photosynthetic efficiency by maintaining the erectness of leaves and minimizing shadowing between leaves in hybrid rice and consequently improves grain yield. Minghui63(MH63) is an elite restorer, which has been widely utilized, popular for the longest time, the largest planting area, and most significant yield increasing in hybrid rice combinations bred during the past30years in China. In this study, we take use of three sets of populations including reciprocal introgression lines (226MH63-ILs and22902428-ILs) and262RILs derived from a same cross between Minghui63(medium low leaf rolling) and02428(flat leaf). None of which has extreme leaf rolling phenotype as those used in previous reports to investigate the possible correlations between leaf rolling and yield component traits in the levels of both phenotype and genotype. A total of16traits were investigated in the three sets of populations and their parents. These16traits can be roughly devided into four groups, which are leaf traits (LL, LW, LRI, and FLW), yield and its component traits (PN, SNP, TGW, SF, BM and GY), agronomic traits (HD, PH, and PL), and grain volumn traits (GL, GW, and GT). Among them, data for FLW and BM were available only in one environment (Beijing).Major results about leaf rolling and yield related traits in two environments (Beijing and Shenzhen) in2012:MH63and02428were significantly different in all traits under both environments except for FLW in BJ, as well as LW and SF in Shenzhen. Correlations between the same traits from different environments were also analysed in progenies. All traits were found to be significantly correlated between different environments, except for LL, SF, and GY in RILs. A total of493cases were found in the associations between the leaf traits, yield component traits and SNP markers. Among them,28loci (main-effect loci, ME-loci) were found to be with multiple supporting evidences, and four regions (genetic-overlap regions, GO regions) where leaf rolling loci located were found to be associated with loci for other traits. These GO regions would explain the complex relationships between leaf rolling and yield component traits. These LRI loci together with some new loci such as GL6.1would offer new useful information for MAS breeding.