Genetic Analysis And Fine Mapping Of LH1and LH2, A Set Of Complementary Genes Controlling Late Heading In Rice(Oryza Sativa L.)

Rice (Oryza sativa L.) is an important cereal crop and the model species of monocots. Heading date is the growth duration from seeding to heading of the first panicle. In rice, heading date is a critical agronomic trait with a complex inheritance, which is responsible for the regional and seasonal adaptation of rice varieties. Therefore, detailed understanding of heading period’s genetic law is significant for rice breeding practice. In this research, we employed three indica cultivars, Bo B, Yuefeng B and Baoxuan2, to develop F2and F3segregant populations and investigated the genetic basis and mechanism of gene interaction in heading date. The main result is as follows:1) We conducted genetic analysis on segregant populations derived from crosses among the indica cultivars Bo B, Yuefeng B and Baoxuan2. A set of dominant complementary genes controlling late heading, designated LH1and LH2, were detected by molecular marker mapping. Genetic analysis revealed that Baoxuan2contains both dominant genes, while Bo B and Yuefeng B each possess only one.2) Using F3segregant populations derived from Bo B and Yuefeng B, LH1and LH2was primarily mapped on chromosome7and chromosome8, respectively. By constructing larger populations with segregant ratios of3:1, we fine-mapped LH1to a63-kb region near the centromere of chromosome7flanked by markers RM5436and RM8034, and LH2to a53-kb region on the short arm of chromosome8between flanking markers Inde18-8and RM22475. Some potential genes were identified through sequencing of Bo B and Yuefeng B in these target regions, and sequence alignment and gene expression analysis was conducted.Our work provides a solid foundation for further study on gene interaction in heading date and has application in marker-assisted breeding of photosensitive hybrid rice in China.