Fine Mapping Of A Main Flowering Time QTL_qFT_c2-1 In Brassica Napus L.

Rapeseed as the largest oil crops in China, offers a lot of cooking oil and feed protein every year. But in recent years, the land-use contradiction between rapeseed and other crops, such as rice and cotton, is more and more serious, resulting in a significant decrease in rapeseed cultivation and a lot of idle farmland during the winter. The key to solve the problem is to breed early-maturity varieties of rapeseed. A large number of studies have proven that there is a significant positive correlation between the flowering stage and the maturity of rapeseed. Therefore, it is important for early maturity improvement that studying the flowering time of rapeseed.This study taking an early flowering time and early maturity Brassica napus pol CMS restorer line R11 which has stable growth before winter and fast growth after the Chinese Spring Festival, and its near-isogenic line R15 with late flowering time and late maturity as materials, through use of the bulked segregant analysis(BSA) combined with whole genome resequencing(WGR), a main flowering time QTL was primary mapped. Subsequently, it was fine mapped by genetic linkage mapping. The fine mapping lays the foundation for the cloning of the gene and early maturity improvement of core materials in our laboratory. The main experiment results were as follows:1. The investigation results in the spring of 2013 showed that the flowering time of R11 was nine days earlier than R15, and the difference of flowering time between them was significant. Besides, the flowering time of their F2 population was a normal distribution as a whole, but with the trend of bimodal distribution, indicating that there may be main flowering time QTLs.2. Through sequencing analysis of R11 、 R15 、 early flowering pool and late flowering pool, the target QTL was localized in the physical region of 0.1-3.1Mb on the C2 chromosome of Brassica oleracea L.3. According to the results of sequencing, 85 pairs of In Del markers were developed within the rage of positioning, and 25 of them showed co-segregation between the marker genotype and the phenotype of the small group of F2; 84 pairs of SSR markers were developed based on the cabbage sequence corresponding to the interval of primary mapping, and 18 of them showed co-segregation between the marker genotype and the phenotype of the small group of F2.4.The flowering time of ―F2-6‖ was a obvious bimodal distribution, and the ratio of early flowering individuals and late flowering individuals was consistent with 1:3. So, it was indicated that the flowering time was controlled by a main QTL, and the late flowering phenotype was dominant.5. By using two markers IMSSR22 and IMSSR53, with the physical distance between them was furthest, the marker genotypes of 3727 F2 individuals were analyzed and 19 recombinant individuals were found. The target gene was finely positioned into a 202 Kb region of 2614287-2816205 on the C2 chromosome of Brassica oleracea L, according to the location of recombination and the flowering phenotype of the progeny of key recombinant individuals.