Fine Mapping Of The Flowering Gene BnFLC-C2 And Its Molecular Mechanism In Brassica Napus

Brassica napus is the most important oil crop in China,and it is also one of the most important oil crops in the world.Flowering is an important turning point from vegetative growth to reproductive growth,and it is affected coordinately by genetic and environmental factors.Flowering period is an important factor affecting the maturity and yield of rapeseed to a large extent.It is of great significance for the breeding new cultivars to excavate flowering-related genes controlling flowering in rapeseed.Based on the initial QTL mapping for flowering using SG-DH(282 lines)population over nine environments,a major-effect QTL(qFTC2)for flowering was identified.Previous studies narrowed down the qFTC2 to the interval of 1.8cM by BC2F1 segregation population.In current study,a BC2F2 population of 627 plants from self crossing of 7 lines of the BC2F1 was constructed.After analysis association molecular genotypes with flowering time in qFTC2 region,the qFTC2 was narrowed down to the interval between C2SGFLO-89 and C2SGFLO-99,with genetic distance of 0.4cM from original 2.8cM,and corresponding physicial distance of 468kb.Combining with the result of transcriptome sequencing analysis in our previous study,it could be concluded that the homologous gene of the FLC(BnFLC-C2)is the unique gene associated with flowering at qFTC2 locus in C2.By cloning and sequencing of BnFLC-C2,we found several polymorphic sites in the promoter region and intron of the parental allele.The correlation between flowering time and allelic polymorphism loci of 51 Brassica napus cultivars was analyzed.The results showed two insertion/deletion(76-bp)in the promoter region of BnFLC-C2 was closely related to the flowering of Brassica napus.