Primary Dissection For The Function Of 2 FT Genes On C6 Chromosome In Brassica Napus

Flowering is a result of interaction between the changing exogenous environment and development state of higher plants. Plants can escape adverse condition for reproduction in appropriate pollination time. The research on the mechanism of flowering time provides useful guidance for breeders to breed new varieties of crops with the strong adaptation to the environment. We constructed a 202 TN DH Brassica napus population lines in our lab. The two parents of the population are winter-typed European cultivar B. napus Tapidor and semi-winter typed Chinese cultivar B.napus Ningyou7. Flowering time QTL analysis showed that there was a QTL cluster on C6 chromosome contributed to accelerate flowering by late flowering Tapidor, while other QTL were all contributing to accelerate flowering by early flowering Ningyou7. We attempted to construct a flowering time QTL targeted near-isolated lines and adopted Tapidor as the donor parent and the Ningyou7 as the recurrent parent.Six BnFT copies were isolated and located in the genome of TN population. The major QTLs on C6 chromosome were dissected and two BnFT paralogues on C6 chromosome may be the candidate genes for the QTL cluster. Our purpose is to further dissection the two BnFT paralogues on C6 chromosome, this work can be divided into three parts:1. Constructing the near-isolated lines which introgression with two BnFT paralogues from Tapidor C6 chromosome separately to analysis this two BnFT paralogues.2. Investigating the phenotypes of the advanced backcross segregation population and the near-isolated lines in different environments to analysis function of two BnFT genes together.3. Using the expression profile to detect the function of two BnFT paralogues of C6 chromosome, respectively.The main results were described as follows:1. Since there is only 0.86cM between the two BnFT genes on C6 chromosome, no recombinant plant was found in the advanced backcross segregation population.2. Each of the two BnFT paralogues has their own effects on the flowering time in both winter and spring environment when analyzing the segregation populations under different condition. The NILs with different origin have different phenotype, which may cause by the content of the background. However, besides the environment, the genotype has an effect upon the flowering time after the analysis of the phenotype of 14 NIL with different origin under 2 different condition.3. With the limitation information of the expressed EST FT in B.rapa, B.napus and B.oleracea, BnFT genes can preliminarily divide into 3 groups:BnFTa, BnFTb, BnFTc in B.napus, hardly to assign the BnFT genes into the highly homology A genome or C genome. However, the results can explain some QTLs effect between the parents expressed EST of BnFT genes in the whole genome. From the content of different type of BnFT expressed in the near-isolated lines, it's clear that the Ningyou7 background have different effects on the BnFTa and BnFTb alleles, and it may cause the early flowering of the NIL compared with the two parents.