The Development Of Brassica Napus EST-SNPs And QTL Mapping Of Petal Color Trait

The charateristics of Single nucleotide polymorphisms (SNP) including the most abundant polymorphism DNA markers in genome, great in number, widely distributed, simple typing and easy to be large-scale and automated provide unprecedented opportunities for the study of molecular breeding and complex agronomic traits. Except for rice, Arabidqpsis, maize, the rapeseed and other plant haven’t been reported in the wild detection of SNP in association mapping population. The reason for this is the lack of coverage of genome-wide SNP markers and SNP detection means immature.Firstly, we download643,937Brassica napus EST sequences in NCBI database, and finally get the result of11059Contig containing the SNP in bioinformatics which contains80,155Relaible SNPs. The average Contig contains7.24SNP. At the same time, we set a local EST-SNP database. Secondly, we compare these ContigS with Arabidopsis thaliana, Brassica oleracea and Brassica rapa genome sequences in Blat. The Contig sequences are highly similar to Arabidopsis thaliana, which shows the highly homologous between them in envolution. We draw a physic map of Brassica napus associated with Brassica oleracea and Brassica rapa genome in MapChart, the number of Contig (the maximum hit length over400bp) is1661and1895representively.According to the theory of PCR amplification of specific alleles (PASA), we establish a platform that is used to detect the various SNP effectively in ordinary PCR and agarose gel electrophoresis. Therefore we develop a stratergy about the mass detection of SNP. PASA can be used to analyse the SNP in most Molecular Biology Laboratorys, which is good at economy and repeatability. For PASA wildly used, we think it is the best way to improve structure and function of Taq DNA polymerase.We delevop six segregating populations (PI, P2, Fl, F2, Bl, B2) of Brassica napus white flowers trait. Based on a mixed genetic model of major genes plus polygenes of plant, visually observed, analysis of spectrophotometer of petal extract and BSA-based QTL mapping, we think Brassica napus white flowers trait is in line with model of E_l which is a mixed genetic model of two major genes with additive-dominant-epistatic effects plus polygenes with additive-dominant effects. Heritability of the main genes is98.57%, at the same time, the main gene A can decide the white flower, and compared with the effect of polygenes, the main gene B is heavier but it can not change the flower color naturelly, and the environmental factor is the lightest in them. The main gene A is possibly QTL located in chromosome C3that is detected. And the phenotypic contribution rate of QTL is60.51%. Gene A is possibly a regulatory factor not a pigment synthetic gene, the reason for the form of white flower mutation is result of pigment synthetic gene inhibition, not because its mutation.