Molecular Biological Studies Of Seed Coat Color In Oilseed Mustard (Brassica Juncea)

The breeding of yellow seed coat rapeseed are attracted increasing attention by rapeseed breeder. The yellow-seed trait is economically benefical to the oil industry, seeds of yellow cultivars have high oil content than those of dark-seed varieties. Yellow seeds of rapeseed have lower fiber and ligin, compared with those of dark-seed varieties. Yellow seed also have higher protein content than dark seeds. The seed coat color heredity in Brassicajuncea is simple, the yellow coat seed is obviously difference to the brown coat seed. In order to know the hereditary and molecular basis of yellow coat seed, we selected the materials which are Sichuan yellow selfing line and Ziyejie selfing line, we carried out the genetics studies of seed coat color and leaf color, RAPD(random amplified polymorphic DNA) analysis of gene which control the seed coat color. Using the primer designed from the gene of dihydroflavonol 4-reductase (DFR) in Arabidopsis thaliana, using the genomic DNA of Sichuan yellow Ziyejie as template, we obtained the DFR gene fragment. Through the research, we got some results as fellows:1 We know the genetics of seed coat color and leaf color in Brassica juncea.the brown seed coat color was dominant character, the yellow seed coat color was recessive character, seed coat color was controlled by two genes, the functions of two genes were independent, the seed coat color in BC1 showed the segregation phenomenon, the ratio for segregation of brown seed and yellow seed is 3:1, the seed coat color in F2 showed the segregation phenomenon, the ratio for segregation of brown seed and yellow seed is 15:1. The leaf color was controlled by one gene, the brown leaf was dominant character, the green leaf was recessive character. The segregation phenomenon of seed coat color and leaf color of Sichuan yellow x (Ziyejie x Sichuan yellow) BC1 in growth house showed that the recombination frequency of seed coat color gene and leaf color gene was 46.2%, which suggest that the inheritance of seed coat color and leaf color was independent.2 Breeding some lines that isolation of independent gene pairs at two loci for seed coat color in Brassicajuncea, one was dominant, the other was recessive. The lines are backcrossed to Sichuan yellow 3 times to obtain the lines that are {Sichuan yellowX (Ziyejie X Sichuan yellow)} X Sichuan yellow.3 Using Sichuan yellow, Ziyejie, Ziyejie X Sichuan yellow and Sichuan yellow X (Ziyejie X Sichuan yellow) as materials, we localized the seed coat color gene in Brassica jimcea. Using the way of bulked sergeant analysis(BSA), 275 10-mer random primers were chosen for polymorphism between the two bulks and Sichuan yellow, Ziyejie, we found two RAPD marker S201000, S73800 linked to brown seed coat color gene.4 We cloned the DFR gene fragment in Sichuan yellow and Ziyejie, knowedthe sequences of the two DFR gene fragments, the length of DFR gene fragment in Sichuan yellow is same to this in Ziyejie, the length of the two DFR gene fragments are 466 base pair(bp). We compared the two sequences to NCBI-BLAST. In Sichuan yellow. 99% sequences are homologous to Brassica napus cultivar Stellar dihydroflavonone isomerase gene(partial cds), expect=0.0,we could consider the fragment was dihydroflavonone isomerase gene(partial cds) fragment; the dihydroflavonone isomerase gene( partial cds) sequences of Brassica oleracea cultivar and Brassica rapa cultivar have 96% and 93% homologization, the dihydroflavonol reductase gene (partial cds) sequences of Brassica carinata and Arabidopsis thaliana have 93% and 90% homologization, respectively, compared with Sichuan yellow DFR sequences. In Ziyejie, 97% sequences are homologous to Brassica napus cultivar Stellar dihydroflavonone isomerase gene(partial cds), expect=0.0,we could consider the fragment was dihydroflavonone isomerase gene(partial cds) fragment; the dihydroflavonone isomerase gene( partial cds) sequences of Brassica oleracea cultivar and Brassica rapa cultivar have 96% and 94% homologization. the dihydroflavonol reductase gene (partial cds) se...