Localization Of Light-Sensitive And Pure Charaters And Screening Of Candidate Gene In Brassica RAPA

Plants have evolved the capacity to respond to wide range of environmental signals, one of the most important of which is light. Plants formed a precise system of reception and transduction of light signal in order to grow and develop optimally. Anthocyanin biosynthesis in higher Plants is regulated by light. Photoreceptors receive light and are involved in light signal transduction to stimulate the metabolism of anthocyanin accumulation. In Arabidopsis anthocyanin biosynthesis is induced by red, UV-A, blue and UV-B light through phytochromes, cryptochromes and UV-B receptor, respectively. In Brassica rapa'Tsuda', however, only UV-A induced anthocyanin biosynthesis. For the anthocyanin biosynthesis character as induced by UV-A light, we constructed a linkage map including public and new SSR markers, and anchored with pure and light-sensitive traits in a F2population crossing by'Yuurgi Akamaru' turnip and'Tsuda'turnip in this study. And connecting public physical map and bioinformatics, we preliminary screen the candidate genes of Light-sensitive and Pure, these would provide scientific basis for anthocyanin biosynthesis.1. In this study,3803Brassica rapa ESTs of'Tsuda'retrieved from Northeast Forestry University, were screened by SSRHunter program and143SSRs including27kinds of repeat motifs were mined out with AG being the most abundant, accounting for3.76%of ESTs. Out of the90EST-SSRs for which PCR primers were designed, under a suitable PCR system,13loci showed polymorphism in the F2populations. The observed (Ho) and expected (HE) heterozygosities of these EST-SSRs were0.1563-0.5417and0.2277-0.5026, respectively. Results indicate that it is a simple and effective approach to develop SSR markers based on ESTs.2. The segregation of different polymorphic markers including90EST-SSRs and1428gSSRs, were analyzed in F2population of Brassica rapa.100pairs of SSR primer were detected the polymorphisms between the parents for constructing F2population,27polymorphic markers showed Mendelian segregation (P>0.05) and others did not. The result indicates the polymorphism and rate of segregation distortion revealed by gSSR marker is higher than that revealed by the marker coming from EST in Brassica rapa.3. Using100pairs of polymorphism primers screen the F2population, we obtained121Loci. Linkage test using JionMap4.0program (LOD>3.0) indicated64of121polymorphic locus derived from100pairs of primer could be mapped into10linkage groups and covered a total genetic distance of681.20cM. The number of the marker locus per linkage group was6.4, which spanned68.12cM of the Brassica rapa genome. And the average distance of the neighboring marker locus were10.64cM.4. Two quality traits including Pure trait and Light-sensitive trait were detected and located from the parents, F1, BC1and F2population using JionMap4.0program. The Light-sensitive was located between B126.3and BRMS042in Chromosome3, distinct0.4cM to BRMS42. The Pure were located BrlD10223and ENA18in Chromosome10, distinct4.7cM to BrlD10223.5. According to location of the two traits, Arabidopsis homologous gene annotation, expression, characteristics of the transcriptome results of Real-time PCR, public physical map and bioinformatics, we selected three candidate genes that Light-sensitive including Bra012920, Pure including Bra009120and Bra009134.