不结球白菜紫叶性状转录组分析及BcTT8基因功能研究

Abstract

Non-heading Chinese cabbage (Brassica campestrisssp.chinensis) is an important vegetative crop in the south of China. As an antioxidant, anthocyanin is the major quality trait for vegetables with purple leaves or petioles. However, the molecular biosynthetic mechanism of anthocyanin in non-heading Chinese cabbage has not been explained exclusively. In this study, two non-heading Chinese cabbage with contrasting colors in the leaves were used as the materials for RNA-seq. A total of 906 DEGs were detected, and we found that the anthocyanin and flavonoid biosynthetic pathways are significantly enriched in the purple NHCC. The transcriptome result was verified by RT-qPCR. Though bioinformatics analysis,BcTT8was selected as the candidate gene for the regulation of anthocyanin synthesis, and the characterization ofBcTT8was elucidated by the functional analyses. The results proved that BcTT8 is a nucleus protein and phylogenetically close to the TT8 protein fromBrassica. After silencingBcTT8, the total anthocyanin content of pTY-BcTT8plants decreased by 42.5%, and the relative expression levels of anthocyanin pathway genesBcDFR,BcLODXandBcUF3GT-1were significantly downregulated, while the transcription level ofBcFLSwas significantly upregulated. Compared with the wild type, the transgenicArabidopsisshowed obvious violet in the cotyledons part, and the anthocyanin biosynthetic genes such asAtDFRandAtLODXwere significantly upregulated. In conclusion,BcTT8is critical in the anthocyanin synthesis process of non-heading Chinese cabbage. Our findings illustrated the molecular mechanism of anthocyanin biosynthesis in non-heading Chinese cabbage.Keywords:non-heading Chinese cabbage;anthocyanin;BcTT8;bHLH TF;transcriptome analysis