Metabolomics and Transcriptomics Provide Insights into Anthocyanin Biosynthesis in the Developing Grains of Purple Wheat (Triticum aestivum L.)

Purple wheat is thought to have beneficial effects on humans owing to its high anthocyanin content. However, a systematic understanding of the anthocyanin biosynthesis process in developing wheat grain is lacking. Here, the dynamic changes in anthocyanin components and transcripts in the grain of purple wheat ZNM168 at five developmental stages (10, 15, 20, 25, and 30 DAF) were characterized. Compared with other anthocyanins, four components, cyanidin 3-O-rutinoside, cyanidin 3-O-glucoside, cyanidin 3,5-O-diglucoside, and malvidin 3-O-glucoside, were significantly accumulated with grain development. In particular, the considerable accumulation of cyanidin 3-O-rutinoside indicated that it was the pivotal pigment for the purple grain. Transcriptome analysis revealed that the nine differentially expressed genes related to anthocyanin biosynthesis belonged to the BZ1 group, the homologous enzyme encoded by the maize Bronze-1 locus, which may primarily serve to glucosylate anthocyanidins. By constructing a gene coexpression network based on weighted gene coexpression network analysis, the TaBZ1 UniGene (TraesCS1D02G019200) was predicted as a core gene in anthocyanin biosynthesis. In addition, correlation analysis between the metabolites and transcripts suggested that TraesCS2A01G527700 (TaCHS) and TraesCS6B01G006200 (TaANS) were considered critical structural genes in the anthocyanin biosynthesis pathway. This study provides insights to exploit genes pinpointed as genetic engineering targets, thereby breeding anthocyanin-enriched wheat.