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.