Integrative Analysis of Metabolomics and Transcriptomics Reveals Molecular Mechanisms of Anthocyanin Metabolism in the Zikui Tea Plant ( Camellia sinensis cv. Zikui).

In this study, we performed an association analysis of metabolomics and transcriptomics to reveal the anthocyanin biosynthesis mechanism in a new purple-leaf tea cultivar Zikui ( Camellia sinensis cv. Zikui) (ZK). Three glycosylated anthocyanins were identified, including petunidin 3- O -glucoside, cyanidin 3- O -galactoside, and cyanidin 3- O -glucoside, and their contents were the highest in ZK leaves at 15 days. This is the first report on petunidin 3- O -glucoside in purple-leaf tea. Integrated analysis of the transcriptome and metabolome identified eleven dependent transcription factors, among which CsMYB90 had strong correlations with petunidin 3- O -glucoside, cyanidin 3- O -galactoside, and cyanidin 3- O -glucoside (PCC > 0.8). Furthermore, we also identified key correlated structural genes, including two positively correlated F3'H (flavonoid-3'-hydroxylase) genes, two positively correlated ANS (anthocyanin synthase) genes, and three negatively correlated PPO (polyphenol oxidase) genes. Overexpression of CsMYB90 in tobacco resulted in dark-purple transgenic calluses. These results showed that the increased accumulation of three anthocyanins in ZK may promote purple-leaf coloration because of changes in the expression levels of genes, including CsMYB90 , F3'Hs , ANSs , and PPOs . These findings reveal new insight into the molecular mechanism of anthocyanin biosynthesis in purple-leaf tea plants and provide a series of candidate genes for the breeding of anthocyanin-rich cultivars.