Multi-omics analysis reveals the regulatory mechanism of flavonol biosynthesis during the formation of petal color in Camellia nitidissima

Camellia nitidissima is a prized woody flower with golden-yellow flowers, and has high ornamental, medicinal and economic value. Previous works indicated that the content of flavonol accumulated greatly during golden petal formation. However, the molecular mechanism of golden flower formation in C. nitidissima remains largely unknown. In this study, we performed an integrative anlysis of transcriptome, proteome and metablome of petals at five developmental stages to construct the regulatory network during golden flower formation in C. nitidissima. Metablome anlysis showed that two flavonols, the quercetin and kaempferol glycosides, were highly accumulated in the golden petals. Furthermore, transcriptome and proteome sequencing suggested that the expression of flavonol biosynthesis genes or proteins was increased in golden petal stage, whereas expression of anthocyanin and proanthocyanidin genes or proteins were decreased. Six MYB and 20 bHLH genes were identified as potentially involved in flavonoid biosynthesis, and the brassinosteroid (BR) and jasmonate (JA) pathways were positively and negatively corretated with flavonol biosynthesis, respectively. Network correlation analysis suggested close relationships among BR and JA, MYB and bHLH, and the flavonoid pathway and flavonoid metabolites. Overall, this study shows a potential regulatory mechanism of flavonol biosynthesis duing golden petal formation in C. nitidissima. HighlightThe BR and JA pathway may positively and negatively regulate flavonol synthesis in Camellia nitidissima, respectively.