Integrated transcriptomics and metabolomics analyses provide insights into anthocyanin biosynthesis for leaf colour formation in Quercus mongolica

Abstract

Abstract Quercus mongolica is a tall tree with a broad, rounded crown and lush leaves. In autumn, the leaves turn red and have great ornamental value. However, the molecular mechanisms that cause the change in leaf colour are unknown. In this study, we identified 12 differentially expressed genes involved in anthocyanin synthesis by analysing the transcriptome of Q. mongolica leaves in six developmental stages (S1 − S6). We further analysed the dynamics of anthocyanin content in Q. mongolica leaves in four developmental stages (S1, S2, S5, and S6) using differential gene expression patterns. We detected a total of 48 anthocyanins and categorised these into seven major anthocyanin ligands. The most abundant anthocyanins in the red leaves of Q. mongolica were cyanidin-3,5-O-diglucoside, cyanidin-3-O-glucoside, cyanidin-3-O-sophoroside, and pelargonidin-3-O-glucoside. Correlation analysis of differentially expressed genes and anthocyanin content identified highly expressed QmANS as a key structural gene associated with anthocyanin biosynthesis in Q. mongolica. A transcription factor-structural gene correlation analysis showed that the 1bHLH, 3bZIP, 1MYB, 10NAC, and 2WRKY transcription factors played strong positive roles in regulating anthocyanin structural genes (|PCC| > 0.90), with the QmNAC transcription factor playing a major role in anthocyanin biosynthesis.