Molecular and metabolic insights into anthocyanin biosynthesis during leaf coloration in autumn

Pistacia chinensis is a native plant of China and is used for the production of biodiesel. Certain species of this plant accumulate anthocyanin in the leaves and turn red during autumn. The mechanism of anthocyanin biosynthesis has been well studied in model and horticultural plants. However, the main factors that induce anthocyanin accumulation during leaf senescence in autumn are still obscure, and the internal mechanism is poorly understood. Here, we performed multi-omic analysis and identified 33 metabolites and 6379 transcripts with different abundance levels during autumn leaf coloration in P. chinensis. The transcriptomic data suggested that 31 structural genes in the anthocyanin biosynthesis pathway were upregulated during leaf coloration. Several genes involved in light and low temperature responses were significantly induced or reduced during autumn leaf coloration. ELONGATED HYPOCOTYL 5 (HY5) is considered as an integrator of light and low temperature signals and facilitates anthocyanin accumulation in the autumn leaves. Interestingly, jasmonic acid content was significantly enriched during leaf coloration, thereby indicating a consistent change with anthocyanin content. Furthermore, under shading treatment, the expression of the structural genes was maintained at a low level, consistent with less anthocyanin accumulation. Notably, the expression of MYB113 was consistent with anthocyanin content under both natural and shading conditions. Combining our data with previous reports, we proposed an anthocyanin biosynthesis model of P. chinensis during autumn leaf coloration. Our findings provide new insights into the preliminary molecular mechanism of autumn leaf coloration and potential target genes for molecular breeding.