Mechanism of GST-mediated anthocyanin transport in purple leaf color formation revealed by multicolored tea plant (Camellia sinensis)

Leaf color trait in tea plant ( Camellia sinensis ) can significantly impact their quality and economic value. Purple tea plant, having unique leaf color, has valued for their anthocyanins. Anthocyanins are important stress-response metabolites in tea plant with a clearly synthesis pathway, but their transport mechanisms remain largely unexplored. Here, 99 tea samples with varying degrees of purple coloration were used to systematically analyze the biochemical basis of leaf color variation. UPLC-MS/MS analysis identified the anthocyanin profile in tea plants, and OPLS-DA revealed that anthocyanins were the most influential pigments determining leaf color. Gene expression pattern analysis showed that the glutathione S-transferase gene ( CsGST ) expression was significant correlated with anthocyanin levels. Purple samples exhibited higher expression. Silencing this gene in purple leaves partially disrupted anthocyanin transport. Further investigation applying microscale thermophoresis (MST) and molecular docking elucidated that GST protein showed a binding preference for glycosylated anthocyanins and revealed that its transport function was achieved through direct binding to the glycosyl moiety of anthocyanins. This study clarified the potential role of GST in leaf color variation, offering a new insight into purple leaf coloration, and provided theoretical foundations for tea product development and resource utilization. • Profiling of 99 diversely colored tea samples revealed the pigment basis of leaf color. • Established a leaf color classification system, aided by machine learning. • Verified the key role of GST-mediated transport in tea anthocyanin accumulation. • Demonstrated CsGST's preference for glycosylated anthocyanins and its binding mechanism.