The CsGT1A-CsSCPL11-IA module positively regulates galloylated catechin biosynthesis in tea plants

Abstract

Galloylated catechins are the dominant bioactive metabolites in tea leaves and have a great impact on tea flavor quality and human health. Trihelix transcription factors are known to perform essential functions in regulating multiple plant developmental processes and environmental responses. Nevertheless, the regulatory mechanism of Trihelix members in modulating tea plant galloylated catechin biosynthesis remains obscure. Here, the Trihelix transcription factor CsGT1A was identified as a candidate gene involved in tea plant galloylated catechin biosynthesis via a genome-wide association study. CsGT1A transcription showed significantly positive correlations with galloylated catechin content. Overexpression of CsGT1A significantly increased galloylated catechin content and upregulated the expression of serine carboxypeptidase-like acyltransferase gene CsSCPL11-IA, the key structural gene in the downstream path of galloylated catechin biosynthesis. Silencing of CsGT1A remarkably reduced galloylated catechin content and downregulated CsSCPL11-IA transcription. The CsSCPL11-IA transcription could be activated by CsGT1A through interacting with its promoter, evidenced by yeast one-hybrid assay and dual-luciferase reporter assay. Light intensity-responsive gene expression analysis showed that CsGT1A transcription was significantly correlated with the transcription of most galloylated catechin biosynthesis-related genes, especially CsSCPL11-IA, as well as the contents of galloylated catechins, under different light intensities. Taken together, these results revealed that CsGT1A could promote galloylated catechin biosynthesis by directly activating CsSCPL11-IA, and CsGT1A-CsSCPL11-IA module is also involved in light intensity-regulated galloylated catechin biosynthesis. This study deepens our comprehension of the regulatory mechanism underlying galloylated catechin biosynthesis, and provides valuable information for the cultivation of high-quality tea plant cultivars.