Huang Xiangxiang, An Zexin, Zhao Tiyue, Xie Nianci, Li Juan, Zhu Mingzhi, Zhao Jian, Liu Zhonghua, Wang Kunbo
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, 410128, China.
College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Plant J. 2025 Jul;123(1):e70341. doi: 10.1111/tpj.70341.
Epigallocatechin gallate (EGCG) is the most abundant and biologically active catechin in tea leaves and has been widely utilized in the development of functional foods. EGCG is catalyzed by serine carboxypeptidase-like 1A (CsSCPL1A) acyltransferases in tea plants. Although CsSCPL family genes are regulated by several transcription factors (TFs), systematic studies on their regulation by MYB TFs are lacking. This study integrates targeted metabolomics, transcriptomics, DNA-protein, and protein-protein interaction analyses to elucidate the transcriptional regulation of EGCG biosynthesis-related genes CsSCPL4 and CsSCPL5-1 by R2R3-MYB TFs. CsMYB219 and CsMYB196 can specifically bind to CsSCPL4 and CsSCPL5-1 promoters and activate their expression. CsMYB196 also interacted with CsTT8a and CsTTG1 to activate the transcription activity of CsSCPL4 and CsSCPL5-1 promoters by forming a MYB/bHLH/WD40 (MBW) complex. Promoter truncation assays delineated MYB-responsive cis-elements in CsSCPL4 (-613 to -1 bp with enhancers at -1967 to -1622) and CsSCPL5-1 (-503 to -296 bp). Silencing of CsMYB219 and CsMYB196 by virus-induced gene silencing (VIGS) assay significantly reduced the expression levels of CsSCPL4 and CsSCPL5-1 and EGCG content in tea leaves. Transient overexpression of CsMYB219 and CsMYB196 in tea leaves upregulated CsSCPL4 and CsSCPL5-1 expression and elevated EGCG content. These findings enhance our understanding of the regulatory network underlying EGCG biosynthesis in tea plants and provide a solid foundation for future genetic improvement of tea plant cultivars.
表没食子儿茶素没食子酸酯（EGCG）是茶叶中含量最丰富且具有生物活性的儿茶素，已被广泛应用于功能性食品的开发。EGCG在茶树中由丝氨酸羧肽酶样1A（CsSCPL1A）酰基转移酶催化合成。虽然CsSCPL家族基因受多种转录因子（TFs）调控，但缺乏关于它们受MYB转录因子调控的系统研究。本研究整合了靶向代谢组学、转录组学、DNA-蛋白质和蛋白质-蛋白质相互作用分析，以阐明R2R3-MYB转录因子对EGCG生物合成相关基因CsSCPL4和CsSCPL5-1的转录调控。CsMYB219和CsMYB196可以特异性结合CsSCPL4和CsSCPL5-1启动子并激活它们的表达。CsMYB196还与CsTT8a和CsTTG1相互作用，通过形成MYB/bHLH/WD40（MBW）复合体激活CsSCPL4和CsSCPL5-1启动子的转录活性。启动子截短试验确定了CsSCPL4（-613至-1 bp，增强子位于-1967至-1622处）和CsSCPL5-1（-503至-296 bp）中的MYB响应顺式元件。通过病毒诱导基因沉默（VIGS）试验沉默CsMYB219和CsMYB196显著降低了茶树叶片中CsSCPL4和CsSCPL5-1的表达水平以及EGCG含量。在茶树叶片中瞬时过表达CsMYB219和CsMYB196上调了CsSCPL4和CsSCPL5-1的表达并提高了EGCG含量。这些发现加深了我们对茶树中EGCG生物合成调控网络的理解，并为未来茶树品种的遗传改良提供了坚实基础。
