CsTCP14b enhances drought tolerance in tea plants during early‐stage drought stress by promoting flavonol‐mediated ROS scavenging

In northern China's tea plantations - where extreme drought is uncommon - subtle yet persistent mild drought increasingly shapes tea yield and quality. However, how tea plants link mild drought-induced secondary metabolite accumulation to drought tolerance remains unknown. By integrating RNA-seq analysis with functional validation and regulatory network characterization of CsTCP14b, we demonstrate that this transcription factor promotes flavonol biosynthesis, thereby enhancing reactive oxygen species (ROS) scavenging and conferring early-stage drought tolerance in tea plants. CsTCP14b is rapidly induced during early drought stress and directly activates CsFLSb transcription by binding to its promoter, leading to increased accumulation of the flavonols kaempferol and quercetin and enhanced ROS detoxification. Yeast library screening and targeted interaction assays further identified HD-ZIP III transcription factor CsREV as an interacting partner. The CsREV-CsTCP14b interaction promotes nuclear retention of CsTCP14b and strengthens its activation of CsFLSb. Cross-cultivar analyses confirmed that the CsTCP14b-CsREV-CsFLSb module is conserved. Under drought stress, the drought-tolerant cultivar Zhongcha 108 (ZC108) shows rapid induction of CsTCP14b and CsREV and increased flavonol accumulation, whereas these responses are weaker in the drought-sensitive cultivar Wuniuzao (WNZ). These findings provide mechanistic insight into tea plant adaptation to mild drought and offer molecular targets for breeding drought-resilient, high-quality tea cultivars.