<scp>CsYABBY1</scp> and <scp>CsMYB114</scp> Enhance Acquired Drought Tolerance by Mediating Flavonoid Biosynthesis in <i>Camellia sinensis</i>
Caiyun Tian, Chengzhe Zhou, Shengjing Wen, Cheng Zhang, Anru Zheng, Lele Jiang, Niannian Yang, Zhuo Tang, Xiaowen Hu, Zhendong Zhang, Jiaxin Fang, Zhong Wang, Yuqiong Guo
Abstract
Drought priming is a critical agronomic strategy for enhancing plant drought tolerance, yet the optimal priming intensity and transcriptional regulatory mechanisms underlying subsequent drought responses in the tea plant (Camellia sinensis) remain poorly characterised. In this study, we systematically evaluated tea plants exposed to recurrent drought stress under varying priming intensities. Results demonstrated that moderate drought priming specifically conferred superior drought tolerance compared to non-primed controls. Integrated metabolomic and transcriptomic profiling identified flavonoid biosynthesis as the key pathway associated with priming-induced drought resilience. Exogenous flavonoid application and overexpression of six biosynthesis genes (CsCHS, CsCHI, CsFLS, CsDFR, CsANS and CsANR) functionally validated flavonoids' role in drought adaptation. Notably, transcriptional regulators CsYABBY1 and CsMYB114 were identified as hub transcription factors demonstrating transcriptional activation potential towards flavonoid biosynthesis. Combinatorial transient overexpression and silencing assays revealed that both CsYABBY1 and CsMYB114 coordinately upregulate flavonoid biosynthesis genes, redirecting metabolic flux towards flavonoid accumulation to enhance drought tolerance. Multimodal validation through yeast one-hybrid assays, dual-luciferase reporter systems and electrophoretic mobility shift assays, as well as molecular docking, confirmed or simulated direct binding of CsYABBY1 and CsMYB114 to promoter regions of flavonoid biosynthesis genes for transcriptional activation. These findings establish a synergistic regulatory model where CsYABBY1 and CsMYB114 cooperatively enhance flavonoid accumulation through transcriptional reprogramming, thereby conferring acquired drought tolerance. This study provides mechanistic insights for developing adaptive cultivation practices and advances molecular breeding strategies for drought-resilient tea cultivars.