Theanine is a crucial indicator of tea quality, its significance is closely tied to the economic value of tea. There were many reports on the regulation mechanism of theanine synthesis and accumulation, but the mechanism of gibberellin regulates theanine synthesis in tea plants is poorly understood. Previous studies have shown that the content of theanine experiences significant changed in the growth stages of tea shoots, displayed a strong correlation with gibberellin. This study confirmed that gibberellin significantly promoted the expression of the major gene of theanine synthesis, known as CsTSI. Additionally, the study identified CsWRKY71, a transcription factor mediated the regulation of gibberellin on theanine synthesis in tea plants. CsWRKY71 was localized in the nucleus and had a typical WRKY domain. It was a member of class IIC sub- and its expression was significantly suppressed following exogenous GA3 treatment. Further assay such as EMSA, dual luciferase and asODN interfering demonstrated that CsWRKY71 significantly interacted with the promoter of CsTSI, which inhibited theanine synthesis by binding to the cis-acting element (C/T)TGAC(T/C) of CsTSI promoter. Overall, the addition of exogenous gibberellin alleviated the inhibition of CsTSI by down-regulating the expression of CsWRKY71, ultimately facilitated the rapid biosynthesis of theanine. This study elucidated the molecular mechanism of CsWRKY71 mediated gibberellin regulation of theanine synthesis in tea plant. The findings not only enhance our understanding of the regulatory processes involved in theanine synthesis in tea plants, but also provide important references for maintaining the characteristics of high theanine in tea plant.

中文翻译：

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赤霉素通过解除茶树 （Camellia sinensis） 中 CsWRKY71 对 CsTSI 的抑制来促进茶氨酸合成


茶氨酸是茶叶质量的重要指标，其重要性与茶叶的经济价值密切相关。关于茶氨酸合成和积累的调控机制的报道很多，但赤霉素调控茶氨酸合成的机制知之甚少。既往研究表明，茶氨酸的含量在茶芽的生长阶段经历了显著变化，与赤霉素表现出很强的相关性。这项研究证实，赤霉素显著促进茶氨酸合成主要基因 CsTSI 的表达。此外，该研究还确定了 CsWRKY71，这是一种转录因子，介导了赤霉素对茶树茶氨酸合成的调节。CsWRKY71 位于细胞核中，具有典型的 WRKY 结构域。它是 IIC 类亚型的成员，外源性 GA3 处理后其表达受到显著抑制。EMSA、双荧光素酶和 asODN 干扰等进一步分析表明，CsWRKY71 与 CsTSI 的启动子显着相互作用，CsTSI 启动子通过与 CsTSI 启动子的顺式作用元件 （C/T） TGAC（T/C） 结合来抑制茶氨酸合成。总体而言，外源赤霉素的添加通过下调 CsWRKY71 的表达减轻了对 CsTSI 的抑制，最终促进了茶氨酸的快速生物合成。本研究阐明了 CsWRKY71 介导赤霉素调控茶叶氨酸合成的分子机制。研究结果不仅增强了我们对茶树中茶氨酸合成所涉及的调控过程的理解，也为维持茶树中高茶氨酸的特性提供了重要参考。