College of Tea Science, Institute of Plant Health & Medicine, Guizhou University, Guiyang 550025, China.
The Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region, Ministry of Education, College of Life Science, Guizhou University, Guiyang 550025, China.
Int J Biol Macromol. 2024 May;268(Pt 2):131725. doi: 10.1016/j.ijbiomac.2024.131725. Epub 2024 Apr 25.
The distinctive flavor and numerous health benefits of tea are attributed to the presence of theanine, a special amino acid found in tea plants. Nitrogen metabolite is greatly impacted by drought; however, the molecular mechanism underlying the synthesis of theanine in drought-stricken tea plants is still not clear. Through the drought transcriptome data of tea plants, we have identified a gene CsMOF1 that appears to play a role in theanine biosynthesis under drought stress, presenting a significantly negative correlation with both theanine content and the expression of CsGS1. Further found that CsMOF1 is a transcription factor containing a MYB binding domain, localized in the nucleus. Upon silencing CsMOF1, there was a prominent increase in the level of the theanine and glutamine, as well as the expression of CsGS1, while glutamic acid content decreased significantly. Conversely, overexpression of CsMOF1 yielded opposite effects. Dual luciferase reporter assay and electromobility shift assays demonstrated that CsMOF1 binds to the promoter of CsGS1, thereby inhibiting its activity. These results indicate that CsMOF1 plays a crucial role in theanine biosynthesis in tea plants under drought stress, acting as a transcriptional repressor related to theanine biosynthesis. This study provides new insights into the tissue-specific regulation of theanine biosynthesis and aids with the cultivation of new varieties of tea plants.
茶的独特风味和众多健康益处归因于茶氨酸的存在，茶氨酸是一种在茶树中发现的特殊氨基酸。氮代谢物受干旱影响很大；然而，干旱胁迫下茶树中天冬氨酸合成的分子机制尚不清楚。通过茶树干旱转录组数据，我们鉴定出一个基因 CsMOF1，它似乎在干旱胁迫下参与茶氨酸的生物合成，与茶氨酸含量和 CsGS1 的表达呈显著负相关。进一步发现 CsMOF1 是一种含有 MYB 结合域的转录因子，定位于细胞核内。沉默 CsMOF1 后，茶氨酸和谷氨酰胺水平明显升高，CsGS1 的表达也明显升高，而谷氨酸含量显著下降。相反，过表达 CsMOF1 则产生相反的效果。双荧光素酶报告基因检测和电泳迁移率变动分析表明，CsMOF1 结合到 CsGS1 的启动子上，从而抑制其活性。这些结果表明，CsMOF1 在干旱胁迫下的茶树中天冬氨酸生物合成中起着关键作用，作为与天冬氨酸生物合成相关的转录抑制因子。本研究为茶氨酸生物合成的组织特异性调控提供了新的见解，并有助于培育新的茶树品种。
