Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, PR China.
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, PR China; National Research Center of Engineering and Technology for Utilization of Botanical Functional Ingredients, Hunan Co-innovation Center for Utilization of Botanical Functional Ingredients and Co-Innovation Center of Education Ministry for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha, Hunan 410128, PR China.
Int J Biol Macromol. 2020 Dec 1;164:4306-4317. doi: 10.1016/j.ijbiomac.2020.08.200. Epub 2020 Aug 28.
The MYB proteins belong to a large family of transcription factors in plant genomes and play significant roles in primary and secondary metabolism. Although several CsMYB genes have been identified in Camellia sinensis, few CsMYBs involved in l-theanine biosynthesis have been analyzed. In this study, we screened and identified 20 CsMYBs related to l-theanine biosynthesis. Transcriptomic analysis revealed that the expression profiles of the CsMYBs were positively or negatively related to dynamic changes in the l-theanine content. Validation of selected l-theanine biosynthetic and CsMYB genes was conducted by qRT-PCR. The results illustrated that most of the structural and CsMYB genes were downregulated with a decrease in the l-theanine levels. Protein-protein interaction networks of CsMYB5, CsMYB12 and CsMYB94 proteins demonstrated that they might form complexes with bHLH and WD 40 proteins. Multiple DNA-binding sites of the R2R3-MYB protein were observed in promoter regions of structural genes, indicating CsMYB family proteins might be involved in l-theanine metabolism via the attachment of AC elements. Moreover, CsMYB73 demonstrated binding specificity to the promoter region of CsGDH2 (CsGDH2-pro). These findings provide fundamental understanding of specific members of the CsMYBs related to the l-theanine biosynthesis pathway.
MYB 蛋白属于植物基因组中转录因子的一个大家族，在初级和次级代谢中发挥重要作用。尽管已经在茶树中鉴定出了几个 CsMYB 基因，但参与茶氨酸生物合成的 CsMYB 基因分析较少。在这项研究中，我们筛选并鉴定了 20 个与茶氨酸生物合成相关的 CsMYB。转录组分析显示，CsMYB 的表达谱与茶氨酸含量的动态变化呈正相关或负相关。通过 qRT-PCR 对选定的茶氨酸生物合成和 CsMYB 基因进行了验证。结果表明，大多数结构基因和 CsMYB 基因随着茶氨酸水平的降低而下调。CsMYB5、CsMYB12 和 CsMYB94 蛋白的蛋白质-蛋白质相互作用网络表明，它们可能与 bHLH 和 WD40 蛋白形成复合物。在结构基因启动子区观察到 R2R3-MYB 蛋白的多个 DNA 结合位点，表明 CsMYB 家族蛋白可能通过附着 AC 元件参与茶氨酸代谢。此外，CsMYB73 表现出对 CsGDH2（CsGDH2-pro）启动子区域的结合特异性。这些发现为理解与茶氨酸生物合成途径相关的 CsMYB 特定成员提供了基础。
