National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
Chair of Genetics and Genomics of Plants, Bielefeld University, 33615, Bielefeld, Germany.
Plant Mol Biol. 2021 May;106(1-2):157-172. doi: 10.1007/s11103-021-01135-x. Epub 2021 Mar 11.
Our results provide insights into the flavonol biosynthesis regulation of M. truncatula. The R2R3-MYB transcription factor MtMYB134 emerged as tool to improve the flavonol biosynthesis. Flavonols are plant specialized metabolites with vital roles in plant development and defense and are known as diet compound beneficial to human health. In leguminous plants, the regulatory proteins involved in flavonol biosynthesis are not well characterized. Using a homology-based approach, three R2R3-MYB transcription factor encoding genes have been identified in the Medicago truncatula reference genome sequence. The gene encoding a protein with highest similarity to known flavonol regulators, MtMYB134, was chosen for further experiments and was characterized as a functional flavonol regulator from M. truncatula. MtMYB134 expression levels are correlated with the expression of MtFLS2, encoding a key enzyme of flavonol biosynthesis, and with flavonol metabolite content. MtMYB134 was shown to activate the promoters of the A. thaliana flavonol biosynthesis genes AtCHS and AtFLS1 in Arabidopsis protoplasts in a transactivation assay and to interact with the Medicago promoters of MtCHS2 and MtFLS2 in yeast 1-hybrid assays. To ascertain the functional aspect of the identified transcription factor, we developed a sextuple mutant, which is defective in anthocyanin and flavonol biosynthesis. Ectopic expression of MtMYB134 in a multiple myb A. thaliana mutant restored flavonol biosynthesis. Furthermore, overexpression of MtMYB134 in hairy roots of M. truncatula enhanced the biosynthesis of various flavonol derivatives. Taken together, our results provide insight into the understanding of flavonol biosynthesis regulation in M. truncatula and provides MtMYB134 as tool for genetic manipulation to improve flavonol synthesis.
我们的研究结果提供了 insight 到 M. truncatula 中类黄酮生物合成调控的 insights。R2R3-MYB 转录因子 MtMYB134 作为 tool 出现，以改善类黄酮生物合成。类黄酮是植物特有的代谢物，在植物发育和防御中起着至关重要的作用，并且已知是有益于人类健康的 diet 化合物。在豆科植物中，参与类黄酮生物合成的调节蛋白尚未得到很好的表征。使用基于同源性的方法，在 Medicago truncatula 参考基因组序列中已经鉴定出三个 R2R3-MYB 转录因子编码基因。选择与已知类黄酮调节剂具有最高相似性的编码蛋白的基因 MtMYB134 进行进一步实验，并将其表征为 M. truncatula 中的功能性类黄酮调节剂。MtMYB134 的表达水平与编码类黄酮生物合成关键酶的 MtFLS2 的表达以及类黄酮代谢物含量相关。在拟南芥原生质体中转激活测定中，MtMYB134 被证明能够激活拟南芥 flavonol 生物合成基因 AtCHS 和 AtFLS1 的启动子，并在酵母 1 杂交测定中与 Medicago 的 MtCHS2 和 MtFLS2 启动子相互作用。为了确定鉴定出的转录因子的功能方面，我们开发了一个六倍突变体，该突变体在花色苷和类黄酮生物合成中存在缺陷。MtMYB134 在 AtMYB 多个拟南芥突变体中的异位表达恢复了类黄酮生物合成。此外，在 M. truncatula 的 hairy roots 中过表达 MtMYB134 增强了各种类黄酮衍生物的生物合成。总之，我们的研究结果为理解 M. truncatula 中类黄酮生物合成调控提供了 insights，并提供了 MtMYB134 作为遗传操作的 tool，以提高类黄酮合成。
