Isoflavonoid synthesis: Role of 14-3-3 proteins and GmMYB176 interactome

异黄酮是一类几乎完全由豆类合成的植物天然化合物，在大豆种子中含量丰富。它们在植物与微生物的相互作用中发挥重要作用，如在感染时抑制病原体生长和诱导固氮细菌中nod基因的表达，从而在大豆根系上形成固氮根瘤。异黄酮类化合物还有助于人类和动物食用大豆对健康产生积极影响。通过基因表达分析，我们确定了CHS7和CHS8是合成异黄酮的关键基因。真核生物的基因表达是由一组被称为转录因子的蛋白质调节的，转录因子识别基因启动子区域的特定序列并与之结合。最近，我们发现了一个调控CHS8基因表达并影响大豆异黄酮合成的转录因子GmMYB176。GmMYB176对CHS8基因和异黄酮合成的调控需要其他附加因子的联合作用。本研究的目的是鉴定与GmMYB176相互作用的蛋白，以详细了解豆类异黄酮合成的调控，并表征大豆14-3-3蛋白参与异黄酮调控和各种其他信号转导过程。包括蛋白质-蛋白质相互作用、功能基因组学、分子遗传学和代谢生物化学在内的方法将用于解决这些目标。本研究将提高我们对异黄酮生物合成调控的认识，并可能导致控制代谢产物水平的生物技术策略，以提高非豆科植物的营养价值或保护植物免受病害或固氮。

Isoflavonoids are a group of plant natural compounds synthesized almost exclusively by legumes and are abundant in soybean seeds. They play important roles in plant-microbial interactions such as inhibition of pathogen growth upon infection and the induction of nod gene expression in nitrogen fixing bacteria that form nitrogen fixing nodules on soybean roots. Isoflavonoids also contribute to the positive health effects associated with soybean consumption by humans and animals. By gene expression analysis, we have identified CHS7 and CHS8 as genes that are critical for isoflavonoid synthesis. Eukaryotic gene expression is regulated by a group of proteins called transcription factors that recognizes a specific sequence in the promoter region of genes and binds with it. Recently, we have identified a transcription factor, GmMYB176, which regulates the expression of CHS8 gene and affects isoflavonoid synthesis in soybean. The regulation of CHS8 gene and isoflavonoid synthesis by GmMYB176 requires combinatorial action of other additional factors. The objectives of this proposal are to identify the interacting proteins with GmMYB176 to achieve a detailed understanding of the regulation of isoflavonoid synthesis in legumes, and to characterise soybean 14-3-3 proteins involved in isoflavonoid regulation and a variety of other signal transduction processes. Approaches including protein-protein interactions, functional genomics, molecular genetics, and metabolic biochemistry will be used to address these goals. The proposed research should improve our understanding of the regulation of isoflavonoid biosynthesis, and may lead to biotechnological strategies to manipulate the metabolite levels either for the enhancement of nutritional value or for protection against plant diseases or for nitrogen fixation in non-legume plants.