Isoflavonoid synthesis: regulatory mechanism of GmMYB176-bZIP complex

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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. 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. A MYB transcription factor GmMYB176 regulates the expression of CHS8 gene and isoflavonoid synthesis in soybean. Recently we discovered that GmMYB176 interacts with two bZIP transcription factors. Both the bZIPs and GmMYB176 bind with CHS8 promoter. The main objective of this proposal is to advance our understanding of isoflavonoid synthesis and accumulation in soybean. Furthermore, using the combination of transcriptomics and metabolomics studies, I will determine all the biological and metabolic processes regulated by GmMYB176-bZIP complex. 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.