14‐3‐3 proteins regulate the intracellular localization of the transcriptional activator GmMYB176 and affect isoflavonoid synthesis in soybean

• DOI: 10.1111/j.1365-313x.2012.04986.x
• Publication Date: 2012-03-08T09:00:20Z
• Authors: Xuyan Li; Ling Chen; Sangeeta Dhaubhadel
• Keywords: Nicotiana; 0303 health sciences; Glycine max; Amino Acid Motifs; Genetic Complementation Test; Arabidopsis; Isoflavones; Plant Roots; Protein Transport; 03 medical and health sciences; 14-3-3 Proteins; Gene Expression Regulation, Plant; Nitrogen Fixation; Two-Hybrid System Techniques; Protein Interaction Mapping; Seeds; Mutagenesis, Site-Directed; Serine; Phosphorylation; Plant Proteins; Sequence Deletion; Transcription Factors

SummaryIsoflavonoids are legume‐specific natural plant compounds that play important functions in nitrogen fixation as well as biotic and abiotic stress responses. Many clinical studies have suggested a role for isoflavonoids in human health and nutrition. We have recently identified an R1 MYB transcription factor GmMYB176 that regulatesCHS8gene expression and isoflavonoid biosynthesis. Here we demonstrate that binding of 14‐3‐3 proteins to GmMYB176 modulates this function. GmMYB176 interacts with all 16 14‐3‐3 proteins (SGF14s) in soybean (Glycine max) with varying activity. The detailed analysis of 14‐3‐3‐binding sites within GmMYB176 identified a critical motif (D2) where Ser29 is potentially phosphorylated. Deletion of the D2 motif from GmMYB176 or substitution of Ser29 with an alanine abolished binding with SGF14 proteins, which altered the subcellular localization of GmMYB176. Overexpression ofSGF14lin soybean hairy roots did not affect the transcript level ofGmMYB176but it reduced the expression levels of key isoflavonoid genes and isoflavonoid accumulation in soybean hairy root. Our results suggest that SGF14–GmMYB176 interaction regulates the intracellular localization of GmMYB176, thereby affecting isoflavonoid biosynthesis in soybean.