Characterization And Functional Analysis Of Transcription Factors Regulating High-Molecular-Weight Glutenin Subunit Gene In Wheat(Triticum Aestivum L.)

Glutenin proteins confer unique viscoelastic properties to wheat dough products and therefore, the concentration and composition of the glutenin seed storage proteins (SSPs) in wheat flour determine its end-use value. The high elasticity and extensibility of wheat dough enable the production of leavened bread and other bakery products.The synthetic of seed storage protein(SSP) and expression of their genes are under tightly transcriptional regulation during seed development. So it is very important for improving wheat quality to find more transcription factors, which involved in regulating the expression of SSP. In this study, several important transcription factors regulating high-molecular-weight glutenin subunit (HMW-GS) in wheat and Arabidopsis were characterized and the main results as follows:1. TaGAMyb fusion protein can bind to a5’-C/TAACAAA/C-3’-like motif in the promoter of wheat HMW-GS genes. The binding activity of TaGAMyb and the protein abundance of HMW-GS were in strong agreement. The transcription pattern of TaGAMyb in the developing endosperm overlaps with that of TaGLU-1, indicating that TaGAMyb has a role in the transcriptional regulation of the HMW-GS genes. By ectopic expression in Arabidopsis, we found that TaGAMyb activated the transcription of TaGLU-1Dy via binding to its promoter.2. TaGCN5, recruited by TaGAMyb, targeted wheat HMW-GS genes and affected the acetylation levels of H3K9and H3K14. This indicated that TaGCN5activates the expression of HMW-GS gene by influncing histone acetylation level of their promoter.3. TaNAC46, a NAC transcription factor expressed in endosperm, shared the similar transcription pattern with TaGLU-1in the developing endosperm. It could activate the expression of HMW-GS genes through binding to its promoter and the wheat transgenic lines of TaNAC46showed the altered expression level of TaGLU-1. Moreover, yeast two-hybrid results indicated that TaNAC46interacted with TaGAMyb, suggesting that TaNAC46and TaGAMyb might work in a complex to participate in regulating the expression of HMW-GS.4. Taken together, the wheat transcription factor TaGAMyb activated the expression of high-molecular-weight glutenin subunit genes by recruiting histone acetyltransferase GCN5during seed development. TaNAC46could bind to the promoter of TaGLU-1Dy, and activated its expression in Arabidopsis and wheat. At the same time, we found that TaNAC46interact with TaGAMyb, which provided new insights into the mechanisms of regulating HMW-GS expression.