The wheat transcription factor Ta GAMyb recruits histone acetyltransferase and activates the expression of a high-molecular-weight glutenin subunit gene.

Glutenin proteins in wheat ( Triticum aestivum L.) flour confer unique viscoelastic properties to dough products and, therefore, the concentration and composition of the glutenin proteins determine its end-use value. However, the mechanisms governing the glutenin gene expression remain elusive. In this study, we report that wheat Ta GAMyb activates the high-molecular-weight glutenin subunit genes ( Ta GLU) through recruiting the histone acetyltransferase GCN5. By sequencing the promoters of Ta GLU-1 genes from 40 modern wheat cultivars, we identified eight types of Ta GAMyb binding motifs and verified these by electrophoretic mobility shift assays. The number of Ta GAMyb binding motifs in Ta GLU-1 genes is correlated with the abundance of glutenin in different cultivars. Chromatin immunoprecipitation plus polymerase chain reaction (Ch IP- PCR) analysis reveals that Ta GCN5 directly targets the promoters of Ta GLU-1 genes in wheat endosperm. We find that Ta GAMyb physically interacts with the wheat histone acetyltransferase Ta GCN5 and also interacts with Arabidopsis thaliana At GCN5. Ta GAMyb ectopically expressed in Arabidopsis binds to the Ta GLU-1Dy promoter on a Ta GLU-1Dy transgene and activates its expression. At GCN5 also targets the Ta GLU-1Dy transgene and is involved in the establishment of acetylation at H3K9 and H3K14. These results demonstrate that Ta GAMyb plays a dual role in activating expression of glutenin gene by directly binding to the Ta GLU promoter and by recruiting GCN5 to modulate histone acetylation during wheat endosperm development. [ABSTRACT FROM AUTHOR]