TaMYB44 represses grain protein content by directly binding to the promoters of HMW-GS genes in wheat
Year: 2026
Type: article
Abstract: Genetic improvement of grain quality remains a perpetual breeding objective in wheat. The end-use processing quality of wheat flour is largely determined by the properties of seed storage proteins (SSPs), particularly the content and composition of high-molecular-weight glutenin subunits (HMW-GSs). Plants' MYB transcription factors are known to play pivotal regulatory roles in diverse biological processes. In this study, we identified TaMYB44, an R2R3-MYB transcription factor encoded by three homoeologous copies (TaMYB44-A, -B, and -D), which exhibits specific and high expression in the developing endosperm but showing negligible transcript abundance in other tissues. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated knockout of TaMYB44 led to no significant alterations in agronomic traits, grain size, or 1,000-grain weight but resulted in a marked increase in overall grain protein content, specifically glutenin. Conversely, TaMYB44 overexpression lines displayed significantly reduced HMW-GS content. Consistently, the expression levels of HMW-GS-encoding genes (e.g., TaGlu-1Bx, -1By, -1Dx, and -1Dy) were upregulated in the knockout line. Dual-luciferase reporter assays and electrophoretic mobility shift assays (EMSAs) further demonstrated that TaMYB44 directly binds to the promoters of HMW-GS genes and represses their transcription. Collectively, our findings establish TaMYB44 as an endosperm-specific transcriptional repressor that negatively regulates HMW-GS accumulation in wheat grains. This work expands the functional repertoire of wheat MYB transcription factors and provides a promising candidate gene for quality breeding in wheat.
Source: Seed Biology
Institution: Yangzhou University
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: hybrid
OpenAlex ID: W7214069798