Promoter DNA hypermethylation of TaGli-γ-2.1 positively regulates gluten strength in bread wheat

• Published in: Journal of advanced research 2022-02, Vol.36, p.163-173
• Main Authors: Zhou, Zhengfu, Liu, Congcong, Qin, Maomao, Li, Wenxu, Hou, Jinna, Shi, Xia, Dai, Ziju, Yao, Wen, Tian, Baoming, Lei, Zhensheng, Li, Yang, Wu, Zhengqing
• Format: Article
• Language: English
• Subjects: Agricultural Science; Bread - analysis; DNA - metabolism; DNA Methylation; Flour - analysis; Gliadin; Gliadin - genetics; Gluten strength; Glutens - genetics; Glutens - metabolism; Plant Breeding; TaGli-γ-2.1; Triticum - genetics; Wheat
• ISSN: 2090-1232; 2090-1224
• DOI: 10.1016/j.jare.2021.06.021

[Display omitted] •TaGli-γ-2.1 belonged to a subgroup of γ-gliadin multigene family.•TaGli-γ-2.1 was a negative regulatory factor in gluten strength.•Methylation of pTaGli-γ-2.1 played a key role in regulating TaGli-γ-2.1 expression.•Lower γ-gliadin content followed with hypermethylation of pTaGli-γ-2.1.•Decreasing TaGli-γ-2.1 expression could be used to improve gluten strength in wheat breeding. Gliadins are the major components of gluten proteins with vital roles on properties of end-use wheat product and health-relate quality of wheat. However, the function and regulation mechanisms of γ-gliadin genes remain unclear. Dissect the effect of DNA methylation in the promoter of γ-gliadin gene on its expression level and gluten strength of wheat. The prokaryotic expression and reduction–oxidation reactions were performed to identify the effect of TaGli-γ-2.1 on dough strength. Bisulfite analysis and 5-Aza-2′-deoxycytidine treatment were used to verify the regulation of TaGli-γ-2.1 expression by pTaGli-γ-2.1 methylation. The content of gluten proteins composition was measured by RP-HPLC, and the gluten strength was measured by Gluten Index and Farinograph. TaGli-γ-2.1 was classified into a subgroup of γ-gliadin multigene family and was preferentially expressed in the later period of grain filling. Addition of TaGli-γ-2.1 protein fragment into strong gluten wheat flour significantly decreased the stability time. Hypermethylation of three CG loci of pTaGli-γ-2.1 conferred to lower TaGli-γ-2.1 expression. Treatment with 5-Aza-2′-deoxycytidine in seeds of strong gluten wheat varieties increased the expression levels of TaGli-γ-2.1. Furthermore, the accumulations of gliadin and γ-gliadin were significantly decreased in hypermethylated wheat varieties, corresponding with the increasing of gluten index and dough stability time. Epigenetic modification of pTaGli-γ-2.1 affected gluten strength by modulating the proportion of gluten proteins. Hypermethylation of pTaGli-γ-2.1 is a novel genetic resource for enhancing gluten strength in wheat quality breeding.