Deletion of high-molecular-weight glutenin subunits in wheat significantly reduced dough strength and bread-baking quality

Yingjun Zhang,Xu Jia,Yuping Liu,Qian Liu,Mengyun Hu,Liangjie Lv,Hui Li,Lijing Sun,Xiyong Chen

doi:10.1186/s12870-018-1530-z

Yingjun Zhang, Xu Jia + Show 7 more

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https://doi.org/10.1186/s12870-018-1530-z

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Abstract

BackgroundHigh-molecular-weight glutenin subunits (HMW-GS) play important roles in the elasticity of dough made from wheat. The HMW-GS null line is useful for studying the contribution of HMW-GS to the end-use quality of wheat.MethodsIn a previous work, we cloned the Glu-1Ebx gene from Thinopyrum bessarabicum and introduced it into the wheat cultivar, Bobwhite. In addition to lines expressing the Glu-1Ebx gene, we also obtained a transgenic line (LH-11) with all the HMW-GS genes silenced. The HMW-GS deletion was stably inherited as a dominant and conformed to Mendel’s laws. Expression levels of HMW-GS were determined by RT-PCR and epigenetic changes in methylation patterns and small RNAs were analyzed. Glutenins and gliadins were separated and quantitated by reversed-phase ultra-performance liquid chromatography. Measurement of glutenin macropolymer, and analysis of agronomic traits and end-use quality were also performed.ResultsDNA methylation and the presence of small double-stranded RNA may be the causes of post-transcriptional gene silencing in LH-11. The accumulation rate and final content of glutenin macropolymer (GMP) in LH-11 were significantly lower than in wild-type (WT) Bobwhite. The total protein content was not significantly affected as the total gliadin content increased in LH-11 compared to WT. Deletion of HMW-GS also changed the content of different gliadin fractions. The ratio of ω-gliadin increased, whereas α/β- and γ-gliadins declined in LH-11. The wet gluten content, sedimentation value, development time and stability time of LH-11 were remarkably lower than that of Bobwhite. Bread cannot be made using the flour of LH-11.ConclusionsPost-transcriptional gene silencing through epigenetic changes and RNA inhibition appear to be the causes for the gene expression deficiency in the transgenic line LH-11. The silencing of HMW-GW in LH-11 significantly reduced the dough properties, GMP content, wet gluten content, sedimentation value, development time and stability time of flour made from this wheat cultivar. The HMW-GS null line may provide a potential material for biscuit-making because of its low dough strength.

Highlights

High-molecular-weight glutenin subunits (HMW-GS) play important roles in the elasticity of dough made from wheat
HMW-GS are silenced in transgenic line LH-11 The spring wheat variety, Bobwhite, was transformed with the Glu-1Ebx gene
None of the HMW-GS were detected in LH-11, including the 5 HMW-GS (1Ax2*, 1Bx7, 1By9, 1Dx5 and 1Dy10) of Bobwhite and the 1Ebx of Thinopyrum bessarabicum as well, by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) (Fig. 1a)

Summary

Introduction

High-molecular-weight glutenin subunits (HMW-GS) play important roles in the elasticity of dough made from wheat. In addition to lines expressing the Glu-1Ebx gene, we obtained a transgenic line (LH-11) with all the HMW-GS genes silenced. Measurement of glutenin macropolymer, and analysis of agronomic traits and end-use quality were performed. Gluten is commonly classified into glutenins and gliadins. Glutenins are of two major types: high-molecular-weight glutenin subunits (HMW-GS) and low-molecular-weight glutenin subunits (LMW-GS), both of which affect the strength and elasticity of wheat dough [2]. Gliadins are spread throughout the dough, exhibiting ‘space-filling’ roles [3], whereas, the HMW-GS are the major factors affecting the end-use quality of wheat [1, 4]

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