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Deletion of high-molecular-weight glutenin subunits in wheat significantly reduced dough strength and bread-baking quality
- Zhang, Yingjun, Hu, Mengyun, Liu, Qian, Sun, Lijing, Chen, Xiyong, Lv, Liangjie, Liu, Yuping, Jia, Xu, Li, Hui
- BMC plant biology 2018 v.18 no.1 pp. 319
- DNA methylation, RNA interference, Thinopyrum bessarabicum, agronomic traits, breads, cultivars, double-stranded RNA, dough, epigenetics, flour, gene expression, genes, genetically modified organisms, gliadin, gluten, glutenins, protein content, reverse transcriptase polymerase chain reaction, ultra-performance liquid chromatography, wheat
- BACKGROUND: High-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. METHODS: In 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. RESULTS: DNA 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. CONCLUSIONS: Post-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.