氮代谢和贮藏蛋白生物合成对小麦面筋品质形成的影响

Influence of Nitrogen Metabolism and Storage Protein Biosynthesis on the Formation of Gluten Quality in Wheat

为探讨不同类型小麦品种面筋品质形成的机制,以面筋强度不同的西农20、西农836、周麦18和西农977为材料,比较分析其面筋结构特性、籽粒灌浆过程蛋白组分积累动态、氮代谢和贮藏蛋白合成相关基因表达的差异,并从生理水平和转录水平探究氮代谢和贮藏蛋白生物合成相关基因表达对小麦面筋品质形成的影响。结果表明,西农20的面团形成时间、稳定时间、蛋白质弱化度最高,其次是西农836、周麦18、西农977;西农20的面筋中二硫键和β-折叠含量最高,而表面疏水性和α-螺旋/β-折叠最低,表现为面筋微观网络交联更加致密;籽粒灌浆期间醇溶蛋白、谷蛋白、谷蛋白大聚体(GMP)快速积累,成熟期西农20籽粒中总蛋白质、醇溶蛋白、谷蛋白及GMP含量比其他三个品种都高;旗叶和籽粒中谷氨酰胺合成酶(GS)和谷丙转氨酶(GPT)活性及其基因表达水平在西农20中最高,从而加强了其旗叶和籽粒中氨基酸代谢;贮藏蛋白合成相关基因 x/y-HMW、 LMW-A/B/D、 TaGAMyb、 TaPBF、 TaSPA、 TaPDIL2-1、 TaSUMO1和 TaPPIase的表达水平也在西农20中最高。这说明小麦籽粒灌浆期间氮代谢和贮藏蛋白生物合成相关基因的高水平表达可促进籽粒贮藏蛋白的合成与聚集,从而提高小麦面筋的品质。

In order to investigate the mechanism of gluten quality formation in different wheat varieties, Xinong 20, Xinong 836, Zhoumai 18 and Xinong 977 with different gluten strength were used as materials to compare and analyze the differences in gluten structure characteristics, protein accumulation dynamics during grain filling, nitrogen metabolism and the expression of genes associated with storage protein biosynthesis. The influences of nitrogen metabolism and storage protein biosynthesis on the quality formation of wheat were investigated from physiological and transcriptional perspectives. The results showed that, the dough development time, dough stability time and protein weakening of Xinong 20 were highest, followed by Xinong 836, Zhoumai 18 and Xinong 977. The contents of disulfide bond and β-sheets in the gluten obtained from Xinong 20 were the highest, but the surface hydrophobicity and ratio of α-helix to β-sheets were lower, appearing as the more compact microstructure of gluten.The gliadin, glutenin and GMP accumulated rapidly in Xinong 20 grains during grain filling, leading to higher contents of total protein, gliadin, glutenin and GMP at maturity than those in the other three wheat grains. Moreover, the activities and gene expression levels of glutamine synthase(GS) and glutamate pyruvate transaminase(GPT) in the flag leaves and grains were the highest in Xinong 20, which enhanced the metabolism of amino acids in the flag leaves and grains.The expression levels of storage protein biosynthesis related genes, including x/y-HMW, LMW-A/B/D, TaGAMyb, TaPBF, TaSPA, TaPDIL2-1, TaSUMO1 and TaPPIase were also highest in Xinong 20.It can be concluded that the high expression levels of genes associated with nitrogen metabolism and storage protein biosynthesis during grain filling were the main reasons for promoting the synthesis and aggregation of grain storage proteins, thereby improving the processing quality of wheat gluten.