Wx蛋白组成对小麦籽粒淀粉合成的影响

Effect of Different Wx Protein Combinations on Wheat Starch Biosynthesis in Developing Endosperm

【目的】通过对籽粒淀粉积累和淀粉合成关键酶的活性进行比较,初步明确不同Wx蛋白组成小麦品种淀粉理化特性差异的酶学基础。【方法】以6类Wx蛋白组成的14个小麦品种为试材,测定其籽粒灌浆过程中直、支链淀粉积累动态和4种淀粉合成关键酶的活性变化,对测定结果进行统计分析。【结果】Wx蛋白数目和类型对4种淀粉合成关键酶活性和直、支链淀粉合成有明显影响。随着Wx蛋白数目的增多,4种淀粉合成关键酶活性呈现升高的趋势,尤其是淀粉粒束缚淀粉合成酶(GBSS),籽粒直链淀粉含量也相应升高。Wx-B1缺失蛋白对GBSS活性影响最大,直链淀粉合成能力下降最明显,其次是缺失Wx-D1蛋白,Wx-A1蛋白缺失作用最小。籽粒灌浆过程中,4种淀粉合成关键酶活性高度相关,并与直、支链淀粉含量密切相关,说明直、支链淀粉的合成是相互影响、相互制约、同步进行的。【结论】Wx基因是影响籽粒直链淀粉含量的重要决定因素,Wx基因可以通过自身数目和组成的变化,控制GBSS的活性,并对其它淀粉合成关键酶的活性产生影响,最终影响直、支链淀粉的合成,形成不同的淀粉理化特性和加工品质。

[Objective] This study was to elucidate the difference in starch physiochemical properties among wheat cultivars differing in Wx protein combinations through the comparison of starch accumulation and activities of starch biosynthetic enzymes. [ Method ] The accumulation of amylose and amylopectin in developing endosperm from 14 wheat cultivars with six types of Wx protein combinations were investigated, together with activities of four key enzymes involved in starch biosynthesis such as ADP-glucose pyrophosphorylase （AGPase）, soluble starch synthase （SSS）, granule bound starch synthase （GBSS）, and starch branching enzyme （SBE）. [Result] The number and type of Wx protein had a significant influence on activities of starch biosynthetic enzymes and the accumulation of amylose and amylopectin in developing endosperm. The activities of starch biosynthetic enzymes increased with the number of Wx protein, especially for GBSS, together with the amylose content in grain. The Wx-B1 protein deficiency induced the lowest GBSS activity and amylose content in grain, then was the Wx-DI protein, and the effect of Wx-A1 protein deficiency was the least. The activities of four starch biosynthetic enzymes correlated to each other significantly, and also correlated to the number of Wx protein, amylose and amylopectin content in grain, which suggested the biosynthesis ofamylose and amylopectin in developing endosperm were interacted and synchronous. [Conclusion] The Wx allele is one of the most determinant factors for amylose content for it can control the activity of GBSS through the number and type of Wx protein and affect other starch biosynthetic enzymes indirectly, then the synthesis of amylose and amylopectin, which result in different starch physiochemical properties and noodle quality finally.