小麦胚乳Wx蛋白缺失对淀粉含量和淀粉特性的影响

Effect of Wx Protein Deficiencies in Wheat Endosperm on Content and Properties of Starch

为给面条小麦亲本材料的筛选提供可靠依据,用SDS-PAGE和STS-PCR结合的方法鉴定了24个品种的Wx蛋白亚基组成,测定了这些品种的淀粉含量、膨胀势和RVA参数。结果表明,与正常材料相比,Wx蛋白亚基缺失材料的胚乳中直链淀粉含量减少,支链淀粉和总淀粉含量变化不明显,Wx蛋白亚基缺失的数目越多,直链淀粉含量减少得就越多,糯麦的直链淀粉含量最少。在本研究参试材料特定遗传背景干扰的情况下,在Wx蛋白的三个亚基中Wx-A1蛋白亚基对直链淀粉含量影响最大。Wx蛋白亚基的缺失还使面粉的膨胀势、RVA参数的高峰粘度、崩解值增大,峰值时间延长,而使最终粘度、回生值和糊化温度降低,Wx蛋白亚基缺失的数目越多,这些特性变化的幅度越大。在缺失单个亚基的情况下,Wx-B1亚基的缺失使小麦粉的淀粉特性表现最好。相关分析表明,直链淀粉合成数量的减少是导致上述淀粉特性发生变化的主要原因。

To gain a accurate result, an improved SDS-PAGE and STS-PCR were used to identificate Wx protein combination of 24 wheat varieties. The starch properties of those varieties were measured. The effect of Wx protein dosage and composition on starch composition and properties were studied. It was found that any null mutation of Wx gene could result in obvious reduction of amylose, and the amylose content decreased more with the increase of number of Wx gene deficiencies, the amylose content of waxy wheat is barely zero. Under the genetic backgrounds of the materials used, the Wx-A1 protein subunit take the most important role to the synthesis of amylose. But the influence of Wx protein deficiencies to starch content and amylopectin content is little. The Wx protein deficiencies resulted in the increase of flour swelling power,peak, through, breakdown and final vise of pasting properties and the decrease of setback and pasting temperature. The dosage effect of Wx protein also existed on starch properties. The deficiency of Wx-B1 protein subunit ：resulted in the most obvious improvement of starch properties. The identification of Wx protein subunits and its selection index in the early generation of crossed were also discussed. We can identify the Wx protein subunit by SDS-PAGE and STS-PCR simultaneously, and both the swelling power and Am/Ap ratio are good selection indexes for the early generation of crosses.