小麦淀粉合成关键酶基因和相关蛋白表达对不同施磷量的响应

为深入研究磷素在小麦淀粉产量和品质形成过程中的作用，以新疆冬小麦主栽品种新冬20号为试验材料，研究0 kg·hm^-2（CK）、105 kg·hm^-2（LP）和210 kg·hm^-2（HP）3种施磷（P₂O₅）量对小麦籽粒灌浆特性、淀粉合成关键酶(AGPase和GBSS)活性和基因表达、胚乳可溶性蛋白和淀粉粒结合蛋白含量及谱带特征、胚乳微观特性等的影响。结果表明，籽粒灌浆后期磷肥对粒重的促进作用逐渐增强；低磷（LP）条件下， agp1、 agp2、 gbss1、 gbss2基因表达量显著提高；3个处理下AGPase活性的变化趋势基本一致；籽粒灌浆中期（14～21 d），低磷处理的GBSS活性显著高于CK；不同磷处理对淀粉粒结合蛋白和胚乳可溶性蛋白含量的影响显著，但对蛋白谱带特征的影响较弱。扫描电镜结果显示，不同磷处理的胚乳淀粉粒形态未发生明显变化；与CK和高磷（HP）处理相比，低磷处理下籽粒胚乳横断面蛋白基质较少，淀粉粒与蛋白质结合较疏松。说明常规施磷（低磷）条件下，淀粉合成关键酶基因（agp和gbss）相对表达量提高或酶活性变化可影响籽粒淀粉合成及胚乳中蛋白与淀粉粒的嵌合度，并最终造成粒重的增加和淀粉特性的变化。

Effect of Phosphorus on the Gene and Protein Expression Related to Starch Biosynthesis in Wheat

This study was conducted to reveal the role of phosphorus in the formation of starch yield and quality.The winter wheat variety in Xinjiang,cv.Xindong 20,was used to explore the effect of different phosphorus treatments,i.e.control(CK,P₂O₅,0 kg·hm^-2),low phosphorus(LP,P₂O₅,105 kg·hm^-2) and high phosphorus(HP,P₂O₅,210 kg·hm^-2),on grain filling characteristics,the activity and gene expression of AGPase and GBSS,the content of starch granule-bound protein,the gel pattern of endosperm soluble protein,and the microstructure characteristics.The results showed that the grain weight was significantly increased by phosphorus at late filling stage.Analysis of gene expression showed significant increase of agp1, agp2, gbss1 and gbss2 from wheat grown under LP conditions.The enzyme activity of AGPase showed the similar pattern under three phosphorus conditions.During the mid-filling stage(14-21 d),the activity of GBSS subjected to LP was significantly higher than that of the control treatment.In response to phosphorus application,the content of starch granule-bound protein was significantly different,however,the gel pattern was similar,respectively.Scanning electron microscopy(SEM) revealed that the shape of starch granules under different phosphorus conditions did not show significant difference.Compared with CK and HP treatments,the sample from LP contained less protein matrix and the combination between protein and starch granules was much looser.Conclusively,LP played an important role in regulation of the gene expression and the enzyme activity of AGPase and GBSS,which further impacted on the starch biosynthesis and the combination of protein and starch in the endosperm.Furthermore,LP increased the grain weight and altered the starch characteristics.