小麦籽粒淀粉合成酶基因表达、相应酶活性及淀粉积累三者的关系

The Relationship among Starch Synthase Gene Expression,the Corresponding Synthase Activity and Starch Accumulation

为研究小麦籽粒淀粉形成的机制,以秦麦11为试验材料,对小麦籽粒灌浆期淀粉合成酶基因表达、相应酶活性及淀粉积累变化进行了研究。结果表明,腺苷二磷酸葡萄糖焦磷酸化酶基因(AGPase)、束缚态淀粉合成酶基因(GBSSI)、可溶性淀粉合成酶基因(SSS)、淀粉分支酶基因(SBE)表达均呈单峰曲线变化,AGPase和SSS基因于花后12 d左右相对表达量最大,GBSSI和SBE基因于花后15 d左右相对表达量最大。4种淀粉合成酶活性变化趋势一致,花后25 d或30 d之前呈上升趋势,之后急剧下降。淀粉及其组分积累量随着灌浆的进行呈不断上升趋势。直、支链淀粉及总淀粉积累速率峰值在花后25 d或30 d。相关分析表明,AGPase、SSS、SBE基因在花后15 d相对表达量与相应酶活性间呈极显著正相关,而GBSS基因的相对表达量与GBSS活性间未检测到相关。暗示AGPase、SSS、SBE基因在籽粒淀粉合成过程中可能属于转录水平调控,而GBSSI基因可能属于转录后调控。4种淀粉合成酶活性与直、支链淀粉及总淀粉积累速率均呈极显著正相关,说明这几种酶对淀粉合成共同起作用。

To study the formation mechanism of starch in strong gluten wheat grain,with Qinmai 11 as the tested material,starch synthase gene expression,the corresponding synthase activity and starch accumulation were studied during the grain filling stage.The results showed that the ADP-glucose pyrophosphate enzyme gene（AGPase）,bound starch synthase gene（GBSSI）,soluble starch synthase gene（SSS）,starch branching enzyme gene（SBE） all showed a single-peak of curve.The expression levels of AGPase and SSS reached the maximum at DPA 12.The expression levels of GBSSI and SBE reached a maximum at DPA 15.The four starch synthesis activities changed in the trend line.They were all showing an upward trend before DPA 25 or 30 and sharply declined after the days.Accumulation of starch and its components constantly rose during the grain filling stage.The accumulation rate peak of amylose,amylopectin and the total starch were at DPA 25 or 30. In addition to GBSSI,the relative expression levels of AGPase,SSS and SBE were highly significantly correlated with the activities of AGPase,SSS and SBE at DPA 15.These hinted that AGPase,SSS,SBE may control starch synthesis at the transcriptional level,and GBSSI may control starch synthesis at the post-transcriptional level.The activities of AGPase,GBSS,SSS,SBE were positively correlated to the rates of amylose,amylopectin and total starch accumulating,which indicated that these four enzymes played a role in promoting the grain starch accumulation of wheat.