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为揭示高温胁迫对春小麦籽粒淀粉合成的影响机制，以宁春4号小麦为材料，分别于花后5、10、15和20 d进行高温（35 ℃±3 ℃）胁迫，利用实时荧光定量PCR法（qPCR）研究花后不同时期高温胁迫下小麦籽粒淀粉合成相关酶基因表达，并将基因表达量与对应籽粒淀粉合成酶活性进行相关性分析。结果表明，束缚态淀粉合成酶Ⅰ（GBSSⅠ）基因对高温不敏感，而腺苷二磷酸葡萄糖焦磷酸化酶（AGPase）基因、淀粉分支酶（SBE）基因、可溶性淀粉合成酶（SSS）基因的表达均被高温胁迫抑制；被测的4种淀粉合成相关酶的活性均被高温协迫抑制。自然生长温度下，除GBSSⅠ酶外，SBE、AGPase和SSS酶活性与其对应基因的表达量极显著或显著正相关；高温胁迫使4种被测的淀粉合成相关酶活性与其对应基因表达量的相关性降低。高温胁迫通过抑制小麦籽粒淀粉合成相关酶基因的表达而影响对应酶活性，使小麦籽粒淀粉的积累发生改变；高温胁迫发生时间越早，对小麦籽粒淀粉积累影响越大。

英文摘要:

To understand the effects of heat stress on starch synthesis in wheat,high temperature (35℃±3℃) was induced to Ningchun 4 wheat at different growth stages after anthesis (5 d,10 d,15 d,20 d). The expression levels of four starch synthase genes,namely,ADP-glucose pyrophosphorylase gene (AGPase),granule-bound starch synthase Ⅰ (GBSSⅠ)gene,starch branching enzyme (SBE) gene,Soluble starch synthase (SSS)gene were investigated by quantitative real-time PCR (qRT-PCR). Meanwhile the change of enzyme (AGPase,SBE,GBSS,SSS) activity in starch biosynthesis and the accumulation of starch were detected during the wheat grain filling stage. Correlation analysis between the gene expression level and the activity of starch synthesis enzyme has been conducted. The results showed that all the genes encoding starch biosynthesis enzymes had high expression level during grain filling stage under normal temperature. Under heat stress,however,only the GBSSⅠ remained its expression level. The AGPase,SBE,and SSS gene expression levels and the activities of the four starch synthase,on the other hand,were all inhibited by high temperature during the grain filling stages. The gene expression level of GBSSⅠdid not correlate with the activity of its starch synthases,while the relative gene expression level of SBE correlated positively with the activity of its starch synthase (P< 0.01),and the relative gene expression level of AGPase and SSS correlated positively with the activity of their starch synthase under normal temperature (P<0.05). Meanwhile,the degree of correlation between the levels SBE,AGPase,SSS expression and the activities of starch synthase enzyme decreased under high temperature. These results suggested that AGPase,SBE,GBSⅠS and SSS may control starch synthesis in wheat grain filling stage,and heat stress can inhibited the accumulation of starch by affecting starch synthase gene expression,thereby affecting the enzyme activities of starch synthase. The inhibitive effects were more significant if high temperature occurred earlier at grain filling stage.

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