控制水稻胚乳淀粉合成代谢若干关键酶基因对花后高温的响应表达

以稻米品质温度敏感型的早籼稻品种嘉早935为材料，利用人工气候箱控温试验和实时荧光定量PCR技术，探讨了不同灌浆温度(日均温分别为22和32 ℃)处理下胚乳淀粉分支酶(SBE)、淀粉去分支酶(DBE)和淀粉合酶(SS)的10个同工型基因(sbe1、sbe3、sbe4、pul、isa1、isa2、isa3、Wx、sss1和sss2a)的相对表达量差异及动态变化特征.结果表明: 淀粉合成相关功能基因对水稻灌浆期高温胁迫的响应表达方式存在明显差异，而且因同工型的类型而不同.在高温处理下，sbe1和sbe3的相对表达量显著下降，二者属于SBE类基因中对高温胁迫较敏感的主要同工型；DBE基因中，pul属于高表达的同工型，而且其对高温胁迫响应比isa1、isa2和isa3敏感；在Wx、sss1和sss2a中，sss2a的相对表达量显著低于sss1和Wx, 但sss2a和sss1对高温胁迫响应比Wx敏感，因此二者可能也是高温胁迫对胚乳淀粉结构进行调控的重要位点，尤其在水稻灌浆的中后期发挥重要作用.

Gene expression of the key enzymes controlling starch synthesis and metabolism in rice grain endosperm under effects of high temperature after anthesis

Taking an early-season indica cultivar 'Jiazao 935' whose grain quality was sensitive to temperature as test material, and by using artificial climatic chamber and real-time fluorescence quantitative PCR (FQ-PCR), this paper studied the relative expression amount and its dynamic changes of ten isoform genes of the key enzymes controlling starch synthesis and metabolism in rice grain endosperm, including sbe1, sbe3, and sbe4 of starch branching enzyme (SBE), isal, isa2, isa3, and pul of starch debranching enzyme (DBE), and Wx, sss1, and sss2a of starch synthase (SS), at the mean daily temperature 22 and 32 degrees C after anthesis. There existed obvious differences in the expression patterns of these genes under the high temperature stress, and the expression patterns were isoform-dependent. The relative expression amount of sbe1 and sbe3 under high temperature decreased significantly, and both of the genes were the sensitive isoform genes of SBE to high temperature stress. Among the DBE genes, pul was the isoform gene with high expression level, being more sensitive to high temperature stress than isa1, isa2, and isa3. Among the SS genes, sss2a had a significantly lower relative expression amount than sss1 and Wx, but sss2a and sss1 were more sensitive to high temperature than Wx, suggesting that sss2a and sss1 could be the important genes that adjusted the starch structure in rice endosperm under high temperature stress, especially at the middle and late grain filling stages.