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为了研究胚乳直链淀粉含量有显著差异的水稻品种胚乳SBEIIb基因表达特性及其启动子,本研究根据日本晴的基因组序列,采用PCR技术克隆了6个品种的SBEIIb启动子序列.结果表明,供试品种的直链淀粉含量在不同的灌浆时期都存在着显著差异;在灌浆过程中胚乳SBEIIb基因的mRNA表达量呈单峰曲线变化,灌浆前期mRNA表达量平稳升高,中期出现峰值,后期快速降低,而且高直链淀粉含量的品种,其胚乳SBEIIb基因mRNA的表达量高,低直链淀粉含量的品种,其胚乳淀SBEIIb基因mRNA的表达量低;不同类型水稻品种SBEIIb基因启动子序列的同源性高达99％以上,SBEIIb基因启动子序列的保守性很强;品种间有性杂交子代SBEIIb基因的启动子序列可发生碱基的变化,但没有导致启动子核心元件发生变化;胚乳SBEIIb基因mRNA表达量的变化受SBEIIb基因启动子的调控影响很少.本研究结果为进一步研究淀粉分支酶基因的表达机制提供理论基础.“,”In order to study the expression characteristics ofSBEIIb gene and its promoter in rice endosperm,which had significant difference of the amylose contents of endosperm.According to the DNA sequence of rice (Oryza sativa),SBEIIb promoter sequences of six varieties were amplified by PCR.The results showed the amylase contents of these varieties had significantly difference during grain filling.The mRNA expression of SBEIIb gene showed a single peak curve changing in the process of grain filling,the mRNA expression of SBEIIb gene rose steadly in the early filling stage,peak value appeared in the middle stage and then decreased rapidly in the late stage.The higher was the amylose content,the higher of the mRNA expression ofSBEIIb gene.The lower was the amylose content,the lower of the mRNA expression of SBEIIb gene.The homology of the promoter sequence of SBEIIb gene in different rice varieties was above 99％,that was great conservative.The promoter sequence of the sex hybrid progeny SBEIIb gene between varieties may be changed,but didn't cause the changing of core elements.The changing ofSBEIIb gene mRNA expression in endosperm was less affected by promoter regulation.The results of this study laid the foundation for the regulatory mechanism of the starch branching enzyme gene expression.