淀粉是植物体内重要的储能物质，也是人类的主要食物和工业生产的原料来源。淀粉中直链淀粉和支链淀粉的相对含量是淀粉品质的主要决定因素。淀粉分支酶是淀粉合成过程中的关键酶，它催化葡萄糖残基以α-1,6糖苷键连接形成葡聚糖分支，从而改变直链淀粉和支链淀粉的比例，影响淀粉的理化性质。玉米淀粉分支酶Ⅱb（ZmSBEⅡb）对玉米胚乳直链淀粉含量的影响很大，其编码基因的突变（玉米ae突变体）可使玉米胚乳中直链淀粉的含量达到50 %。因此，ZmSBEⅡb及其互作因子的作用机理的研究，对揭示淀粉特别是直链淀粉合成调控的分子机理具有重要理论意义。本项研究根据原有的酵母双杂交对ZmSBEⅡb互作因子的高通量筛选结果，克隆出了ZmSBEⅡb互作因子ZmSIP1编码基因的全长序列，分析了ZmSBEⅡb同ZmSIP1的互作结构域，确定了ZmSBEⅡb同ZmSIP1的亚细胞定位，并检测了ZmSBEⅡb同ZmSIP1在不同玉米品种不同器官以及高直链玉米籽粒发育过程中的表达状况。主要研究结果如下：1、利用同源克隆结合5’ RACE的方法，克隆出ZmSIP1的全长序列（其Genebank登录号为FJ766095），ORF框大小为1971 bp，编码657个氨基酸，分子量为75 KD，等电点为8.7，含有一个保守结构域DUF590（功能未知）。2、构建ZmSBEⅡb 及其互作因子ZmSIP1的不同结构域片段，确定有效互作结构域。结果表明ZmSBEⅡb三维结构的维持是与ZmSIP1互作最为理想的，其中ZmSBEⅡbP7，即ZmSBEⅡb的catalytic domain和C-terminal all-beta domain在与ZmSIP1的互作上具有较大的贡献。3、利用烟草原生质体转化方法确定了ZmSBEⅡb和ZmSIP1的亚细胞定位。结果表明，ZmSBEⅡb定位于叶绿体中，而ZmSIP1则定位于叶绿体周围的细胞质中。因此认为ZmSIP1有可能同ZmSBEⅡb在细胞质内的翻译后修饰有关。4、应用半定量RT-PCR技术，检测了不同品种玉米不同器官中ZmSBEⅡb和ZmSIP1的表达状况。结果表明，ZmSBEⅡb的表达量与玉米籽粒中直链淀粉含量之间存在负相关的关系，在直链淀粉含量更高的品种Hamy-ae的籽粒内，ZmSBEⅡb的表达水平相对较低，而ZmSIP1在不同品种玉米胚乳中表达模式与ZmSBEⅡb几乎一致，在Hamy-ae的籽粒内丰度较低。因此，ZmSIP1和ZmSBEⅡb可能是玉米籽粒中影响直链淀粉合成的关键因子，ZmSIP1和ZmSBEⅡb表达量的高低决定了玉米籽粒中直链淀粉含量的高低，甚至可能决定玉米籽粒淀粉的品质。

Starch is not only the predominant energy storage material, but also people’s main food source. Currently, starch also plays an important role in many industies. Starch includes two different glucan chains, amylose and amylopectin. The relative amounts of amylose and amylopectin determine starch’s unique physical and properties, which covey specific functionality and could be biotechnological importance. Starch branching enzyme ( SBE ) is the key enzyme of the process of starch biosynthesis. SBE catalyze the formation of α-1,6 linkages, thereby changing the ratio of amylose to amylopectin, affecting the physical and properties of starch. ZmSBEⅡb plays an essential role in the amylopectin biosynthesis，the content of amylopectin of the mutantion in SBEⅡb ( named ae ) is high to 50 %. As a matter of fact, the study on ZmSBEⅡb and the its interaction proteins will provide improtant theoretic bases for clarifying the molecular mechanisms in starch especially amylopectin biosynthesis.According to the previous results of yeast two-hybrid, we cloned the full-length sequence of Zea mays starch branching enzyme interaction protein 1 ( ZmSIP1 ) encoding gene. We also analysed the interaction domain of ZmSIP1 and ZmSBEⅡb，identify the subcellular localization of ZmSIP1 and ZmSBEⅡb. And then we detected the expression of ZmSIP1 and ZmSBEⅡb in different organs of different maize varieties, as well as in the developmental process the kernel of high-amylose maize. The research results in present work are as follows:1、Using homology cloning and 5’ RACE methods, we have cloned the full-length sequence of ZmSIP1(its Genebank accession number is FJ766095), the ORF of this gene is 1971 bp, encoding 657 animo acids, and the Molecular Weight of ZmSIP is 75 KD, with the isoelectric point of 8.7, it contains a conserved domain named DUF590 (Domain of Unknown Function 590).2、During the study of mapping all the domains , the catalytic domain and C-terminal all-beta domain of ZmSBEⅡb have the greatest intensity of interaction with ZmSIP1, but neither the catalytic domain nor the C-terminal all-beta domain interact with ZmSIP1 alone. And compared with the full length of ZmSBEⅡb, ZmSBEⅡb-P7 has less intensity of interaction with ZmSIP1. Therefore the maintenance of three-dimensional structure of ZmSBEⅡb is best for the interaction with ZmSIP1, of all that, the catalytic domain and C-terminal all-beta domain of ZmSBEⅡb play an essential role in interaction with ZmSIP1.3、To clarify the cellular physiological functions of ZmSIP1and ZmSBEⅡb genes, the transient subcellular localizations was examined by transforming tobacco leaf protoplasts method. The results showed that ZmSBEⅡb localized in the chloroplast, and ZmSIP1 localized in the cytoplasm around the chloroplast. That meaned ZmSIP1 may take part in the Post-translational modification of ZmSBEⅡb in the cytoplasm. 4、We used the semi-quantitative RT-PCR technology to detect the expression of different organs of maize of ZmSBEⅡb and ZmSIP1. The results showed that the expression of ZmSBEⅡb in maize endosperm had negative correlation with the amylose content of the endosperm. In the endosperm of Hamy-ae, which had higher amylose content, ZmSBEⅡb has low expression levels relatively. As well as ZmSBEⅡb, ZmSIP1’s expression was lower in Hamy-ae and higher in Stizm 51. Therefore, ZmSIP1 and ZmSBEⅡb may be the key factors which influence amylose synthesis of maize, ZmSIP1 and ZmSBE Ⅱ b expression determines the level of amylose content in maize endosperm, and may even decide the quality of maize starch.