糯玉米胚乳支链淀粉精细结构的形成机制及氮素调控

糯玉米胚乳淀粉几乎全由支链淀粉组成，支链淀粉精细结构是影响淀粉理化特性进而决定应用品质的主要因素，其形成主要受淀粉合成关键酶活性及编码基因表达的调节。氮肥运筹是调控籽粒淀粉特性的主要措施。本项目选用不同的糯玉米品种（品系）为材料，采用酶学方法、Native-PAGE、实时荧光定量PCR与Northern杂交技术，研究胚乳发育期间支链淀粉精细结构的变化，测定淀粉合成关键酶的活性，鉴定其同工酶类型及表达特性，探讨淀粉合成相关基因的表达模式，明确糯玉米胚乳支链淀粉精细结构的形成机制；分析成熟期胚乳淀粉的理化特性，明确支链淀粉精细结构与淀粉理化特性的关系；研究施氮对支链淀粉精细结构、淀粉合成关键酶活性及同工酶和相关基因表达的影响，阐明氮素对支链淀粉精细结构形成的调控效应。研究结果将深化糯玉米淀粉品质形成机制研究，为糯玉米淀粉品质调优技术的确立提供理论依据。

Waxy maize endosperm starch is composed of nearly 100% amylopectin. Amylopectin fine structure is the important determinant for starch physicochemical properties and quality, and its formation is controlled by the activities of starch synthesis enzymes and the expression of starch synthesis genes. Nitrogen application is the key measure to regulate starch properties. In this project, different waxy maize varieties and strains are used. During endosperm development, the changes of amylopectin fine structure are studied, the activities of starch synthesis enzymes are determined by enzymatic method, the isozyme types and expression traits are identified by Native-PAGE, the expression profiles of starch synthesis genes are discussed by real-time fluorescence quantitative PCR and northern blot, so as to clarify formation mechanism of amylopectin fine structure in waxy maize endosperm. In mature endosperm, starch physicochemical properties are analyzed to identify the relationship of amylopectin fine structure and starch physicochemical properties. The effects of nitrogen application on amylopectin fine structure, starch synthesis enzyme activities, isozyme and gene expression profiles of starch synthesis are studied to clarify the effects of nitrogen regulation on amylopectin fine structure formation in waxy maize endosperm. The results will deepen the study of formation mechanism and provide a theoretical basis for optimization technology establishment of waxy maize starch quality.