纤维素合酶复合体由多种纤维素合酶及结合蛋白组成，复合体的组成和活性对纤维素的合成速度和结构特征具有重要影响。本课题研究棉花纤维素合酶复合体中的纤维素合酶CESA8、甾醇糖苷转移酶SGT2和钙依赖蛋白激酶CDPK32对纤维素的合成速度、结晶度和聚合度的影响，以及对纤维强度的影响，解析它们在纤维素合成中的功能。以陆地棉和海岛棉为材料，用蛋白组学和生物化学方法鉴定棉纤中纤维素合酶复合体的各种CESA和结合蛋白，分析CESA8、SGT2和CDPK32的互作关系，CESA8与复合体中各种CESA的互作关系。用生物化学方法鉴定纤维素合酶复合体的组成和活性，研究CESA8、SGT2和CDPK32对复合体活性的影响。用转基因方法在棉花中抑制或超量表达CesA8、SGT2和CDPK32基因，分析棉纤中纤维素合酶复合体的组成和活性，纤维素的合成速度、结晶度和聚合度，以及纤维强度，研究它们在纤维素合成中的功能。

Cotton is an important economic crop in China. Fibers strength, a main factor to evaluate the quality of cotton fibers, is determined by the cellulose content, crystallinity and degree of polymerization. These characteristics are closely related to the cellulose synthesis..Cellulose synthase complex is composed of a variety of cellulose synthases and binding proteins. The composition of the complex has an important influence on cellulose synthesis speed and structural characteristics. Our preliminary results indicate that the cellulose synthase CESA8, sterol glucosyltransferase SGT2 and calcium dependent protein kinase CDPK32 are important proteins in the cotton cellulose synthase complex. In this proposal, we will identify the functions of CESA8, SGT2 and CDPK32 in cellulose synthesis, and explore their relationship with cellulose synthesis speed and structural features. By using Co-IP, LC-MS, and Western blotting methods, we will initially identify the compostion of cotton cellulose synthase complex, validate the interaction relations among the CESA8, SGT2 and CDPK32, and confirm the interaction between CESA8 and other cellulose synthase. Than, we will analyze the catalytic activity of the cellulose synthase complex, identify the effect on activity of CESA8, SGT2 and CDPK32. Finally, by using transgenic methods, we will inhibit or overexpress the three genes in cotton, analyse the synthesis rate of cellulose, cellulose crystallinity and degree of polymerization, validate the functions of the three genes in cotton cellulose synthesis.