中文摘要：

选择棉纤维比强度差异明显的2个品种,研究了棉纤维发育关键酶（蔗糖合成酶和β-1,3-葡聚糖酶）活性的变化特征及其与纤维比强度的关系。结果表明,棉纤维发育过程中蔗糖合酶、β-1,3-葡聚糖酶活性变化特征在生化和mRNA转录水平上均存在明显的差异,影响纤维素的沉积特性及纤维比强度。高强纤维品种（科棉1号,平均比强度为35cN tex^-1）的蔗糖合酶和β-1,3-葡聚糖酶活性及其基因表达量和维持高表达时间均高于低强纤维品种（德夏棉1号,平均比强度为26cN tex^-1）。其中,高强纤维品种蔗糖合酶的基因表达量铃龄25d时明显高于低强纤维品种,而β-1,3-葡聚糖酶的基因表达量则在铃龄10～25d高于低强纤维品种。在纤维素形成过程中,高强纤维品种的纤维素累积平缓且纤维素累积持续期长于低强纤维品种,品种间差异程度受棉株果枝部位影响。在棉纤维发育过程中,Expansin、β-1,4-葡聚糖酶的基因表达量随铃龄的增加呈下降趋势（铃龄20d时表达量显著下降）,这与棉纤维形成过程（铃龄25d前伸长较快,随后趋于停止）一致,且高强纤维品种维持高表达时间长与其纤维伸长期较长相吻合。

英文摘要：

Fiber specific strength is one of the important criterions of cotton quality,and many complex physiological and biochemical processes are involved in fiber formation.To detect the relationship enzyme activities in cotton fiber development with fiber specific strength,two cotton cultivars（Kemian 1 which is a cultivar with high strength fiber,average fiber specific strength is 35 cN tex^-1;Dexiamian 1 which is a cultivar with low strength fiber,average fiber specific strength is 26 cN tex^1）were used to investigate the characteristics of sucrose synthase（SuSy）and β-1,3-glucanase which play very important roles in developing cotton fiber,and dynamic changes of the related gene（sucrose synthase,β-1,3-glucanase,β-1,4-glucanase,Expansin）expression.The results showed that there were differences between the two cultivars in variations of the cellulose deposition and fiber specific strength which was related with the changes of key enzyme activities and the gene expression levels.The activity and gene expression of sucrose synthase and β-1,3-glucanase were higher in Kemian 1 than in Dexiamian 1.High concentration and high gene expression of SuSy and β-1,3-glucanase in cotton fiber resulted in a long period and tempered cellulose accumulation and high strength fiber formation.Dexiamian 1 had low activities of the key enzymes and low expression levels which led to a short and rapid cellulose accumulation duration and low strength fiber.From results above,we suggest that the different characteristics of key enzymes activity（sucrose synthase and β-1,3-glucanase）in fiber of different cotton cultivars may cause the differences in the cellulose accumulation and fiber strength.