Abstract:

Fiber 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.

Key words:

Enzyme activity, Gene expression, Cellulose accumulation, Fiber strength