Effects of Key Enzyme Activities in Sucrose Metabolism on Fiber Quality in High Quality Upland Cotton

Abstract

Fiber strength is an important index that measures the fiber quality, which determined by cellulose deposition characteristics. Cellulose synthesis and accumulation are affected by many enzymes including sucrose synthetase (SS), sucrose phosphate synthetase (SPS) and so on. Up to date, there have been few reports about cellulose accumulation and key enzymes relating to sucrose metabolism in high quality upland cotton cultivars. To investigate the relationship between fiber quality differences and relating sucrose metabolism enzymes, a filed experiment was conducted at Shandong Agricultural University in 2006–2007. Three upland cotton cultivars including Ludimianlu 324 and Yumian1(YM-1) (high quality) and Lumianyan (18) (common quality) were used in the experiment. Leaves were sampled at 15, 30, 45, and 60 days after leaf unfolding. Flowers were labeled at anthesis and sampled every 7 days from 7 days after anthesis. The result showed that the sucrose content was higher with higher SPS activities in high quality upland cotton leaves. The simulation with Logistic equation of cotton cellulose accumulation showed that the accumulation duration was longer and the accumulation rate was moderate, so the final cellulose content was higher in high quality upland cotton cultivar. Compared with common upland cotton, the sucrose content was higher in fiber at early growth stage in high quality upland cotton, which supplied enough original substrate for secondary wall thickening. Meanwhile, the SS activity was higher and consistent with cellulose accumulation duration in high quality upland cotton. Furthermore, high quality upland cotton had higher SPS activity before termination of cellulose accumulation duration. It was suggested that SPS activity in leaves, SS and SPS activities in fibers had close correlation with cellulose accumulation and fiber quality.