[Low-temperature responses of enzyme activities related to fiber development of two cotton (Gossvpium hirsutum L.) cultivars with different temperature-sensitivity].

Taking two cotton cultivars with difterent temperature-sensitivity during tneir liner strength formation as test materials, a field experiment of different sowing dates was conducted in Nanjing of Jiangsu Province in 2006 and 2007 to study the effects of low temperature on the activities and gene expression of the enzymes related to fiber development. The low temperature induced by late sowing (with the mean daily minimum temperature being 21.1, 20.5, and 18.1 degrees C during fiber development period) had definite effects on the enzyme activities, and accordingly, the fiber strength formation. Low temperature increased the invertase and beta-1, 3-glucanase activities, decreased the sucrose synthase and sucrose phosphate synthase activities, prolonged the time with higher gene expression level of Expansin and sucrose synthase, and delayed the expression peak and decreased the gene expression quantity of beta-1,3-glucanase. There existed significant differences in the low-temperature responses of related enzymes activities between the two cultivars, with the change ranges of the enzyme activities being larger for temperature-sensitive cultivar Sumian 15 than for temperature-insensitive cultivar Kemian 1, which could be the main reasons leading to the different temnerature-sensitivitv of the two cotton cultivars during their fiber strength formation.