中文摘要：

选用纤维比强度形成存在温度敏感性差异的两个棉花品种（科棉1号：温度弱敏感型品种，苏棉15：温度敏感型品种）为材料，于2006-2007年在江苏南京设置大田分期播种试验，使棉纤维发育处于不同的温度条件，研究低温对棉纤维发育相关酶（蔗糖酶、蔗糖合成酶、磷酸蔗糖合成酶、β-1，3-葡聚糖酶）活性及相应基因表达的影响．结果表明：由晚播造成的低温（棉纤维发育期日均最低温分别为21．1、20．5和18．1℃）影响了纤维发育相关酶的活性变化，从而影响了棉纤维素累积和纤维比强度的形成．低温提高了纤维中蔗糖酶和β-1，3-葡聚糖酶的活性，降低了蔗糖合成酶和磷酸蔗糖合成酶的活性．低温使Expansin、蔗糖合成酶基因的高表达时间延长，β-1，3-葡聚糖酶基因的表达峰值出现时间延迟，且表达量降低．两个棉花品种的纤维素合成相关酶对低温的响应存在差异，温度敏感型品种（苏棉15）的酶活性的变化幅度明显高于温度弱敏感型品种（科棉1号），可能是导致不同棉花品种纤维比强度形成存在温度敏感性差异的主要原因．

英文摘要：

Taking two cotton cuhivars with different temperature-sensitivity during their fiber 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℃ during fiber development period） had definite effects on the enzyme activities, and accordingly, the fiber strength formation. Low temperature increased the invertase and 13-1,3-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 β-1,3-glucanase. There existed significant differences in the low-temperature responses of related enzymes activities between the two cuhivars, with the change ranges of the enzyme activities being larger for temperature-sensitive cultivar Sumian 15 than for temperature-insensitive cuhivar Kemian 1, which could be the main reasons leading to the different temperature-sensitivity of the two cotton cuhivars during their fiber strength formation.