中文摘要：

【目的】研究低温对纤维比强度形成的影响。【方法】通过设置大田分期播种试验，使相同果枝部位棉铃可以处于不同的温度条件下发育，研究低温对棉纤维发育关键酶活性及相关基因表达的影响。【结果】低温影响纤维素的累积速率并最终影响纤维比强度的形成，其原因是在不同水平上影响了纤维发育关键酶的活性。在生化水平上，低温（铃龄0～50d日均温〈23．0℃，铃龄25～50d日均温〈21．0℃）提高了纤维中 β-1，3-葡聚糖酶的活性、降低了蔗糖合成酶的活性，且前者对温度更为敏感。在基因表达水平上，低温使Expansin、蔗糖合成酶基因的表达量增加， β-1，3-葡聚糖酶基因的表达与此相反，低温下Expansin到达表达峰值时间推后且维持高表达的时间延长，低温可导致15d铃龄纤维 β-1，3-葡聚糖酶基因表达量显著降低，而蔗糖合成酶基因表达量显著升高。【结论】在纤维品质形成上，低温导致棉纤维伸长期及伸长高峰推后，低温下纤维素累积量、纤维比强度的变化特征与纤维蔗糖合成酶活性及 β-1，3-葡聚糖酶基因表达的变化特征高度一致，与 β-1，3-葡聚糖酶活性及蔗糖合成酶基因表达受低温影响的规律相反。

英文摘要：

[Objective] This experiment was carded out to study the effects of low temperature on cotton fiber strength development. [Method] The effects of low temperature on the dynamics of several key enzymes activity and the gene expression pattern were studied by setting different seeding times, thus the fiber developing process can be arranged at different temperature conditions. [Result] The results showed that the dynamics of the enzymes activity and the genes expression were influenced in by low temperature conditions. At the biochemical level, the activity of the β-1,3-glucanase was decreased with the increasing of the temperature while the sucrose synthetase activity behaved oppositely. Evidences also showed that the β-1,3-glucanase were much more sensitive to temperature variation than sucrose synthetase. At the gene expression level, the effect of low temperature （mean daily temperature of 0-50 DPA （days post anthesis） and 25-50 DPA was lower than 23.0℃ and 21.0℃, respectively） on different genes expression was quite different. At low temperature, the expression of the β-1,3-glucanase gene was remarkably inhibited in the days around the 15 DPA and the high expression period of the expansin gene was prolonged. For the fiber strength development, the peak of the fiber elongation was prolonged and that was accordant with the variation of the expression pattern of the expansin gene, the β-1,3-glucanase and the sucrose synthetase gene. [Conclusion] The variation of the cellulose deposition and the textile processing was highly accordant with the changes of the β-1,3-glucanase gene expression pattern and variation of the dynamics of sucrose synthetase activity, while it was absolutely opposite to the changes of the sucrose synthetase gene expression pattern and variation of the dynamics of β-1,3-glucanase activity.