中文摘要：

以Bt基因来源于中国的棉花品种泗抗1号（常规种）、泗抗3号（杂交种）和来源于美国的棉花品种99B（常规棉）、岱杂1号（杂交棉）为材料,研究了不同高温水平下Bt棉盛铃期铃壳中Bt蛋白含量变化及氮代谢生理特征.结果表明：铃壳中Bt蛋白含量随温度升高而降低,与对照相比（32℃）,常规棉品种在38℃、杂交棉品种在40℃以上时,铃壳中Bt蛋白含量大幅度下降.其中,常规种泗抗1号和99B在38℃时分别下降53.0%和69.5%;杂交种泗抗3号和岱杂1号在40℃时下降64.8%和54.1%.铃壳Bt杀虫蛋白含量下降显著时,其可溶性蛋白含量明显下降,游离氨基酸含量明显提高,GPT活性显著下降,蛋白酶活性显著增加.高温影响铃壳的氮代谢引起Bt蛋白的分解加剧,合成减弱,从而造成Bt蛋白含量减少,抗虫性下降.

英文摘要：

Bt cotton cultivar Sikang 1（ a conventional cultivar） and Sikang 3（ a hybrid cultivar）from China,and 99B（ a conventional cultivar） and Daiza 1（ a hybrid cultivar） from USA were selected as experimental materials,the ball wall Bt protein content and nitrogen metabolic physiology were investigated under different high temperature levels at peak boll stage. The results showed that the Bt protein content of boll wall decreased with the increasing temperature. Compared with the control（ 32 ℃）,the boll wall Bt protein content decreased significantly when the temperature was above 38 ℃ for the conventional cultivars and above 40 ℃ for the hybrid cultivars. The Bt protein contents of cultivar Sikang 1 and 99 B decreased by 53. 0% and 69. 5% respectively with the temperature at 38 ℃,and that of cultivar Sikang 3 and Daiza 1 decreased by 64. 8% and 54. 1% respectively with the temperature at 40 ℃. Greater reductions in the boll wall soluble protein contents and GPT activities,larger increments for the boll wall free amino acid contents and proteinsase activities were also observed when the boll wall Bt protein content was significantly reduced. Therefore,high temperature resulted in the reduction of Bt protein synthesis and increase of the insecticidal protein degradation in the boll wall significantly,which caused the reductions in boll wall Bt protein content and insect resistance.