中文摘要：

以来源于中国的Bt棉品种泗抗1号（常规种）、泗抗3号（杂交种）和来源于美国的Bt棉品种99B（常规种）、岱杂1号（杂交种）为材料,研究了不同高温对Bt棉盛蕾期蕾中Bt蛋白表达量变化及氮代谢生理特征的影响.结果表明： 与对照（32 ℃）相比,在38 ℃以上高温时,4个品种棉蕾中Bt蛋白表达量均显著下降,且随温度升高,Bt蛋白含量下降幅度增大.杂交种棉蕾中Bt蛋白表达量要高于常规种,且受高温影响较小.Bt杀虫蛋白表达量下降幅度大的品种,其可溶性蛋白含量、谷氨酸丙酮酸转氨酶（GPT）活性、谷氨酸草酰乙酸转氨酶（GOT）活性下降幅度也大,游离氨基酸含量、蛋白酶活性、肽酶活性增加幅度较大.

英文摘要：

Taking Bt cotton Sikang 1 （a conventional cultivar）, Sikang 3 （a hybrid cultivar） from China and 99B （a conventional cultivar）, Daiza 1 （a hybrid cultivar） from USA as test materials, the effects of different high temperatures on the square Bt proteins expression and nitrogen metabolic physiology were investigated. The results showed that the square Bt protein contents of the four cultivars decreased significantly above 38 ℃ compared with that at 32 ℃. The higher the temperature was above 38 ℃, the greater the reduction extent of the Bt protein content was. The square Bt protein contents of the hybrid cultivars were higher than that of the conventional cultivars, and were less reduced under the high temperature stress. The cultivars with bigger reductions in Bt protein content also showed greater reductions in the square soluble protein contents, pyruvic transaminase activities and glutamic oxaloacetic transaminase activities, while larger increments were detected for the square free amino acid contents, proteinsase activities and peptidase activities.