温度胁迫对转Bt基因抗虫棉毒蛋白的表达和棉铃虫死亡率的影响

Effects of Temperature Stress on Bt Insecticidal Protein Expression in Bt Transgenic Cotton Leaves and Death Rate of Cotton Bollworm

于花铃期对科棉1号棉株进行连续48 h的不同温度处理,用处理后的叶片饲喂棉铃虫,研究叶片活性、毒蛋白和棉铃虫死亡率之间的关系。结果表明,游离氨基酸含量一直增加,12h内增加最快;可溶性蛋白含量一直下降,12 h内降幅最大。毒蛋白含量24 h内显著下降,12h内降幅最大。25℃处理下的死亡率明显高于20℃和35℃处理。同一温度下,胁迫时间越长,棉铃虫取食后的死亡率越低。棉铃虫取食72 h后的死亡率明显低于144 h后的死亡率。取食72 h后的死亡率与可溶性蛋白、游离氨基酸和毒蛋白含量呈显著或极显著相关,与可溶性蛋白和毒蛋白变化量之间呈显著相关。

With Bt transgenic cotton plants of Kemian 1 as the testing material, temperature stress experiments （20℃, 25℃, 35℃ ,and 40℃） were carried out in temperature and light controlled compartments to investigate Bt insecticidal protein content in cotton leaves at flowering stage, the death rate of bollworm fed on cotton leaves, and the relationship between them. The results indicated that free amino acid content increased under temperature stress, with the biggest increment during the first 12 h. The content of soluble protein decreased, presenting a sharp decrement during the first 12 h. Bt insecticidal protein content in leaves subjected to temperature stress decreased significantly during the first 24 h, and the biggest decrements occurred during the first 12 h. The death rate of bollworm fed on the leaves subjected to 25℃ was higher than the death rates of bollworm eating the leaves subjected to 20℃ and 35℃. Under the same temperature, the longer the leaves were subjected to temperature stress, the lower the death rate of bollworm fed on these leaves was. The death rate of bollworm 72 h after eating the leaves was significantly higher than the death rate of bollworm 144 h after eating the leaves. Correlation analyses showed that the contents of Bt insecticidal protein, free amino acid, soluble protein and the death rate of bollworm 72 h after eating the leaves were significantly correlated at 0.05 level or at 0.01 level. The increment of free amino acid, the decrement of Bt insecticidal protein, and the death rate of bollworm 72 h after eating the treated leaves were significantly correlated at 0.05 level.