Expression patterns of Bacillus thuringiensis insecticidal protein and the control to cotton bollworm of different Bt transgenic cotton
In recent years, the damage caused by cotton bollworm is becoming serious in some field of Anhui province. To detect the influence of different cotton varieties to cotton bollworm damage, the ELISA was used to analyze Bacillus thuringiensis protein contents in different developmental stages of 12 Bt transgenic cotton varieties in Anhui. Meanwhile, the morality of cotton bollworm Helicoverpa armigera(Hubner) fed on the corresponding cotton was studied through laboratory bioassay. It was showed that there were significant differences in the Bt contents between different Bt transgenic cotton varieties. First, Bt protein could be relatively stably expressed in different tissues and organs and each growth stage of Zhongmiansuo 71, Zhongmiansuo 65, Aimian 1 and Daiza 2. Secondly, Bt protein content was relatively high in some growth stages and tissues of Tongza 411, Qyanyinmian 4 and Wanmian 17. Compared with the above-mentioned species, Chuang 072, Xiangzamian 7, Jiayuan 216, Nongfengmian 1 and Ezamian 26 have little Bt protein in different tissues and organs and different growth stages. Generally, the expression levels of Bt protein in Bt cottons were decreased with the season, however, the declining trend is not linear. The expression levels of Bt protein would picked up at some developmental stage in different cottons. Twelve Bt transgenic cotton varieties have little Bt protein when they have three leaves. With the growth of cotton, these cotton varieties have a peak of Bt protein expression appeared in the period of the seven-leaf-stage to bud. The tendency of larval moralities in the laboratory bioassay was consistent with the Bt expression level in different developmental periods/organs.