转Bt基因抗虫棉经过20多年的研究和生产应用,虽然取得了巨大的生态和经济效益,但棉铃虫的抗性风险也逐渐增加,因此,通过发掘不同杀虫机理的Bt基因,不仅可以提高杀虫效率,而且有效的避免或延迟昆虫的抗性.依据棉花遗传密码子偏好性,对来源于苏云金芽胞杆菌(Bacillus thuringiensis,Bt)新型Bt基因cry2Ah-like进行了密码子优化改造,利用农杆菌介导法导人烟草.通过荧光定量PCR方法,Southern blot和Western blot方法,证明了转基因烟草中外源基因在RNA和蛋白水平上均稳定表达,并且已整合到烟草基因组中.生物活性检测结果表明,饲喂转基因烟草叶片4d后,棉铃虫幼虫校正死亡率达86.59％,达到高抗水平,进一步证明密码子优化后的cry2Ah-M基因能够高效表达且具有较高的杀虫活性,是有效防治棉铃虫的新型基因.“,”Transgenic Bt cotton has gained great ecological and economic benefits after application in research and production for over 20 a,but the resistance risk of cotton boll worm is also increasing gradually.Therefore,exploration of Bt genes by different insecticidal mechanism can not only improve insecticidal efficiency,but also avoid or delay insect resistance effectively.Based on preference of cotton genetic codon,this study optimized the codon of new Bt gene cry2Ah-like from Bacillus thuringiensis (Bt),constructed plant expression vector,and introduced into tobacco mediated by agro-bacterium.The fact of foreign gene in transgenic tobacco was expressed steadily,RNA was proven and protein level had already been integrated into tobacco genome.The results of biological activity detection showed that after feeding 4 d with transgenic tobacco leaves,the corrected mortality of cotton boll worm can be 86.59％ and achieving high resistance level.This result further proved that cry2Ah-M gene after codon optimization can express effective and with higher insecticidal activity,and was a new gene for effective prevention of cotton boll worm.