苏云金杆菌营养期杀虫蛋白基因vip3A的检测与杀虫活性测定

为获取高活性的野生Bt菌株,对从土壤中分离的99株Bt菌株进行了营养期杀虫蛋白的分子鉴定和生物活性测定。根据已知的vip3 A基因序列设计1对特异性引物,进行PCR鉴定,55株扩增得到1.2 kb的目的片段。对31株阳性菌株的营养期杀虫蛋白活性进行了初步测定,结果显示,Bt LS1和LS8菌株毒力最高,2菌株对2龄甜菜夜蛾的体重抑制率分别为91.14%和93.59%。选取Bt LS1和LS8菌株进行胞内外营养期蛋白杀虫活性测定,发现Bt LS1和LS8菌株对初孵甜菜夜蛾体重抑制率分别为45.1%和43.2%,对初孵棉铃虫的校正死亡率分别为(22.1±1.4)%和(55.3±3.7)%,对2龄棉铃虫的体重抑制率分别为(78.7±6.6)%和(50.4±2.4)%。

Detection of vip3A gene and bioassay of VIP3A protein from Bacillus thuringiensis isolates

PCR detection and bioassay from Vip3A proteins were carried out among 99 wild Bacillus thuringiensis,which were isolated by our lab.A pair of specific primers were designed according to the sequences of known vip3A a gene.The vip3A-type genes in 99 wild strains were assayed by PCR amplification.The results showed that 55 strains contain vip3A gene.Bioassay showed that the strains of Bt LS1 and LS8 have high toxicity toward Helicoverpa armigera and Spodoptera exigua.The morality rates against Helicoverpa armigera(1st instar) were(22.1±1.4)% and(50.3±3.7)% respectively.The weight inhibitory rates against Helicoverpa armigera(second star larvae) were(78.7±6.6)% and(50.4±2.4)% respectively,and the weight inhibitory rates against Spodoptera exigua(1st instar) were 45.1% and 43.2% respectively.