一株对鳞翅目蔬菜害虫具有广谱高毒力的新Bt菌株

从河北省土壤分离出苏云金芽胞杆菌（Bacillus thuringiensis,Bt）MB-15菌株,利用室内生物活性测定的方法,与Bt标准菌株HD-1的杀虫毒力进行比较,结果发现该菌株胞晶混合液对棉铃虫(Helicoverpa armigera)、甜菜夜蛾(Spodoptera exigua)、小菜蛾(Plutella xylostella)、斜纹夜蛾(Spodoptera litura)和菜青虫(Pieris rapae)等5种鳞翅目蔬菜害虫的毒力均高于标准菌株Bt HD-1胞晶混合液。对发酵液各组分活性的分析发现,该菌株的上清液对胞晶混合物的杀虫活性有明显的增效作用。光学显微镜下观察该菌株伴胞晶体为菱形,SDS-PAGE分析显示其伴胞晶体主要由130.0 kDa和65.0 kDa 两种晶体蛋白组成。利用PCR-RFLP对其杀虫基因型进行鉴定,结果表明该菌株含有cry1Ac、cry2Aa、cry1I和vip3Aa基因。推断该菌株是一株对鳞翅目蔬菜害虫的防治具有潜在的商业开发价值的Bt野生株。

Data Survey and Analysis of Transgene Flow Frequencies and Distances in Major Crops Ⅴ.Rapeseed

Prior to approval of commercialization,transgenic plants are required to be confined in order to prevent foreign gene dispersal.According to the current Chinese regulation of GMP biosafety assessment,the isolation distance for field experiment of GM rapeseed is 1 000 m,which is larger than required distance set by almost all countries and regions.According to the review of studies on rapeseed gene flow,the outcrossing rate of rapeseed(Brassica napus) is below 3%,and below 1% is the most cases.Isolation distance and buffer zone are effective ways to reduce outcrossing rate.Beyond 400 m the outcrossing rate becomes significantly lower than 0.01%,though it is much higher for the B.rapa,sterile lines and self-incompatible lines.It is suggested that biosafety management be based on the classification and threshold principles and that the isolation distance be adjusted to 400 m for common rapeseed varieties of B.napus while kept 1 000 m for the self-incompatible lines and sterile lines in the confined field experiment.