二化螟Cry1Ac汰选品系对不同Bt蛋白的敏感性
Variation in the susceptibility of a Chilo suppressalis Cry1Ac-selective strain to different Bacillus thuringiensis insecticidal proteins

为明确靶标害虫对Bt蛋白的抗性及对不同类型Bt蛋白的交互抗性，采用生物测定法进行了二化螟Chilo suppressalis（Walker）敏感品系和Cry1Ac汰选品系在Cry1Ac毒饲料上的时间-死亡率反应、对不同Bt杀虫蛋白的敏感性及不同Bt蛋白复配组合对二化螟毒力效果的研究。结果表明，二化螟Cry1Ac汰选品系已对36.67 μg/mL（LC50）的Cry1Ac杀虫蛋白产生了一定的适应性，但对308.69 μg/mL （LC90）的Cry1Ac蛋白反应仍较敏感。Cry1Ac敏感品系和汰选品系对Cry1Ab蛋白的LC50分别为1.40 μg/mL和3.86 μg/mL，二者差异显著，但对Cry1Ca（1.63 μg/mL和1.73 μg/mL）或Cry2Aa（127.48 μg/mL和144.50 μg/mL）的LC50差异不显著，即Cry1Ac汰选品系与Cry1Ab存在明显的交互抗性，但与Cry1Ca和Cry2Aa不存在交互抗性。在不同Bt蛋白复配组合中（1：1复配），Cry1Ab+Cry1Ca、Cry1Ab+Cry2Aa和Cry1Ca+Cry2Aa增效作用最为显著。表明抗虫基因cry1Ca和cry2Aa可作为双价转基因抗虫水稻研发的候选基因。
The time-mortality responses of Cry1Ac-susceptible and-selective Chilo suppressalis strains,variations in the two strains's susceptibility to different Bacillus thuringiensis(Bt) insecticidal proteins,and synergism of different Bt protein combinations on C.suppressalis were studied.In the time-mortality response experiment,the Cry1Ac-selective strain had a degree of tolerance to the LC50 treatment with 36.67 μg/mL and absolute susceptibility to the LC90 treatment with 308.69 μg/mL of the Cry1Ac-containing diet.The LC50 values of Cry1Ac-susceptible and-selective strains to Cry1Ab were 1.40 μg/mL and 3.86 μg/mL,respectively,showing significant differences between the two values.However,there was no significant difference in the LC50 values of Cry1Ca (1.63,1.73 μg/mL) or Cry2Aa (127.48,144.50 μg/mL) between Cry1Ac-susceptible and-selective strains.The Cry1Ac-selective strain of C.suppressalis exhibited cross-resistance to Cry1Ab,but not to Cry1Ca or Cry2Aa.The 1:1 combinations of Cry1Ab+Cry1Ca,Cry1Ab+Cry2Aa,and Cry1Ca+Cry2Aa showed significant synergistic interactions against C.suppressalis,indicating that insect-resistant gene,cry1Ca or cry2Aa may be used to develop pyramided genetically modified rice.