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为了防治多种鳞翅目害虫,表达Cry1Fa的转基因玉米和棉花已在美国商业化种植。明确棉铃虫Helicoverpa armigera对Cry1Fa与Cry1Ac的交互抗性及这两种杀虫蛋白之间的协同作用,可以为表达Cry1Fa+Cry1Ac的转双价抗虫棉花的合理应用提供依据。本实验测定了Cry1Fa对棉铃虫敏感品系(96S)及用Cry1Ac筛选的抗性品系(BtR,抗性倍数2194.15倍)的毒力,发现Cry1Fa对敏感棉铃虫的毒力远低于Cry1Ac,LC50值是Cry1Ac的504.80倍;而且抗性品系BtR对Cry1Fa存在19.98倍的交互抗性。Cry1Fa与Cry1Ac混用可以提高Cry1Fa毒杀敏感棉铃虫的效果,尤其是Cry1Fa浓度较低时,加入Cry1Ac,可以显著增加Cry1Fa的毒力;但只有加入较高浓度的Cry1Fa时才能增加Cry1Ac的毒力。由于BtR品系已经对Cry1Ac产生抗性,Cry1Ac对抗性棉铃虫的毒力明显降低;在较高浓度的Cry1Ac中加入Cry1Fa可以显著增加棉铃虫的死亡率(P=0.0015,F=6.88,df=6),但最高死亡率仅为58.33%。D-饱和最优试验的结果证实,Cry1Ac对于敏感棉铃虫的死亡率的影响达到显著水平(t1=13.76﹥t0.05),Cry1Ac与Cry1Fa的交互作用对毒力的影响也达到显著水平(t22=2.42﹥t0.05;t11=6.95﹥t0.05;t12=3.43﹥t0.05)。Cry1Ac和Cry1Fa对抗性棉铃虫死亡率的影响都达到显著水平(t1=3.03﹥t0.05;t2=2.59﹥t0.05),但Cry1Ac是决定抗、感棉铃虫死亡率的关键因素;Cry1Ac与Cry1Fa最佳浓度配比范围都是1.41～2.10μg/cm2;在抗性品系中,Cry1Ac和Cry1Fa的交互作用不显著。所以,尽管Cry1F+Cry1A作物扩大了杀虫谱,但棉铃虫对这两种蛋白存在交互抗性,而且这两种蛋白混用对治理抗Cry1Ac棉铃虫的效果不理想,因此不建议在中国种植表达Cry1F+Cry1A的棉花。
In order to control a variety of Lepidoptera pests, transgenic corn and cotton expressing Cry1Fa have been commercialized in the United States. It is clear that the reciprocal resistance of Helicoverpa armigera to Cry1Fa and Cry1Ac and the synergism between these two insecticidal proteins can provide a basis for the rational application of transgenic cotton expressing Cry1Fa + Cry1Ac. The virulence of Cry1Fa against the susceptible strain of cotton bollworm (96S) and the resistant strain (BtR, 2194.15-fold resistance) screened with Cry1Ac was determined in this experiment. The results showed that the virulence of Cry1Fa against the susceptible strain was lower than that of Cry1Ac and LC50 Was 504.80 times that of Cry1Ac; and the resistant strain BtR had 19.98 times of cross-resistance to Cry1Fa. The effect of Cry1Fa and Cry1Ac could increase the toxicity of Cry1Fa to insecticidal cotton bollworm. Especially when the concentration of Cry1Fa was low, the addition of Cry1Ac could increase the toxicity of Cry1Fa significantly; however, the toxicity of Cry1Ac could only be increased by adding Cry1Fa at higher concentration. Cry1Ac was significantly less resistant to Cry1Ac than Cry1Ac due to its resistance to Cry1Ac. Adding Cry1Fa to higher concentrations of Cry1Ac significantly increased the mortality of H. armigera (P = 0.0015, F = 6.88, df = 6 ), But the highest death rate was only 58.33%. The results of optimal D-saturation test confirmed that the effect of Cry1Ac on the mortality of susceptible cotton bollworm reached a significant level (t1 = 13.76> t0.05), and the interaction of Cry1Ac with Cry1Fa also reached a significant level (t22 = 2.42> t0.05; t11 = 6.95> t0.05; t12 = 3.43> t0.05). The effects of Cry1Ac and Cry1Fa on cotton bollworm mortality were all significant (t1 = 3.03> t0.05; t2 = 2.59> t0.05), but Cry1Ac was the key factor to determine the resistance and susceptibility to cotton bollworm. Cry1Ac and The optimum concentration range of Cry1Fa was 1.41 ~ 2.10μg / cm2. In the resistant lines, the interaction between Cry1Ac and Cry1Fa was not significant. Therefore, although the insecticidal spectrum was broadened by the Cry1F + CrylA crop, the cotton bollworm showed cross-resistance to the two proteins, and the combination of the two proteins was not effective in controlling the anti-Cry1Ac cotton bollworm and therefore it is not recommended to plant the expression in China CrylF + CrylA cotton.