PNAS：美国爱荷华州立大学发现害虫在转基因玉米中出现抗性

2003年开始推广的转基因Bt玉米携带有苏云金芽孢杆菌(Bacillus thuringiensis)的一个基因，它能产生杀虫的Bt毒素，杀死西方玉米根虫(WCR)。然而，2011年Aaron Gassmann及其同事在爱荷华发现了Bt玉米田遭受了西方玉米根虫(WCR)造成的严重根损伤，尽管这些玉米制造了具有活性的Bt毒素。

为了确定这些昆虫是否发展出了对Bt毒素的耐药性，这组作者从受损玉米中收集了西方玉米根虫(WCR)成虫，在实验室收获了这种昆虫的卵，然后用不同类型的Bt玉米培养这些幼虫。

这组作者报告说，当使用Cry3Bb1 和 mCry3A玉米培养这些昆虫的时候——在那些田里遭受严重损伤的就是这两种Bt玉米——来自Bt玉米田的西方玉米根虫(WCR)品种的后裔比从未接触过Bt玉米的西方玉米根虫(WCR)品种表现出了更高的存活。

此外，来自Bt玉米田的西方玉米根虫(WCR)在Cry3Bb1 和 mCry3A玉米上的生存状况与在不产生Bt毒素的玉米上一样好。在该研究中测试的西方玉米根虫(WCR)品种也表现出了对Cry3Bb1 玉米和 mCry3A玉米的交叉耐性。

这组作者说，这些结果提示，西方玉米根虫(WCR)可能发展出对转基因玉米制造的Bt毒素的耐药性，而Bt玉米制造的低剂量的Bt毒素可能加速了Bt毒素耐药性，而不同的Bt毒素的作用模式的相似性可能产生交叉耐药性。

原文摘要：

Field-evolved resistance by western corn rootworm to multiple Bacillus thuringiensis toxins in transgenic maize

Aaron J. Gassmann, Jennifer L. Petzold-Maxwell, eric H. Clifton, Mike W. Dunbar, Amanda M. Hoffmann,David A. Ingber, and Ryan S. Keweshan

The widespread planting of crops genetically engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) places intense selective pressure on pest populations to evolve resistance. Western corn rootworm is a key pest of maize, and in continuous maize fields it is often managed through planting of Bt maize. During 2009 and 2010, fields were identified in Iowa in which western corn rootworm imposed severe injury to maize producing Bt toxin Cry3Bb1. Subsequent bioassays revealed Cry3Bb1 resistance in these populations. Here, we report that, during 2011, injury to Bt maize in the field expanded to include mCry3A maize in addition to Cry3Bb1 maize and that laboratory analysis of western corn rootworm from these fields found resistance to Cry3Bb1 and mCry3A and cross-resistance between these toxins. Resistance to Bt maize has persisted in Iowa, with both the number of Bt fields identified with severe root injury and the ability western corn rootworm populations to survive on Cry3Bb1 maize increasing between 2009 and 2011. Additionally, Bt maize targeting western corn rootworm does not produce a high dose of Bt toxin, and the magnitude of resistance associated with feeding injury was less than that seen in a high-dose Bt crop. These first cases of resistance by western corn rootworm highlight the vulnerability of Bt maize to further evolution of resistance from this pest and, more broadly, point to the potential of insects to develop resistance rapidly when Bt crops do not achieve a high dose of Bt toxin.

标签: 转基因玉米 耐药性 西方玉米根虫 Bt毒素

作者：生物帮 点击：次

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