CSIRO Entomology, ACRI, Narrabri, Australia.
PLoS One. 2010 Sep 7;5(9):e12567. doi: 10.1371/journal.pone.0012567.
Combinations of dissimilar insecticidal proteins ("pyramids") within transgenic plants are predicted to delay the evolution of pest resistance for significantly longer than crops expressing a single transgene. Field-evolved resistance to Bacillus thuringiensis (Bt) transgenic crops has been reported for first generation, single-toxin varieties and the Cry1 class of proteins. Our five year data set shows a significant exponential increase in the frequency of alleles conferring Cry2Ab resistance in Australian field populations of Helicoverpa punctigera since the adoption of a second generation, two-toxin Bt cotton expressing this insecticidal protein. Furthermore, the frequency of cry2Ab resistance alleles in populations from cropping areas is 8-fold higher than that found for populations from non-cropping regions. This report of field evolved resistance to a protein in a dual-toxin Bt-crop has precisely fulfilled the intended function of monitoring for resistance; namely, to provide an early warning of increases in frequencies that may lead to potential failures of the transgenic technology. Furthermore, it demonstrates that pyramids are not 'bullet proof' and that rapid evolution to Bt toxins in the Cry2 class is possible.
转植物内不同杀虫蛋白（“金字塔”）的组合预计将比表达单一转基因的作物更能显著延缓害虫抗药性的进化。已经报道了第一代、单毒素品种和 Cry1 类蛋白的苏云金芽孢杆菌（Bt）转基因作物的田间进化抗性。我们五年的数据显示，自从采用表达这种杀虫蛋白的第二代双毒素 Bt 棉花以来，澳大利亚钻蛀性棉铃虫田间种群中赋予 Cry2Ab 抗性的等位基因的频率呈显著指数增长。此外，来自种植区的种群中 Cry2Ab 抗性等位基因的频率比来自非种植区的种群高 8 倍。这种对双毒素 Bt 作物中一种蛋白质的田间进化抗性的报告，正好满足了监测抗性的预期功能；也就是说，提供了对可能导致转基因技术失效的频率增加的早期预警。此外，它表明金字塔并非“无懈可击”，Cry2 类中的 Bt 毒素可能会迅速进化。
