Department of Entomology and Plant Pathology, The University of Tennessee, 2431 Joe Johnson Drive, 205 Ellington Plant Sciences Building, Knoxville, TN 37996-4560, USA.
Appl Environ Microbiol. 2011 May;77(10):3182-8. doi: 10.1128/AEM.02791-10. Epub 2011 Mar 25.
The use of combinations of Bacillus thuringiensis (Bt) toxins with diverse modes of action for insect pest control has been proposed as the most efficient strategy to increase target range and delay the onset of insect resistance. Considering that most cases of cross-resistance to Bt toxins in laboratory-selected insect colonies are due to alteration of common toxin binding sites, independent modes of action can be defined as toxins sharing limited or no binding sites in brush border membrane vesicles (BBMV) prepared from the target insect larvae. In this paper, we report on the specific binding of Cry2Ae toxin to binding sites on BBMV from larvae of the three most commercially relevant heliothine species, Heliothis virescens, Helicoverpa zea, and Helicoverpa armigera. Using chromatographic purification under reducing conditions before labeling, we detected specific binding of radiolabeled Cry2Ae, which allowed us to perform competition assays using Cry1Ab, Cry1Ac, Cry1Fa, Vip3A, Cry2Ae, and Cry2Ab toxins as competitors. In these assays, Cry2Ae binding sites were shared with Cry2Ab but not with the tested Cry1 or Vip3A toxins. Our data support the use of Cry2Ae toxin in combination with Cry1 or Vip3A toxins in strategies to increase target range and delay the onset of heliothine resistance.
将不同作用模式的苏云金芽孢杆菌（Bt）毒素组合使用以控制昆虫害虫，被认为是增加靶标范围和延缓昆虫产生抗性的最有效策略。考虑到在实验室选择的昆虫品系中，对 Bt 毒素的交叉抗性大多数情况下是由于常见毒素结合位点的改变，因此可以将独立的作用模式定义为在目标昆虫幼虫的刷状缘膜小泡（BBMV）中共享有限或没有结合位点的毒素。在本文中，我们报告了 Cry2Ae 毒素与三种最具商业相关性的夜蛾属物种（Heliothis virescens、Helicoverpa zea 和 Helicoverpa armigera）幼虫的 BBMV 上的结合位点的特异性结合。通过在标记前进行还原条件下的色谱纯化，我们检测到放射性标记的 Cry2Ae 的特异性结合，这使我们能够使用 Cry1Ab、Cry1Ac、Cry1Fa、Vip3A、Cry2Ae 和 Cry2Ab 毒素作为竞争物进行竞争测定。在这些测定中，Cry2Ae 结合位点与 Cry2Ab 共享，但与测试的 Cry1 或 Vip3A 毒素不共享。我们的数据支持在增加靶标范围和延缓夜蛾抗性产生的策略中，将 Cry2Ae 毒素与 Cry1 或 Vip3A 毒素联合使用。
