Department of Botany, University of Delhi, Delhi, India.
Lett Appl Microbiol. 2010 Jul;51(1):42-7. doi: 10.1111/j.1472-765X.2010.02856.x. Epub 2010 Apr 23.
To select a toxin combination for the management of maize stem borer (Chilo partellus) and to understand possible mechanism of synergism among Bacillus thuringiensis Cry1A toxins tested.
Three Cry1A toxins were over expressed in Escherichia coli strain JM105 and used for diet overlay insect bioassay against C. partellus neonate larvae, both alone and in combinations. Probit analysis revealed that the three Cry1A toxins tested have synergistic effect against C. partellus larvae. In vitro binding analysis of fluorescein isothiocyanate (FITC)-labelled Cry1A toxins to midgut brush border membrane vesicle (BBMV) shows that increase in toxicity is directly correlated to an increase in binding of toxin mix.
A high Cry1Ac to Cry1Ab ratio leads to an increase in efficacy of these toxins towards C. partellus larvae and this increase in toxicity comes from an increase in toxin binding.
Use of Cry1Ab and Cry1Ac combination could be an effective approach to control C. partellus. Furthermore, we show it first time that possible reason behind increase in toxicity of synergistic Cry1A proteins is an increase in toxin binding.
选择一种毒素组合来防治玉米螟（Chilo partellus），并了解所测试的苏云金芽孢杆菌 Cry1A 毒素之间协同作用的可能机制。
在大肠杆菌 JM105 菌株中过表达了三种 Cry1A 毒素，并将其单独和组合用于玉米螟幼虫的饲料覆盖昆虫生物测定。概率分析显示，测试的三种 Cry1A 毒素对玉米螟幼虫具有协同作用。用荧光素异硫氰酸酯（FITC）标记的 Cry1A 毒素与中肠刷状缘膜囊泡（BBMV）的体外结合分析表明，毒性的增加与毒素混合物结合的增加直接相关。
高 Cry1Ac 与 Cry1Ab 的比例会增加这些毒素对玉米螟幼虫的功效，而这种毒性的增加来自于毒素结合的增加。
使用 Cry1Ab 和 Cry1Ac 组合可能是控制玉米螟的有效方法。此外，我们首次表明，协同 Cry1A 蛋白毒性增加的可能原因是毒素结合的增加。
