Department of Entomology, Cornell Universitygrid.5386.8, Geneva, New York, USA.
Appl Environ Microbiol. 2022 Oct 26;88(20):e0119422. doi: 10.1128/aem.01194-22. Epub 2022 Oct 6.
The Cry proteins from Bacillus thuringiensis (Bt) are major insecticidal toxins in formulated Bt sprays and are expressed in genetically engineered Bt crops for insect pest control. However, the widespread application of Bt toxins in the field imposes strong selection pressure on target insects, leading to the evolution of insect resistance to the Bt toxins. Identification and understanding of mechanisms of insect resistance to Bt toxins are an important approach for dissecting the modes of action of Bt toxins and providing knowledge necessary for the development of resistance management technologies. In this study, cabbage looper (Trichoplusia ni) strains resistant to the transgenic dual-Bt toxin WideStrike cotton plants, which express Bt toxins Cry1Ac and Cry1F, were selected from strains resistant to the Bt formulation Bt-DiPel. The WideStrike-resistant larvae were confirmed to be resistant to both Bt toxins Cry1Ac and Cry1F. From the WideStrike-resistant , the Cry1F resistance trait was further isolated to establish a strain resistant to Cry1F only. The levels of Cry1F resistance in the WideStrike-resistant and the Cry1F-resistant strains were determined, and the inheritance of the Cry1F-resistant trait in the two strains was characterized. Genetic association analysis of the Cry1F resistance trait indicated that the Cry1F resistance in isolated in this study is not shared with the Cry1Ac resistance mechanism nor is it associated with a mutation in the ABCC2 gene, as has so far been reported in Cry1F-resistant insects. Insecticidal toxins from Bacillus thuringiensis (Bt) are highly effective for insect control in agriculture. However, the widespread application of Bt toxins exerts strong selection for Bt resistance in insect populations. The continuing success of Bt biotechnology for pest control requires the identification of resistance and understanding of the mechanisms of resistance to Bt toxins. Cry1F is an important Bt toxin used in transgenic cotton, maize, and soybean varieties adopted widely for insect control. To understand the mode of action of Cry1F and mechanisms of Cry1F resistance in insects, it is important to identify Cry1F-specific resistance and the resistance mechanisms. In this study, Trichoplusia ni strains resistant to commercial "WideStrike" cotton plants that express Bt toxins Cry1Ac and Cry1F were selected, and a Cry1F-specific resistant strain was isolated. The isolation of the novel Cry1F-specific resistance in the provided an invaluable biological system to discover a Cry1F-specific novel resistance mechanism.
苏云金芽孢杆菌（Bt）的 Cry 蛋白是配方 Bt 喷雾中的主要杀虫毒素，并且在用于防治虫害的基因工程 Bt 作物中表达。然而，Bt 毒素在田间的广泛应用对靶标昆虫施加了强烈的选择压力，导致昆虫对 Bt 毒素产生了抗性。鉴定和了解昆虫对 Bt 毒素的抗性机制是剖析 Bt 毒素作用模式的重要途径，也为开发抗性管理技术提供了必要的知识。在这项研究中，从对 Bt 制剂 Bt-DiPel 具有抗性的品系中选择了对转双价 Bt 毒素 WideStrike 棉花植株具有抗性的菜粉蝶（Trichoplusia ni）品系，该植株表达 Bt 毒素 Cry1Ac 和 Cry1F。结果证实，WideStrike 抗性幼虫对 Bt 毒素 Cry1Ac 和 Cry1F 均具有抗性。从 WideStrike 抗性品系中，进一步分离出 Cry1F 抗性特性，建立了仅对 Cry1F 具有抗性的品系。测定了 WideStrike 抗性品系和 Cry1F 抗性品系中 Cry1F 的抗性水平，并对这两个品系中 Cry1F 抗性特性的遗传进行了特征描述。Cry1F 抗性特性的遗传关联分析表明，本研究中分离的 Cry1F 抗性与 Cry1Ac 抗性机制无关，也与迄今为止报道的 Cry1F 抗性昆虫中的 ABCC2 基因突变无关。苏云金芽孢杆菌（Bt）的杀虫毒素在农业中对防治昆虫非常有效。然而，Bt 毒素在昆虫种群中的广泛应用对 Bt 抗性施加了很强的选择压力。Bt 生物技术继续成功用于害虫防治需要确定对 Bt 毒素的抗性和了解其抗性机制。Cry1F 是一种用于转基因棉花、玉米和大豆品种的重要 Bt 毒素，广泛用于防治昆虫。为了了解 Cry1F 在昆虫中的作用模式和 Cry1F 抗性机制，识别 Cry1F 特异性抗性和抗性机制非常重要。在这项研究中，选择了对表达 Bt 毒素 Cry1Ac 和 Cry1F 的商业“WideStrike”棉花植株具有抗性的烟粉虱品系，并分离出了 Cry1F 特异性抗性品系。在 中分离出的新型 Cry1F 特异性抗性为发现 Cry1F 特异性新型抗性机制提供了宝贵的生物系统。
