National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Wuhan, Hubei, China.
Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, College of Plant Protection, Hunan Agricultural University, Changsha, China.
Insect Mol Biol. 2019 Aug;28(4):520-527. doi: 10.1111/imb.12570. Epub 2019 Feb 27.
Insecticidal crystal (Cry) proteins produced by the bacterium Bacillus thuringiensis (Bt) are toxic to a diverse range of insects. Transgenic rice expressing Cry1A, Cry2A and Cry1C toxins have been developed that are lethal to Chilo suppressalis, a devastating insect pest of rice in China. Identifying the mechanisms underlying the interactions of Cry toxins with susceptible hosts will improve both our understanding of Cry protein toxicology and long-term efficacy of Bt crops. In this study, we tested the hypothesis that V-ATPase subunit A contributes to the action of Cry1Ab/1Ac, Cry2Aa and Cry1Ca toxins in C. suppressalis. The full-length V-ATPase subunit A transcript was initially cloned from the C. suppressalis larval midgut and then used to generate double-stranded RNA (dsRNA)-producing bacteria. Toxicity assays using transgenic rice lines TT51 (Cry1Ab and Cry1Ac fusion genes), T2A-1 (Cry2Aa), and T1C-19 (Cry1Ca) in conjunction with V-ATPase subunit A dsRNA-treated C. suppressalis larvae revealed significantly reduced larval susceptibility to T2A-1 and T1C-19 transgenic rice, but not to TT51 rice. These results suggest that the V-ATPase subunit A plays a crucial role in mediating Cry2Aa and Cry1Ca toxicity in C. suppressalis. These findings will have significant implications on the development of future resistance management tools.
苏云金芽孢杆菌（Bt）产生的杀虫晶体蛋白（Cry）对多种昆虫具有毒性。已经开发出表达 Cry1A、Cry2A 和 Cry1C 毒素的转基因水稻，这些毒素对中国水稻上的毁灭性害虫二化螟具有致死作用。确定 Cry 毒素与敏感宿主相互作用的机制将提高我们对 Cry 蛋白毒理学的理解和 Bt 作物的长期功效。在这项研究中，我们检验了假设，即 V-ATPase 亚基 A 有助于 Cry1Ab/1Ac、Cry2Aa 和 Cry1Ca 毒素在二化螟中的作用。首先从二化螟幼虫中克隆出全长 V-ATPase 亚基 A 的转录本，然后用它来产生双链 RNA（dsRNA）产生细菌。使用含有 Cry1Ab 和 Cry1Ac 融合基因的 TT51（转 Cry1Ab 和 Cry1Ac 融合基因）、T2A-1（Cry2Aa）和 T1C-19（Cry1Ca）的转基因水稻系与 V-ATPase 亚基 A dsRNA 处理的二化螟幼虫进行的毒性测定显示，T2A-1 和 T1C-19 转基因水稻的幼虫敏感性显著降低，但 TT51 水稻的敏感性没有降低。这些结果表明，V-ATPase 亚基 A 在介导二化螟中 Cry2Aa 和 Cry1Ca 毒性方面起着关键作用。这些发现将对未来抗性管理工具的发展产生重大影响。
