PLoS Pathogens:农科院植保所吴孔明研究组揭示棉铃虫对Bt作物的抗

摘要 : 2月12日，国际著名顶尖核心期刊杂志《PLoS Pathogens》上在线发表中国农业科学院植物保护研究所吴孔明院士发表的一篇研究论文，文章揭示了棉铃虫对Bt作物的抗性新机制。

2月12日，国际著名顶尖核心期刊杂志《PLOS Pathogens》上在线发表中国农业科学院植物保护研究所吴孔明院士发表的一篇研究论文，文章揭示了棉铃虫对Bt作物的抗性新机制。植物保护研究所为论文的第一完成单位，肖玉涛博士为论文第一作者，吴孔明院士为论文通讯作者。

苏云金芽孢杆菌(Bt)代谢过程中产生的晶体蛋白对多种害虫具有毒杀作用，利用转基因技术培育的Bt棉花、Bt玉米和Bt大豆已在全球范围内商业化种植。我所棉花害虫研究组研究发现， 棉铃虫Bt毒素受体基因ABCC2的变异可以导致其对Bt作物产生高水平的抗性，但这种变异显著增加了抗性棉铃虫对另外一种生物毒素阿维菌素的敏感性。

阿维菌素是一类具有杀虫、杀螨和杀线虫活性的十六元大环内酯化合物，由链霉菌中阿维链霉菌发酵产生，广泛用于农业害虫的防治。腺苷三磷酸结合盒式转运蛋白(ABC转运蛋白)是一类膜整合蛋白，对维持细胞正常的生理功能起重要作用;ABCC2是ABC转运体家族基因的重要成员，负责在昆虫的肠腔及消化道中富集运送重金属离子、次生代谢物到体外，是昆虫体内新发现的潜在的毒素受体，在昆虫代谢清除外源毒素的过程中发挥重要功能。本项研究研究发现：棉铃虫ABCC2是Bt-Cry1Ac毒素的受体，其变异可导致Bt-Cry1Ac毒素丧失在棉铃虫中肠内的结合位点而产生对Bt作物的高水平抗性。由于棉铃虫ABCC2基因具有从虫体内代谢排除阿维菌素的生物学功能，ABCC2的变异导致了阿维菌素在虫体内的积累而显著增加了其杀虫毒性。此项科学发现证实了棉铃虫对两种生物毒素存在负交互抗性现象并阐述了其分子机理，为棉铃虫等靶标害虫对Bt作物的抗性治理提供了新思路。同时，本研究还为深入解析棉铃虫/Bt毒素/阿维菌素的互作关系，进一步明确昆虫与病原微生物的协同进化机制奠定了基础。

原文链接：

Resistance to Bacillus thuringiensis Mediated by an ABC Transporter Mutation increases Susceptibility to Toxins from Other Bacteria in an Invasive Insect

原文摘要：

evolution of pest resistance reduces the efficacy of insecticidal proteins from the gram-positive bacterium Bacillus thuringiensis (Bt) used widely in sprays and transgenic crops. Recent efforts to delay pest adaptation to Bt crops focus primarily on combinations of two or more Bt toxins that kill the same pest, but this approach is often compromised because resistance to one Bt toxin causes cross-resistance to others. Thus, integration of Bt toxins with alternative controls that do not exhibit such cross-resistance is urgently needed. The ideal scenario of negative cross-resistance, where selection for resistance to a Bt toxin increases susceptibility to alternative controls, has been elusive. Here we discovered that selection of the global crop pest, Helicoverpa armigera, for >1000-fold resistance to Bt toxin Cry1Ac increased susceptibility to abamectin and spineotram, insecticides derived from the soil bacteriaStreptomyces avermitilis and Saccharopolyspora spinosa, respectively. Resistance to Cry1Ac did not affect susceptibility to the cyclodiene, organophospate, or pyrethroid insecticides tested. Whereas previous work demonstrated that the resistance to Cry1Ac in the strain analyzed here is conferred by a mutation disrupting an ATP-binding cassette protein named ABCC2, the new results show that increased susceptibility to abamectin is genetically linked with the same mutation. Moreover, RNAi silencing of HaABCC2 not only decreased susceptibility to Cry1Ac, it also increased susceptibility to abamectin. The mutation disrupting ABCC2 reduced removal of abamectin in live larvae and in transfected Hi5 cells. The results imply that negative cross-resistance occurs because the wild type ABCC2 protein plays a key role in conferring susceptibility to Cry1Ac and in decreasing susceptibility to abamectin. The negative cross-resistance between a Bt toxin and other bacterial insecticides reported here may facilitate more sustainable pest control.

DOI:10.1371/journal.ppat.1005450

作者：吴孔明

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