吡蚜酮对褐飞虱机械感受器的影响及其分子机制研究

Pymetrozine, the best insecticide for controlling brown planthopper(BPH),has been detected obvious resistance in most regions of China because of the large scale abuse.If BPH developed high level resistance to pymetrozine, there will be a failure on controlling brown planthopper, it will lead a disaster on rice production. But its molecular mechanism still keep the least unknown. Based on previous studies, pymetrozine selectively inhibits homopteran feeding behaviour and mechanosensory transduction, possibly by affecting mechanoreceptors. No mechanoreceptor potential C (NOMPC),which belongs to TRP (transient receptor potential) ion channel family, acts as a mechanotransducer in Drosophila melanogaster. Because there is no NOMPC orthologues gene in mammals,it could be as the new target sites of insecticides. We have selected a high level resistant BPH strain to pymetrozine and identified one NOMPC-like gene by analysing the transcriptome of BPH. In the preliminary experiments, it was found that pymetrozine application results in constriction of hindleg in BPH and NOMPC gene was significantly down-regulated in pymetrozine-resistant strain. Hence, we speculate that pymetrozine affects the mechanotransduction of NOMPC channel and then impacts the feeding behaviour and mechanosensory transduction of BPH. In this project, we will verified this hypothesis in both behavioral and molecular levels on the basis of behavioural studies, immunohistochemistry, RNA interference and electrophysiological-recording. We believe the resistance mechanism research could provide an strong basis on the mechanism of pymetrozine, and this project will enrich the contents of the insecticide toxicology by providing new ideas and new targets for the insecticide research and development.

吡蚜酮是防治褐飞虱的当家品种，但作用机制不详，其大规模使用已导致褐飞虱对其产生抗性，一旦其失去防治效果，稻飞虱及其传播的病毒病将会给水稻生产造成重大损失。有报道认为吡蚜酮通过影响昆虫的机械感受器进而影响害虫的取食与机械感受行为来发挥杀虫作用。NOMPC（No mechanoreceptor potential C）蛋白属于TRP（transient receptor potential）离子通道家族，作为机械感受通道在引起果蝇触刺激介导的行为反应中发挥重要作用，且其在哺乳动物中无直系同源基因，是很好的药物作用靶标。本研究以对吡蚜酮高抗褐飞虱品系为研究对象，运用行为学测定、免疫组织化学、转录组测序及电生理学技术相结合的方法，探析吡蚜酮对褐飞虱机械感受器的影响，明确NOMPC通道蛋白在吡蚜酮抗性中的作用。本项研究可丰富杀虫剂毒理学研究内容，也可为有害生物防治中新药剂的研发提供新思路和新靶点。

吡蚜酮是防治褐飞虱的当家品种，其大规模使用已导致褐飞虱对其产生抗性，一旦其失去防治效果，稻飞虱及其传播的病毒病将会给水稻生产造成重大损失。有文献报道吡蚜酮的作用靶标是瞬时电位感受器（transient receptor potential, TRP）通道家族中的Nanchung 和Inactive蛋白复合体，通过影响昆虫的机械感受器进而影响害虫的取食与机械感受行为来发挥杀虫作用。NOMPC（No mechanoreceptor potential C）蛋白属于TRP离子通道家族的另一成员，作为机械感受通道在果蝇听觉、运动、轻触反应以及食物质地检测中发挥重要作用，且其在哺乳动物中无直系同源基因，是很好的药物作用靶标。本研究以农业害虫褐飞虱为对象，克隆得到了褐飞虱全部共13个TRP通道家族基因（包括NompC），利用定量PCR技术探明了各基因在褐飞虱不同龄期和成虫各组织中的表达分布，其中NlNompC沉默后的褐飞虱存活率下降，表现出明显的运动失调，足无法正常的伸展或弯曲，同时NlNompC沉默会导致褐飞虱轻触反应和取食量的下降。该结果明确了NompC作为一个机械感受器在褐飞虱本体感受、运动以及取食中发挥了重要作用。本研究不仅为褐飞虱TRP家族基因的功能研究开启新篇章，也可为有害生物防治中新药剂的研发提供新思路和新靶点。