肠道细菌介导小菜蛾适应寄主植物次生代谢物的效应和机制

Plant secondary metabolites play a key role in the process of co-evolution of plants and herbivory. The diamondback moth, Plutella xylostella (L.), must behaviorally and physiologically adapt to a variety of plant defense chemicals while co-evolving with cruciferous plants. Recent studies have shown that the gut bacteria play an important role in herbivory, development and immune response of host insects. Based on the tritrophic interactions of “diamondback moth - gut bacteria – cruciferous crops”, this project aims to study the role of the gut bacteria in adaptation of P. xylostella to the plant secondary metabolites by the comparison of fitness between common and gut germ-free P. xylostella , we will carried out high-performance liquid chromatography - mass spectrometry (HPLC-MS) to analyze the component of plant secondary metabolites, next generation sequencing and metagenomics will be performed to analyze the plant secondary metabolites degradation genes in P. xylostella gut bacteria, and microbial isolation and functional identification will also be introduced to analyze the degradation potential of P. xylostella gut bacteria on plant secondary metabolites, and elucidate the mechanism of gut bacteria mediated the adaptation of P. xylostella to its host plant secondary metabolites. This project is a continuation and extension of our previous researches on the gut microbiota in P. xylostella. Hopefully it will provide updated evidences of the effect and mechanism of the gut bacteria involved with co-evolution between P. xylostella and its host plants, and facilitate the study on using the host plant secondary metabolites as biological agents for pest control.

植物次生代谢物在植物与植食性昆虫的协同进化过程中起着关键性的作用。小菜蛾与十字花科植物协同进化，必须在行为和生理上适应寄主植物多样的化学防御。近年来的研究表明肠道细菌对宿主昆虫的食性、发育和免疫反应具有重要的作用。本项目拟从“小菜蛾-肠道细菌-十字花科植物”的三级营养关系出发，通过适合度评价，比较植物次生代谢物对肠道细菌清除前、后小菜蛾的效应，研究肠道细菌对小菜蛾适应寄主植物次生代谢物的作用；利用HPLC-MS分析植物次生代谢物的成分，使用高通量测序和宏基因组学技术分析小菜蛾肠道细菌降解植物次生代谢物的基因；利用微生物分离培养和功能验证等方法，研究肠道细菌降解植物次生代谢物，介导小菜蛾适应寄主植物次生代谢物的机制。本项目是课题组近年来开展小菜蛾肠道微生物相关研究的延伸和深化，对揭示肠道细菌介导植食性昆虫与寄主植物的协同进化具有重要意义，同时也可以为利用植物次生代谢物防治害虫提供理论基础。

植物次生代谢物在植物与植食性昆虫的协同进化过程中起着关键性的作用。小菜蛾与十字花科植物协同进化，必须在行为和生理上适应寄主植物多样的化学防御。近年来的研究表明肠道细菌对宿主昆虫的食性、发育和免疫反应具有重要的作用。本项目从“小菜蛾-肠道细菌-十字花科植物”的三级营养关系出发，研究小菜蛾肠道共生菌介导宿主适应寄主植物次生代谢物的效应和机制。通过本项目的研究，明确了十字花科植物萝卜苗次生代谢物的主要成分，其对小菜蛾的毒性效应；阐明了小菜蛾肠道细菌，特别是EbPXG5利用其对植物次生代谢物的降解功能，减轻植物次生代谢物对小菜蛾的毒性效应，从而协助小菜蛾更好的适应寄主植物的机制。本研究不仅明确了肠道细菌在降解十字花科植物次生代谢物中的功能，其结果对于研究昆虫与植物的共进化具有重要的理论指导意义，同时对未来基于植物次生代谢物以及以肠道细菌为靶点的害虫生防也具有重要的借鉴意义。