根际聚集有益菌介导的紫茎泽兰入侵扩张机制

Commensalistic changes of soil microbial community are regarded as one kind of ecological strategy for alien invasive plants to exclude native plants, where the allelochemicals in rhizosphere and soil functional bacteria always play an important role. Ageratina adenophora is a notorious invasive weed in China, which could continuous dispersal and exclude native plants via allelopathy. Recently, it was found that contents of the beneficial bacteria Bacillus cereus in rhizosphere of A. adenophora increased with the deepening invasion process. In order to explain how to accumulate the B. cereus in rhizosphere and receive it’s positive feedback effect for A. adenophora, one research program is carried out with the main methods of chemical ecology and biogeographic comparison, while the A. adenophora populations from Mexico, two native plants are selected as control materials. Effects of A. adenophora on the growth of B. cereus, positive feedback effects of B. cereus on A. adenophora, and their comparisons with original A. adenophora from Mexico will be investigated. Based on this research, one new hypothesis of accumulation of beneficial bacteria in rhizosphere help alien invasive plant for further dispersal will be formed; the adaptive evolution characteristics of invasive plants from the changes of beneficial bacteria in rhizosphere will be revealed. Results of our research will offer some scientific basis for improvement of soil micro ecological environment and replacement of A. adenophora with native plants.

偏利性改变土壤微生物群落是外来植物入侵后排挤本地植物一种生态对策，这其中根际化感物质和土壤功能菌常起着重要作用。紫茎泽兰是我国的外来有害杂草，化感作用是推动其持续入侵扩张的主要因素之一。最近发现，随着入侵程度的加深，紫茎泽兰根际植物促生菌蜡样芽胞杆菌含量也在增加。本项目围绕“紫茎泽兰根际如何聚集蜡样芽胞杆菌并受到正反馈效应”这一科学问题，以墨西哥原产地紫茎泽兰和两种本地伴生植物为对照材料，应用化学生态和生物地理比较等技术和方法，首先探明紫茎泽兰对蜡样芽胞杆菌增长的影响，再揭示蜡样芽胞杆菌对紫茎泽兰的反馈效应，继而与原产地紫茎泽兰种群比较这种影响和反馈效应。研究结果可提出根际聚集有益菌促进入侵植物扩张的新假说，并揭示紫茎泽兰入侵后（较原产地种群）“植物-土壤微生物互作”的适应性进化特性，拓延外来植物入侵机理的内涵，还为紫茎泽兰防除后的土壤微生态环境改良和利用本地植物替代控制提供科学依据。

偏利性改变土壤微生物群落是外来植物入侵后排挤本地植物一种生态对策，这其中根际化感物质和土壤功能菌常起着重要作用。紫茎泽兰是我国的外来有害杂草，随着入侵程度的加深，紫茎泽兰根际植物促生菌蜡样芽胞杆菌含量也在增加。本项目围绕“紫茎泽兰根际如何聚集蜡样芽胞杆菌并受到正反馈效应”这一科学问题，以墨西哥原产地紫茎泽兰和两种本地伴生植物为对照材料，应用化学生态和生物地理比较等技术和方法，重点研究紫茎泽兰对蜡样芽胞杆菌增长的影响，揭示蜡样芽胞杆菌对紫茎泽兰的反馈效应，继而与原产地紫茎泽兰种群比较这种影响和反馈效应。结果表明：紫茎泽兰入侵程度加深及天敌寄生会促进根际有益菌蜡样芽孢杆菌的增长，蜡样芽孢杆菌可通过促进化感物质的降解以削弱紫茎泽兰的自毒作用等，产生对紫茎泽兰生长的偏利反馈。对比原产地种群，紫茎泽兰入侵地种群对根际蜡样芽胞杆菌的促生作用更明显，且蜡样芽孢杆菌对入侵地种群的正反馈效应大于原产地种群的。研究结果从根际有益菌变化及其反馈效应的角度阐释紫茎泽兰入侵机制，为基于土壤微生态环境改良和植物替代的紫茎泽兰防控技术提供科学依据。