Feedback Of Arbuscular Mycorrhizal Fungi To The Exotic Weed, Ageratina Adenophora (Sprengel) In Invaded Habitats

Exotic plant invasion mechanism is the focus of international research, and the study on the feedback of soil biota to plant invsion attracts more concern. Here we based on theories of interactions of soil biota and plant, and provided a thread of exotic plant-soil biota-native plant, we focused on Ageratina. adenophora which is an invasive weed in southwest China, and investigated the effects of A. adenophora invasion on the mycorrhizal fungi (MF) community including arbuscular mycorrhizal fung (AMF), and studied the interactions and response among exotic plant, AMF and native plants. We also explored the effects of soil AMF on the interactions and resources competition between exotic and native weeds.We attempted to expatiate the mechanism of AMF feedback to exotic plant invasion. The main results and conclusions were as follows:1. The results of nested PCR showed that, the structure of MF community including AMF was altered by A. adenophora invasion, and Glomus was accumulated in A. adenophora rhizosphere. Results of morphologic evaluation indiacted that, A. adenophora invasion not only restrained the colonization of AMF to native weeds, but also changed the structure and diversities of AMF community, and Glomus claroideum was selected accumulated in A. adenophora rhizosphere.2. Experiments of fungicide treatments in invaded area indicated that, AMF can facilitate the photosynthesis and uptake of N, P, and K, enlarge leaf area of A. adenophora, and the approach of AMF feedback to A. adenophora was distinct according to different phases of invasion.3. AMF-plant feedback pot experiment in glasshouse indicated that, AMF community that altered by A. adenophora invasion, in reverse facilitated A. adenophora invasiveness by offering positive feedback, while restrained competitive capacity of natives. And the effects of AMF on the interaction between A. adenophora and natives was distinct for different native species.A. adenophora invasion altered the structure and diversity of MF community, disrupted the mutualism of AMF and ntiave plants, accumulated Glomus claroideum, and formed mutualism with soil AMF, by which it may used as a self-reinforced soil microbial mechanism.