A review on the effects of invasive plants on mycorrhizal fungi of native plants and their underlying mechanisms

Mycorrhizal fungi symbiosis is an important strategy for plant to uptake soil nutrients. Alien plants could thwart the symbiotic relationship between native plants and mycorrhizal fungus, and thus suppress the growth of native plants, which is an important mechanism for alien plant invasion, and has been increasingly emphasized in recent studies. In the present review, we summarized several key aspects of such mycorrhizal-related mechanism of plant invasion: 1) the impacts of alien plants on mycorrhizal fungi of native plants (i.e. mycorrhizal colonization rate, internal structures of mycorrhizal hyphae, amount of external hyphae, mycorrhizal and non-mycorrhizal composition, and mycorrhizal network); 2) mechanisms of alien-plant impacts on mycorrhizal fungi of native plants, including ecological mechanisms such as resource competition, allelopathy and edaphic fertility, as well as their molecular mechanisms; 3) variations of the above mentioned alien-plant impacts and related mechanisms at different durations of plant invasion. Despite thwarting mycorrhizal fungi of native plants is an important mechanism for alien plant invasion, researches on such mechanism are still scarce comparing to other mechanisms such as natural enemy release and new weapon hypothesis. Therefore, we proposal several research areas that need to be focused on in future studies: 1) how do global changes affect the alien-plant-invasion impacts on mycorrhizal fungi of native plants; 2) what are the relationships among different mechanisms including the mycorrhizal-related mechanism; 3) how does the mycorrhizae-related mechanism change at large spatio-temporal scales.