Dispersal, distribution and establishment of arbuscular mycorrhizal fungi: a review

The aim of this paper is to review and assess scientific literature relevant to arbuscular mycorrhizal fungi (AMF) population dynamics: reproduction and dispersal mechanisms, and establishment and distribution in natural ecosystems. Arbuscular mycorrhizal fungi (AMF) are obligated root symbionts with an extraordinary capacity for growing, dispersing and surviving, but their life history is not well understood yet. Although there is information concerning AMF dispersal, distribution and establishment, some data are still ambiguous and contradictory. Arbuscular mycorrhizal fungi (AMF) life cycle responds to surrounding environment but even when they only reproduce asexually, their populations encompass a high genetic and functional diversity within ecosystems. Environmental disturbances create new habitats for AMF dispersal, which can take place by root to root contact, animal transport and erosion processes. These agents are the common dispersal mechanisms of AMF in nature. Distribution of AMF is influenced mainly by the environment and soil and plant communities, but the specific AMF-host plant association is thought to be secondary because the AMF must invade and colonize any host root for establishment. Thus, inoculum density, host and fungal genetic compatibility, edaphic factors and plant-microbial activity determine the formation of mycorrhizal infections.