Nutritional ecology of arbuscular mycorrhizal fungi

Despite their large role in ecosystems and plant nutrition, our knowledge of the nutritional ecology of the fungi involved in the arbuscular mycorrhizal symbiosis, the Glomeromycota, is poor. We briefly describe the mechanisms that underlie the fluxes of the three major elements (C, N and P) and outline a model for the interchange of these between the partners. This model is consistent with data from physiological, ecological and taxonomic studies and allows a new and necessary focus on the nutritional requirements of the fungus itself, separately from its role in the symbiosis. There is an urgent need for new studies to identify the sources of nutrients such as N and P that AM fungi (AMF) use for their own growth and to elucidate the mechanisms that control the transfer of these to the plant in relation to fungal demand.