Microbial ecology of the arbuscular mycorrhiza

Arbuscular mycorrhizal (AM) fungi interact with a wide variety of organisms during all stages of their life. Some of these interactions such as grazin g of the external mycelium are detrimental, while others including interact ions with plant growth promoting rhizobacteria (PGPR) promote mycorrhizal f unctioning. Following mycorrhizal colonisation the functions of the root be come modified. with consequences for the rhizosphere community which is ext ended into the mycorrhizosphere due to the presence of the AM external myce lium. However, we still know relatively little of the ecology of AM fungi a nd, in particular, the mycelium network under natural conditions. This area merits attention in the future with emphasis on the fungal partner in the association rather than the plant which has been the focus in the past. (C) 2000 Federation of European Microbiological Societies. Published by Elsevi er Science B.V. All rights reserved.