Arbuscular mycorrhizal associations in plant nutrition and health

Plants and arbuscular mycorrhizal fungi have co-evolved over a period of at least 450 million years. This fungal-plant association involves the transfer of carbon to the obligate biotropic fungus, in return for a wide range of beneficial functions. Although this is usually a mutualistic relationship, it can become parasitic to the plant under adverse conditions. Here, the research examining mechanisms by which mycorrhizal associations improve plant fitness is reviewed. Although there is strong evidence that a number of beneficial functions are performed by mycorrhizae, the mechanisms behind these are often not clear. There are numerous factors which influence these mechanisms and their outcomes, one or more of which can be affecting the association simultaneously. The knowledge we have on arbusular mycorrhizal associations with plants could be applied to various land management practices in order to improve soil degradation brought about by anthropogenic activities. These include erosion, drought, nutrient stress and salinization, and are often a result of poor land management. In order to use mycorrhizal fungi as a biomanagement tool, more research is required, particularly in mature field communities over long timescales. There is a need to invest in the development of sustainable agroecological management methods and to design future policy and legislation that encourages large organizations to incorporate more sustainable practices whilst protecting small-scale farmers.