Arbuscular mycorrhiza: Nutritional aspects

Abstract

Arbuscular mycorrhizae (AM) engage in the most common underground symbiosis that occurs with plants. More than 80% of the higher plants have the ability to form arbuscular mycorrhizal associations. Plants exchange carbohydrates and lipids for nutrients, especially phosphates from AM. Five billion tons of carbon are transferred from plants to fungi via AM each year, worldwide. The fungus in AM symbiosis forms hyphae outside the plant, which provide a connection between the soil and inner part of plant. Phosphorus is transported from the soil solution across the membrane of the hyphae, moves to the arbuscule, unloads from the fungal arbuscule at the arbuscule-cortical interface and is then taken up by the plant cortical cell. AM, in turn, derive carbon from the host plant in the form of hexose/sucrose, which is taken up at the interface and is converted to trehalose and glycogen, typical fungal carbohydrates. This review discusses the transfer of phosphate from soil to plant via AM and the carbon flux and metabolism in AM fungi.