Environmental stress and role of arbuscular mycorrhizal symbiosis

Mycorrhizae are widespread symbioses between plant roots and soil fungi, involved in the absorption of nutrients from the soil. Arbuscular mycorrhizae (AMs) are made up of a wide range of land plants, including at least 80% Angiosperms, and fungi belonging to the Glomeromycota. They generally have a positive effect on plant growth and nutrition, and improve the absorption of relatively immobile nutrients, such as phosphate, particularly in low nutrient soils or under drought. Moreover, AMs have been shown to promote plant fitness under a variety of stress conditions. In this chapter, we will provide an overview of the effects of AM colonization on host plants subjected to drought stress and soil pollution, two of the most common types of stress that limit plant growth, and of the possible mechanisms involved in the beneficial effects of AM fungi.