Arbuscular Mycorrhizal Fungi Improve Tolerance of Agricultural Plants to Cope Abiotic Stress Conditions

Abstract

Abiotic stresses have strong impact on agriculture, decreasing the stability of agroecosystems worldwide, due mainly to water and nutrient limitations and the presence of toxic elements. Several studies have demonstrated that soil microorganisms can improve plant growth, even more when plants are under stressful conditions, being probably the most important are the arbuscular mycorrhizal fungi (AMF). This kind of fungi forms symbiosis with approximately 80% of plant species, including the majority of agricultural plants, and is present in all terrestrial ecosystems. Via its extraradical mycelium, the AMF can improve the absorption of water and nutrients of their host plants under stress conditions, as well as contribute to cope with the presence of toxic elements such as phytotoxic aluminum and other toxic metal(loid)s, increasing plant growth and crop production. Moreover, several studies have determined that AMF strains isolated from agroecosystems affected by different abiotic limiting conditions enhance the growth of plants than those isolated from soils without such limiting condition. In this chapter we describe the main ways by which AMF contribute to the plant tolerance to cope the abovementioned abiotic stresses. Moreover, the physiological, biochemical, and molecular bases that explain the responses mediated by AMF in host plants are covered. Finally, biotechnological prospects of AMF present under stress conditions and their potential use as bio-inoculants are presented.