Plant-Microorganism Interactions: Effects on the Tolerance of Plants to Biotic and Abiotic Stresses

Abstract

Arbuscular mycorrhizal fungi (AMF) establish mutualistic symbiosis (arbuscular mycorrhiza—AM), with the roots of most species of terrestrial plants, acting as a bridge between the soil and plants. AMF are critical in the establishment and adaptation of plants in locations severely disturbed. They affect also the physico-chemical properties of substrate and act for the formation and maintenance of soil structure, acting in the aggregation of soil particles. The AM occurs in the roots of most plants, promoting improvements in the growth and development of plants and increase in tolerance and/or plant resistance to various adverse environmental agents and can also be used as a potential biological control agent of plant diseases. The different responses of plants to this symbiosis can be assigned to the functional diversity of AM, depending of the interaction between AMF, plants and environmental conditions. The establishment and functioning of MAs during stress conditions involves a complex process of recognition and development, concurrently at physiological, biochemical and molecular changes in both symbionts. In addition, mycorrhizal colonization of roots has a significant impact on the gene expression of several plants that encode proteins presumably involved in tolerance to stress. In this context, whereas the AMF are essential in the establishment and adaptation of plants on disturbed sites, this chapter will be covered the molecular and physiological mechanisms of the association MA, responsible for this adaptation and greater tolerance of plants to biotic and abiotic stresses.