WATER STRESS TOLERANCE IN PLANT-ARBUSCULAR MYCORRHIZAL FUNGI INTERACTION: ENERGY METABOLISM AND PHYSIOLOGY

Arbuscular mycorrhizal fungi (AMF) are symbiotic microorganisms associated to plants that increase plant tolerance to water stress by modifying photosynthetic and transpiration rates, leaf and soil water potentials, osmolyte concentration, water use efficiency and nutrient uptake by plants. This association may become parasitic when costs outweigh benefits, thus affecting plants under stressed conditions since photosynthates transferred to fungi could be used by the host itself to modify its metabolism and minimize negative stress effects. Carbon and energy use efficiency determine the success of the association, which in turn depends upon host characteristics (species and developmental stage), fungi (species and adaptation capability) and environmental conditions. This review analyzes the benefits of this symbiosis in terms of energetic metabolism and carbon transfer under drought and salinity conditions, when the efficiency in nutrients assimilation and in photosynthates use are determinants for plant survival.