Elucidating the Mechanisms Underlying Enhanced Drought Tolerance in Plants Mediated by Arbuscular Mycorrhizal Fungi

Abstract

Plants are often subjected to various environmental stresses during their life cycle, among which drought stress is perhaps the most significant abiotic stress limiting plant growth and development. Arbuscular mycorrhizal (AM) fungi, a group of beneficial soil fungi, can enhance the adaptability and tolerance of their host plants to drought stress after infecting plant roots and establishing a symbiotic association with their host plant. Therefore, AM fungi represent an eco-friendly strategy in sustainable agricultural systems. There is still a need, however, to better understand the complex mechanisms underlying AM fungi-mediated enhancement of plant drought tolerance to ensure their effective use. AM fungi establish well-developed, extraradical hyphae on root surfaces, and function in water absorption and the uptake and transfer of nutrients into host cells. Thus, they participate in the physiology of host plants through the function of specific genes encoded in their genome. AM fungi also modulate morphological adaptations and various physiological processes in host plants, that help to mitigate drought-induced injury and enhance drought tolerance. Several AM-specific host genes have been identified and reported to be responsible for conferring enhanced drought tolerance. This review provides an overview of the effect of drought stress on the diversity and activity of AM fungi, the symbiotic relationship that exists between AM fungi and host plants under drought stress conditions, elucidates the morphological, physiological, and molecular mechanisms underlying AM fungi-mediated enhanced drought tolerance in plants, and provides an outlook for future research.

Arbuscular Mycorrhizal Fungi and Endophytic Fungi Activate Leaf Antioxidant Defense System of Lane Late Navel Orange

“…AM fungi in the soil could establish a symbiotic relationship with many terrestrial plants, including citrus [ 10 ]. One the most important characteristics of this AM symbiosis is to help the host absorb nutrients and water that cannot be reached by the root, to enhance the resistance of the host plant to abiotic stress [ 11 , 12 ]. The AM symbiosis between AM fungi and host plants enhances the resistance of host plants to drought, salt stress, high temperature, nutrient stress, aluminum toxicity, and waterlogging stress by affecting their antioxidant enzyme defense systems [ 13 , 14 , 15 , 16 ].…”

Biostimulatory Response of Easily Extractable Glomalin-Related Soil Protein on Soil Fertility Mediated Changes in Fruit Quality of Citrus

“…Arbuscular mycorrhizal fungi (AMF) represent a group of soil microbial communities, known to colonize 72% of roots of terrestrial plants, establishing a symbiotic association with host plants to acquire the desired nutrients, enhance resistance to biotic and abiotic stresses and stabilize the soil structure [8][9][10]. Citrus plants in the field are widely reported possessing fewer root hairs and considered dramatically dependent on AMF facilitating elevated nutrient acquisition [11,12].…”

Using the Maize Nested Association Mapping (NAM) Population to Partition Arbuscular Mycorrhizal Effects on Drought Stress Tolerance into Hormonal and Hydraulic Components

“…Global warming and reduced rainfall are leading to frequent episodes of drought globally, causing a serious impact on crop growth and productivity [ 1 ]. Thus, under the current climate change scenario, increasing crop tolerance to new environmental conditions is of crucial importance in order to secure food production for the ever-increasing human population [ 2 ].…”

“…The AM symbiosis activates the host’s physiological, molecular and morphological plant responses, increasing the ability of host plants to survive and maintain vigour under drought conditions. Hence, the AM fungi-plant interaction represents a clear example of a sustainable agricultural strategy and represents one of the most sustainable strategies to increase the tolerance of plants to adverse conditions such as water limitation [ 1 , 11 , 12 ].…”

“…The positive effects of the AM symbiosis against drought have been explained not only as a result of a more efficient nutrient uptake and transfer of water through the fungal hyphae to the host plant [ 13 ] but also because of changes in soil water retention properties and soil structure, better osmotic adjustment of AM plants, enhancement of plant gas exchange and water use efficiency and protection against the oxidative damage generated by drought reviewed by [ 1 , 12 , 14 , 15 ].…”