The Role of Arbuscualr Mycorrhizae in Inducing Resistance to Drought and Salinity Stress in Crops

Abstract

Arbuscular mycorrhizal (AM) fungi are commonly occurring soil microbes whose association with roots can have wide ranging effects on growth of the host plants. These fungi are frequent root colonizers of trees, shrubs, terrestrial orchids and a broad range of plants in temperate and tropical habitats. During the establishment of AM symbiosis, a range of chemical and biological parameters are affected in plants. These fungi are considered instrumental in promoting plant establishment and growth in these environments by enhancing plant nutrient and water uptake, protecting plants from root herbivores and pathogens and improving soil structure. This symbiosis is alleged to improve plant resistance to drought and nutrient stress. There are several reports which show that AM induce physiological drought tolerance, involving both increased dehydration avoidance and dehydration tolerance. Majority of the experiments have shown that when the symbiosis improves host drought resistance it does so by aiding drought avoidance. AM symbiosis has frequently increased resilience of host plants to salinity stress. The AM plants in the saline soils had increased phosphate and decreased Na concentrations in shoots compared to non-AM ones. Salt resistance has been shown to improve by AM colonization in a number of crops like maize, mungbean, clover, cucumber, lettuce, tomato, and many more. A correlation has been established between AM colonization and improved osmoregulation or proline accumulation. AM colonization has also been documented to improve NaCl resistance in tomato, with the extent of improvement related to salt sensitivity of a cultivar. AM improvement of salt resistance has usually been associated with AM-induced increases in P acquisition and plant growth. However, there are scanty reports of AM induced effects on host plants being more pronounced when plants were exposed to osmotic stress in salinized soils.

Arbuscular Mycorrhiza in Crop Improvement under Environmental Stress

“…Most plants depend on mycorrhizal fungal symbionts for their nutrient uptake (Lambers et al, 2008). Nearly 10 to 20% carbon of net primary productivity is allocated to associated mycorrhizal fungi (Hobbie, 1992;Genre and Bonfante, 2010;Nasim, 2010) and plants in turn absorb a majority of their mineral nutrients Khan et al, 2010).…”

Unraveling the role of fungal symbionts in plant abiotic stress tolerance

“…Arbuscular mycorrhizal fungi (AMF), which are microscopic filamentous fungi, colonize the roots and their rhizosphere simultaneously and spread out over several centimeters in the form of ramified filaments. 180 AM fungi is the most extensively studied fungal symbionts which are associated with approximately 90% of all land plants and contribute multiple benefits to their host plants. 1 This filamentous network dispersed inside as well as outside the roots allows the plant to have access to a greater quantity of water and soil minerals required for its nutrition.…”

“…191,192 On the whole, the growth and health of colonized plants is improved and at the same time, obtain increased protection against biotic and abiotic stresses detrimental to their survival. 180 However, attempts to incorporate these valuable symbionts into mainstream agricultural production practices have not yet been successful. 193 Drought.…”

The Role of Bio-Fertilization in Improving Fruits Productivity—A Review

“…Arbuscular mycorrhizal fungi can establish extra radical mycelia, which disperse outside the roots to have access to a greater quantity of water and soil minerals for the host plants. The fungi receive plant carbohydrates for the completion of their life cycle [20]. [21] stated that vesicular-arbuscular species could supplement or replace chemical fertilizers of crops in varying environmental conditions.…”