Arbuscular mycorrhizal fungi (AMF) for sustainable soil and plant health in salt-affected soils

Abstract

Continuous utilization of quality land in civilization and industrialization has gained interest in the utilization of salt-affected soils for crop production. However, crop growth and productivity is severely affected in saline soil. Many strategies were proposed to overcome the salt detrimental effects like development of salt-tolerant cultivars through breeding and/or genetic engineering, removal of excessive salt accumulation in soil, desalinization of irrigation water etc. Though these strategies are efficient but costly. Hence, a cost-effective new alternative attempt has taken up to mitigate soil salinity which involves inoculation of salt-tolerant arbuscular mycorrhizal fungi (AMF) in agricultural crop. Mechanisms of amelioration of salt stress in AMF-plant symbiosis involve enhancing the uptake of less mobile phosphorus, increasing nutrient acquisition, maintaining osmotic balance, enhancing antioxidants and polyamines, altering hormonal status, reducing ion toxicity and enhancing photosynthetic efficiency. AMF colonization induces an increase in root hydraulic conductivity of the host plants under osmotic stress conditions. Furthermore, AMF symbiosis also alters expression of cation channels and transporters, late embryogenesis abundant protein and aquaporins. AMF symbiosis not only changes plant physiology but also changes nutritional and physical properties of the rhizosphere. In the mycorrhizosphere, AMF interact with natural and introduced microorganisms and affect soil properties and quality. The quality of soil largely depends on its physical and chemical properties as well as diversity and activity of soil biota. Thus, AMF have been considered as bio-ameliorators of saline soils.