Arbuscular mycorrhizal fungi and its major role in plant growth, zinc nutrition, phosphorous regulation and phytoremediation

Abstract

Arbuscular mycorrhizae fungi (AMF) are a big player of the ecosystem which shows a major concern over plant nutrition by providing access to the soil-derived nutrients. Naturally, an intimate association between plant roots and AMF is observed. AMF are involved in improvement on the soil water regime and nutrient uptake both in the biotic and abiotic stress situations such as drought, temperature extreme, heavy metals, salinity, pathogen and metal pollution. This kind of symbiotic relationship between plant roots and fungal hyphae is observed to be 80% of the terrestrial plant species worldwide. In plant AMF association fungal hyphae are benefitted by obtaining sugar from the host plants root and host plants root are ameliorated by improved uptake of water and nutrients from soil surface. AMF have a dual role to manage the Zn nutrition in soil. For example below a critical Zn concentration, Zn uptake is enhanced by AMF application and above the critical level, Zn translocation to plant shoots is restricted. Synergistic association between Zn and AMF is important for sustainable yield and quality. It is observed that grain Zn content in the field is increased with applying AMF. AMF help in the plant growth, development and reproduction, as the Zn is essential for pollen tube formation. By AMF application there is an increment in the content of lycopene, vitamin C, vitamin A and antioxidant activities than non AMF plants in tomato. In traditional driven agriculture, inherent soil fertility is the major source of P with an occasional supply of manure for the crops. But after modernization in agriculture results in overexploitation of the P and results in low crop yield and farm income. Rock phosphate is the major source of the phosphatic fertilizer and is non-renewable which could be exhausted in the next 50–100 years. Moreover, the stimulation of secondary metabolites synthesis results in the improvement of crop quality by sustainable use of phosphatic fertilizers. So P application techniques which can also ameliorate AMF are widely promising. This is how AMF play a pivotal role in developing present era farming practices towards sustainable agriculture. Phytoremediation of heavy metals from different soil types has potential benefit of using AMF in soil. Mycorrhizae disrupt the uptake of the different heavy metals from the rhizosphere and movement from the root to the aerial parts. The major role of AMF in plant growth and development during stressful environments is to translocate important immovable nutrients like Cu, Zn and P and reducing metal toxicity in the host plant.