Mycorrhiza: An Ecofriendly Bio-Tool for Better Survival of Plants in Nature

Abstract

Modern agriculture is currently enduring rapid changes in defiance of the continuing increase of the global population and the various consequent environmental challenges. Crop quality is becoming as important as crop yield and can be characterized by several parameters. Extensive use of chemical fertilizers leads to food safety concerns globally; hence, the use of mycorrhizal symbionts have proven to be beneficial for the sustainable growth of the agricultural cropping system. Microflora inhabiting the soil entails various ecological interactions which are associated with agricultural performances. Amongst these microflora, mycorrhizal fungi are the critical suppliers of nutrients, with restricted diffusion capacities of minerals such as phosphorus, nitrate, zinc, sulfur etc. Mycorrhizae are the obligatory biotrophs that depend upon their host plant for the nutritional requirements. They act as the key contributors to sustainable agro-ecological enforcement and impact globally on the eco-systemic processes. These soil inhabitants devote themselves to the continuous nutrient flow and extemporize resistance against various environmental stresses like drought, flood, metal toxicity, salinity, etc. This review briefly highlights the taxonomic co-evolution, factors affecting mycorrhizal behaviors (phytohormonal regulation), and the concise mechanistic approach (improved water status, photosystems, stomatal conductance, ionic uptake, C & N fixation) to combat various environmental stresses (biotic/abiotic). Plant growth regulators play a crucial role in this symbiotic establishment with the plant roots. Auxins, brassinosteroids, and strigolactones are responsible for the establishment of mycorrhizal association. On the other hand, ethylene, abscisic acid, and jasmonic acids can promote or downregulate this process in the plants. Whereas, gibberellic acids and salicylic acids negatively impact on mycorrhizal association. The hormonal homeostasis (in response to fungal associations) leads to the activation of transcriptional and signaling cascades which ensues various physio-morphological changes for the benefit of the plant. The role of phytohormones in the regulation of plant-fungus mutualism, and the impact of mycorrhization on the activation of molecular and transcriptional cascades, have been described along with the potential applications of agricultural produce and soil rehabilitation.