Microbes and Their Role in Abiotic Stress Tolerance in Food Crops

Abstract

Different abiotic stresses, such as drought, salinity, heavy metals etc., are considered as serious threat for agricultural productivity, which have been addressed all over the world. The food crops encounter wide range of abiotic stresses due to the persistence of adverse climatic conditions such as prolonged droughts, excess rains and floods, temperature and heat, excess salinity levels, metal toxicity, and frost damages. The adverse external pressure exerted by a variety of abiotic environmental stresses and different edaphic conditions limit the crop productivity, affect quality of food, growth and development of crop, and it also majorly hinders the global food security. The crop plants need to withstand these limiting factors through their intrinsic biological processes. Therefore, under the continuous rise in climatic alterations, it is important to define and interpret the concept of plant-microbe interaction in terms of protection against different abiotic stresses. In this case, microbes may serve as boon for the alleviation of these abiotic stresses in crop plants. Exploiting the potential of plant growth-promoting rhizobacteria (PGPR) is a promising approach to improve stress tolerance in plants. Rhizospheric soil microbes play a pivotal role in mitigating abiotic stresses, beside these are also known as the natural occupants of diverse ecosystem exhibiting enormous metabolic capabilities. The plant-microbe interaction is considered as a cost-effective technique for the management and tolerance of abiotic stresses. Furthermore, PGPRs produce different enzymes, exopolysaccharides, and biofilm layers which are very effective against the abiotic stresses. Moreover, PGPR reduce the impact of drought and salinity in plants through a process called induced systemic tolerance. This includes bacterial production of cytokinins, antioxidants and the degradation of the ethylene precursor ACC by bacterial ACC deaminase. Microbes like symbiotic fungi, such as arbuscular mycorrhizal fungi, and other endophytic rhizospheric bacteria also have great tendency to mitigate the environmental abiotic stresses. Various kinds of microorganisms are involved in providing tolerance to abiotic stresses directly or indirectly and maintaining the quality of agricultural production. Meanwhile, the current chapter highlights the mechanisms underlying plant-microbe interactions. It addresses widespread concerns about the solutions against different environmental stress factors and mitigation of these stress factors for the sustainable management of food crops.