Microbial diversity in soil: Biological tools for abiotic stress management in plants

Abstract

Soil is a dynamic and complex biological system comprising of various populations of microbes. These microorganisms enhance soil richness or fertility and water retention ability and have a major impact on the growth of the vegetation present on the ground. The range of diversity of microbes plays an essential role in improvement of soil quality that varies with depth, pH and horizons as well as soil health. Abiotic stresses comprising drought, salinity, high and low temperature and heavy metal (HM) toxicity are the principal restraining factors for microbial inhabitants and agricultural productivity. Several reports have indicated that inoculation of microbes in nutrient-deficient or stressed soil has significantly improved soil as well as plant health and established supportable way of agriculture. Microorganisms interact with plants and regulate systemic and local mechanisms to provide defence under adverse environmental conditions. Besides providing non-nutritional effects such as limiting soil erosion and detoxifying insecticides as well as pesticides, microbes also help in atmospheric nitrogen (N2) fixation; activation of antioxidants, phytohormones and osmolytes; solubilization of mineral phosphates; decomposition of organic wastes; regulation of gene expression; improvement of nutrient cycling and plant-water relation; etc. and assist the plant to survive under unfavourable conditions. In addition, use of harmonious multiple microbial associations (e.g. fungal and bacterial) provides several benefits and is a promising approach towards this direction. This review deals with the potential of soil and its inhabitant microbes to nurture plants, plant-microbe interactions and their roles in abiotic stress management.