Changes in Plant Microbiome in Response to Abiotic Stress

Heavy metal, drought, salinity, temperature, and nutrient shortage are among abiotic factors that influence crop plants and jeopardize agricultural output. The association of a variety of microbes with plants is very significant for the growth and health of the plants for nutrient uptake, protection against phytopathogens, hormonal signaling for homeostasis, and acquired tolerance against various abiotic stresses. A community of these microbes that associates with plant is termed as plant microbiome. Recent research reveals that phenotypic and genotypic traits including length, water storage content, water storage capacity, nitrogen content, the phosphorus content of leaf, transpiration rate, and net photosynthetic rate are correlated with the composition of bacterial, archaeal, and fungal communities. Hence, a shift in the population density of these microbes in response to the abiotic stresses could significantly affect plant morphology and physiology. For example, drought could alter the microbial compositions in the rhizosphere and endosphere. The experimental studies revealed the depletion of several Acidobacteria, Verrucomicrobia, and Deltaproteobacteria followed by the enrichment of Actinobacteria and Chloroflexi during drought stress. Halotolerant microbes survive in high salt concentration expressing such traits that help plants to live in elevated salinity environments. All microorganisms respond to extreme temperatures by making specific polypeptides called heat shock proteins (HSPs). Certain bacterial strains produce exopolysaccharides (EPSs) that possess distinctive characteristics of holding water and also has cementing characteristics. The higher temperature increased Bacteroidetes and Verrucomicrobia while causing a decrease in the abundance of Proteobacteria. Engineering the rhizosphere of plants with specific abiotic stress-tolerant microbes makes a specific environment for the plant to nourish. This chapter will focus on different abiotic factors that affect the plant microbiome.