Rhizospheric Microbiome: Biodiversity, Significance, and Prospects for Biotechnological Advancements

The rhizosphere, the thin space around the root surface, is an important microenvironment housing a highly diversified microbial community. It includes of three zones named endorhizosphere, ectorhizosphere, and rhizosphere. Each zone harbors microorganisms with defined functions like nutrient cycling, disease protection, and pathogenicity. The rhizosphere microbiome is a critical community since it is implicated in the interactions linking roots (plant), soil, and microorganisms. This community comprises bacteria, fungi, oomycetes, viruses, and other harmful and beneficial microorganisms. While the harmful organisms are the causal agents of diseases, soil drought, and other negative impacts on plants and the environment, the beneficial species balance these stresses by producing secondary metabolites. These include antibiotics and other bioactive compounds such as hydrolytic enzymes and volatile organic compounds active in plant growth promotion, plant immuno-system improvement, and local environment bioremediation. Studies for sustainable agriculture significantly considered the rhizosphere microorganisms, and showed the importance of using this community to enhance crop development and yield, as a response to food crisis. This chapter focuses on the diversity, significance, mechanisms and modes of action of rhizosphere microorganisms, particularly in plant protection, environmental bioremediation, and sustainable agriculture.