The book emphasizes role of functional microbes in soil to improve fertility and plant health in agro-ecosystem. In this compendium main emphasis is on occurrence and distribution of microbial communities, In situ active microbial quorum in rhizosphere, metratranscriptomics for microflora- and fauna, and fnctional diversity in rhizosphere. The book also highlights the importance of PGPRs in rhizosphere, root endotrophic microbes, functional niche under biotic stress, functional niche under abiotic stress, functional root derived signals, as well as functional microbe derived signals. Approaches deployed in metatranscriptomics, and molecular Tools used in rhizosphere are also discussed in detail. The book presents content is useful for students, academicians, researchers working on soil rhizosphere and as a policy document on sustenance of agriculture.