StreptomycesSGopalakrishnanauthorVSrinivasauthorS LPrasannaauthorStreptomyces is a Gram-positive bacterium, with a high guanine þ cytosine (G þ C) content, belonging to the family Streptomycetaceae and order Actinomycetales. It is found commonly in marine and fresh water, rhizosphere soil, compost, and vermicompost. Streptomyces plays an important role in the plant growth promotion (PGP), plant health promotion (crop protection), degradation of organic residues, and production of byproducts (secondary metabolites) of commercial interest in agriculture and medical fields. Streptomyces, in the rhizosphere and rhizoplane, help crops in enhancing shoot and root growth, grain and stover yield, biologic nitrogen fixation, solubilization of minerals (such as phosphorus and zinc), and biocontrol of insect pests and plant pathogens. There is a growing interest in the use of secondary metabolites produced by Streptomyces such as blasticidin-s, kusagamycin, streptomycin, oxytetracycline, validamycin, polyoxins, natamycin, actinovate, mycostop, abamectin/ avermectins, emamectin benzoate, polynactins and milbemycin for the control of insect pests and plant pathogens as these are highly specific, readily degradable, and less toxic to environment (Aggarwal et al., 2016). The PGP potential of Streptomyces is well documented in tomato, wheat, rice, bean, chickpea, pigeonpea, and pea. This chapter emphasizes the usefulness of Streptomyces in PGP, grain and stover yields, soil fertility, and plant health promotion.Plant PathologyPlant Growth2020-05Academic Press IncBook Section