Monika Singh - Centre of Advance study in Botany, Institute of Science, Banaras Hindu University, Varanasi, India.
Meenakshi Srivastava - Centre of Advance study in Botany, Institute of Science, Banaras Hindu University, Varanasi, India.  
Ajay Kumar - Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel.
A.K.Singh - Krishi Vigyan Kendra, Khalilabad, India.
K.D.Pandey - Centre of Advance study in Botany, Institute of Science, Banaras Hindu University, Varanasi, India

Agricultural activities are increasingly occupying a prominent place since the advent of chemical fertilizers, synthetic growth regulators, and pesticides to meet the needs of ever-increasing population. Application of synthetic and chemical substances to check the spread of phytopathogens in the crop fields is not appreciable in any cost. Thus, the elimination of huge application of agrochemicals through deployment of biological agents would improve the agricultural practices in a sustainable manner. Plant growth-promoting microorganisms (PGPMs), particularly endophytes play a major role in controlling such problems and unlike chemical agents, work well without losing the core benefits as imparted by the chemical and synthetic agents. Endophytes associate with compatible host plants and provide benefit to them through various production of phytohormones, supplementation of nutrients, and suppression of pathogen access to host system and thus improving plant growth and yield. The biotechnological and industrial potential of these microbes could be better estimated by analyzing their modes and constraints with host plant interaction. The net consequences of plant growth-promoting rhizobacteria (PGPR) and endophytes activities are growth stimulation of plants. This chapter deals with the importance of endophytic bacteria, and their role as biocontrolling agents for disease management of important crop plants.