Large numbers of bacterial and fungal endophytes have been reported from different plant tissues: roots, nodules, leaves, flowers and sprouts of legumes, with numbers ranging from few to more than 150. Endophytes can accelerate seedling emergence, promote plant establishment under adverse conditions and enhance plant growth. Endophytic microbes promote plant growth by helping plants in acquiring nutrients, e.g. via nitrogen fixation, phosphate solubilization or iron chelation, by preventing pathogen infections via antifungal or antibacterial agents, by outcompeting pathogens for nutrients by siderophore production, or by establishing the plant's systemic resistance. Further growth promotion is affected by producing phytohormones such as auxin or cytokinin, or by producing the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which lowers plant ethylene levels. For establishment of endophytes in different tissues, endophytic microbes must be compatible with the host plants and able to colonize the tissues of the host plants without being recognized as pathogens. A particular bacterium or fungus may affect plant growth and development using one or more of these mechanisms, and they may use different mechanisms at various times. The population density of endophytes is highly variable, depending mainly on the microbial species and host genotypes, developmental stage and environmental conditions. Genotypic and cultivar specific endophytes have also been reported. The quantum benefit derived by plants from an endophyte and vice versa is still not clear. It seems that the endophytic genus or species best adapted for living inside a plant is naturally selected. Here, we concentrate on soil or rhizosphere-derived endophytes recruited out of a large pool of soil or rhizospheric microbes. Some endophytes are more aggressive colonizers and displace others, but seeming lack of strict specificity has been observed. However, the processes of host-microbe signaling and colonization and the mechanisms leading to mutual benefits are less-well characterized. It is still not clear which population of microorganisms (endophytes or rhizospheric) promotes plant growth and the way the interactions among endophytes influence plant productivity. Though attempts to know the molecular ecology and interactions are underway, a high amount of progress is required to fully understand the mechanism of establishment, the way interactions take place in planta, between different microbes and plants and exlusive benefits by endophytes and plants.

Endophytic bacteria from roots (12 isolates) and nodules (76 isolates) of chickpea legume grown under CCS Haryana Agricultural University farm were isolated. Among the endophytic bacteria, 50% from roots and 93.4% from nodules were Gram positive spore formers. Large number of endophytes from roots and nodules solubilized phosphate and produced ammonia. Isolate CRE3, and CNE215, were most efficient P solubilizers and. CRE12 and CNE76 being most efficient ammonia producer. Interestingly, few endophytic bacteria produced organic acid. Further selected 62 isolates were used to determine molecular diversity by RFLP of PCR amplified 16S rDNA. Endophytes from roots formed five separate clusters and nodule endophytes formed 13 clusters. Isolate CNE215 from nodules and CRE1 from roots possessed multiple beneficial traits and belonged two different clusters. These two isolates were identified after amplification and sequencing of 16S rRNA gene. Isolate CNE215 showed more than 98% similarity with partial sequence of 16S rRNA gene of Bacillus subtilis, whereas CRE1 showed more than 98% similarity with Bacillus licheniformis. Efficacy of these two strains was evaluated under field conditions and an increase up to 22.5% in grain yield over uninoculated control was observed with B. subtilis strain CNE215, whereas all the recommended biofertilizers were able to record an increase upto 14.4%.