Bacterial Endophytes of Medicinal Plants: Applications and Recent Developments

Endophytic bacteria are endosymbionts that reside within plant tissues without causing apparent disease in the host. Bacteria employ various traits (lipopolysaccharides, flagella, pili, twitching motility, etc.) to colonize host plants. In this colonization process a variety of compounds released by plants in addition to bacteria play a key role in plant growth. Endophytes are in symbiotic association with their host plant and show beneficial effect on them using various direct and indirect mechanisms of plant growth promotion. In addition to plant growth promotion, endophytes also confer stress tolerance in the current scenario of climate change. Furthermore, endophytes have emerged as an important source of novel metabolites, enzymes of industrial importance and as stress alleviators of host plant, but still several features of endophytic associations are unknown. However, little is documented about plant growth-promoting endophytes (PGPE) of medicinal plants. Current review focused on the drivers of endophyte community structure with an attempt to relate it with plant growth promotion, its mechanisms and the current as well as future aspects of molecular techniques to reveal these communities. In-depth knowledge of the mechanism of host infection and role of endophytes could be exploited to enhance agricultural productivity in terms of plant growth promotion and biocontrol.