Plant probiotics - Endophytes pivotal to plant health

Endophytes as a ubiquitous associate of the plant are considered as a promising candidate for sustainable agriculture. These organisms play a pivotal role in the regulation of the primary and secondary metabolism of their host plant. The direct and long-lasting interaction of endophytes with the host enables them to escape from harsh environmental conditions. Especially, their endophytic nature makes them better candidates over epiphytes and rhizospheric microbes in interaction with plants. Current research findings revealed that the endophytes help plants in making nutrient acquisition from the soil, nitrogen fixation, phosphate availability, phytohormone and antimicrobial production. There is a huge potential for developing novel products like endophytes-based microbial formulations and elicitors to improve plant health, ameliorating stress tolerance in plants and source of therapeutically important secondary metabolites. The present review specifically dealt with attributes such as host-tissue specificity of endophytes, the importance of seed-associated endophytes, endophyte-parasite plant-host plant interaction as well as their applications in plant in-vitro systems and as microbial consortium. In addition, the conserved endophytic microbial communities in different plants are also looked upon possibly to understand the plant-endophytic microbiome on similar lines of the animal-gut microbiome. Primarily, the purpose of this review is to implicate the endophytic flora as probiotics influencing overall plant health and their survival under extreme environmental conditions.