Mechanistic insights on plant root colonization by bacterial endophytes: a symbiotic relationship for sustainable agriculture

Plant–microbe and soil interactions are one of the oldest muse for multi-disciplinary researchers. Plant growth promoting microorganisms influence the host physiology by secreting regulatory chemical signals in the vicinity of plant roots and play a key role in the enhancement of plant growth and expansion. The present review deals with the in-depth understanding of steps involved in host tissues colonization by bacterial endophytes. The molecular insights of these events, particularly for endophytic bacteria, are poorly documented till date. The endophytic bacteria must coexist with the host plant and capable of colonizing the internal plant tissues without being recognized as a pathogen. A proper understanding of exchange of signals between the host plant and bacterial communities is required which may facilitate the development of new strategies to promote beneficial interactions between them. This knowledge can be instrumental in agricultural practices as well as for phytoremediation of pollutants. Keeping these facts in mind, the present review attempts to explore the systematic understanding of steps involved and molecular insights of plant colonization events by endophytic bacteria. We conclude that molecular mechanisms and factors affecting endophytic bacterial colonization deserve more research attention in order to exploit their beneficial aspects for sustainable agriculture and environment.