Endophytic Bacteria: Prospects and Applications for the Plant Disease Management

Abstract

Biological control of plant diseases has metamorphosed into a unique field of science and development, and this field is fast happening in recent years. Bacterial endophytes are a group of microorganism which can colonise in any part of a plant devoid of symptoms or harmful effects in the plant in which they inhabit for their survival. The endophytic bacterial species have been identified by numerous researchers, and they have increasingly been reported to reduce the growth and activity of a plethora of plant pathogens. The interest of the researchers in this field is ever expanding given the potential it possesses to serve as an alternative to synthetic fungicides. The primary aim of this review is to trace the development in endophytic bacterial research and to communicate the researchers with updated information which will serve as a catalyst for their research endeavours. The review started with a prologue about endophytes, their diversity and existence. A systematic review on the colonisation of endophytic bacteria has been given which unravels the processes involved in their entry into the rhizosphere, then cortex and xylem and further their movement to the vegetative and reproductive organs of plants. This has followed the review on the control of various plant diseases through endophytic bacteria, viz. wilt, damping off and rot, foliar fungal diseases and bacterial diseases. The control of postharvest diseases and nematodes by endophytic bacteria has also been discussed. The major processes involved in the mode of action or mechanism of control of diseases have been discussed in different heads, namely, competitive root colonisation, competition for ferric iron ions, antibiosis and antibiotics suppressing pathogens, induced systemic resistance (ISR), signal interference, food and space competition, and minimization of the factors responsible for virulence of pathogens. Quite a few literatures have been discussed on the application of bacterial endophytes through different modes of applications. The review ends with future thrust which will go long way in indicating the future niche research areas on endophytic bacteria.