Microbial Endophytes of Tuber Crops

Abstract

Endophytes are symbiotic micro-organisms which comprise mainly selected taxa of bacteria and fungi that colonize internal tissues of plants. They have been acknowledged to be beneficial to the host plant in diverse ways such as induced biotic and abiotic stresses, increase in biomass, nitrogen fixation, protection against pathogens, among others. But where the immunity of the host plant is compromised, they can become pathogenic. In order to colonize host plant tissues and compete favourably with other microorganisms, endophytes produce a variety of secondary metabolites like antibiotics, antifungal compounds, toxins, enzymes, among others. Tuber crops are major source of energy giving food next to cereals, but little information is available regarding how endophytes interact with them, which is necessary for their survival. Symbiotic interaction of endophytes with tuber crops have been documented as antagonistic against some major plant pathogens like Phytophthora infestans, Sclerotium rolfsii, Pythium aphanidermatum and Rhizoctonia solani while a good number of bacteria and actinomycetes participated in nitrogen fixation and starch degradation, hence, are reportedly potential source of bio-fertilizers and heat-stable amylases used in major industrial process like starch hydrolysis. This review therefore attempts to discuss the various benefits of tubers-endophytes interaction and the need to intensify research to tap into the immersed potentials of endophytes associated with tuber cultivation yet to be explored.