Microbial consortium-mediated plant defense against phytopathogens: Readdressing for enhancing efficacy

Microorganisms under natural habitats live in communities and some provides benefits to plant. Further, microbes when introduced to soil as consortium and interact with a host plant, partially mimic the natural soil conditions. The current research trend has therefore oriented towards investigating the role of small microbial consortia in promoting plant growth and health against various invading pathogens. This is a paradigm shift from the original investigations involving a single microbe. In the recent past, information on various mechanisms by which microbial consortia promoted plant growth and triggered defense responses in host plants during pathogen ingress have become available. It was also unveiled that microbes in small consortia enhance the defense signaling cascades leading to enhanced transcriptional activation of several metabolic pathways. However, an additive or synergistic effect is not achieved every time a microbial consortium is used. With progress in time a sizable understanding on microbial consortium-induced plant defense responses had been reached. Further generation of information on host's responses to pathogenic challenge in the presence of diverse microbial consortia at functional level is underway. In this review, we have presented the outcomes of small microbial consortia used so far to protect crop plants from various pathogens. We have also provided possible explanations for reduction in diseases when a microbial consortium was used, compared the effects of microbes when used alone as well as in consortium, possible shortcomings for not obtaining desired outcome from the introduced consortia, and provided the rationale for development of effective microbial consortia capable of inducing enhanced systemic resistance. Finally, we have suggested some potential biotechnological applications to sustain the effect of microbe-induced defense responses in host plants. (C) 2015 Elsevier Ltd. All rights reserved.