Root-associated microbes in sustainable agriculture: models, metabolites and mechanisms

Authors: Thomashow, Linda; KWAK, YOUN-SIG - Gyeongsang National University; Weller, David

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2018
Publication Date: 3/13/2019
Citation: Thomashow, L.S., Kwak, Y., Weller, D.M. 2019. Root-associated microbes in sustainable agriculture: models, metabolites and mechanisms. Pest Management Science. 75(9):2360-2367. https://doi.org/10.1002/ps.5406.
DOI: https://doi.org/10.1002/ps.5406

Interpretive Summary: The discovery of phenazine antibiotics on the roots of wheat in 1988 provided the first direct scientific evidence that antibiotics are synthesized by bacteria in nature and are produced in quantities sufficient to provide protection against soilborne root pathogens. This and subsequent studies showed that the environment determines which antibiotics will be produced in nature, and for what diseases they will provide protection. Genomics opened the door to a wealth of biosynthesis genes for new antibiotics and the ability to manipulate their synthesis and activity. More recently, the discovery of protective bacterial endophytes from plants has spawned a renaissance in recognition of the importance of microbe-plant associations and recognition of the potential to overcome the barriers that until now have limited their development of bacterial biocontrol agents for application to agricultural sustainability. This manuscript presents key developments that have established the importance of plant-associated microbes and their metabolites in the control of pathogens, discuss concepts resulting from the exploration of classical model systems, and highlights advances emerging from ongoing investigations.

Technical Abstract: Since the discovery of penicillin in 1928 and throughout the “age of antibiotics” spanning the years from the 1940s until the 1980s, the detection of novel antibiotics was restricted by lack of knowledge about the distribution and ecology of antibiotic producers in nature. That a phenazine compound produced by Pseudomonas bacteria could suppress soilborne plant pathogens, and its recovery from rhizosphere soil in 1990, provided the first incontrovertible evidence that natural metabolites are produced in sufficient amounts to control plant pathogens in the environment and opened a new era in biological control by root-associated rhizobacteria. Similarly, the advent of genomics, the availability of highly sensitive bioanalytical instrumentation, and the discovery of protective endophytes from plants have spawned a renaissance in recognition of the importance of microbe-plant associations and recognition of the potential to overcome the impediments that until now have limited their development for application to agricultural sustainability. Here, we present key developments that have established the importance of plant-associated microbes and their metabolites in the control of pathogens, discuss concepts resulting from the exploration of classical model systems, and highlight advances emerging from ongoing investigations.