Aminobutyric acid (GABA) is a non-protein amino acid that has recently been discovered to play an important role in plant-pathogen interactions. In this proposal, we will comprehensively investigate the potential of GABA metabolism to boost plant immunity against fungal and bacterial pathogens using tomato and Arabidopsis as model plant systems. The effectiveness of exogenous applications of GABA will be compared with known inducers of disease resistance in laboratory and greenhouse trials, and then novel formulations will be developed and evaluated. Mechanisms by which GABA mediates control of the pathogens will be investigated by microscopic assessment, determining the levels of expression for marker genes and of key metabolites, as well as the use of genetic mutants of GABA metabolism. This work will set the stage for efficacy testing of a novel product that could be registered and sold as a bio-control agent nationally and internationally, and provide insight about the mode of action of the actives and products that will be invaluable for product marketing.