1. Complex combinations of nutrients in exudates released from seeds and roots cause stress in plant-beneficial bacteria. Stress-inducing environments occupied by plant-beneficial bacteria have a negative impact on performance by these bacteria. These stress-inducing environments need to be identified and their impacts on plant-beneficial bacteria determined so that strategies can be developed to minimize the negative impacts of these environments. Using a mutant of the plant-beneficial bacterium Enterobacter cloacae it was shown that the RpoE stress response pathway is critical for biological control of soilborne pathogens, colonization of plant roots, and growth on complex mixtures of nutrients found in exudates from roots. This is the first time that the RpoE stress response pathway was demonstrated to be important in growth on root exudates and by extension the first time that it was demonstrated that complex mixtures of nutrients in root exudates cause bacterial stress. This information will be useful to scientists devising strategies to enhance performance of biological control bacteria for suppression of soilborne plant diseases.
Baker, C.J., Owens, R.A., Whitaker, B.D., Mock, N.M., Deahl, K.L., Roberts, D.P., Averyanov, A.A. 2010. Effect of viroid infection on the dynamics of phenolic metabolites in the apoplast of tomato. Physiological and Molecular Plant Pathology. 74:214-220.