Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/9/2004
Publication Date: 3/3/2005
Citation: Baker, C.J., Whitaker, B.D., Mock, N.M., Rice, C., Roberts, D.P., Deahl, K.L., Averyanov, A.A. 2005. Induction of redox sensitive extracellular phenolics during plant-bacterial interactions. Physiological and Molecular Plant Pathology. 66:90-98. Interpretive Summary: The goal of this study was to gain new insight into plant/pathogen interactions in order to develop new means to improve crop resistance to disease. Here we report the identity of several chemicals that have the ability to regulate the interaction between a plant and a disease-causing organism (pathogen). These chemical regulators may determine whether the interaction will be resistant or susceptible. These particular chemical regulators were produced by plant cells soon after their inoculation with bacteria. By being aware of and being able to quantify these chemical regulators we will improve our understanding of how plants and pathogens interact and we can attempt to improve plant disease resistance. This work will benefit ARS and scientists by providing new knowledge about plant/pathogen interactions and help further investigations leading to improved crop disease resistance.
Technical Abstract: This study focuses on the transient and complex nature of phenolics that accumulate in the extracellular environment of plant suspension cells during the first few hours of the interaction between these plant cells and bacterial pathogens. Using suspension cells of Nicotiana tabacum we identified 4 acetophenones and 4 hydroxycinnamic acid amides that accumulate in the extracellular environment. Treatment of the suspension cells with isolates of the plant pathogen Pseudomonas syringae or with pathogen-related extracts increased elicitation of extracellular phenolics and differentially determined the phenolic compounds that accumulated. The phenolics were sensitive to oxidative stress; when suspension cells were treated with bacterial strains or elicitors that triggered an oxidative burst, the phenolics were oxidized and depleted for the duration of the burst. Other critical parameters that affected the qualitative and quantitative makeup of these phenolics were plant cell age and density. This is the first study that we are aware of that closely follows the kinetics of individual extracellular phenolic compounds and the concurrent oxidative stress during the first few hours of a plant bacterial interaction. This study provides the basis for further investigations of the roles of these bioactive phenolics on the host/pathogen interaction. stages of plant/pathogen interactions.