Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/24/2006
Publication Date: 4/24/2006
Citation: Baker, C.J., Roberts, D.P., Whitaker, B.D., Mock, N.M., Deahl, K.L., Aver'Yanov, A.A. 2005. Apoplastic redox metabolism: synergistic phenolic oxidation and a novel oxidative burst. Physiological and Molecular Plant Pathology. 67:296-303. 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 how certain chemicals in the plant tissue are able, when the tissue becomes stressed, to modify the chemical composition of tissue. In many cases this could change the bioactivity of these chemicals and therefore affect the interaction between the plant and a disease-causing organism (pathogen). This situation is similar to ‘drug cross-reactivity’ in humans where one drug causes another drug to be modified resulting in changes in its desired effect. This study describes the phenomenon in plant cells and begins to investigate the chemical mechanisms that are involved. By being aware of and being able to monitor this activity, 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: The plant apoplast is an important zone of communication for the cell cytoplasm with the outer environment. Because it is separate from the cytoplasm, the events that occur here are can be very different and more extreme than in the cytoplasm. Phenolics, some of which are bioactive, accumulate in the apoplast and the composition and magnitude of each varies with the varying stresses or conditions. During oxidative events these phenolics can act to buffer the apoplastic environment from drastic changes in the redox potential. Here we investigate a unique interaction of phenolics in which rather than acting as antioxidants, they stimulate an oxidative burst. Acetosyringone and hydroxyacetophenone in the presence of H2O2 and peroxidase interact to increase their rate of oxidation and in the present of plant cells, produce an oxidative burst. Phenolic co-oxidation in animals is a concern because it modifies the bioactivity of drugs. This study demonstrates that certain phenolics in plants can do the same thing although less is known about the bioactivity of many of these phenolics.