PLANT PHYSIOLOGY , Vol 108, Issue 1 353-359, Copyright © 1995 by American Society of Plant Biologists
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PLANT-MICROBE AND PLANT-INSECT INTERACTIONS |
A Noninvasive Technique for Monitoring Peroxidative and H2O2-Scavenging Activities during Interactions between Bacterial Plant Pathogens and Suspension Cells
C. J. Baker, G. L. Harmon, J. A. Glazener and E. W. Orlandi
Molecular Plant Pathology Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705
Stimulation of active oxygen metabolism occurs during the early stages of
interactions involving bacteria and plant cell suspensions. Although many
cellular processes are known to affect active oxygen metabolism in plants,
it is not known which of these factors affect active oxygen levels during
plant-bacteria interactions. Extracellular peroxidases have been shown to
participate in both the production and utilization of active oxygen species
such as H2O2 and superoxide. Catalase and other scavenging mechanisms also
affect the overall level of active oxygen. In this study the
luminol-dependent chemiluminescent reaction previously used to measure H2O2
levels in suspension cells was modified to allow the assay of both
peroxidase and H2O2-scavenging activity. The early stages of the
interactions between tobacco (Nicotiana tabacum) and Pseudomonas syringae
pv syringae, as well as between soybean (Glycine max) and P. syringae pv
glycinea, were investigated. This method of monitoring peroxidase and
H2O2-scavenging activity proved to be rapid, sensitive, and nonintrusive,
allowing the processing of multiple samples using intact cells or cell-free
preparations. The results from the study demonstrate that the scavenging
activities can be significant and must be considered when studying active
oxygen production in biological interactions.