Peroxidase as a Component of the Signaling Pathway in Potato Cells during Ring Rot Infection

Changes in the activity of peroxidase, a component of the NADPH oxidase signaling pathway, in potato cells were studied. This activity increased sharply during ring rot pathogenesis. Two mechanisms of peroxidase activation were distinguished. One of them was the enzyme de novo synthesis; it was characteristic of the potato cultivar susceptible to the pathogen. Another mechanism characteristic of the resistant cultivar included not only the enzyme synthesis but also the activation of preexisting enzyme molecules. Bacterial infection and exopolysaccharides secreted by the pathogen induced changes in the pattern of intra- and extracellular peroxidases of the susceptible cultivar. No changes were noted in the peroxidase patterns of the resistant cultivar. A sharp activation of the extracellular peroxidase of R_f 15 occurred in the infected or exopolysaccharide-treated cells of the resistant cultivar.