[Effect of stress conditions on the activity and isozyme composition of peroxidase of vacuoles and tissue extract of red beet roots].

Changes in the enzymatic activity of phenol-dependent peroxidase (PO) of vacuoles and tissue extract of red beet (Beta vulgaris L.) roots in different phases of plant development and in hyperosmotic stress and pathogen infection were found. The highest activity was observed during root growth and the lowest PO activity occurred in dormancy, respectively. Activation of the enzyme was observed in infected roots. The isozyme composition of PO was characterized by lability, and the number of cationic isoforms varied significantly. The optimum pH of the enzyme changed depending on the growth phase and stressor, tending to shift towards low values at rest and in hyperosmotic stress. The shift in the optimum pH coincided with the appearance of additional cationic PO isoforms.