SEASONAL-CHANGES OF ISOPEROXIDASES FROM POPLAR BARK TISSUES

Peroxidases extracted from poplar bark tissues during both the active and the dormant seasons were fractionated and characterized using different substrates. Fast migrating anionic peroxidases, present in cytoplasm as well as in cell walls were able to oxidize all tested substrates, unlike the cationic isoforms which oxidized strongly PPD-PC, and to a much lesser extent, syringaldazine and ferulic acid salts. Moreover. the fast migrating anionic isoforms were the only ones to show a significant decrease between the active and resting seasons, which suggests their possible involvement in lignification.