Hormonal Control of Peroxidase Activity in Cultured Pelargonium Pith

Freshly excised Pelargonium pith tissue lacks peroxidase activity toward guaiacol or benzidine, but it develops such activity within 24–36 hr in aseptic culture. All the activity is manifested as a single enzyme moving toward the cathode during electrophoresis on starch gel at p H 9.0. This development of peroxidase activity is at first (up to ca. 50 hr in culture) inhibited and later (ca. 100–150 hr in culture) promoted by IAA. This dual effect of IAA resembles that previously reported for specific isoperoxidases in tobacco pith cells. Kinetin alone also inhibits peroxidase formation, but in the presence of IAA those concentrations which enhance growth enhance peroxidase formation as well.