CHANGES IN PEROXIDASE-ACTIVITY ASSOCIATED WITH CELL-WALLS DURING PINE HYPOCOTYL GROWTH

Peroxidases active against 2,2'-azino-bis-[3-ethylbenzthiazoline-6-acid] (ABTS) and guaiacol were found in the apoplastic fluid, as well as ionically and covalently associated with pine cell walls. The highest activity was found covalently bound to cell walls, while the lowest activity was in the apoplastic fluid. Both ABTS and guaiacol peroxidases increased with the hypocotyl age in the three fractions, apoplastic, ionically and covalently bound. Furthermore, the changes in both peroxidases along the hypocotyl were also studied. Both apoplastic ABTS- and guaiacol-peroxidases increased from the apical towards the basal region of the hypocotyls of 10-d-old seedlings. A relation between peroxidase activity in the apoplastic fluid and the cell wall stiffening in pine hypocotyls is proposed.