ROOTING RESPONSES IN RELATION WITH PO, PPO AND IAA-O ACTIVITIES ON WALNUT (JUGLANS REGIA L.) EXPLANTS
Peroxidase (PO) and polyphenol oxidase (PPO) activities in CLA explants showed a progressive increase along induction phase followed by a decrease in the root manifestation phase. A peak of PO activity is observed when CP explants are cultured in rooting medium. No changes were detected in Indol Acetic Oxidase (IAA-o) activity in any explant along the rhizogenic process.
The treatment of the explants with TIBA (an inhibitor of auxin transport) or cycloheximide (inhibitor of protein synthesis) gave rise to a total inhibition of the rooting responses together a gradual decrease of PO and PPO activities respect explants no treated with inhibitor substances.
These results allow to confirm that PO and PPO activities are involved in the definition of the beginning and length of the walnut rooting phases.