Peroxidase Activity and Isoenzymes in the Leaves and Bark of Avocado Trees Affected with Rough Bark and Phytophthora Root Rot

Abstract

Summary A quantitative increase in the activity of two peroxidase (PO) isoenzymes in leaves of avocado (Persea americana Mill. ) trees unaffected by Phytophthora root rot, as a result of an increased PO enzyme activity was confirmed. This therefore, excludes the possibility of a qualitative increase in isoenzyme bands. Rootstock and scion bark from healthy trees also have a higher bark PO activity compared with infected trees, in the absence of rough bark. Rough bark may be associated with either a weak graft union or with incompatibility and can be identified by a significant increase in PO enzyme activity in the rootstock and root bark compared with normal trees but with no apparent association with any specific PO isoenzymes.