Localization and general properties of developing peach seed coat and endosperm peroxidase isoenzymes

Changes of soluble and ionically bound peroxidase and indoleacetic acid (IAA) oxidase activities were followed during peach seed development. Soluble peroxidase activity was located mainly in the embryo plus endosperm tissue, whereas wall ionically bound activities were found predominantly in the integument tissue. The different peroxidase isoenzymes present in the extracts were characterized by polyacrylamide gel electrophoresis and isoelectric focusing; the main soluble isoenzyme of embryo plus endosperm tissue was an anionic isoperoxidase of R-F 0.07. Basic ionically bound isoenzymes were located only in the integument tissue, but two soluble anionic isoenzymes of R-F 0.23 and 0.51 were also present in this tissue, In parallel, peroxidase protein content was estimated specifically using polyclonal antibodies, The kinetic data and the changes of seed IAA oxidase activity during fruit development suggested that basic peroxidase isoenzymes from ionically bound extracts of integument might be involved in IAA degradation.