Changes in Peroxidase in Isolated Aleurone Layers in Response to Gibberellic Acid

Abstract

The effect of gibberellic acid (GA₃) on peroxidase activity and isoenzyme complement was followed in isolated aleurone layers of barley (Hordeurn vulgare L.) over a 48-h period. A high level of peroxidase activity was initially present in freshly isolated aleurone layers. Disc electrophoresis resolved nine peroxidase isoenzymes. By 36 h incubation, total peroxidase activity had doubled in response to GA₃ and two new peroxidase isoenzymes were observed. Peroxidase release from isolated aleurone layers was also greatly stimulated by GA₃ and more isoenzymes were found in the medium. The time course of release was similar to that for α-amylase. Peroxidase activity in endosperm of whole germinating grains began to increase after 2 days, peaked at 4 days and subsequently declined.