| Abstract: | Smirnoff, N. and Colomb?, S. V. 1988. Drought influences theactivity of enzymes of the chloroplast hydrogen peroxide scavengingsystem.—J. exp. Bot. 39: 1097–1108. The effect of drought on the activity of ascorbate peroxidase(AP), glutathione reductase (GR) and monodehydroascorbate reductase(MDAR) in leaves of barley (Hordeum vulgare) and tef {Eragrostistef) was studied. These enzymes are components of the chloroplasthydrogen peroxide scavenging system. Severe leaf water deficit(<–30 M Pa) resulted in increased activity (leaf dryweight basis) of GR and MDAR in barley and of AP and MDAR intef. The specific activity of all the scavenging enzymes wasgreater in droughted plants. The activities (dry weight basis)of two ‘control’ enzymes, malate dehydrogenase (barley)and phosphoenolpyruvate carboxylase (tef), not directly involvedin the scavenging system, were not affected by drought. These data suggest that drought may cause an increase in thecapacity of the hydrogen peroxide scavenging system and thatit may, therefore, increase the rate of hydrogen peroxide formationin chloroplasts. Key words: Water stress, hydrogen peroxide, enzyme activity |
