ANALYSIS OF ANTIOXIDANT ENZYMES ACTIVITY, LIPID PEROXIDATION AND PROLINE CONTENT OF Agropyron desertorum UNDER DROUGHT STRESS

Abstract

Agropyron desertorum Fischer is one of the most important drought- tolerant grasses. This grass has been recently proposed as ground cover in landscapes. The objective of this investigation was evaluation of morphological and physiological responses of A. desertorum subjected to drought stress conditions in semiarid regions of Iran. A. desertorum was grown in six replicates and exposed to outdoors by withholding irrigation for 20d until leaf wilting of most plants reach 90% then rewatered for 8d. During the stress period, all traits such as relative water content (RWC), electrolyte leakage (EL), leaf wilting (LW), grass quality (GQ), chlorophyll content (Chl), superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), malondialdehyde (MDA) and proline were measured 5d intervals in this experiment. The results showed that drought stress declined grass quality and chlorophyll content, while electrolyte leakage and leaf wilting increased with prolonged stress treatment. Leaf wilting decreased during rewatering and it was similar to control plants at 8d. Drought stress had no effect on RWC, whereas induced oxidative injury due to increase in lipid peroxidation. Superoxide dismutase (SOD) and catalase (CAT) initially increased and then decreased at 20d, while ascorbate peroxidase (APX) remained unchanged for 10 days and then increased. The higher activities of catalase (CAT), glutathione peroxidase (GPX) and proline content were observed during exposure to drought stress in comparison with control plants. The physiological indicators under drought stress were significantly correlated each other except CAT and SOD. These results suggested that drought tolerance could be related to increase in antioxidant activities and proline content. However, prolonged drought stress suppressed SOD and CAT activities and induced lipid peroxidation.