Hypoxia Induced Changes in the Lipid Peroxidation, Membrane Permeability, Reactive Oxygen Species Generation, and Antioxidative Response Systems in Zea mays Leaves

The effects of hypoxia on the activities of some enzymes of antioxidative, non- enzymatic scavenging system, membrane permeability, lipid peroxidation, and some reactive oxygen species (ROS) in leaves of Zea mays were investigated. Samples were taken 48, 96, 144, and 192 h after the start of hypoxia treatment. A 192 h hypoxia treatment resulted in a significant rise in membrane permeability, lipid peroxidation (malondialdehyde level), and the production of hydrogen peroxide (H2O2) and superoxide (O2) in maize leaves. A short duration of hypoxia enhanced the activity of superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11), and glutathione reductase (GR; EC 1.6.4.2), while further hypoxia significantly decreased the enzyme activity but increased the content of reduced glutathione (GSH) and ascorbic acid (AsA). It was observed that the reduction in SOD activity was greater than that in GR and APX (H2O2 scavengers). Our results showed that O2 induced membrane damage and lipid peroxidation, and that excessive accumulation of O2 is due to the reduced activity of SOD under hypoxia.