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RESPONSE OF OXIDATIVE STRESS DEFENSE SYSTEMS IN RICE (ORYZA SATIVA) LEAVES WITH SUPPLEMENTAL UV-B RADIATION
Citation:
Dai, Q., B. Yan, S. Huang, X. Liu, S. Peng, M. L. Miranda, A. Q. Chavez, B. S. Vergara, AND D. Olszyk. RESPONSE OF OXIDATIVE STRESS DEFENSE SYSTEMS IN RICE (ORYZA SATIVA) LEAVES WITH SUPPLEMENTAL UV-B RADIATION. Physiologia Plantarum 101(2):301-308, (1997).
Description:
The impact of elevated ultraviolet-B radiation (UV-B, 280-320 nm) on membrane systems and lipid peroxidation, and possible involvement of active oxygen radicals was investigated in leaves of two UV-B susceptible rice cultivars (Oryza sativa L. cvs IR74 and Dular). Rice seedlings were grown in a greenhouse for 10 days and then treated with biologically effective UV-B(UV-B-BE)radiation for 28 days. Oxidative stress effects were evaluated by measuring superoxide anion (0-2-) generation rate, hydrogen peroxide (H-20-2) content, malondialdehyde (MDA) concentration and relative electrolyte conductivity (EC) for IR74 and Dular at 0 (control), 6 or 13 kJ m-2 day-1 UV-B-BE. Significant increases in these parameters were found in rice plants grown at 13 vs 0 kJ m-2 day-1 UV-BOO after 28 days; indicating that disruption of membrane systems may be an eventual reason for UV-B-induced injury in rice plants. There was a positive correlation between 0-2-generation and increases in EC or MDA in leaves. Activities of catalase and superoxide dismutase (but not ascorbate peroxidase)and concentrations of ascorbic acid and glutathione were enhanced by 13 vs 0 UV-B-BE after 14 days of UV-B exposure. Further exposure to 28 days of UV-B was associated with a decline in enzyme activities and ascorbic acid, but not glutathione. It is suggested that UV-B-induced injury may be associated with disturbance of active oxygen metabolism through the destruction and alteration of both enzymatic and nonenzymatic defense systems in rice.