Induction of oxidative stress in barley by drought and chilling

Abstract

Environmental stresses such as draught, chilling, salinity, high light induce oxidative stress in plants (1). The measurements of reactive oxygen species (ROS) and lipid peroxidation provide information about oxidative state of the exposed plants (2). Peroxidases are important antioxidant enzymes with role in utilizing H202 (3). In this work we investigated the effect of draught and chilling on barley seedlings. Plants were grown in growth chamber with a light intensity of 100 µmol m-2 sec-1 at 22°C and 80% humidity for seven days on a 16/8-hour day/night cycle. Draught was induced by omitting water for 10 days while maintaining normal humidity, temperature, and 16/8 day/night light cycle. For induction of chilling stress plants were exposed to 0°C for 4 h prior to measurements. We measured level of thiobarbituric acid reactive substances (TBARS) as a marker of lipid peroxidation, concentration of hydrogen peroxide and activity of total peroxidases using guiacol as a substrate. Results showed that both stresses induced oxidative damage of membranes by increasing lipid peroxidation levels. Higher levels were observed in plant exposed to chilling stress in comparison with drought. Concentration of H2O2 and activity of guiaiacol peroxidase were higher in plants exposed to draught. These observed differences could be due to the time of exposure to the particular stress as well as barley genotype.