Response of ROS-Scavenging Systems to Salinity Stress in Two Different Wheat (Triticum aestivum L.) Cultivars

Salinity leads to oxidative stress in plant cells due to increased production of reactive oxygen species. The response of two wheat (Triticum aestivum L.) cultivars, salt sensitive ('Darab2') and salt-tolerant ('Arta') were studied to salinity-induced oxidative stress (0, 75 and 150 mM NaCl). Increasing of lipid peroxidation caused oxidative stress in both sensitive and tolerant cultivars. The result showed that reactive oxygen species (ROS) viz., superoxide and hydrogen peroxide increased in leaves of 'Darab2' under salinity stress. Under salinity stress, the salt-tolerant cv. 'Arta' showed higher activity of the ROS scavenging enzymes like ascorbate peroxidase and peroxidases than 'Darab2'. Furthermore, in sensitive cv. 'Darab2' the activities of these enzymes in leaves were unable to prevent the scavenging of H2O2. Unlike 'Arta', there were no significant differences in superoxide dismutases and glutathione reductase activities in sensitive cv. 'Darab2' under salinity stress. The amount of reduced glutathione, reduced/oxidized glutathione ratio in leaves of 'Darab2' was lower than ` Arta' under saline conditions. It seems that in salt tolerant cultivars like 'Arta', both enzymatic and non-enzymatic ROS scavenging machineries is critical point to overcome salinity-induced oxidative stress.