Role of Salicylic Acid in Regulating Cadmium Induced Oxidative Stress in Oryza Sativa L. Roots

In the present investigation we studied the role of salicylic acid in cadmium induced physiological and biochemical changes and the possible induction of oxidative stress in developing rice roots. 24h cadmium treatment resulted in the inhibition of root dry biomass, root elongation and increased cadmium accumulation in roots. Salicylic acid presoaking for 16hrs resulted in protection against cadmium, minor changes in root dry biomass, root elongation and minimal accumulation of cadmium. Cadmium applied to salicylic acid free plants increased the level of lipid peroxidation, hydrogen peroxide content and superoxide radical production. Salicylic acid treatment decreased the toxic level of cadmium manifested by lower lipid peroxidation, lesser production of hydrogen peroxide and reduction in the generation of superoxide radical. The extent of membrane integrity loss was higher in salicylic acid free plants compared to salicylic acid treated ones, under cadmium application. To test the antioxidant efficiency of various enzymes, the activity of superoxide dismutase, catalase, peroxidase and glutathione reductase were measured. Higher increase in the activity of these antioxidant enzymes was observed in salicylic acid free plants than in the salicylic treated ones. Elevated level of ascorbate and glutathione was observed in salicylic acid free plants. Glutathione, however, decreased at higher concentration. Data show the potentiating effect of salicylic acid in regulating cadmium induced oxidative stress in Oryza sativa L. roots.