Cadmium-induced oxidative damage is reduced by nitric oxide in sunflower plants

N.V. LASPINA; M.D. GROPPA; M.L. TOMARO; M.P. BENAVIDES

Viena, Austria

Congreso; 9th International Congress on Amino Acids and Proteins.; 2005

Cadmium (Cd) is a heavy metal present in soils, toxic for humans, animals and plants at very low concentrations. Nitric oxide is a bioactive free radical involved in many physiological responses. Cadmium toxicity and NO protection were evaluated in relation to some antioxidant parameters, as soluble and enzymatic antioxidants, in sunflower leaves, after 10 days of treatment with 0.5 mM Cd2Cl, in plants pretreated for 7 days with 100 µM SNP (as NO donor). Plant growth (DW) was significantly reduced by Cd and was recovered in plants pretreated with NO. Chlorophyll content decreased to 48% and TBARS increased 33% over the controls, but NO returned their contents to 88% and 100% of the C. Ascorbate peroxidase (APOX) and superoxide dismutase (SOD) activities increased significantly with Cd, while CAT and GPOX activities decreased. Glutathione (GSH) content was lower and ascorbic acid (AsA) content was higher than controls in Cd-treated plants. Nitric oxide pretreatment alone did not modify the studied parameters respect to the control, except for APOX activity and AsA content, which increased even in the absence of the metal. SOD activity was reduced to C levels, CAT and GPOX activities were returned to values close to the controls, while GSH decline was reverted by NO pretreatment. In the present work, we present evidence of the protection exerted by NO against the oxidative stress and toxicity induced by Cd on sunflower leaves.