ROS Scavenging and Nitrogen Fertilizer Roles in Alleviation of Cd-Induced Oxidative Stress in Arabidopsis thaliana

Arabidopsis thaliana (L.) Heynh. receiving ammonium, were transferred on modified Hoagland nutrient solution containing Cd (25 mu M) alone or supplemented with buthionine sulfoximine (BSO, an inhibitor of glutathione synthesis). In ammonium-fed A. thaliana treated with Cd alone, leaf and root growth was not negatively affected. Carbon metabolism was stimulated through activation of Rubisco and maintain of phosphoenol pyruvate carboxylase (PEP) and NADP(+)-isocitrate dehydrogenase (NADP(+)-ICDH). In another way, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (GPX), and ascorbate-glutathione-regenerating enzymes (glutathione reductase (GR), dehydroascorbate reductase(DHAR) and monodehydroascorbate reductase (MDHAR) activities were stimulated by Cd. Ascorbate (AsA) and dehydroascorbate (DHA) contents were significantly raised. More that, the high NAD/NADH ratio in Cd-treated A. thaliana fed with ammonium proved the capacity of leaf cells to maintain NAD homeostasis under stressful conditions. The dramatic effect of BSO when added currently with Cd was reflected by the imbalance of all the patterns shown and described previously. Growth was inhibited in parallel to MDA and H2O2 accumulation. Carbon metabolism, ascorbate-glutathione-regenerating and antioxidative enzymes were all reduced. Revealing that alleviation of Cd toxicity by ammonium nitrogen is due to a beneficial relationship between carbon metabolism activation and ROS production minimization also than there may be scavenging enhancement.