The Role of Nano-Chelated Iron in Modulating the Oxidative Stress Pathway of Lettuce (Lactuca Sativa L.) Under Cadmium Stress

Cadmium (Cd2+) is a toxic heavy metal that causes environmental pollution. Its high concentrations impede the growth, biochemical and physiological characteristics of plants. Among the micronutrient elements, iron has the potential to minimize the harmful effects of cadmium, limit its entry into the human diet, improve growth characteristics and increase the antioxidant potential of plants. In the present study, lettuce plants were treated with different concentrations of cadmium chloride (CdCl2), nano-chelated iron. The interaction effect of cadmium + nano-chelated iron was also evaluated. In the presence of cadmium, growth indices decreased, whereas application of nano-chelated iron to plants under cadmium stress improved growth parameters. In combination treatments of cadmium and nano-chelated iron, the activity of antioxidant enzymes such as catalase (CAT; EC 1.11.1.6), peroxidase (POD; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1), and ascorbate peroxidase (APX; EC 11.1.11.1), proline content, relative water content (RWC), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity increased compared to plants treated with cadmium alone. The application of nano-chelated iron in plants treated with cadmium resulted in a decrease in hydrogen peroxide (H2O2) and malondialdehyde (MDA). In general, the data revealed that the supply of nano-chelated iron synergistically minimized the toxicity and destructive effects of cadmium in the redox pathways of the lettuce plant. Additionally, the application of nano-chelated iron on plants under cadmium stress can introduce new ways to manage/mitigate oxidative stress caused by abiotic stressors.