Antioxidant response of <i>Lepidium sativum</i> L. to oxidative stress induced by exposure to chosen heavy metals

Abstract Soil contamination with heavy metals is a significant concern, resulting in adverse effects on soil properties and limitations on both its productivity and its environmental capabilities. The aim of this study was to determine the response of Lepidium sativum L. to oxidative stress induced by the addition of zinc (Zn), nickel (Ni) and copper (Cu) separately to the soil in which the plants were cultivated. The range of metal ion concentrations was determined in accordance with the soil quality standards set by the Ministry of Environmental Regulation (Dz.U.02.165.1359) on September 9, 2002. The quantity and activity of selected antioxidants belonging to enzymatic and non-enzymatic antioxidant systems were then evaluated. This study compared the antioxidant responses of the plant to different heavy metals. Based on the obtained results, it can be seen that heavy metal ions induced oxidative stress, which caused an activation of the antioxidant response system through the enhanced production of secondary metabolites such as phenolic compounds, ascorbic acid, and glutathione, as well as an increase in the activity of particular enzymes: catalase (CAT), superoxide dismutase (SOD), guaiacol peroxidase (POD), and glutathione transferase (GSTs). It can thus be concluded that in response to oxidative stress caused by Zn, Ni and Cu, L. sativum plants have evolved efficient enzymatic and non-enzymatic defence mechanisms to counteract the excessive production of reactive oxygen species. These responses allow plants to survive in adverse environmental conditions and help us evaluate whether the imposed standards influenced L. sativum’s metabolic changes.