Oxidative damage and antioxidant response caused by excess copper in leaves of maize

Abstract

Adequate copper (Cu²⁺) concentrations are required for plants, but at higher concentrations it can cause toxic effects. In this study, physiological parameters and antioxidant enzymes were assayed in the leaves of maize variety Zhendan958, which is one of the dominant cultivar of maize (Zea mays L.) in China due to its better traits in production, after the seedling was treated with 2 to 8 mM Cu for 96 h. Cu inhibited the bioaccumulation of leaf biomass, but increased the accumulation of Cu in leaves. In addition, Cu stress induced the generation of O₂- and H₂O₂ as revealed by the histochemical staining and increased malondialdehyde content. It also stimulated the activity of superoxide dismutase, peroxidase,  ascorbate peroxidase, glutathione reductase and glutathione   S-transferase. Cu stress altered the content of glutathione (GSH) and ascorbic acid (AsA) significantly. These demonstrated that Cu induced the oxidative stress on seedlings of Zhendan958, while the heated antioxidant
responses indicated a bioaccumulation potential of this cultivar in the phytoremediation of Cu contaminated soils.

Key words: Maize, superoxide dismutase, peroxidase, ascorbate peroxidase, glutathione reductase, glutathione S-transferase.