Cadmium accumulation and antioxidative defenses in leaves of Triticum aestivum L. and Zea mays L.
Corn (Zea Mays L.) and wheat (Triticum aestivum L. ) seedlings were grown in four cadmium (Cd) concentration levels (0 - 1 mg/l) in a hydroponic system to analyze the antioxidant enzyme system, Cd concentration in the shoots and roots of plants, proline contents, growth responses and chlorophyll contents in the leaves of corn and wheat. The results showed that there was a significant increase in malondialdehyde (MDA) concentration from 0 to 1 mg/l, and peroxidase (POD) and catalase (CAT) activities in the corn and wheat subjected to 0 – 1 mg/l of Cd. However, there was a significant decrease in the superoxide dismutase (SOD) activities in the corn and wheat subjected to 0 - 1 mg/l of Cd. This indicated that Cd stress induced an oxidative stress response in corn and wheat seedlings, characterized by an accumulation of MDA, decrease in the activities of SOD and increase in the activities of POD and CAT. Root and leaf Cd concentrations of corn and wheat increased with their exposure to the Cd level,s and the highest Cd concentration occurred in roots, followed by the leaves. An increase in proline in the leaves of corn and wheat seedlings exposed to Cd occurred as well as a decrease in chlorophyll (CHL) contents and shoots and roots biomass. Thus, Cd levels negatively affected the corn and wheat seedlings growth.
Key words: Cadmium, corn (Zea mays L.), wheat (Triticum aestivum L.).