Response of Antioxidative Enzymes to Cadmium Stress in Leaves and Roots of Radish (Raphanus sativus L.)

Abstract

Presented study has demonstrated that exposure of plants to toxic heavy metal Cd results a reduction in plant growth. Varied concentrations of CdCl2, ranging from 0.0 to 50 ppm in the germinating media reduced leaf area of radish plant, chlorophyll and carotenoid contents. Greater loss of chlorophyll b content than chlorophyll a was observed especially under 50 ppm Cd exposure. With regards to the distribution of Cd in roots and leaves, the obtained data showed that the maximum accumulation of Cd occurred in roots followed by leaves. Generally, Fe, Zn, Mn and Cu declined in leaves compared to the roots. Furthermore, substantial increases were observed in antioxidant enzymes, such as catalase (CAT), glutathione S-transferase (GST) and peroxidase (POD), in Cd-stressed plants in comparison with control. The Cd stress also induced several changes in CAT and POD isozyme profiles and enhanced their activities. The results suggest that the reduction of leaf area and pigment content together with antioxidant enzymes and isozyme patterns can be used as indicators to Cd contamination.