Comparison of antioxidant responses to cadmium and lead in Bruguiera gymnorrhiza seedlings

Abstract

Seedlings of mangrove plant Bruguiera gymnorrhiza cultured in sand with Hoagland's nutrient solution were treated with 1 to 30 mM Cd(NO3)2 or Pb(NO3)2 for 2 months. In all Cd/Pb treatments, the malondialdehyde content increased while the chlorophyll content declined. Peroxidase (POD) and superoxide dismutase (SOD) activities in roots increased at moderate Cd/Pb concentrations (1-10 mM), whereas decreased at higher concentrations (20-30 mM). Catalase (CAT) activity in roots was inhibited by 1-10 mM Cd but enhanced by 1-10 mM Pb. The activities of POD, SOD and CAT in leaves were less affected by Cd and Pb than in roots. A new SOD and three CAT isoenzymes were induced by Pb. In contrast, no additional SOD and CAT isoenzymes were induced by Cd.

Keywords

• antioxidant enzymes
• catalase
• mangrove
• peroxidase
• superoxide dismutase