Effect of heavy metal ion excess on sunflower leaves: evidence for involvement of oxidative stress

• Published in: Plant science (Limerick) 1996-12, Vol.121 (2), p.151-159
• Main Authors: Gallego, Susana M., Benavídes, María P., Tomaro, María L.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Antioxidants; Applied ecology; Biological and medical sciences; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Fundamental and applied biological sciences. Psychology; Heavy metals; Helianthus annuus; Oxidative stress
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/S0168-9452(96)04528-1

The relationship between heavy metal ion toxicity and oxidative stress in plant cells was studied. Leaf segments from 14 day old sunflower seedlings were incubated in solutions containing 0.5 mM Fe(II), Cu(II) or Cd(II) ions for 12 h in the light. Treatment with metal ions studied produced a decrease in chlorophyll and GSH contents as well as increases in lipid peroxidation and lipoxygenase activity. Free radical scavengers, such as sodium benzoate and mannitol, prevented the decrease in chlorophyll and GSH content and the lipid peroxidation and lipoxygenase increases. While Fe(II) and Cd(II) ions caused a decrease in superoxide dismutase activity, Cu(II) ions raised its level. However, all three metal ions caused decreases in other antioxidant enzymes (catalase, ascorbate peroxidase, glutathione reductase and dehydroascorbate reductase). Free radical scavengers protected these enzymes against inactivation. No effect of these scavengers was observed on superoxide dismutase activity. These results indicate that excess Fe(II), Cu(II) or Cd(II) ions produce oxidative damage in plant leaves.