Copper toxicity in expanding leaves of Phaseolus vulgaris L.: antioxidant enzyme response and nutrient element uptake

• Published in: Ecotoxicology and environmental safety 2010-09, Vol.73 (6), p.1304-1308
• Main Authors: Bouazizi, Houda, Jouili, Hager, Geitmann, Anja, El Ferjani, Ezzeddine
• Format: Article
• Language: English
• Subjects: Antioxidants; Antioxidants - metabolism; CAT; Catalase - metabolism; Copper; Copper - pharmacokinetics; Copper - toxicity; Glutathione Peroxidase - metabolism; GPX; Growth; H2O2; Iron - metabolism; Lipid Peroxidation - drug effects; MDA; Mineral nutrition; Phaseolus - drug effects; Phaseolus - enzymology; Phaseolus - growth & development; Phaseolus - metabolism; Phaseolus vulgaris; Phaseolus vulgaris L; Plant Leaves - drug effects; Plant Leaves - enzymology; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Physiological Phenomena - drug effects; Potassium - metabolism; Soil Pollutants - pharmacokinetics; Soil Pollutants - toxicity; Young leaves; Zinc - metabolism
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2010.05.014

Bioaccumulation and toxicity of copper (CuSO4) were assessed in expanding leaves of 14-day-old bean seedlings. CuSO4 was administrated in the growth medium for three days and changes in the activities of the antioxidant enzymes guaiacol peroxidase (GPX) and catalase (CAT), and in the H2O2 production and mineral element contents were measured. Copper accumulated in exposed plants caused severe symptoms such as chlorosis and necrosis as well as a dramatic reduction in dry weight production. Simultaneously, concentrations of iron, zinc and potassium were reduced significantly suggesting that a change in nutrient homeostasis may be responsible for the observed symptoms. Contrary to mature tissues, the expanding leaves did not display significant oxidative stress, since malondialdehyde (MDA) content was unchanged, the activities of GPX and CAT were lowered or unaltered, and endogenous H2O2 only increased at high copper concentrations. Our results suggest that while excess copper slightly alters the activity of the antioxidative enzyme system in young expanding leaves of bean plants, it exerts its toxicity primarily through causing a disturbance in the nutrient balance.