Cupric stress induces oxidative damage marked by accumulation of H2O2 and changes to chloroplast ultrastructure in primary leaves of beans ( Phaseolus vulgaris L.).
The effect of copper excess (CuSO 4 ) on lipid peroxidation, H2O2 content, and antioxidative enzyme activities was studied in primary leaves of bean seedlings. Fourteen-day-old bean seedlings were cultured in a nutrient solution containing Cu 2+ at various concentrations (50 and 75 microM) for 3 days. Excess of copper significantly increased malondialdehyde content and endogenous H2O2 . This radical accumulated in the intercellular spaces of palisade mesophyll cells. In addition, cupric stress induced changes in antioxidant enzyme activities. GPX (guaiacol peroxidase, EC 1.11.1.7) activity was decreased in 50 microM Cu-stressed leaves whereas 75 microM of CuSOP 4 resulted in an increase of enzyme activity. On the contrary, CAT (catalase, EC 1.11.1.6) activity was stimulated at 50 microM CuSO 4 but unaltered at 75 microM CuSO 4 . Transmission electron microscopy revealed that excess copper induced changes in the ultrastructure of chloroplasts visible in form of a deterioration in the grana structure and the accumulation and swelling of starch grains in the stroma.
Faculty of Sciences Bizerte Laboratory of Bio-Cell Physiology 7021 Zarzouna Tunisia.
Houda
H
Bouazizi
Hager
H
Jouili
Anja
A
Geitmann
Ezzeddine
E
Ferjani
D000975:Antioxidants / Q000737:chemistry; D002736:Chloroplasts / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure*; D003300:Copper / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007887:Fabaceae / Q000187:drug effects* / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology*; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000494:pharmacology; D046529:Microscopy, Electron, Transmission / Q000379:methods; D018384:Oxidative Stress; D018515:Plant Leaves / Q000187:drug effects* / Q000378:metabolism*; D012639:Seeds / Q000378:metabolism; D013213:Starch / Q000737:chemistry
D000975:Antioxidants; D008315:Malondialdehyde; D003300:Copper; D013213:Starch; D006861:Hydrogen Peroxide