Antioxidative defense system in lupin roots exposed to increasing concentrations of lead

    loading  Checking for direct PDF access through Ovid

Abstract

Yellow lupin (Lupinus luteus) cv. Juno seedlings exposed to increasing concentrations of Pb2+ (50-350 mg l-1) were analysed in respect to its effect on the degradation of lipids, the content of antioxidants (ascorbate, α-tocopherol) and the activity of the ascorbate glutathione cycle enzymes (dehydroascorbate reductase DAR; EC 1.8.5.1 and glutathione reductase GR; EC 1.6.4.2). Lipid peroxidation, expressed as the content of TBArm (thiobarbituric acid reactive metabolites), increased only at 50 and 100 mg l-1 Pb2+, whereas at higher lead concentrations it decreased as compared with the control. The level of free fatty acids was not significantly affected as a result of Pb2+ exposure, except for 300 mg l-1 Pb2+. The content of α-tocopherol increased significantly at the range of concentrations between 150 and 300 mg l-1 and at these concentrations lipid peroxidation was inhibited. Ascorbic acid (AA) and dehydroascorbic acid (DHA) content increased considerably in roots treated with 100 and 150 mg l-1 Pb2+. In general the activity of DHAR and GR was stimulated by lead, however at higher Pb2+ concentrations (300 and 350 mg l-1) GR revealed lower enzymatic activity. Our results suggest that in lead-treated roots lipids might be protected against reactive oxygen species (ROS) by lipid-soluble molecules of α-tocopherol and this direct defense seems to be supported by AA as well as the enzymes: DHAR and GR.

    loading  Loading Related Articles