Antioxidant system activation by mercury in Pfaffia glomerata plantlets

• Published in: Biometals 2010-04, Vol.23 (2), p.295-305
• Main Authors: Calgaroto, N. S, Castro, G. Y, Cargnelutti, D, Pereira, L. B, Gonçalves, J. F, Rossato, L. V, Antes, F. G, Dressler, V. L, Flores, E. M. M, Schetinger, M. R. C, Nicoloso, F. T
• Format: Article
• Language: English
• Subjects: Amaranthaceae - anatomy & histology; Amaranthaceae - drug effects; Amaranthaceae - metabolism; Antioxidants; Antioxidants - metabolism; Ascorbic Acid - metabolism; Biochemistry; Biomedical and Life Sciences; Botany; Carotenoids - metabolism; Cell Biology; Chlorophyll - metabolism; Hydrogen Peroxide - metabolism; Life Sciences; Lipid Peroxidation; Medicine/Public Health; Mercury; Mercury - pharmacology; Microbiology; Oxidants - metabolism; Oxidation; Oxidative Stress; Peroxidation; Pharmacology/Toxicology; Plant Physiology; Plant Roots - drug effects; Plant Roots - growth & development; Plant Roots - metabolism; Plant Shoots - drug effects; Plant Shoots - growth & development; Plant Shoots - metabolism; Roots; Shoots; Superoxide Dismutase - metabolism; Toxicology
• ISSN: 0966-0844; 1572-8773
• DOI: 10.1007/s10534-009-9287-3

Oxidative stress caused by mercury (Hg) was investigated in Pfaffia glomerata plantlets grown in nutrient solution using sand as substrate. Thirty-day-old acclimated plants were treated for 9 days with four Hg levels (0, 1, 25 and 50 μM) in the substrate. Parameters such as growth, tissue Hg concentration, toxicity indicators (δ-aminolevulinic acid dehidratase, δ-ALA-D, activity), oxidative damage markers (TBARS, lipid peroxidation, and H₂O₂ concentration) and enzymatic (superoxide dismutase, SOD, catalase, CAT, and ascorbate peroxidase, APX) and non-enzymatic (non-protein thiols, NPSH, ascorbic acid, AsA, and proline concentration) antioxidants were investigated. Tissue Hg concentration increased with Hg levels. Root and shoot fresh weight and δ-ALA-D activity were significantly decreased at 50 μM Hg, and chlorophyll and carotenoid concentration were not affected. Shoot H₂O₂ concentration increased curvilinearly with Hg levels, whereas lipid peroxidation increased at 25 and 50 μM Hg, respectively, in roots and shoots. SOD activity showed a straight correlation with H₂O₂ concentration, whereas CAT activity increased only in shoots at 1 and 50 μM Hg. Shoot APX activity was either decreased at 1 μM Hg or increased at 50 μM Hg. Conversely, root APX activity was only increased at 1 μM Hg. In general, AsA, NPSH and proline concentrations increased upon addition of Hg, with the exception of proline in roots, which decreased. These changes in enzymatic and non-enzymatic antioxidants had a significant protective effect on P. glomerata plantlets under mild Hg-stressed conditions.