title: Antioxidant system activation by mercury in Pfaffia  glomerata plantlets.
abstract: 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 microM) in the substrate. Parameters such as growth, tissue Hg concentration, toxicity indicators (delta-aminolevulinic acid dehidratase, delta-ALA-D, activity), oxidative damage markers (TBARS, lipid peroxidation, and H(2)O(2) 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 delta-ALA-D activity were significantly decreased at 50 microM Hg, and chlorophyll and carotenoid concentration were not affected. Shoot H(2)O(2) concentration increased curvilinearly with Hg levels, whereas lipid peroxidation increased at 25 and 50 microM Hg, respectively, in roots and shoots. SOD activity showed a straight correlation with H(2)O(2) concentration, whereas CAT activity increased only in shoots at 1 and 50 microM Hg. Shoot APX activity was either decreased at 1 microM Hg or increased at 50 lM Hg. Conversely, root APX activity was only increased at 1 microM 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.
authors.affiliation: Departamento de Biologia, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS 97105-900, Brazil.
authors.forename: N S
authors.initials: NS
authors.lastname: Calgaroto
authors.forename: G Y
authors.initials: GY
authors.lastname: Castro
authors.forename: D
authors.initials: D
authors.lastname: Cargnelutti
authors.forename: L B
authors.initials: LB
authors.lastname: Pereira
authors.forename: J F
authors.initials: JF
authors.lastname: Gonçalves
authors.forename: L V
authors.initials: LV
authors.lastname: Rossato
authors.forename: F G
authors.initials: FG
authors.lastname: Antes
authors.forename: V L
authors.initials: VL
authors.lastname: Dressler
authors.forename: E M M
authors.initials: EM
authors.lastname: Flores
authors.forename: M R C
authors.initials: MR
authors.lastname: Schetinger
authors.forename: F T
authors.initials: FT
authors.lastname: Nicoloso
mesh_terms: D027703:Amaranthaceae / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism*; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation; D008628:Mercury / Q000494:pharmacology*; D016877:Oxidants / Q000378:metabolism; D018384:Oxidative Stress; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016877:Oxidants; D002734:Chlorophyll; D002338:Carotenoids; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D008628:Mercury; D001205:Ascorbic Acid