title: Zinc tolerance modulation in Myracrodruon urundeuva plants.
abstract: We investigated Zn tolerance and related tolerance mechanisms of Myracrodruon urundeuva by evaluating the growth (biomass production, pigment content, and photosynthetic activity) and antioxidant systems (redox potential and antioxidant enzyme activities) of seedlings exposed to increasing Zn doses. Plants were grown for 120 days in substrates with 0, 50, 80, 120 and 200 mg Zn kg(-1) and demonstrated Zn-tolerance. Zn doses greater than 80 mg Zn kg(-1) were phytotoxic but not lethal, and Zn toxicity under these conditions was imposed by oxidative stress caused by hydrogen peroxide (H2O2) accumulation and related lipid peroxidation. Zn tolerance in M. urundeuva is linked to the activity of antioxidant systems in their leaves that are modulated by that metal: both superoxide dismutase (SOD) and catalase (CAT) were always higher in the presence of Zn; lower Zn doses stimulated ascorbate peroxidase (APX) and glutathione reductase (GR) activities, but enzyme activity was inhibited at high doses; APX appeared to be the main peroxidase in H2O2 scavenging as stimulated guaiacol peroxidase (GPX) activity was not sufficient to avoid H2O2 accumulation at higher Zn doses; the modulation of APX and GR activities was linked to changes in the redox status of leaves.
authors.affiliation: Université du Québec à Montréal, Institut des Sciences de l'environnement, Succ. Centre-Ville, C.P. 8888, H3C 3P8 Montréal, Québec, Canada; Universidade Federal de Lavras, Departamento de Biologia, Campus UFLA, C.P. 3037, 37200-000 Lavras, MG, Brazil. Electronic address: marcelopgom@yahoo.com.br.
authors.forename: M P
authors.initials: MP
authors.lastname: Gomes
authors.affiliation: Universidade Federal de Minas Gerais, Departamento de Botânica, C.P. 486, 31270-970 Belo Horizonte, MG, Brazil.
authors.forename: D M
authors.initials: DM
authors.lastname: Duarte
authors.affiliation: Universidade Federal de Lavras, Departamento de Biologia, Campus UFLA, C.P. 3037, 37200-000 Lavras, MG, Brazil.
authors.forename: M M L C
authors.initials: MM
authors.lastname: Carneiro
authors.affiliation: Universidade Federal de Minas Gerais, Departamento de Botânica, C.P. 486, 31270-970 Belo Horizonte, MG, Brazil.
authors.forename: L C
authors.initials: LC
authors.lastname: Barreto
authors.affiliation: Universidade Federal de Lavras, Departamento de Biologia, Campus UFLA, C.P. 3037, 37200-000 Lavras, MG, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Carvalho
authors.affiliation: Universidade Federal de Lavras, Departamento de Biologia, Campus UFLA, C.P. 3037, 37200-000 Lavras, MG, Brazil.
authors.forename: A M
authors.initials: AM
authors.lastname: Soares
authors.affiliation: Universidade Federal de Lavras, Departamento de Ciência do Solo, Campus UFLA, 37200-000 Lavras, MG, Brazil.
authors.forename: L R G
authors.initials: LR
authors.lastname: Guilherme
authors.affiliation: Universidade Federal de Minas Gerais, Departamento de Botânica, C.P. 486, 31270-970 Belo Horizonte, MG, Brazil.
authors.forename: Q S
authors.initials: QS
authors.lastname: Garcia
mesh_terms: D027926:Anacardiaceae / Q000187:drug effects / Q000378:metabolism*; D060387:Ascorbate Peroxidases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology*
chemical_list: D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D015032:Zinc
keywords: Antioxidant; Enzymes; Glutathione; Tolerance; Trace element; Zinc