title: Antioxidant response of Phragmites australis to Cu and Cd contamination.
abstract: Metals are known to induce oxidative stress in plant cells. Antioxidant thiolic compounds are known to play an important role in plants׳ defence mechanisms against metal toxicity but, regarding salt marsh plants, their role is still very poorly understood. In this work, the involvement of non-protein thiols (NPT), such as cysteine (Cys), reduced glutathione (GSH), oxidised glutathione (GSSG) and total acid-soluble SH compounds (total thiols), in the tolerance mechanisms of the marsh plant Phragmites australis against Cu and Cd toxicity was assessed. Specimens of this plant, freshly harvested in an estuarine salt marsh, were exposed, for 7 days, to rhizosediment soaked with the respective elutriate contaminated with Cu (0, 10 and 100 mg/L) or Cd (0, 1, 10 mg/L). In terms of NPT production, Cu and Cd contamination induced different responses in P. australis. The content of Cys increased in plant tissue after plant exposure to Cu, whereas Cd contamination led to a decrease in GSSG levels. In general, metal contamination did not cause a significant variation on GSH levels. Both metals influenced, to some extent, the production of other thiolic compounds. Despite the accumulation of considerable amounts of Cu and Cd in belowground tissues, no visible toxicity signs were observed. So, antioxidant thiolic compounds were probably involved in the mechanisms used by P. australis to alleviate metal toxicity. As P. australis is considered suitable for phytostabilising metal-contaminated sediments, understanding its tolerance mechanisms to toxic metals is important to optimise the conditions for applying this plant in phytoremediation procedures.
authors.affiliation: CIIMAR/CIMAR and Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal. Electronic address: cristinasrocha@gmail.com.
authors.forename: A Cristina S
authors.initials: AC
authors.lastname: Rocha
authors.affiliation: Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal.
authors.forename: C Marisa R
authors.initials: CM
authors.lastname: Almeida
authors.affiliation: CIIMAR/CIMAR and Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
authors.forename: M Clara P
authors.initials: MC
authors.lastname: Basto
authors.affiliation: Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal.
authors.forename: M Teresa S D
authors.initials: MT
authors.lastname: Vasconcelos
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002104:Cadmium / Q000633:toxicity*; D003300:Copper / Q000633:toxicity*; D003545:Cysteine / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D006109:Poaceae / Q000187:drug effects* / Q000378:metabolism; D012989:Soil Pollutants / Q000633:toxicity*; D053833:Wetlands
chemical_list: D000975:Antioxidants; D012989:Soil Pollutants; D002104:Cadmium; D003300:Copper; D005978:Glutathione; D003545:Cysteine; D019803:Glutathione Disulfide
keywords: Cysteine; Oxidised glutathione; Phragmites australis; Reduced glutathione