title: Assessment of the role of silicon in the Cu-tolerance of the C4 grass Spartina densiflora.
abstract: An experiment was designed to investigate the effect of silicon supply (0 and 500 μM) on Spartina densiflora plants grown at two copper (Cu) concentrations: 0 and 15 mM. Growth parameters together with total concentrations of calcium, Cu, potassium, magnesium, manganese, sodium and nitrogen were determined in roots and leaves. Photosynthetic traits were followed by measurement of leaf gas exchange, efficiency of PSII biochemistry, total content of photosynthetic pigments and concentration and carbamylation of Rubisco sites concentration ([Rubisco]). Respiration and oxygen isotope fractionation were measured in roots to study the in vivo activities of cytochrome oxidase (COX) and alternative oxidase (AOX) pathways, as well as AOX capacity. The results confirm that Si supply improves growth of S. densiflora under Cu stress. Improved growth was associated with higher net photosynthetic rate. Beneficial effect of Si on S. densiflora photosynthetic apparatus was associated with a reduction of the Cu impact on active Rubisco sites, as well as on the photochemical apparatus and chlorophyll concentration. Moreover, ameliorative effects of Si were associated with the avoidance of Cu translocation from roots to leaves. Finally in vivo activities of COX and AOX pathways were strongly inhibited in Cu-treated plants, and this reduction was not mitigated by Si-treatment. Therefore, Si appears to play an important role in Cu-tolerance of S. densiflora, not by avoiding its uptake by roots, but via some mechanism to avoid Cu translocation from roots to leaves, resulting in a general reduction of Cu-induced deleterious effects on the leaf photosynthetic apparatus.
authors: Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, 1095, 41080 Sevilla, Spain. Electronic address: emana@us.es.
authors: Enrique
authors: E
authors: Mateos-Naranjo
authors: Grup de Recerca en Biologia de les Plantes Mediterrànies, Departament de Biologia (UIB-IMEDEA), Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors: Alexander
authors: A
authors: Gallé
authors: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
authors: Igor
authors: I
authors: Florez-Sarasa
authors: Grup de Recerca en Biologia de les Plantes Mediterrànies, Departament de Biologia (UIB-IMEDEA), Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors: Juan Alejandro
authors: JA
authors: Perdomo
authors: Grup de Recerca en Biologia de les Plantes Mediterrànies, Departament de Biologia (UIB-IMEDEA), Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors: Jeroni
authors: J
authors: Galmés
authors: Grup de Recerca en Biologia de les Plantes Mediterrànies, Departament de Biologia (UIB-IMEDEA), Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors: Miquel
authors: M
authors: Ribas-Carbó
authors: Grup de Recerca en Biologia de les Plantes Mediterrànies, Departament de Biologia (UIB-IMEDEA), Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
authors: Jaume
authors: J
authors: Flexas
mesh_terms: D003300:Copper / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D006109:Poaceae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D012825:Silicon / Q000494:pharmacology*
chemical_list: D003300:Copper; D012825:Silicon
keywords: Cu-stress; Growth rate; Photosynthesis; Root respiration; Rubisco; Silicon