title: Evaluation of nickel tolerance in Amaranthus paniculatus L. plants by measuring photosynthesis, oxidative status, antioxidative response and metal-binding molecule content.
abstract: Among metals, Ni has been indicated as one of the most dangerous for the environment, and plants exposed to this metal are frequently reported to undergo a severe stress condition. In this work, the tolerance responses to different Ni concentrations at physiological and biochemical levels were evaluated in Amaranthus paniculatus L., a plant species previously characterised for their ability to phytoremove Ni from metal-spiked water. Results indicated a good metal tolerance of this plant species at environmentally relevant Ni concentrations, while clear symptoms of oxidative damages were detected at higher Ni concentrations, both in roots and leaves, by measuring lipid peroxide content. At the photosynthetic level, pigment content determination, chlorophyll fluorescence image analysis and gas-exchange parameter measurements revealed a progressive impairment of the photosynthetic machinery at increasing Ni concentrations in the solution. Regarding biochemical mechanisms involved in antioxidative defence and metal binding, antioxidative enzyme (ascorbate peroxidase, APX; catalase, CAT; guaiacol peroxidase, GPX; superoxide dismutase, SOD) activity, polyamine (PA) content, polyamine oxidase (PAO) activity and organic acid (OA) content were differently affected by Ni concentration in the growth solution. A role for GPX, SOD, PAs, and oxalic and citric acid in Ni detoxification is suggested. These results can contribute to elucidate the tolerance mechanisms carried out by plants when facing environmentally relevant Ni concentrations and to identify some traits characterising the physiological and biochemical responses of Amaranthus plants to the presence and bioaccumulation of Ni.
authors: Institute of Agro-environmental and Forest Biology, National Research Council of Italy, Via Salaria Km 29,300, 00015, Monterotondo Scalo, RM, Italy.
authors: Fabrizio
authors: F
authors: Pietrini
authors: Valentina
authors: V
authors: Iori
authors: Alexandra
authors: A
authors: Cheremisina
authors: Nina I
authors: NI
authors: Shevyakova
authors: Nataliya
authors: N
authors: Radyukina
authors: Vladimir V
authors: VV
authors: Kuznetsov
authors: Massimo
authors: M
authors: Zacchini
mesh_terms: D000222:Adaptation, Physiological; D027721:Amaranthus / Q000187:drug effects / Q000378:metabolism*; D000975:Antioxidants / Q000378:metabolism; D060387:Ascorbate Peroxidases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D009532:Nickel / Q000378:metabolism / Q000494:pharmacology*; D018384:Oxidative Stress; D009195:Peroxidase / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism; D012989:Soil Pollutants / Q000378:metabolism / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D011073:Polyamines; D012989:Soil Pollutants; D009532:Nickel; C121048:guaiacol peroxidase; D060387:Ascorbate Peroxidases; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase