title: Root based responses account for Psidium guajava survival at high nickel concentration.
abstract: The presence of Psidium guajava in polluted environments has been reported in recent studies, suggesting that this species has a high tolerance to the metal stress. The present study aims at a physiological characterization of P. guajava response to high nickel (Ni) concentrations in the root-zone. Three hydroponic experiments were carried out to characterize the effects of toxic Ni concentrations on morphological and physiological parameters of P. guajava, focusing on Ni-induced damages at the root-level and root ion fluxes. With up to 300μM NiSO4 in the root-zone, plant growth was similar to that in control plants, whereas at concentrations higher than 1000μM NiSO4 there was a progressive decline in plant growth and leaf gas exchange parameters; this occurred despite, at all considered concentrations, plants limited Ni(2+) translocation to the shoot, therefore avoiding shoot Ni(2+) toxicity symptoms. Maintenance of plant growth with 300μM Ni(2+) was associated with the ability to retain K(+) in the roots meanwhile 1000 and 3000μM NiSO4 led to substantial K(+) losses. In this study, root responses mirror all plant performances suggesting a direct link between root functionality and Ni(2+) tolerance mechanisms and plant survival. Considering that Ni was mainly accumulated in the root system, the potential use of P. guajava for Ni(2+) phytoextraction in metal-polluted soils is limited; nevertheless, the observed physiological changes indicate a good Ni(2+) tolerance up to 300μM NiSO4 suggesting a potential role for the phytostabilization of polluted soils.
authors.affiliation: LINV - Department of Agrifood Production and Environmental Sciences - University of Florence, Viale delle Idee 30, 50019 Sesto F.no, Florence, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Bazihizina
authors.affiliation: LINV - Department of Agrifood Production and Environmental Sciences - University of Florence, Viale delle Idee 30, 50019 Sesto F.no, Florence, Italy.
authors.forename: Mirvat
authors.initials: M
authors.lastname: Redwan
authors.affiliation: LINV - Department of Agrifood Production and Environmental Sciences - University of Florence, Viale delle Idee 30, 50019 Sesto F.no, Florence, Italy.
authors.forename: Cosimo
authors.initials: C
authors.lastname: Taiti
authors.affiliation: Centro di Microscopie Elettroniche "Laura Bonzi" (Ce.M.E.), ICCOM, CNR, Via Madonna del Piano, 50019 Sesto F.no, Florence, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Giordano
authors.affiliation: LINV - Department of Agrifood Production and Environmental Sciences - University of Florence, Viale delle Idee 30, 50019 Sesto F.no, Florence, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Monetti
authors.affiliation: LINV - Department of Agrifood Production and Environmental Sciences - University of Florence, Viale delle Idee 30, 50019 Sesto F.no, Florence, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Masi
authors.affiliation: LINV - Department of Agrifood Production and Environmental Sciences - University of Florence, Viale delle Idee 30, 50019 Sesto F.no, Florence, Italy. Electronic address: elisa.azzarello@unifi.it.
authors.forename: Elisa
authors.initials: E
authors.lastname: Azzarello
authors.affiliation: LINV - Department of Agrifood Production and Environmental Sciences - University of Florence, Viale delle Idee 30, 50019 Sesto F.no, Florence, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Mancuso
mesh_terms: D002118:Calcium / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D017097:Electric Impedance; D007477:Ions; D009532:Nickel / Q000378:metabolism / Q000633:toxicity*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D054046:Plant Stomata / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D031647:Psidium / Q000187:drug effects / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure; D013052:Spectrometry, X-Ray Emission
chemical_list: D007477:Ions; D002734:Chlorophyll; D002245:Carbon Dioxide; D002338:Carotenoids; D009532:Nickel; D011188:Potassium; D002118:Calcium
keywords: Gas exchange; Heavy metals; Impedance spectroscopy; Ion fluxes; Phytostabilization