title: High salinity helps the halophyte Sesuvium portulacastrum in defense against Cd toxicity by maintaining redox balance and photosynthesis.
abstract: NaCl alleviates Cd toxicity in Sesvium portulacastrum by maintaining plant water status and redox balance, protecting chloroplasts structure and inducing some potential Cd (2+) chelators as GSH and proline. It has been demonstrated that NaCl alleviates Cd-induced growth inhibition in the halophyte Sesuvium portulacastrum. However, the processes that mediate this effect are still unclear. In this work we combined physiological, biochemical and ultrastructural studies to highlight the effects of salt on the redox balance and photosynthesis in Cd-stressed plants. Seedlings were exposed to different Cd concentrations (0, 25 and 50 µM Cd) combined with low (0.09 mM) (LS), or high (200 mM) NaCl (HS) in hydroponic culture. Plant-water relations, photosynthesis rate, leaf gas exchange, chlorophyll fluorescence, chloroplast ultrastructure, and proline and glutathione concentrations were analyzed after 1 month of treatment. In addition, the endogenous levels of stress-related hormones were determined in plants subjected to 25 µM Cd combined with both NaCl concentrations. In plants with low salt supply (LS), Cd reduced growth, induced plant dehydration, disrupted chloroplast structure and functioning, decreased net CO2 assimilation rate (A) and transpiration rate (E), inhibited the maximum potential quantum efficiency (Fv/Fm) and the quantum yield efficiency (Φ PSII) of PSII, and enhanced the non-photochemical quenching (NPQ). The addition of 200 mM NaCl (HS) to the Cd-containing medium culture significantly mitigated Cd phytotoxicity. Hence, even at similar internal Cd concentrations, HS-Cd plants were less affected by Cd than LS-Cd ones. Hence, 200 mM NaCl significantly alleviates Cd-induced toxicity symptoms, growth inhibition, and photosynthesis disturbances. The cell ultrastructure was better preserved in HS-Cd plants but affected in LS-Cd plants. The HS-Cd plants showed also higher concentrations of reduced glutathione (GSH), proline and jasmonic acid (JA) than the LS-Cd plants. However, under LS-Cd conditions, plants maintained higher concentration of salicylic acid (SA) and abscisic acid (ABA) than the HS-Cd ones. We conclude that in S. portulacastrum alleviation of Cd toxicity by NaCl is related to the modification of GSH and proline contents as well as stress hormone levels thus protecting redox balance and photosynthesis.
authors.affiliation: Laboroitre des Plantes Extrêmophiles, Centre de Biotechnologie de Borj Cedria, BP 901 Hammam_Lif, 2050, Tunis, Tunisia.|Laboratorio de Fisiología Vegetal, Facultad de Biociencias, Universidad Autònoma de Barcelona, Bellaterra, 08193, Barcelona, Spain.
authors.forename: Mariem
authors.initials: M
authors.lastname: Wali
authors.affiliation: Laboratorio de Fisiología Vegetal, Facultad de Biociencias, Universidad Autònoma de Barcelona, Bellaterra, 08193, Barcelona, Spain.
authors.forename: Benet
authors.initials: B
authors.lastname: Gunsè
authors.affiliation: Laboratorio de Fisiología Vegetal, Facultad de Biociencias, Universidad Autònoma de Barcelona, Bellaterra, 08193, Barcelona, Spain.
authors.forename: Mercè
authors.initials: M
authors.lastname: Llugany
authors.affiliation: Laboratorio de Fisiología Vegetal, Facultad de Biociencias, Universidad Autònoma de Barcelona, Bellaterra, 08193, Barcelona, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Corrales
authors.affiliation: Laboroitre des Plantes Extrêmophiles, Centre de Biotechnologie de Borj Cedria, BP 901 Hammam_Lif, 2050, Tunis, Tunisia.
authors.forename: Chedly
authors.initials: C
authors.lastname: Abdelly
authors.affiliation: Laboratorio de Fisiología Vegetal, Facultad de Biociencias, Universidad Autònoma de Barcelona, Bellaterra, 08193, Barcelona, Spain.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Poschenrieder
authors.affiliation: Laboroitre des Plantes Extrêmophiles, Centre de Biotechnologie de Borj Cedria, BP 901 Hammam_Lif, 2050, Tunis, Tunisia. Tahar.ghnaya@gmail.com.
authors.forename: Tahar
authors.initials: T
authors.lastname: Ghnaya
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000502:physiology; D035722:Aizoaceae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D003517:Cyclopentanes / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D010084:Oxidation-Reduction; D054883:Oxylipins / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D018526:Plant Transpiration / Q000187:drug effects; D011392:Proline / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D055051:Salt-Tolerant Plants / Q000187:drug effects* / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism / Q000494:pharmacology*; D013312:Stress, Physiological; D014867:Water / Q000378:metabolism
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; D002104:Cadmium; D014867:Water; D002734:Chlorophyll; D012965:Sodium Chloride; C011006:jasmonic acid; D000040:Abscisic Acid; D011392:Proline; D005978:Glutathione; D020156:Salicylic Acid
keywords: ABA; Cd tolerance; Glutathione; Jasmonic acid; Leaf ultrastructure; Salt; Sesuvium