title: Suppression of Reactive Oxygen Species Accumulation in Chloroplasts Prevents Leaf Damage but Not Growth Arrest in Salt-Stressed Tobacco Plants.
abstract: Crop yield reduction due to salinity is a growing agronomical concern in many regions. Increased production of reactive oxygen species (ROS) in plant cells accompanies many abiotic stresses including salinity, acting as toxic and signaling molecules during plant stress responses. While ROS are generated in various cellular compartments, chloroplasts represent a main source in the light, and plastid ROS synthesis and/or elimination have been manipulated to improve stress tolerance. Transgenic tobacco plants expressing a plastid-targeted cyanobacterial flavodoxin, a flavoprotein that prevents ROS accumulation specifically in chloroplasts, displayed increased tolerance to many environmental stresses, including drought, excess irradiation, extreme temperatures and iron starvation. Surprisingly, flavodoxin expression failed to protect transgenic plants against NaCl toxicity. However, when high salt was directly applied to leaf discs, flavodoxin did increase tolerance, as reflected by preservation of chlorophylls, carotenoids and photosynthetic activities. Flavodoxin decreased salt-dependent ROS accumulation in leaf tissue from discs and whole plants, but this decline did not improve tolerance at the whole plant level. NaCl accumulation in roots, as well as increased osmotic pressure and salt-induced root damage, were not prevented by flavodoxin expression. The results indicate that ROS formed in chloroplasts have a marginal effect on plant responses during salt stress, and that sensitive targets are present in roots which are not protected by flavodoxin.
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina.
authors.forename: Anabella F
authors.initials: AF
authors.lastname: Lodeyro
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina.
authors.forename: Mariana
authors.initials: M
authors.lastname: Giró
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina.
authors.forename: Hugo O
authors.initials: HO
authors.lastname: Poli
authors.affiliation: Department of Biological Sciences, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Bettucci
authors.affiliation: Department of Biological Sciences, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina.
authors.forename: Adriana
authors.initials: A
authors.lastname: Cortadi
authors.affiliation: Department of Analytical Chemistry, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina.
authors.forename: Alejandro M
authors.initials: AM
authors.lastname: Ferri
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina.
authors.forename: Néstor
authors.initials: N
authors.lastname: Carrillo
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D005418:Flavodoxin / Q000378:metabolism; D007477:Ions; D008054:Lipid Peroxides / Q000378:metabolism; D009995:Osmosis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D030821:Plants, Genetically Modified; D018087:Plastids / Q000187:drug effects / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D054712:Salinity; D012965:Sodium Chloride / Q000633:toxicity*; D013312:Stress, Physiological / Q000187:drug effects*; D014026:Nicotiana / Q000187:drug effects / Q000254:growth & development*
chemical_list: D005418:Flavodoxin; D007477:Ions; D008054:Lipid Peroxides; D017382:Reactive Oxygen Species; D012965:Sodium Chloride