title: Mitochondrial GPX1 silencing triggers differential photosynthesis impairment in response to salinity in rice plants.
abstract: The physiological role of plant mitochondrial glutathione peroxidases is scarcely known. This study attempted to elucidate the role of a rice mitochondrial isoform (GPX1) in photosynthesis under normal growth and salinity conditions. GPX1 knockdown rice lines (GPX1s) were tested in absence and presence of 100 mM NaCl for 6 d. Growth reduction of GPX1s line under non-stressful conditions, compared with non-transformed (NT) plants occurred in parallel to increased H2 O2 and decreased GSH contents. These changes occurred concurrently with photosynthesis impairment, particularly in Calvin cycle's reactions, since photochemical efficiency did not change. Thus, GPX1 silencing and downstream molecular/metabolic changes modulated photosynthesis differentially. In contrast, salinity induced reduction in both phases of photosynthesis, which were more impaired in silenced plants. These changes were associated with root morphology alterations but not shoot growth. Both studied lines displayed increased GPX activity but H2 O2 content did not change in response to salinity. Transformed plants exhibited lower photorespiration, water use efficiency and root growth, indicating that GPX1 could be important to salt tolerance. Growth reduction of GPX1s line might be related to photosynthesis impairment, which in turn could have involved a cross talk mechanism between mitochondria and chloroplast originated from redox changes due to GPX1 deficiency.
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceará, CEP 60451-970, Fortaleza, Ceará, Brazil.
authors.forename: Yugo
authors.initials: Y
authors.lastname: Lima-Melo
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceará, CEP 60451-970, Fortaleza, Ceará, Brazil.
authors.forename: Fabricio E L
authors.initials: FE
authors.lastname: Carvalho
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceará, CEP 60451-970, Fortaleza, Ceará, Brazil.
authors.forename: Márcio O
authors.initials: MO
authors.lastname: Martins
authors.affiliation: Department of Genetics, Federal University of Rio Grande do Sul, CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Gisele
authors.initials: G
authors.lastname: Passaia
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceará, CEP 60451-970, Fortaleza, Ceará, Brazil.
authors.forename: Rachel H V
authors.initials: RH
authors.lastname: Sousa
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceará, CEP 60451-970, Fortaleza, Ceará, Brazil.
authors.forename: Milton C Lima
authors.initials: MC
authors.lastname: Neto
authors.affiliation: Department of Genetics, Federal University of Rio Grande do Sul, CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Márcia
authors.initials: M
authors.lastname: Margis-Pinheiro
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceará, CEP 60451-970, Fortaleza, Ceará, Brazil.
authors.forename: Joaquim A G
authors.initials: JA
authors.lastname: Silveira
mesh_terms: D018533:Biomass; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D005740:Gases / Q000378:metabolism; D020868:Gene Silencing / Q000187:drug effects / Q000528:radiation effects; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008027:Light; D015227:Lipid Peroxidation / Q000187:drug effects / Q000528:radiation effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D012275:Oryza / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D010641:Phenotype; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D010940:Plant Proteins / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D054712:Salinity; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000528:radiation effects
chemical_list: D005740:Gases; D010940:Plant Proteins; D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; D005978:Glutathione
keywords: CO2 assimilation; Oryza sativa; glutathione peroxidase; photochemistry; redox homeostasis