title: Over-expression of Trxo1 increases the viability of tobacco BY-2 cells under H2O2 treatment.
abstract: OBJECTIVE
  Reactive oxygen species (ROS), especially hydrogen peroxide, play a critical role in the regulation of plant development and in the induction of plant defence responses during stress adaptation, as well as in plant cell death. The antioxidant system is responsible for controlling ROS levels in these processes but redox homeostasis is also a key factor in plant cell metabolism under normal and stress situations. Thioredoxins (Trxs) are ubiquitous small proteins found in different cell compartments, including mitochondria and nuclei (Trxo1), and are involved in the regulation of target proteins through reduction of disulphide bonds, although their role under oxidative stress has been less well studied. This study describes over-expression of a Trxo1 for the first time, using a cell-culture model subjected to an oxidative treatment provoked by H2O2.
  
  
  METHODS
  Control and over-expressing PsTrxo1 tobacco (Nicotiana tabacum) BY-2 cells were treated with 35 mm H2O2 and the effects were analysed by studying the growth dynamics of the cultures together with oxidative stress parameters, as well as several components of the antioxidant systems involved in the metabolism of H2O2. Analysis of different hallmarks of programmed cell death was also carried out.
  
  
  RESULTS
  Over-expression of PsTrxo1 caused significant differences in the response of TBY-2 cells to high concentrations of H2O2, namely higher and maintained viability in over-expressing cells, whilst the control line presented a severe decrease in viability and marked indications of oxidative stress, with generalized cell death after 3 d of treatment. In over-expressing cells, an increase in catalase activity, decreases in H2O2 and nitric oxide contents and maintenance of the glutathione redox state were observed.
  
  
  CONCLUSIONS
  A decreased content of endogenous H2O2 may be responsible in part for the delayed cell death found in over-expressing cells, in which changes in oxidative parameters and antioxidants were less extended after the oxidative treatment. It is concluded that PsTrxo1 transformation protects TBY-2 cells from exogenous H2O2, thus increasing their viability via a process in which not only antioxidants but also Trxo1 seem to be involved.
authors.affiliation: CEBAS-CSIC, Department of Stress Biology and Plant Pathology, Campus Universitario de Espinardo Murcia, E-30100, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Ortiz-Espín
authors.affiliation: Laboratory of Plant Biochemistry and Food Science, Campus Bio-Medico University of Rome, Via Alvaro del Portillo 21, I-00128, Rome, Italy and.
authors.forename: Vittoria
authors.initials: V
authors.lastname: Locato
authors.affiliation: CEBAS-CSIC, Department of Stress Biology and Plant Pathology, Campus Universitario de Espinardo Murcia, E-30100, Spain.
authors.forename: Daymi
authors.initials: D
authors.lastname: Camejo
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Department of Plant Biotechnology, Forckenbeckstrasse 6, D-52074, Aachen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schiermeyer
authors.affiliation: Laboratory of Plant Biochemistry and Food Science, Campus Bio-Medico University of Rome, Via Alvaro del Portillo 21, I-00128, Rome, Italy and.
authors.forename: Laura
authors.initials: L
authors.lastname: De Gara
authors.affiliation: CEBAS-CSIC, Department of Stress Biology and Plant Pathology, Campus Universitario de Espinardo Murcia, E-30100, Spain.
authors.forename: Francisca
authors.initials: F
authors.lastname: Sevilla
authors.affiliation: CEBAS-CSIC, Department of Stress Biology and Plant Pathology, Campus Universitario de Espinardo Murcia, E-30100, Spain, ajimenez@cebas.csic.es.
authors.forename: Ana
authors.initials: A
authors.lastname: Jiménez
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D018384:Oxidative Stress; D018532:Pisum sativum / Q000235:genetics* / Q000378:metabolism; D059828:Plant Cells / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D050050:Protein Carbonylation / Q000187:drug effects; D013879:Thioredoxins / Q000235:genetics* / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D013879:Thioredoxins; D006861:Hydrogen Peroxide
keywords: Ascorbate; Nicotiana tabacum; TBY-2 cells; cell death; cell viability; glutathione; hydrogen peroxide; over-expression; oxidative stress; reactive oxygen species; thioredoxin o; tobacco