title: Silenced rice in both cytosolic ascorbate peroxidases displays pre-acclimation to cope with oxidative stress induced by 3-aminotriazole-inhibited catalase.
abstract: The maintenance of H2O2 homeostasis and signaling mechanisms in plant subcellular compartments is greatly dependent on cytosolic ascorbate peroxidases (APX1 and APX2) and peroxisomal catalase (CAT) activities. APX1/2 knockdown plants were utilized in this study to clarify the role of increased cytosolic H2O2 levels as a signal to trigger the antioxidant defense system against oxidative stress generated in peroxisomes after 3-aminotriazole-inhibited catalase (CAT). Before supplying 3-AT, silenced APX1/2 plants showed marked changes in their oxidative and antioxidant profiles in comparison to NT plants. After supplying 3-AT, APX1/2 plants triggered up-expression of genes belonging to APX (OsAPX7 and OsAPX8) and GPX families (OsGPX1, OsGPX2, OsGPX3 and OsGPX5), but to a lower extent than in NT plants. In addition, APX1/2 exhibited lower glycolate oxidase (GO) activity, higher CO2 assimilation, higher cellular integrity and higher oxidation of GSH, whereas the H2O2 and lipid peroxidation levels remained unchanged. This evidence indicates that redox pre-acclimation displayed by silenced rice contributed to coping with oxidative stress generated by 3-AT. We suggest that APX1/2 plants were able to trigger alternative oxidative and antioxidant mechanisms involving signaling by H2O2, allowing these plants to display effective physiological responses for protection against oxidative damage generated by 3-AT, compared to non-transformed plants.
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza/CE, 60451-970, Brazil.
authors.forename: Aurenivia
authors.initials: A
authors.lastname: Bonifacio
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza/CE, 60451-970, Brazil.
authors.forename: Fabrício E L
authors.initials: FEL
authors.lastname: Carvalho
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza/CE, 60451-970, Brazil.
authors.forename: Marcio O
authors.initials: MO
authors.lastname: Martins
authors.affiliation: Biosciences Institute, São Paulo State University, UNESP, Coastal Campus, São Vicente/SP, P.O. Box 73601, 11380-972, Brazil.
authors.forename: Milton C
authors.initials: MC
authors.lastname: Lima Neto
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza/CE, 60451-970, Brazil.
authors.forename: Juliana R
authors.initials: JR
authors.lastname: Cunha
authors.affiliation: Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre/RS, 91501-970, Brazil.
authors.forename: Carolina W
authors.initials: CW
authors.lastname: Ribeiro
authors.affiliation: Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre/RS, 91501-970, Brazil.
authors.forename: Marcia
authors.initials: M
authors.lastname: Margis-Pinheiro
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza/CE, 60451-970, Brazil. Electronic address: silveira@ufc.br.
authors.forename: Joaquim A G
authors.initials: JAG
authors.lastname: Silveira
mesh_terms: D000064:Acclimatization / Q000187:drug effects*; D000640:Amitrole / Q000633:toxicity*; D000975:Antioxidants / Q000378:metabolism; D060387:Ascorbate Peroxidases / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D002374:Catalase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019069:Cell Respiration / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D055785:Gene Knockdown Techniques; D020868:Gene Silencing / Q000187:drug effects*; D017343:Genes, Plant; D005978:Glutathione / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D012275:Oryza / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D010788:Photosynthesis / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D000975:Antioxidants; D007527:Isoenzymes; D010940:Plant Proteins; D012333:RNA, Messenger; D060387:Ascorbate Peroxidases; D002374:Catalase; D005978:Glutathione; D001205:Ascorbic Acid; D000640:Amitrole
keywords: Ascorbate peroxidase; Hydrogen peroxide; Oryza sativa; Photorespiration; Photosynthesis; Redox metabolism