title: Reactive oxygen species formation and cell death in catalase-deficient tobacco leaf discs exposed to paraquat.
abstract: In the present work, the response of tobacco (Nicotiana tabaccum L.) wild-type SR1 and transgenic CAT1AS plants (with a basal reduced CAT activity) was evaluated after exposure to the herbicide paraquat (PQ). Superoxide anion (O (2) (.-) ) formation was inhibited at 3 or 21 h of exposure, but H(2)O(2) production and ion leakage increased significantly, both in SR1 or CAT1AS leaf discs. NADPH oxidase activity was constitutively 57% lower in non-treated transgenic leaves than in SR1 leaves and was greatly reduced both at 3 or 21 h of PQ treatment. Superoxide dismutase (SOD) activity was significantly reduced by PQ after 21 h, showing a decrease from 70% to 55%, whereas catalase (CAT) activity decreased an average of 50% after 3 h of treatment, and of 90% after 21 h, in SR1 and CAT1AS, respectively. Concomitantly, total CAT protein content was shown to be reduced in non-treated CAT1AS plants compared to control SR1 leaf discs at both exposure times. PQ decreased CAT expression in SR1 or CAT1AS plants at 3 and 21 h of treatment. The mechanisms underlying PQ-induced cell death were possibly not related exclusively to ROS formation and oxidative stress in tobacco wild-type or transgenic plants.
authors.affiliation: Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina.
authors.forename: María Florencia
authors.initials: MF
authors.lastname: Iannone
authors.forename: Eliana Paola
authors.initials: EP
authors.lastname: Rosales
authors.forename: María Daniela
authors.initials: MD
authors.lastname: Groppa
authors.forename: María Patricia
authors.initials: MP
authors.lastname: Benavides
mesh_terms: D015153:Blotting, Western; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D016373:DNA, Antisense / Q000235:genetics; D006540:Herbicides / Q000633:toxicity; D006861:Hydrogen Peroxide / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism; D010269:Paraquat / Q000633:toxicity*; D018515:Plant Leaves / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors; D014026:Nicotiana / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D016373:DNA, Antisense; D006540:Herbicides; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D013481:Superoxides; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D019255:NADPH Oxidases; D010269:Paraquat