title: Ethylene is required for elicitin-induced oxidative burst but not for cell death induction in tobacco cell suspension cultures.
abstract: The signal compound ethylene and its relationships with oxidative burst and cell death were analyzed in cultured tobacco cells treated with the proteinaceous elicitor quercinin. Quercinin belongs to the protein family of elicitins and was isolated from the soil-born oak pathogen Phytophthora quercina. It was shown to induce a dose-dependent oxidative burst in tobacco cell culture in concentrations from 0.05 to 0.5 nM, and subsequently, cell death. The characteristics of quercinin-induced cell death included both membrane damage and DNA fragmentation in tobacco cell culture. At higher quercinin concentrations (2 nM), H(2)O(2) formation and ethylene biosynthesis were inhibited. Ethylene at low concentrations proved to be necessary for induction and maintenance of H(2)O(2) production in tobacco cells treated with quercinin. It was demonstrated that external addition of inhibitors of ethylene biosynthesis such as alpha-amino-oxy-acetic acid (AOA) and CoCl(2) also decreased or even inhibited the quercinin-induced oxidative burst, but did not influence cell death induction. These results demonstrate evidence for a requirement of the plant hormone ethylene for the onset of the quercinin-induced oxidative burst.
authors.affiliation: Institute of Pathology of Woody Plants, Life Science Center Weihenstephan, Technische Universität München, Am Hochanger 13, 85350 Freising-Weihenstephan, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Koehl
authors.forename: Alma
authors.initials: A
authors.lastname: Djulic
authors.forename: Veronika
authors.initials: V
authors.lastname: Kirner
authors.forename: Tach Thao
authors.initials: TT
authors.lastname: Nguyen
authors.forename: Ingrid
authors.initials: I
authors.lastname: Heiser
mesh_terms: D020418:Algal Proteins / Q000494:pharmacology*; D000625:Aminooxyacetic Acid / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005030:Ethylenes / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D010838:Phytophthora; D016897:Respiratory Burst / Q000187:drug effects*; D013997:Time Factors; D014026:Nicotiana / Q000166:cytology* / Q000187:drug effects*
chemical_list: D020418:Algal Proteins; D005030:Ethylenes; D000625:Aminooxyacetic Acid; D003035:Cobalt; C036216:ethylene; D006861:Hydrogen Peroxide; C018021:cobaltous chloride