title: Polyamine oxidase is one of the key elements for oxidative burst to induce programmed cell death in tobacco cultured cells.
abstract: Programmed cell death plays a critical role during the hypersensitive response in the plant defense system. One of components that triggers it is hydrogen peroxide, which is generated through multiple pathways. One example is proposed to be polyamine oxidation, but direct evidence for this has been limited. In this article, we investigated relationships among polyamine oxidase, hydrogen peroxide, and programmed cell death using a model system constituted of tobacco (Nicotiana tabacum) cultured cell and its elicitor, cryptogein. When cultured cells were treated with cryptogein, programmed cell death occurred with a distinct pattern of DNA degradation. The level of hydrogen peroxide was simultaneously increased, along with polyamine oxidase activity in apoplast. With the same treatment in the presence of alpha-difluoromethyl-Orn, an inhibitor of polyamine biosynthesis, production of hydrogen peroxide was suppressed and programmed cell death did not occur. A gene encoding a tobacco polyamine oxidase that resides in the apoplast was isolated and used to construct RNAi transgenic cell lines. When these lines were treated with cryptogein, polyamines were not degraded but secreted into culture medium and hydrogen peroxide was scarcely produced, with a concomitant suppression of cell death. Activities of mitogen-activated protein kinases (wound- and salicylic acid-induced protein kinases) were also suppressed, indicating that phosphorylation cascade is involved in polyamine oxidation-derived cell death. These results suggest that polyamine oxidase is a key element for the oxidative burst, which is essential for induction of programmed cell death, and that mitogen-activated protein kinase is one of the factors that mediate this pathway.
authors.affiliation: Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630-0192, Japan. h-yoda@bs.naist.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yoda
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Hiroi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sano
mesh_terms: D020418:Algal Proteins; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000502:physiology*; D002478:Cells, Cultured; D016166:Free Radical Scavengers / Q000378:metabolism; D005656:Fungal Proteins; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst / Q000502:physiology*; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D000097667:Polyamine Oxidase
chemical_list: D020418:Algal Proteins; D016166:Free Radical Scavengers; D005656:Fungal Proteins; D020928:Mitogen-Activated Protein Kinases; D000587:Oxidoreductases Acting on CH-NH Group Donors; D017382:Reactive Oxygen Species; D000097667:Polyamine Oxidase; C061032:cryptogein protein, Phytophthora cryptogea