title: Hydrogen peroxide is necessary for abscisic acid-induced senescence of rice leaves.
abstract: The role of H2O2 in abscisic acid (ABA)-induced rice leaf senescence is investigated. ABA treatment resulted in H2O2 production in rice leaves, which preceded the occurrence of leaf senescence. Dimethylthiourea, a chemical trap for H2O2, was observed to be effective in inhibiting ABA-induced senescence, ABA-increased matondialdehyde (MDA) content, ABA-increased antioxidative enzyme activities (superoxide dismutase, ascorbate peroxidase, glutathione reductase and catalase), and ABA-decreased antioxidant contents (ascorbic acid and reduced glutathione) in rice leaves. Diphenyteneiodonium chloride (DPI) and imidazole (IMD), inhibitors of NADPH oxidase, and KCN and NaN3, inhibitors of peroxidase, prevented ABA-induced H2O2 production, suggesting NADPH oxidase and peroxidase are H2O2-generating enzymes in ABA-treated rice leaves. DPI, IMD, KCN, and NaN3 also inhibited ABA-promoted senescence, ABA-increased MDA contents, ABA-increased antioxidative enzyme activities, and ABA-decreased antioxidants in rice leaves. These results suggest that H2O2 is involved in ABA-induced senescence of rice leaves.
authors.affiliation: Department of Agronomy, National Taiwan University, Taipei, Taiwan, ROC.
authors.forename: Kuo Tung
authors.initials: KT
authors.lastname: Hung
authors.forename: Ching Huei
authors.initials: CH
authors.lastname: Kao
mesh_terms: D000040:Abscisic Acid / Q000502:physiology*; D060387:Ascorbate Peroxidases; D001205:Ascorbic Acid / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D012275:Oryza / Q000378:metabolism / Q000502:physiology*; D010544:Peroxidases / Q000378:metabolism; D010937:Plant Growth Regulators / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors
chemical_list: D010937:Plant Growth Regulators; D010940:Plant Proteins; D008315:Malondialdehyde; D000040:Abscisic Acid; C038983:1,3-dimethylthiourea; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005978:Glutathione; D013890:Thiourea; D001205:Ascorbic Acid