title: Nitric oxide counteracts the senescence of rice leaves induced by abscisic acid.
abstract: In the present study, we evaluate the protective effect of nitric oxide (NO) against senescence of rice leaves promoted by ABA. Senescence of rice leaves was determined by the decrease of protein content. ABA treatment resulted in (1) induction of leaf senescence, (2) increase in H2O2 and malondialdehyde (MDA) contents, (3) decrease in reduced form glutathione (GSH) and ascorbic acid (AsA) contents, and (4) increase in antioxidative enzyme activities (superoxide dismutase, ascorbate peroxidase, glutathione reductase, and catalase). All these ABA effects were reduced by free radical scavengers such as sodium benzoate and GSH. NO donors [N-tert-butyl-alpha-phenylnitrone (PBN), sodium nitroprusside, 3-morpholinosydonimine, and AsA + NaNO2] were effective in reducing ABA-induced leaf senescence. PBN prevented ABA-induced increase in the contents of H2O2 and MDA, decrease in the contents of GSH and AsA, and increase in the activities of antioxidative enzymes. The protective effect of PBN on ABA-promoted senescence, ABA-increased H2O2 content and lipid peroxidation, ABA-decreased GSH and AsA, and ABA-increased antioxidative enzyme activities was reversed by 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a NO-specific scavenger, suggesting that the protective effect of PBN is attributable to NO released. Reduction of ABA-induced senescence by NO in rice leaves is most likely mediated through its ability to scavenge active oxygen species including H2O2.
authors.affiliation: Department of Agronomy, National Taiwan University, Taipei, Taiwan, Republic of China.
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 / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D016922:Cellular Senescence / Q000187:drug effects; D003497:Cyclic N-Oxides / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology*; D007700:Kinetics; D015227:Lipid Peroxidation; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009589:Nitrogen Oxides / Q000494:pharmacology*; D012275:Oryza / Q000187:drug effects / Q000502:physiology*; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
chemical_list: D003497:Cyclic N-Oxides; D007093:Imidazoles; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; C029217:phenyl-N-tert-butylnitrone; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D005978:Glutathione