title: The participation of hydrogen peroxide in methyl jasmonate-induced NH(4)(+) accumulation in rice leaves.
abstract: Ammonium is a central intermediate in the nitrogen metabolism of plants. We have previously shown that methyl jasmonate (MJ) not only increases the content of H(2)O(2), but also causes NH(4)(+) accumulation in rice leaves. More recently, H(2)O(2) is thought to constitute a general signal molecule participating in the recognition of and the response to stress factors. In this study, we examined the role of H(2)O(2) as a link between MJ and subsequent NH(4)(+) accumulation in detached rice leaves. MJ treatment resulted in an accumulation of NH(4)(+) in detached rice leaves, which was preceded by a decrease in the activity of glutamine synthetase (GS) and an increase in the specific activities of protease and phenylalanine ammonia-lyase (PAL). GS, PAL, and protease appear to be the enzymes responsible for the accumulation of NH(4)(+) in MJ-treated detached rice leaves. Dimethylthiourea (DMTU), a chemical trap for H(2)O(2), was observed to be effective in inhibiting MJ-induced NH(4)(+) accumulation in detached rice leaves. Scavengers of free radicals (sodium benzoate, SB, and glutathione, GSH), nitric oxide donor (N-tert-butyl-alpha-phenylnitrone, PBN), the inhibitors of NADPH oxidase (diphenyleneiodonium chloride, DPI, and imidazole, IMD), and inhibitors of phosphatidylinositol 3-kinase (wortmannin, WM, and LY 294002, LY), which have previously been shown to prevent MJ-induced H(2)O(2) production in detached rice leaves, inhibited MJ-induced NH(4)(+) accumulation. Similarly, changes in enzymes responsible for NH(4)(+) accumulation induced by MJ were observed to be inhibited by DMTU, SB, GSH, PBN DPI, IMD, WM, or LY. Seedlings of rice cultivar Taichung Native 1 (TN1) are jasmonic acid (JA)-sensitive and those of cultivar Tainung 67 (TNG67) are JA-insensitive. On treatment with JA, H(2)O(2) accumulated in the leaves of TN1 seedlings but not in the leaves of TNG67. Ethylene action inhibitor, silver thiosulfate, was observed to inhibit MJ- and abscisic acid-induced accumulation of NH(4)(+) and changes in enzymes responsible for NH(4)(+) accumulation in detached rice leaves, suggesting that the action of MJ and ABA is ethylene dependent.
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 / Q000494:pharmacology; D000085:Acetates / Q000494:pharmacology*; D003517:Cyclopentanes / Q000494:pharmacology*; D005030:Ethylenes / Q000494:pharmacology; D005978:Glutathione; D006861:Hydrogen Peroxide / Q000378:metabolism*; D020030:Nitric Oxide Donors; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D054883:Oxylipins / Q000494:pharmacology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D036226:Seedlings / Q000235:genetics; D020160:Sodium Benzoate / Q000494:pharmacology; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D005030:Ethylenes; D020030:Nitric Oxide Donors; D054883:Oxylipins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000644:Quaternary Ammonium Compounds; D000040:Abscisic Acid; C038983:1,3-dimethylthiourea; C072239:methyl jasmonate; C036216:ethylene; D006861:Hydrogen Peroxide; D005978:Glutathione; D013890:Thiourea; D020160:Sodium Benzoate