The participation of hydrogen peroxide in methyl jasmonate-induced NH(4)(+) accumulation in rice leaves.
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.
Hung
Kuo Tung
KT
Department of Agronomy, National Taiwan University, Taipei, Taiwan, Republic of China.
Kao
Ching Huei
CH
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
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