Abstract
15N-Nuclear magnetic resonance spectroscopy was used to follow nitrogen assimilation and amino-acid production in Wolffia arrhiza (L.) Hork. ex. Wimmer, clone Golan exposed to 4.0 mM 15NH4Cl solutions for 24 h. The main 15N-labelled metabolites were asparagine and glutamine, as well as substantial amounts of unreacted, intracellular NH +4 . These results were compared with those of a previous study on Lemna gibba L. clone Hurfeish (Monselise et al., 1987, New Phytol. 10, 341–345) with regard to NH +4 uptake, assimilation and detoxification efficiencies. Both species, grown under continuous white light, were capable of preferential uptake of NH +4 in the presence of nitrate. Relative growth rates indicate that both species tolerate increased levels of NH +4 , up to 10−2 mol · 1−1, with L. gibba showing a slightly greater tolerance. No 15N-labelled free NH +4 was detectable in L. gibba, while in W. arrhiza excess NH +4 was found within the cells. This fact indicates that L. gibba is more efficient in detoxification than W. arrhiza, presumably because of inability of W. arrhiza to regenerate the “NH +4 traps”, glutamate and aspartate, rapidly enough. This is also evident from the observation that addition of α-ketoglutarate to the medium caused nearly complete assimilation of intracellular NH +4 in W. arrhiza. In both plants, addition of α-ketoglutarate increased both NH +4 uptake and assimilation. Addition of l-methionine dl-sulfoximine, an inhibitor of glutamine synthetase inhibited NH +4 assimilation, while addition of azaserine, an inhibitor of glutamate synthase, resulted in 15N incorporation into the glutamine-amide position only. These results are consistent with the glutamine synthetase-glutamate synthase pathway being the major route of NH +4 assimilation in the two plants under the conditions used.
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Abbreviations
- AZA:
-
azaserine (O-diazoacetyl-l-serine)
- GOGAT:
-
glutamine oxoglutarate amine transferase=]glutamate synthase E.C. 1.4.7. and E.C. 1.4.1.13.
- GS:
-
glutamine synthetase E.C. 6.3.1.2.
- α-KG:
-
α-ketoglutarate=2-oxoglutarate
- MSO:
-
l-methionine dl-sulphoximine
- NMR:
-
nuclear magnetic resonance
- RGR:
-
relative growth rate
References
Amancio, S., Santos, H. (1992) Nitrate and ammonium assimilation by roots of Maize (tZea mays L.) Seedlings as investigated by in vivo 15N-NMR. J. Exp. Bot. 43, 633–639
Avron, M. (1960) Photophosphorylation by swiss-chard chloroplasts. Biochim. Biophys. Acta. 40, 257–272
Belton, P.S., Lee, R.B., Ratcliffe, R.G. (1985) A 14N-Nuclear magnetic resonance study of inorganic nitrogen metabolism in barley, maize and pea roots. J. Exp. Bot. 36, 190–210
Cammerts, D., Jacobs, M. (1985) A study of the role of glutamate dehydrogenase in nitrogen metabolism of Arabidopsis thaliana. Planta 163, 517–526
Dell, B., Botton, B., Martin, F., Letacon, F. (1989) Glutamate dehydrogenases in ectomycorrhizas of spruce (Picea excelsa L.) and beech (Fagus sylvatica L.). New Phytol. 111, 683–692
Ericsson, T., Larsson, C.M., Tillberg, E. (1982) Growth responses of Lemna to different levels of nitrogen limitation. Z. Pflanzenphysiol. 105, 331–340
Gauthier, D.L. (1983) Effect of l-methionine-dl-sulfoximine on acetylene reduction and vesicle formation in depressed cultures of Frankia strain D11. Can. J. Microbiol. 29, 1003–1006
Givan, C.V. (1979) Metabolic detoxification of ammonia in higher plants. Phytochemistry 18, 375–382
Haran, N., Kahana, Z.E., Lapidot, A. (1983) In vivo 15N-NMR studies of regulation of nitrogen assimilation and amino acid production by Brevibacterium lactofermentum. J. Biol. Chem. 10, 12929–12933
Hartmann, T., Ehme, A. (1986) Metabolism of organic N-compounds. Progr. Bot. 48, 124–132
Lea, P.J. (1985) Ammonia assimilation and amino acid biosynthesis. In: Techniques in bioproduction and photosynthesis, 2nd edn., Coombs, J., Hall, D.O., Long, S.P., Scurlock, J.M.O., eds. pp. 173–187, Pergamon Press, Oxford, UK
Lee, R.B., Ratcliffe, R.G. (1991) Observation on the subcellular distribution of the ammonium ion in maize root tissue using in-vivo 14N-nuclear magnetic resonance spectroscopy. Planta 183, 359–367
Lipkin, Y. (1973) Wolffia arrhiza (L.) Hor. ex Wimmer on the Golan Plateau. Israel J. Bot. 22, 175–177
Martin, F., Stewart, G.R., Genetet, I., Letacon, F. (1986) Assimilation of 15NH +4 by beech (Fagus sylvatica L.) ectomycorrhizas. New Phytol. 102, 85–94
Miflin, B.J., Lea, P.J. (1977) Amino acid metabolism. Annu. Rev. Plant Physiol. 28, 299–329
Monselise, E.B-I. (1988) Characterizing the heterogeneity in preferential ammonium-ion uptake and assimilation in six species of Lemnaceae with respect to clone evaluation for aquaculture. Ph.D. thesis, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Monselise, E.B-I., Kost, D., Porath, D., Tal, M. (1987) 15N Nuclear magnetic resonance study of ammonium-ion assimilation by Lemna gibba L. New Phytol. 10, 341–345
Neeman, M., Aviv, D., Degani, H., Galun, E. (1985) Glucose and glycine metabolism in regenerating tobacco protoplasts. Plant Physiol. 77, 374–378
Porath, D., Efrat, Y., Arzee, T. (1980) Morphological patterns and heterogeneity in populations of duckweed. Aquatic Bot. 9, 159–168
Puritch, G.S., Barker, A.V. (1967) Structure and function of tomato-leaf chloroplasts during ammonium toxicity. Plant Physiol. 42, 1229–1238
Rand, H.C., Greenberg, A.E., Trans, M.J. (1975) Standard methods for the examination of water and wastewater, 14th edn, American Public Health Association, Washington, D.C. USA
Rhodes, D., Rich, P.J., Brunk, D.G. (1989) Amino acid metabolism of Lemna minor L. VI. 15N-labelling kinetics of the amide and amino groups of glutamine and asparagine. Plant Physiol. 89, 1161–1171
Robinson, S.A., Slade, A.P., Fox, G.G., Phillips, R., Ratcliffe, G., Stewart, G.R. (1991) The role of glutamate dehydrogenase in plant nitrogen metabolism. Plant Physiol. 95, 509–516
Schuster, C., Schmidt, S., Mohr, H. (1989) Effect of nitrate, ammonium, light and a plastidic factor on the appearance of multiple forms of nitrate reductase in mustard (Sinapis alba L.) cotyledons. Planta 177, 74–83
Singh, R.P., Srivastava, H.S. (1982) Glutamate dehydrogenase activity and assimilation of inorganic nitrogen in maize seedlings. Biochem. Physiol. Pfl. 177, 633–642
Stewart, G.R., Rhodes, D. (1977) Evidence for the assimilation of ammonia via the glutamine pathway in nitrate-grown Lemna minor L. FEBS Lett. 46, 340–342
Takashi, T., Sung, H.C., Shinji, W., Tatsurokuro, T. (1983) Purification and some properties of glutamate synthase from Gluconobacter suboxydans grown on glutamate as a nitrogen source. J. Ferment. Technol. 61, 179–184
Thorpe, T.A., Bagh, K., Cutler, A.J., Dunstan, D.I., McIntyre, D.D., Vogel, H.J. (1989) A 14N and 15N Nuclear magnetic resonance study of nitrogen metabolism in shoot-forming cultures of White Spruce (Picea glauca) buds. Plant. Physiol. 91, 193–202
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This article is dedicated to Professor Bernhard Schrader on the occasion of his 60th birthday
We wish to thank Professor Robert Glaser for helpful discussions, and Mrs. Aliza Levkoviz and Mr. Gideon Raziel for skillful assistance.
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Monselise, E.BI., Kost, D. Different ammonium-ion uptake, metabolism and detoxification efficiencies in two Lemnaceae. Planta 189, 167–173 (1993). https://doi.org/10.1007/BF00195073
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DOI: https://doi.org/10.1007/BF00195073