Abstract
The pericarp of the dormant sugarbeet fruit acts as a storage reservoir for nitrate, ammonium and α-amino-N. These N-reserves enable an autonomous development of the seedling for 8–10 d after imbibition. The nitrate content of the seed (1% of the whole fruit) probably induces nitrate-reductase activity in the embryo enclosed in the pericarp. Nitrate that leaks out of the pericarp is reabsorbed by the emerging radicle. Seedlings germinated from seeds (pericarp was removed) without external N-supply are able to take up nitrate immediately upon exposure via a low-capacity uptake system (vmax = 0.8 μmol NO -3 ·(g root FW)−1·h−1; Ks = 0.12 mM). We assume that this uptake system is induced by the seed nitrate (10 nmol/seed) during germination. Induction of a high-capacity nitrate-uptake system (vmax = 3.4 μmol NO -3 ·(g root FW)−1·h−1; Ks = 0.08 mM) by externally supplied nitrate occurs after a 20-min lag and requires protein synthesis. Seedlings germinated from whole fruits absorb nitrate via a highcapacity uptake mechanism induced by the pericarp nitrate (748 nmol/pericarp) during germination. The uptake rates of the high-capacity system depend only on the actual nitrate concentration of the uptake medium and not on prior nitrate pretreatments. Nitrate deprivation results in a decline of the nitrate-uptake capacity (t1/2 of vmax = 5 d) probably caused by the decay of carrier molecules. Small differences in Ks but significant differences in vmax indicate that the low- and high-capacity nitrate-uptake systems differ only in the number of identical carrier molecules.
Similar content being viewed by others
Abbreviations
- NR:
-
nitrate reductase
- pFPA:
-
para-fluorophenylalanine
References
Behl, R., Tischner, R., Raschke, K. (1988) Induction of a high-capacity nitrate-uptake mechanism in barley roots promoted by nitrate uptake through a constitutive low-capacity mechanism. Planta 176, 235–240
Clarkson, D.T. (1986) Regulation of the absorption and release of nitrate by plants cells: A review of current ideas and methodology. In: Fundamental ecological and agricultural aspects of nitrogen metabolism in higher plants, pp. 3–27, Lambers, H., Neeteson, J.J., Stulen, I., eds. Martinus Nijhoff, Dordrecht
Cowie, D.B., Cohen, G.N., Bolton, E.T., de Robichon-Szulmajster, H. (1959) Amino acid analogon incorporation into bacteroid proteins. Biochim. Biophys. Acta 41, 98–103
Funkhouser, E.A., Garey, A.S. (1981) Appearance of nitrate in soybean seedlings and Chlorella caused by nitrogen starvation. Plant Cell Physiol. 22, 1279–1286
Goyal, S.S., Huffaker, R.C. (1986) The uptake of -3 , NO -2 , and NH +4 by intact wheat (Triticum aestivum) seedlings. I. Induction and kinetics of transport systems. Plant Physiol. 82, 1051–1056
Heath-Paglusio, S., Huffaker, R.C., Allard, R.W. (1984) Inheritance of nitrite reductase and regulation of nitrate reductase, nitrite reductase, and glutamine synthetase isoenzymes. Plant Physiol. 76, 353–358
Jackson, W.A., Flesher, D., Hageman, R.H. (1973) Nitrate uptake by dark grown corn seedlings: some characteristics of apparent induction. Plant Physiol. 51, 120–127
Jaworski, E.G. (1971) Nitrate reductase assay in intact plant tissue. Biochem. Biophys. Res. Commun. 43, 1274–1279
Lee, R.B., Drew, M.C. (1986) Nitrogen-13 studies of nitrate fluxes in barley roots. J. Exp. Bot. 37, 1768–1779
Mäck, G. (1988) Untersuchungen zum Stickstoffmetabolismus in Zuckerrübenpflanzen unterschiedlicher Entwicklungsstadien. Thesis, University Göttingen, FRG
McKown, C.T., Volk, R.J., Jackson, W.A. (1982) Nitrate assimilation by decapitated corn root systems: Effect of ammonium during induction. Plant Sci. Lett. 24, 295–302
Ngambi, J.-M., Amblard, P., Bismuth, E., Champigny, M.-L. (1981) Étude des activities enzymatiques nitrate reductase et glutamine synthetase liés á l'assimilation des nitrates chez un Mil, Pennisetum americanum 23 DB. Can. J. Bot. 59, 1050–1055
Peuke, A. (1987) Der Effekt von Schwefeldioxid-, Ozon-und Stickstoffdioxid-Begasung auf den Stickstoffmetabolismus steril kultivierter Fichtenkeimlinge (Picea abies(L.) Karst.). Thesis, University Göttingen, FRG
Rehm, S. (1953) The origin of toxic ammonia in germinating garden beet seed. J. Hort. Sci. 28, 1–13
Thayer, J.R., Huffaker, R.C. (1980) Determination of nitrate and nitrite by high-pressure liquid chromatography: Comparison with other methods for nitrate determination. Anal. Biochem. 102, 110–119
Tischner, R., Lorenzen, H. (1979) Nitrate uptake and nitrate reduction in synchronous Chlorella. Planta 146, 287–292
Ward, M.R., Grimes, H.D., Huffaker, R.C. (1988) Latent nitrate reductase activity is associated with the plasma membrane of corn roots. Planta 177, 470–475
Author information
Authors and Affiliations
Additional information
This work was supported by a grant from Bundesministerium für Forschung und Technologie and by Kleinwanzlebener Saatzucht AG, Einbeck.
Rights and permissions
About this article
Cite this article
Mäck, G., Tischner, R. The effect of endogenous and externally supplied nitrate on nitrate uptake and reduction in sugarbeet seedlings. Planta 182, 169–173 (1990). https://doi.org/10.1007/BF00197106
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00197106