Abstract
13N-labeled nitrate was used to trace short-term nitrate influx into Lemna gibba L. G3 in experiments where disappearance of both radioactivity and total nitrate from the incubation medium was measured continuously and simultaneously. In plants performing net nitrate uptake from an initial nitrate concentration of 40 to 60 micromolar, there was no discrepancy between net uptake and influx, irrespective of the N status of the plants, indicating that concomitant nitrate efflux was low or nil. Plants treated with tungstate to inactivate nitrate reductase were able to take up nitrate following induction of the uptake system by exposure to a low amount of nitrate. Also, in this case, net uptake was equivalent to influx. In tungstate-treated plants preloaded with nitrate, both net uptake and influx were nil. In contrast to these observations, a clear discrepancy between net uptake and influx was observed when the plants were incubated at an initial nitrate concentration of approximately 5 micromolar, where net uptake is low and eventually ceases. It is concluded that plasmalemma nitrate transport is essentially unidirectional in plants performing net uptake at a concentration of 40 to 60 micromolar, and that transport is nil when internal nitrate sinks (vacuole, metabolism) are eliminated. The efflux component becomes increasingly important when the external concentration approaches the threshold value for net nitrate uptake (the nitrate compensation point) where considerable exchange between internal and external nitrate occurs.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Deane-Drummond C. E., Glass A. D. Nitrate Uptake into Barley (Hordeum vulgare) Plants : A New Approach Using ClO(3) as an Analog for NO(3). Plant Physiol. 1982 Jul;70(1):50–54. doi: 10.1104/pp.70.1.50. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Deane-Drummond C. E., Glass A. D. Short Term Studies of Nitrate Uptake into Barley Plants Using Ion-Specific Electrodes and ClO(3): I. Control of Net Uptake by NO(3) Efflux. Plant Physiol. 1983 Sep;73(1):100–104. doi: 10.1104/pp.73.1.100. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gersberg R., Krohn K., Peek N., Goldman C. R. Denitrification Studies with 13N-Labeled Nitrate. Science. 1976 Jun 18;192(4245):1229–1231. doi: 10.1126/science.192.4245.1229. [DOI] [PubMed] [Google Scholar]
- Glass A. D., Thompson R. G., Bordeleau L. Regulation of NO(3) Influx in Barley : Studies Using NO(3). Plant Physiol. 1985 Feb;77(2):379–381. doi: 10.1104/pp.77.2.379. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ingemarsson B. Nitrogen Utilization in Lemna: I. Relations between Net Nitrate Flux, Nitrate Reduction, and in Vitro Activity and Stability of Nitrate Reductase. Plant Physiol. 1987 Nov;85(3):856–859. doi: 10.1104/pp.85.3.856. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kochian L. V., Lucas W. J. Potassium Transport in Corn Roots : II. The Significance of the Root Periphery. Plant Physiol. 1983 Oct;73(2):208–215. doi: 10.1104/pp.73.2.208. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Morgan M. A., Volk R. J., Jackson W. A. Simultaneous Influx and Efflux of Nitrate during Uptake by Perennial Ryegrass. Plant Physiol. 1973 Feb;51(2):267–272. doi: 10.1104/pp.51.2.267. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rufty T. W., Thomas J. F., Remmler J. L., Campbell W. H., Volk R. J. Intercellular localization of nitrate reductase in roots. Plant Physiol. 1986 Nov;82(3):675–680. doi: 10.1104/pp.82.3.675. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tomino Y., Sakai H., Woodroffe A. J., Clarkson A. R. Studies on glomerular immune solubilization by complement in patients with IgA nephropathy. Acta Pathol Jpn. 1987 Nov;37(11):1763–1767. doi: 10.1111/j.1440-1827.1987.tb02869.x. [DOI] [PubMed] [Google Scholar]