Abstract
The short-lived radiotracer 13N was used to study feedback regulation of nitrate influx through the inducible high-affinity transport system of barley (Hordeum vulgare L. cv Steptoe) roots. Both wild-type plants and the mutant line Az12:Az70 (genotype nar1a;nar7w), which is deficient in the NADH-specific and NAD(P)H-bispecific nitrate reductases (R.L. Warner, R.C. Huffaker [1989] Plant Physiol 91: 947-953) showed strong feedback inhibition of nitrate influx within approximately 5 d of exposure to 100 fmu]M nitrate. The result with the mutant, in which the flux of nitrogen into reduced products is greatly reduced, indicated that nitrate itself was capable of exercising feedback regulation upon its own influx. This conclusion was supported by the observation that feedback in wild-type plants occurred in both the presence and absence of L-methionine sulfoximine, an inhibitor of ammonium assimilation. Nitrite and ammonium were also found to be capable of exerting feedback inhibition upon nitrate influx, although it was not determined whether these ions themselves or subsequent metabolites were responsible for the effect. It is suggested that feed-back regulation of nitrate influx is potentially mediated through several nitrogen pools, including that of nitrate itself.
Full Text
The Full Text of this article is available as a PDF (845.5 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Aslam M., Rosichan J. L., Huffaker R. C. Comparative induction of nitrate reductase by nitrate and nitrite in barley leaves. Plant Physiol. 1987;83:579–584. doi: 10.1104/pp.83.3.579. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Aslam M., Travis R. L., Huffaker R. C. Comparative kinetics and reciprocal inhibition of nitrate and nitrite uptake in roots of uninduced and induced barley (Hordeum vulgare L.) seedlings. Plant Physiol. 1992;99:1124–1133. doi: 10.1104/pp.99.3.1124. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bloom A. J., Sukrapanna S. S. Effects of Exposure to Ammonium and Transplant Shock upon the Induction of Nitrate Absorption. Plant Physiol. 1990 Sep;94(1):85–90. doi: 10.1104/pp.94.1.85. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bloom A. J., Sukrapanna S. S., Warner R. L. Root respiration associated with ammonium and nitrate absorption and assimilation by barley. Plant Physiol. 1992 Aug;99(4):1294–1301. doi: 10.1104/pp.99.4.1294. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fentem P. A., Lea P. J., Stewart G. R. Ammonia Assimilation in the Roots of Nitrate- and Ammonia-Grown Hordeum Vulgare (cv Golden Promise). Plant Physiol. 1983 Mar;71(3):496–501. doi: 10.1104/pp.71.3.496. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ingemarsson B., Oscarson P., Af Ugglas M., Larsson C. M. Nitrogen Utilization in Lemna: II. Studies of Nitrate Uptake Using NO(3). Plant Physiol. 1987 Nov;85(3):860–864. doi: 10.1104/pp.85.3.860. [DOI] [PMC free article] [PubMed] [Google Scholar]
- King B. J., Siddiqi M. Y., Glass A. D. Studies of the uptake of nitrate in barley : v. Estimation of root cytoplasmic nitrate concentration using nitrate reductase activity-implications for nitrate influx. Plant Physiol. 1992 Aug;99(4):1582–1589. doi: 10.1104/pp.99.4.1582. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Siddiqi M. Y., Glass A. D., Ruth T. J., Fernando M. Studies of the Regulation of Nitrate Influx by Barley Seedlings Using NO(3). Plant Physiol. 1989 Jul;90(3):806–813. doi: 10.1104/pp.90.3.806. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Siddiqi M. Y., Glass A. D., Ruth T. J., Rufty T. W. Studies of the Uptake of Nitrate in Barley: I. Kinetics of NO(3) Influx. Plant Physiol. 1990 Aug;93(4):1426–1432. doi: 10.1104/pp.93.4.1426. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Siddiqi M. Y., King B. J., Glass A. D. Effects of nitrite, chlorate, and chlorite on nitrate uptake and nitrate reductase activity. Plant Physiol. 1992 Oct;100(2):644–650. doi: 10.1104/pp.100.2.644. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Warner R. L., Huffaker R. C. Nitrate transport is independent of NADH and NAD(P)H nitrate reductases in barley seedlings. Plant Physiol. 1989;91:947–953. doi: 10.1104/pp.91.3.947. [DOI] [PMC free article] [PubMed] [Google Scholar]