Abstract
Root hairs as specialized epidermal cells represent part of the outermost interface between a plant and its soil environment. They make up to 70% of the root surface and, therefore, are likely to contribute significantly to nutrient uptake. To study uptake systems for mineral nitrogen, three genes homologous to Arabidopsis nitrate and ammonium transporters (AtNrt1 and AtAmt1) were isolated from a root hair-specific tomato cDNA library. Accumulation of LeNrt1-1, LeNrt1-2, and LeAmt1 transcripts was root-specific, with no detectable transcripts in stems or leaves. Expression was root cell type-specific and regulated by nitrogen availability. LeNrt1-2 mRNA accumulation was restricted to root hairs that had been exposed to nitrate. In contrast, LeNrt1-1 transcripts were detected in root hairs as well as other root tissues under all nitrogen treatments applied. Analogous to LeNrt1-1, the gene LeAmt1 was expressed under all nitrogen conditions tested, and root hair-specific mRNA accumulation was highest following exposure to ammonium. Expression of LeAMT1 in an ammonium uptake-deficient yeast strain restored growth on low ammonium medium, confirming its involvement in ammonium transport. Root hair specificity and characteristics of substrate regulation suggest an important role of the three genes in uptake of mineral nitrogen.
Full text
PDF





Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- 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., Chapin F. S. Differences in steady-state net ammonium and nitrate influx by cold- and warm-adapted barley varieties. Plant Physiol. 1981 Nov;68(5):1064–1067. doi: 10.1104/pp.68.5.1064. [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]
- Crawford N. M. Nitrate: nutrient and signal for plant growth. Plant Cell. 1995 Jul;7(7):859–868. doi: 10.1105/tpc.7.7.859. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dubois E., Grenson M. Methylamine/ammonia uptake systems in saocharomyces cerevisiae: multiplicity and regulation. Mol Gen Genet. 1979 Aug;175(1):67–76. doi: 10.1007/BF00267857. [DOI] [PubMed] [Google Scholar]
- Franco A. R., Cárdenas J., Fernández E. Two different carriers transport both ammonium and methylammonium in Chlamydomonas reinhardtii. J Biol Chem. 1988 Oct 5;263(28):14039–14043. [PubMed] [Google Scholar]
- Goyal S. S., Huffaker R. C. The uptake of NO3-, NO2-, and NH4+ by intact wheat (Triticum aestivum) seedlings. I. Induction and kinetics of transport systems. Plant Physiol. 1986;82:1051–1056. doi: 10.1104/pp.82.4.1051. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Henriksen G. H., Raman D. R., Walker L. P., Spanswick R. M. Measurement of Net Fluxes of Ammonium and Nitrate at the Surface of Barley Roots Using Ion-Selective Microelectrodes : II. Patterns of Uptake Along the Root Axis and Evaluation of the Microelectrode Flux Estimation Technique. Plant Physiol. 1992 Jun;99(2):734–747. doi: 10.1104/pp.99.2.734. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Imsande J., Touraine B. N Demand and the Regulation of Nitrate Uptake. Plant Physiol. 1994 May;105(1):3–7. doi: 10.1104/pp.105.1.3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kosola K. R., Bloom A. J. Methylammonium as a Transport Analog for Ammonium in Tomato (Lycopersicon esculentum L.). Plant Physiol. 1994 May;105(1):435–442. doi: 10.1104/pp.105.1.435. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lazof D. B., Rufty T. W., Redinbaugh M. G. Localization of Nitrate Absorption and Translocation within Morphological Regions of the Corn Root. Plant Physiol. 1992 Nov;100(3):1251–1258. doi: 10.1104/pp.100.3.1251. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Marini A. M., Vissers S., Urrestarazu A., André B. Cloning and expression of the MEP1 gene encoding an ammonium transporter in Saccharomyces cerevisiae. EMBO J. 1994 Aug 1;13(15):3456–3463. doi: 10.1002/j.1460-2075.1994.tb06651.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ninnemann O., Jauniaux J. C., Frommer W. B. Identification of a high affinity NH4+ transporter from plants. EMBO J. 1994 Aug 1;13(15):3464–3471. doi: 10.1002/j.1460-2075.1994.tb06652.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Padgett P. E., Leonard R. T. Contamination of Ammonium-Based Nutrient Solutions by Nitrifying Organisms and the Conversion of Ammonium to Nitrate. Plant Physiol. 1993 Jan;101(1):141–146. doi: 10.1104/pp.101.1.141. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Raper C. D., Jr, Vessey J. K., Henry L. T., Chaillou S. Cyclic variations in nitrogen uptake rate of soybean plants: effects of pH and mixed nitrogen sources. Plant Physiol Biochem. 1991;29(3):205–212. [PubMed] [Google Scholar]
- Rentsch D., Laloi M., Rouhara I., Schmelzer E., Delrot S., Frommer W. B. NTR1 encodes a high affinity oligopeptide transporter in Arabidopsis. FEBS Lett. 1995 Aug 21;370(3):264–268. doi: 10.1016/0014-5793(95)00853-2. [DOI] [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]
- Steiner H. Y., Song W., Zhang L., Naider F., Becker J. M., Stacey G. An Arabidopsis peptide transporter is a member of a new class of membrane transport proteins. Plant Cell. 1994 Sep;6(9):1289–1299. doi: 10.1105/tpc.6.9.1289. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tsay Y. F., Schroeder J. I., Feldmann K. A., Crawford N. M. The herbicide sensitivity gene CHL1 of Arabidopsis encodes a nitrate-inducible nitrate transporter. Cell. 1993 Mar 12;72(5):705–713. doi: 10.1016/0092-8674(93)90399-b. [DOI] [PubMed] [Google Scholar]
- Vessey J. K., York E. K., Henry L. T., Raper C. D., Jr Uniformity of environmental conditions and plant growth in a hydroponic culture system for use in a growth room with aerial CO2 control. Biotronics. 1988;17:79–94. [PubMed] [Google Scholar]
- Wang M. Y., Siddiqi M. Y., Ruth T. J., Glass ADM. Ammonium Uptake by Rice Roots (II. Kinetics of 13NH4+ Influx across the Plasmalemma). Plant Physiol. 1993 Dec;103(4):1259–1267. doi: 10.1104/pp.103.4.1259. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zobel R. W., Del Tredici P., Torrey J. G. Method for growing plants aeroponically. Plant Physiol. 1976 Mar;57(3):344–346. doi: 10.1104/pp.57.3.344. [DOI] [PMC free article] [PubMed] [Google Scholar]