Uptake of intact amino acids by plants depends on soil amino acid concentrations

verfasst von: L. Sauheitl, B. Glaser, A. Weigelt
Abstract: Studies in different ecosystems have shown that plants take up intact amino acids directly but little is known about the influence of free amino acid concentrations in the soil on this process. We investigated the effect of three different soil amino acid N concentrations (0.025, 0.13 and 2.5 μg N g^-1 soil) on direct uptake of four dual labelled (¹⁵N, ¹³C) amino acids (glycine, tyrosine, lysine, valine) in a greenhouse experiment using Anthoxantum odoratum as a model plant. Our results revealed that 8-45% of applied ¹⁵N was incorporated into plant root and shoot tissue 48 h after labelling. Additional ¹³C enrichment showed that 2-70% of this incorporated ¹⁵N was taken up as intact amino acid. Total ¹⁵N uptake and ¹⁵N uptake as intact amino acids were significantly affected by soil amino acid N concentrations and significantly differed between the four amino acids tested. We found a positive effect of soil amino acid concentrations on uptake of mineralized ¹⁵N relative to amino acid concentrations for all amino acids which was presumably due to higher diffusion rates of mineralized tracer to the root surface. However, intact amino acid uptake relative to amino acid concentrations as well as the proportion of total ¹⁵N taken up directly decreased with increasing soil amino acid N concentrations for all amino acids, irrespective of their microbial degradability. This effect is most likely controlled by the mineral N concentration in soil and perhaps in plants which inhibits direct amino acids uptake. Overall, we conclude that plant internal regulation of amino acid uptake controlled by mineral N is the main mechanism determining direct uptake of amino acids and thus a lower contribution of intact amino acid uptake to the plants N nutrition has to be expected for higher amino acid concentrations accompanied by mineralization in soil.
Organisationseinheit(en): Institut für Bodenkunde
AG Bodenchemie
Externe Organisation(en): Universität Bayreuth
Friedrich-Schiller-Universität Jena
Typ: Artikel
Journal: Environmental and Experimental Botany
Band: 66
Seiten: 145-152
Anzahl der Seiten: 8
ISSN: 0098-8472
Publikationsdatum: 05.2009
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Ökologie, Evolution, Verhaltenswissenschaften und Systematik, Agronomie und Nutzpflanzenwissenschaften, Pflanzenkunde
Elektronische Version(en): https://doi.org/10.1016/j.envexpbot.2009.03.009 (Zugang: Unbekannt)

BibTeX

@article{2415f882f5a447dc968ecb03c31bf8bf,
title = "Uptake of intact amino acids by plants depends on soil amino acid concentrations",
abstract = "Studies in different ecosystems have shown that plants take up intact amino acids directly but little is known about the influence of free amino acid concentrations in the soil on this process. We investigated the effect of three different soil amino acid N concentrations (0.025, 0.13 and 2.5 μg N g-1 soil) on direct uptake of four dual labelled (15N, 13C) amino acids (glycine, tyrosine, lysine, valine) in a greenhouse experiment using Anthoxantum odoratum as a model plant. Our results revealed that 8-45% of applied 15N was incorporated into plant root and shoot tissue 48 h after labelling. Additional 13C enrichment showed that 2-70% of this incorporated 15N was taken up as intact amino acid. Total 15N uptake and 15N uptake as intact amino acids were significantly affected by soil amino acid N concentrations and significantly differed between the four amino acids tested. We found a positive effect of soil amino acid concentrations on uptake of mineralized 15N relative to amino acid concentrations for all amino acids which was presumably due to higher diffusion rates of mineralized tracer to the root surface. However, intact amino acid uptake relative to amino acid concentrations as well as the proportion of total 15N taken up directly decreased with increasing soil amino acid N concentrations for all amino acids, irrespective of their microbial degradability. This effect is most likely controlled by the mineral N concentration in soil and perhaps in plants which inhibits direct amino acids uptake. Overall, we conclude that plant internal regulation of amino acid uptake controlled by mineral N is the main mechanism determining direct uptake of amino acids and thus a lower contribution of intact amino acid uptake to the plants N nutrition has to be expected for higher amino acid concentrations accompanied by mineralization in soil.",
keywords = "C, N, Microbial competition, Organic nitrogen, Plant nutrition, Stable isotope",
author = "L. Sauheitl and B. Glaser and A. Weigelt",
note = "Funding information: We thank the German Research Foundation (GL 327/4,4) and the Hanns-Seidel-Stiftung for financial support of this study. Special thanks go to the Prof. Dr. E. Steudle, chair for plant physiology of the University of Bayreuth, and Prof. Dr. G. Gebauer, Centre of Stable Isotope Analysis in Bayreuth, for providing a climatic chamber and laboratory work place. Michael Zech provided helpful comments to an earlier draft of the manuscript.",
year = "2009",
month = may,
doi = "10.1016/j.envexpbot.2009.03.009",
language = "English",
volume = "66",
pages = "145--152",
journal = "Environmental and Experimental Botany",
issn = "0098-8472",
publisher = "Elsevier",
number = "2",
}