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Open AccessArticle

d-Amino Acids Are Exuded by Arabidopsis thaliana Roots to the Rhizosphere

Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany
Authors to whom correspondence should be addressed.
Int. J. Mol. Sci. 2018, 19(4), 1109;
Received: 8 March 2018 / Revised: 3 April 2018 / Accepted: 5 April 2018 / Published: 7 April 2018
(This article belongs to the Special Issue Amino Acids Transport and Metabolism)
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Proteinogenic l-amino acids (l-AAs) are essential in all kingdoms as building blocks of proteins. Their d-enantiomers are also known to fulfill important functions in microbes, fungi, and animals, but information about these molecules in plants is still sparse. Previously, it was shown that d-amino acids (d-AAs) are taken up and utilized by plants, but their ways to reduce excessive amounts of them still remained unclear. Analyses of plant d-AA content after d-Ala and d-Glu feeding opened the question if exudation of d-AAs into the rhizosphere takes place and plays a role in the reduction of d-AA content in plants. The exudation of d-Ala and d-Glu could be confirmed by amino acid analyses of growth media from plants treated with these d-AAs. Further tests revealed that other d-AAs were also secreted. Nevertheless, treatments with d-Ala and d-Glu showed that plants are still able to reduce their contents within the plant without exudation. Further exudation experiments with transport inhibitors revealed that d-AA root exudation is rather passive and comparable to the secretion of l-AAs. Altogether, these observations argued against a dominant role of exudation in the regulation of plant d-AA content, but may influence the composition of the rhizosphere. View Full-Text
Keywords: d-amino acids; chiral LC-MS; root exudation; plant-rhizosphere interactions; molecular transport d-amino acids; chiral LC-MS; root exudation; plant-rhizosphere interactions; molecular transport

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Hener, C.; Hummel, S.; Suarez, J.; Stahl, M.; Kolukisaoglu, Ü. d-Amino Acids Are Exuded by Arabidopsis thaliana Roots to the Rhizosphere. Int. J. Mol. Sci. 2018, 19, 1109.

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