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Title: Metabolic origin of δ15N values in nitrogenous compounds from Brassica napus L. leaves
Author: Gauthier, P.
Lamothe, M.
Molero Milán, Gemma
Mahé, A.
Hodges, M.
Nogués Mestres, Salvador
Tcherkez, G.
Keywords: Crucíferes
Respiració de les plantes
Metabolisme de les plantes
Plant respiration
Plant metabolism
Issue Date: 2013
Publisher: John Wiley & Sons
Abstract: Nitrogen isotope composition (δ15N) in plant organic matter is currently used as a natural tracer of nitrogen acquisition efficiency. However, the δ15N value of whole leaf material does not properly reflect the way in which N is assimilated because isotope fractionations along metabolic reactions may cause substantial differences among leaf compounds. In other words, any change in metabolic composition or allocation pattern may cause undesirable variability in leaf δ15N. Here, we investigated the δ15N in different leaf fractions and individual metabolites from rapeseed (Brassica napus) leaves. We show that there were substantial differences in δ15N between nitrogenous compounds (up to 30 ) and the content in (15N enriched) nitrate had a clear influence on leaf δ15N. Using a simple steady-state model of day metabolism, we suggest that the δ15N value in major amino acids was mostly explained by isotope fractionation associated with isotope effects on enzyme-catalysed reactions in primary nitrogen metabolism. δ15N values were further influenced by light versus dark conditions and the probable occurrence of alternative biosynthetic pathways. We conclude that both biochemical pathways (that fractionate between isotopes) and nitrogen sources (used for amino acid production) should be considered when interpreting the δ15N value of leaf nitrogenous compounds
Note: Versió preprint del document publicat a:
It is part of: Plant Cell and Environment, 2013, vol. 36, num. 1, p. 128-137
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ISSN: 0140-7791
Appears in Collections:Articles publicats en revistes (Biologia Evolutiva, Ecologia i Ciències Ambientals)

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