How stable isotopes may help to elucidate primary nitrogen metabolism and its interaction with (photo)respiration in C3 leaves.
Intense efforts are currently devoted to elucidate the metabolic networks of plants, in which nitrogen assimilation is of particular importance because it is strongly related to plant growth. In addition, at the leaf level, primary nitrogen metabolism interacts with photosynthesis, day respiration, and photorespiration, simply because nitrogen assimilation needs energy, reductant, and carbon skeletons which are provided by these processes. While some recent studies have focused on metabolomics and genomics of plant leaves, the actual metabolic fluxes associated with nitrogen metabolism operating in leaves are not very well known. In the present paper, it is emphasized that (12)C/(13)C and (14)N/(15)N stable isotopes have proved to be useful tools to investigate such metabolic fluxes and isotopic data are reviewed in the light of some recent advances in this area. Although the potential of stable isotopes remains high, it is somewhat limited by our knowledge of some isotope effects associated with enzymatic reactions. Therefore, this paper should be viewed as a call for more fundamental studies on isotope effects by plant enzymes.
Tcherkez
Guillaume
G
Plateforme Métabolisme-Métabolome, IFR 87, Bât. 630, Université Paris Sud-XI, F-91405 Orsay cedex, France. guillaume.tcherkez@u-psud.fr
Hodges
Michael
M
D002244:Carbon / Q000378:metabolism; D002247:Carbon Isotopes; D002940:Circadian Rhythm; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010101:Oxygen Consumption; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism*; D010944:Plants / Q000201:enzymology; D000644:Quaternary Ammonium Compounds / Q000378:metabolism
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D000644:Quaternary Ammonium Compounds; D002244:Carbon; D009584:Nitrogen