Divergence in delta(13)C of dark respired CO(2) and bulk organic matter occurs during the transition between heterotrophy and autotrophy in Phaseolus vulgaris plants.
Substantial evidence has been published in recent years demonstrating that postphotosynthetic fractionations occur in plants, leading to (13)C-enrichment in heterotrophic (as compared with autotrophic) organs. However, less is known about the mechanism responsible for changes in these responses during plant development. The isotopic signature of both organic matter and respired CO(2) for different organs of French bean (Phaseolus vulgaris) was investigated during early ontogeny, in order to identify the developmental stage at which isotopic changes occur. Isotopic analyses of metabolites and mass balance calculations helped to constrain the metabolic processes involved. At the plant scale, apparent respiratory fractionation was constantly positive in the heterotrophic phase (c. 1 per thousand) and turned negative with autotrophy acquisition (down to -3.08 per thousand). Initially very close to that of the dry seed (-26.83 +/- 0.69 per thousand), isotopic signatures of organic matter and respired CO(2) diverged (in opposite directions) in leaves and roots after onset of photosynthesis. Respired CO(2) reached values up to -20 per thousand in leaves and became (13)C-depleted down to -29 per thousand in roots. It was concluded that isotopic differences between organs occurred subsequent to metabolic changes in the seedling during the transition from heterotrophy to autotrophy. They were especially related to respiration and respiratory fractionation.
Bathellier
Camille
C
Laboratoire d'Ecologie, Systématique et Evolution (ESE), CNRS-UMR 8079 - IFR 87, Bâtiment 362, Université Paris-Sud, F-91405 Orsay cedex, France.
Badeck
Franz-W
FW
Potsdam Institute for Climate Impact Research (PIK), PO Box 601203, D-14412 Potsdam, Germany.
Couzi
Philippe
P
Institut National de Recherche Agronomique (INRA), UMR 1272, Physiologie de l'Insecte: Signalisation et Communication (PISC), Route de Saint Cyr, F-78026 Versailles cedex, France.
Harscoët
Sébastien
S
Laboratoire d'Ecologie, Systématique et Evolution (ESE), CNRS-UMR 8079 - IFR 87, Bâtiment 362, Université Paris-Sud, F-91405 Orsay cedex, France.
Mauve
Caroline
C
Plateforme 'Métabolisme-Métabolome', IFR 87 Plante et son Environnement, Institut de Biotechnologie des Plantes, Bâtiment 630, Université Paris-Sud, F-91405 Orsay cedex, France.
Ghashghaie
Jaleh
J
Laboratoire d'Ecologie, Systématique et Evolution (ESE), CNRS-UMR 8079 - IFR 87, Bâtiment 362, Université Paris-Sud, F-91405 Orsay cedex, France.
D000222:Adaptation, Physiological; D002244:Carbon; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes / Q000378:metabolism; D004734:Energy Metabolism; D010101:Oxygen Consumption; D027805:Phaseolus / Q000254:growth & development* / Q000378:metabolism*; D012639:Seeds / Q000254:growth & development* / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000378:metabolism
D002247:Carbon Isotopes; D014867:Water; D002245:Carbon Dioxide; D002244:Carbon