title: (13)C/(12)C isotope labelling to study leaf carbon respiration and allocation in twigs of field-grown beech trees.
abstract: In situ (13)C/(12)C isotopic labelling was conducted in field-grown beech (Fagus sylvatica) twigs to study carbon respiration and allocation. This was achieved with a portable gas-exchange open system coupled to an external chamber. This method allowed us to subject leafy twigs to CO(2) with a constant carbon isotope composition (delta(13)C of -51.2 per thousand) in an open system in the field. The labelling was done during the whole light period at two different dates (in June 2002 and October 2003). The delta(13)C values of respiratory metabolites and CO(2) that is subsequently respired during the night were measured. It was found that night-respired CO(2) is not completely labelled (only ca. 58% and 27% of new carbon is found in respired CO(2) immediately after the labelling in June 2002 and October 2003, respectively) and the labelling level progressively disappeared during the next day. It is concluded that the carbon respired by beech leaves after illumination was supplied by a mixture of carbon sources in which current carbohydrates were not the only contributors. In addition, as has been found in herbaceous plants, isotopic data before labelling showed that carbon isotope discrimination favoring the (13)C isotope occurred during the night respiration of beech leaves.
authors.affiliation: Laboratoire d'Ecologie Systématique et Evolution, Unité Mixte de Recherche 8079, Université de Paris XI, Bâtiment 362, 91405 Orsay, France. salvador.nogues@ub.edu
authors.forename: Salvador
authors.initials: S
authors.lastname: Nogués
authors.forename: Claire
authors.initials: C
authors.lastname: Damesin
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tcherkez
authors.forename: Florence
authors.initials: F
authors.lastname: Maunoury
authors.forename: Gabriel
authors.initials: G
authors.lastname: Cornic
authors.forename: Jaleh
authors.initials: J
authors.lastname: Ghashghaie
mesh_terms: D002244:Carbon / Q000032:analysis / Q000378:metabolism*; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D002250:Carbon Radioisotopes; D019069:Cell Respiration / Q000502:physiology*; D029964:Fagus / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007553:Isotope Labeling / Q000379:methods; D018515:Plant Leaves / Q000378:metabolism*; D018547:Plant Stems / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D002250:Carbon Radioisotopes; D002245:Carbon Dioxide; D002244:Carbon