JXB Advance Access originally published online on April 20, 2009
Journal of Experimental Botany 2009 60(8):2419-2431; doi:10.1093/jxb/erp100
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This article appears in the following Journal of Experimental Botany issue: Special Issue: Mesophyll conductance to CO2: mechanisms, modelling, and ecological implications [View the issue table of contents]
Mesophyll Conductance in Field Stressful Environments |
The diversity of 13C isotope discrimination in a Quercus robur full-sib family is associated with differences in intrinsic water use efficiency, transpiration efficiency, and stomatal conductance
1INRA, UMR1137 Ecologie et Ecophysiologie Forestières, IFR 110 Génomique, Ecophysiologie, Ecologie Fonctionnelle, F-54280 Champenoux, France and Nancy Université, UMR1137 Ecologie et Ecophysiologie Forestières, F54500 Vandoeuvre, France
2INRA, UMR1202 Biodiversité, Gènes, Communautés, F-33612 Cestas, France and Université de Bordeaux I, UMR1202 Biodiversité, Gènes, Communautés F33405 Talence, France
* To whom correspondence should be addressed. E-mail: brendel{at}nancy.inra.fr
13C discrimination in organic matter with respect to atmospheric CO2 (
13C) is under tight genetic control in many plant species, including the pedunculate oak (Quercus robur L.) full-sib progeny used in this study.
13C is expected to reflect intrinsic water use efficiency, but this assumption requires confirmation due to potential interferences with mesophyll conductance to CO2, or post-photosynthetic discrimination. In order to dissect the observed
13C variability in this progeny, six genotypes that have previously been found to display extreme phenotypic values of
13C [either very high (high
) or low (low
) phenotype] were selected, and transpiration efficiency (TE; accumulated biomass/transpired water), net CO2 assimilation rate (A), stomatal conductance for water vapour (gs), and intrinsic water use efficiency (Wi=A/gs) were compared with
13C in bulk leaf matter, wood, and cellulose in wood. As expected, high
displayed higher values of
13C not only in bulk leaf matter, but also in wood and cellulose. This confirmed the stability of the genotypic differences in
13C recorded earlier. High
also displayed lower TE, lower Wi, and higher gs. A small difference was detected in photosynthetic capacity but none in mesophyll conductance to CO2. High
and low
displayed very similar leaf anatomy, except for higher stomatal density in high
. Finally, diurnal courses of leaf gas exchange revealed a higher gs in high
in the morning than in the afternoon when the difference decreased. The gene ERECTA, involved in the control of water use efficiency, leaf differentiation, and stomatal density, displayed higher expression levels in low
. In this progeny, the variability of
13C correlated closely with that of Wi and TE. Genetic differences of
13C and Wi can be ascribed to differences in stomatal conductance and stomatal density but not in photosynthetic capacity.
Key words: Carbon isotope discrimination, pedunculate oak, stomatal conductance, stomatal density, transpiration efficiency, water use efficiency
Received 26 November 2008; Revised 6 March 2009 Accepted 9 March 2009