Séminaire IBIP
Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)

Jeudi 17 novembre 2011
Salle 106 (Cœur d’Ecole) à 14h

Leaf conductance for CO2 diffusion – an update on its role during water stress and in controlling water use efficiency (WUE)

Alexander Gallé
University of the Balearic Islands in Mallorca, Spain

Leaf`s conductance for CO2 diffusion is composed of stomatal (gs) and mesophyll conductance (gm). Despite the lack of knowledge about the factors controlling gm, there is compelling evidence that gm is finite and can change as rapid as gs to varying environmental conditions. In fact, drought-induced limitation of photosynthesis can be strongly influenced by gm, which makes gm a key factor for the rate of photosynthetic recovery after relief of stress. Therefore, modifying the relationship between gm and gs provides the possibility to improve photosynthesis under sub-optimal growth conditions. Moreover, leaf intrinsic water use efficiency (WUE, i.e. carbon gain per unit water used) can be raised, as WUE depends on both, the ratio of gm to gs and on the ratio of net photosynthesis (AN) to gs. With regard to that and irrespectively of other approaches (e.g. improving Rubisco), WUE may be improved by i) increasing gm while gs remains unaltered, or by ii) maintaining gm while gs decreases. Evidence for the latter scenario will be presented from data on mutants with altered stomatal responses to abscisic acid (ABA), which also present constitutive changes of maximum gs. In addition, data from literature and unpublished results will be analyzed with regard to altered gm/gs and AN/gs ratios among several species and growth forms, which also include aquaporin, carbonic anhydrase, chloroplast and mitochondrial re-arrangement mutant lines. Finally, the potential of increasing gm/gs ratios (via modifications of gm, gs or both) to improve WUE as well as its realization will be discussed.


Contact : Bertrand Müller

Contacts IBIP :
Sabine Zimmermann
Philippe Nacry
Christine Granier
Chantal Baracco