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

jeudi 22 février à 14h – Amphi 206

Rob Roelfsema

(Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, University of Würzburg, Germany)

Drought-induced stomatal closure: Guard cell calcium-signals, or no calcium-signals?

During drought, the closure of stomatal pores in the leaf surface of seed plants is mediated by the stress hormone Abscisic Acid (ABA). Experiments in the 1990ies provided evidence that ABA can trigger cytosolic calcium signals in guard cells and that anion channels are activated by high cytosolic calcium levels. Based on these results, it was postulated that ABA activates anion channels in guard cells via cytosolic calcium signals. However, more recent data show the core ABA signaling pathway is composed of calcium-independent components. Because of these contrasting results the involvement of calcium signal in ABA-induced stomatal closure was studies, in Vicia faba, Nicotiana tabacum and Arabidopsis thaliana. Our results show that the activation of plasma membrane anion channels is required and sufficient to close stomata. In contrast, cytosolic calcium signals are sufficient, but not essential for ABA-induced stomatal closure. We conclude that calcium signals enhance the efficiency by which ABA provokes the closure of stomata.

Contact : Doan-Trung Luu

Contacts IBIP :
Sabine Zimmermann (sabine.zimmermann@cnrs.fr)
Justine Drouault (justine.drouault@inrae.fr)
Jessica Bertheloot (jessica.bertheloot@inrae.fr)
Chantal Baracco (chantal.baracco@inrae.fr)