Plant adaptation to fluctuating environment and biomass production are strongly dependent on guard cell potassium channels

Anne Lebaudy (1) , Alain Vavasseur (2) , Eric Hosy (1) , Ingo Dreyer (1) , Nathalie Leonhardt (2) , Jean-Baptiste Thibaud (1) , Anne-Aliénor Véry (1) , Thierry Simonneau (3) , Hervé Sentenac (1)

1 BPMP - Biochimie et Physiologie Moléculaire des Plantes
2 LEMS - Laboratoire des Echanges Membranaires et Signalisation
3 LEPSE - Écophysiologie des Plantes sous Stress environnementaux

At least four genes encoding plasma membrane inward K+ channels (Kin channels) are expressed in Arabidopsis guard cells. A double mutant plant was engineered by disruption of a major Kin channel gene and expression of a dominant negative channel construct. Using the patch-clamp technique revealed that this mutant was totally deprived of guard cell Kin channel (GCKin) activity, providing a model to investigate the roles of this activity in the plant. GCKin activity was found to be an essential effector of stomatal opening triggered by membrane hyperpolarization and thereby of blue light-induced stomatal opening at dawn. It improved stomatal reactivity to external or internal signals (light, CO2 availability, and evaporative demand). It protected stomatal function against detrimental effects of Na+ when plants were grown in the presence of physiological concentrations of this cation, probably by enabling guard cells to selectively and rapidly take up K+ instead of Na+ during stomatal opening, thereby preventing deleterious effects of Na+ on stomatal closure. It was also shown to be a key component of the mechanisms that underlie the circadian rhythm of stomatal opening, which is known to gate stomatal responses to extracellular and intracellular signals. Finally, in a meteorological scenario with higher light intensity during the first hours of the photophase, GCKin activity was found to allow a strong increase (35%) in plant biomass production. Thus, a large diversity of approaches indicates that GCKin activity plays pleiotropic roles that crucially contribute to plant adaptation to fluctuating and stressing natural environments. physiology by engineering an Arabidopsis mutant totally deprived of this activity.

Mots clés: Arabidopsis; circadian rhythm; inward Shaker; stomata; transpirational water loss

Domaines: Biologie végétale

Anne Lebaudy, Alain Vavasseur, Eric Hosy, Ingo Dreyer, Nathalie Leonhardt, et al.. Plant adaptation to fluctuating environment and biomass production are strongly dependent on guard cell potassium channels. Proceedings of the National Academy of Sciences of the United States of America, 2008, 105 (13), pp.5271-5276. ⟨10.1073/pnas.0709732105⟩. ⟨hal-00267539⟩