Résumé
Plants, when faced with unfavorable osmotic conditions (e.g. water shortage), have developed mechanisms and fast responses to cope with these challenging environments. Among other responses, osmotic stress induces, within minutes, an increased internalization of plasma membrane proteins by endocytosis. We have recently found that this is related to Reactive Oxygen Species (ROS) accumulation in cells. ROS serve as secondary messengers in numerous signaling events that can be generated by 2 main pathways in the case of osmotic stress: through NADPH-oxidase (Rboh) and the Fe/Ascorbate coupling. Changes in the osmotic balance trigger an upstream element that belongs to Rho Of Plant gene family, ROP6. ROP6 is a molecular signaling transducer that can ‘translate’ an extracellular into intracellular signal. Here we are demonstrating a role of ROP6 in triggering osmotic response which acts on the 2 ROS producing mechanisms. In addition, by the use of a dominant active ROP6, we state that this gene is sufficient to regulate ROS in Arabidopsis. Finally, by FRET with FLIM, we were able to capture physical interactions of the dominant active ROP6 protein with one of the major isoforms of Rboh in roots, RbohD. Our results suggest that ROP6 is an important feature ofthe osmotic signaling cascade.