Understanding the ion flux network in Arabidopsis guard cells to control gas exchanges – NetFlux

In eukaryotes, intracellular processes such as signaling rely on a network of ion flux between the different intracellular compartments. Although crucial, ion flux coordination between membranes in series is still poorly understood. Plants offer an ideal cellular/biophysical model, the guard cells, to investigate ion flux coordination between compartments in a highly relevant biological process, the control of stomata aperture. Guard cells regulate the aperture of the stomata pores and in this way regulate gas exchanges between the leaves and the atmosphere. Given their function at the interface with the atmosphere, stomata are essential elements for plant adaptation to the environment directly impacting plant biomass production and adaptation to stress conditions. To control the stomata pore aperture guard-cells are able to change their intracellular turgor. This changes of turgor induce changes of the guard cell shape modifying the stomata pore aperture. Massive and coordinated fluxes of ions across the two major membranes (i.e. plasma and vacuolar membranes) of guard cells delimiting two intracellular compartments (i.e. the cytosol and vacuole) modify intracellular turgor. Despite its importance for stomata responses to environmental stimuli, the coordination of ion fluxes between cellular membranes is still poorly understood. The Netflux proposal will explore the molecular/biophysical basis of ion flux coordination between cellular membranes and compartments using guard cells as model system. To achieve its objectives, the Netflux project involves three partners with complementary competences in order to develop an innovative and interdisciplinary approach. Combining genetics, cell imaging, electrophysiology and mathematical modelling we will tackle the coordination of ion fluxes during cellular responses. The project will exploit unique and original genetic resources from the partners to analyze, based on cutting edge experimental techniques and mathematical tools, the dynamics of ionic fluxes in compartmentalized living cells. Further, within the NetFlux we will set a unique and innovative forward genetic screen to uncover new important regulators of ion fluxes in guard cells. The strategy we propose will be a great opportunity to unravel new fundamental mechanisms operating in eukaryotic cells during cellular responses to the environment. In the context of guard cell physiology, the results we will obtain will open new perspectives in our understanding of the stomata functioning. This will be instrumental to combine plant biomass production with tolerance to stress conditions in the context of the future challenges that agriculture will have to face.