Ion transport in plant is of central interest in plant biology. Indeed, ion fluxes across the membranes are essential for example in mineral nutrition, cell elongation, signal transduction and stomata movements. Therefore, understanding the molecular details of ion transport is a major issue in plant biology. Different protein families are involved in mediating the transport of the different ion species. In the last decade several anion transporters families have been identified. Among them the ALMT (Aluminium Activated Malate Channel) was shown to be implicated in the transport of anions across the plasma membrane and the tonoplast. In the present project we will focus on the members of the ALMT family localised in the vacuolar membrane. We want to characterise their functional properties and to understand their role in the plant anion homeostasis. Several fundamental questions are still open concerning these proteins. Are the different vacuolar ALMTs involved in different cellular processes? Do they perform their function as homomers or heteromers? What is their role for plant growth, development and stress resistance? We will address these issues using different approaches:
A) an electrophysiological characterisation of the vacuolar ALMTs for which any functional information is lacking .
B) a combination of biochemical and microscopy techniques to investigate the quaternary structure of these proteins and to elucidate if they can form heteromeric complexes in vivo
C) an analysis of single and multiple loss-of-function mutant plants and of multiple silenced lines that we will generate during this project.
The combination of these different approaches will allow us understanding the role of the vacuolar ALMTs at different level of integration: the organelle, the cell and the plant.