This sub-line uses an integrated approach to study the biochemical and molecular mechanisms of ion homeostasis in plants in order to develop biotechnological applications to improve salt tolerance and mineral nutrition efficiency. The identification and function of transport systems of Na+, K+ and H+ and their regulatory proteins are investigated in model systems (yeast and Arabidopsis) and crop plants (tomato). For this purpose we use in vitro and in planta functional analysis. In vitro approaches imply membrane protein purification and reconstitution in liposomes, whereas in planta analysis is mainly based on gene overexpression and silencing (RNAi) experiments.