Plants show distinct responses when roots encounter high sodium concentrations in the soil. Roots are for example bending away from these high sodium concentrations, this response is specific for sodium and not initiated by osmotic stress, high potassium or chloride levels. On the cellular level, signaling molecules like Ca2+ and cGMP are rapidly increasing and Ca2+ waves are observed throughout the whole plant. To date it is, however, not shown how these responses are initiated or in other words, how plants sense that sodium levels are increasing. The aim of my project will be to investigate this putative sensor and study its downstream signaling pathway.