Leaf growth is a complex developmental process that is tightly regulated to react dynamically to changing environmental conditions. Under drought stress, leaf growth is reduced to limit the evaporative surface and save energy. In the last years, research conducted on Arabidopsis and crops highlighted a role for the phytohormone ethylene in the regulation of cell division, leaf growth and yield under drought. Nevertheless, the molecular mechanisms underlying this process remain largely elusive. With the proposed project, I aim to unravel the role of ethylene in leaf growth inhibition under drought. By using cutting-edge technologies and last-generation genetic tools, both made available through international collaborations, I will measure and understand the ethylene accumulation in leaves under drought. Next, I will elucidate at the molecular level how ethylene triggers downstream pathways for leaf growth inhibition. Automated phenotyping on a broad range of ethylene mutants and transgenic lines with reduced ethylene levels will enable to pinpoint key genes and mechanisms involved in leaf growth inhibition under drought. Finally, by performing cell type-specific transcriptome analysis in leaves using the INTACT technology, I will aim to model how ethylene mediates cell cycle arrest under drought. With this novel and multidisciplinary approach, we will significantly enhance our current view on the molecular pathways enabling phenotypic plasticity under adverse conditions.