Morphodynamics is aimed at understanding how shape in plants is controlled during development, a major issue in developmental biology.. So far, research in the field has been mainly based on qualitative observations of mutants, with little considerations for the physics of the cells and tissues leaving many questions unanswered or unexplored. Here, using recent technological advances, to which the applicant has largely contributed, we propose an interdisciplinary and quantitative analysis of molecular and biophysical growth parameters from the cell to the organ level.Because the mechanical properties of the cell wall are generally accepted to control local growth rates and directions, their contribution to morphogenesis will be the central focus. How the molecular regulatory networks, including cell identity genes, influence cell wall synthesis and structure to induce local growth rates and directions is largely unknown at present, mainly because our knowledge lacks integration at different levels of complexity. In addition to the quantitative and interdisciplinary character of this proposal, an original aspect of the project will address the multi-scale nature of a growing tissue, establishing a causality link between local wall properties and multi-cellular outputs.To address this issue, we will combine cutting edge live imaging tools and micromechanical approaches with modelling frameworks recently developed in our laboratory. This will be performed using the developing flower in Arabidopsis, one of the best studied systems in biology and which has the strong advantage to grow without cell migration or rearrangement, vastly facilitating the dialog between the observations and the predictions from the models.In summary, using different interdisciplinary concepts and methods, developed in our laboratory and coming from biology, physics and computer science, we will produce for the first time a mechanistic and multi-scale view of the growing flower bud.