Significant loss in agricultural products is caused by increasingly variable climate and vulnerability of crops to pathogen attacks or extreme environmental conditions. In addition, the agro-industry and the final market often require highly homogeneous crops. This raises the issue of resilience: How to produce robust and homogeneous crops? Here we address the corresponding key question in developmental biology: How do organs form with consistent sizes and shapes in the face of internal and external perturbations? We have assembled an interdisciplinary team to resolve the apparent dichotomy between highly variable cells and robust organs. Previous research has focused on mutants and conditions that affect the global size and shape of organs, enabling the discovery of a large number of regulators. However, most analyses have considered only average cell behaviours, overlooking local heterogeneity and stochastic variation. Here we adopt an orthogonal approach: We screen for mutants with enhanced variability in organ size or shape. Plants produce many flowers, allowing us to detect variability within an individual organism. We have chosen the abaxial sepal, the outermost leaf-like floral organ, for its accessibility for imaging and micromanipulation: the whole process of organogenesis from a primordium to the mature organ can be observed with a confocal microscope. Variability of sepal size and shape can be assessed within an individual plant. Based on our previous work, we propose that tissue mechanics and mechanosensing are key regulators of organ variability, because morphogenesis directly depends on the mechanical control of growth and because mechanical stress is largely prescribed by organ size and shape. We will test this hypothesis in Arabidopsis thaliana, chosen for the availability of genetic and molecular resources. Our main objectives are (i) to analyse spatial and temporal variability in sepal morphogenesis at all scales, considering growth and its effectors, (ii) to identify and characterise genes that regulate variability, by performing a directed screen among mutants affecting the cell wall, plant hydraulics, and mechanosensing, and (iii) to integrate the corresponding mechanisms in mechanical models of growth and test these models experimentally, notably by local mechanical and genetic perturbations to sepals. Overall, our project addresses a central question in developmental biology and is relevant to food security, especially in the context of increasing climatic fluctuations. On the one hand, we will isolate and characterise molecular regulators of the robustness of flower organs. We will overexpress these regulators in plant lines and examine if these lines have more homogeneous organs (e.g. homogenous siliques). On the other hand, we will develop biophysical measurements in the context of plant sciences, which may apply to a broad range of R&D problems, from fruit firmness to biomaterial properties or biomechanical resilience.