Robust Organ Shape During Growth Requires Local Morphogen Signaling and Global Curvature Feedback

Precise organ shape during development requires feedback between organ-scale geometry and cell-level growth dynamics. Here, we use the apical hook of dicotyledonous plants as a model to study this multiscale control. This protective structure forms a ∼180° bend that is stably maintained despite rapid elongation. Combining quantitative growth mapping, multiscale modeling, and hormone analysis, we identify the cellular dynamics underlying hook maintenance. Contrary to the prevailing model, hook stability does not arise from sustained inner–outer growth asymmetry. Instead, stable curvature emerges from a biphasic, self-similar growth pattern that remains spatially fixed despite continuous cell flux. Auxin-driven growth asymmetry induces bending but is spatially restricted and insufficient to maintain shape. By contrast, a graded, auxin-independent autotropic response provides curvature-dependent growth regulation that counteracts bending and stabilizes shape against perturbations. Together, these findings establish a general principle in which local morphogen-driven bending and global geometry-dependent feedback jointly maintain robust organ shape during growth.