Format: ORAL

Marco Saltini1, Caroline Robertson2, Haoran Xue3, Nicola Illing2, Michael Lenhard3, Eva Deinum1

1 Mathematical and Statistical Methods, Plant Science Group, Wageningen University and Research, Wageningen, The Netherlands 2 Department of Molecular and Cell Biology, University of Cape Town, Cape Town, South Africa 3 Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany

The widespread occurrence of left/right symmetry breaking in the biological realm underscores a pervasive yet not fully comprehended phenomenon. In particular, the molecular basis of handedness in helical plant growth and the mechanical forces driving asymmetric development in reproductive organs are central, unresolved questions in plant developmental biology. The mirror-image flowers of Cyanella alba serve as a striking example of the asymmetric development of plant reproductive organs. In these flowers, the style is deflected either to the left or right side of the floral axis, with a pollinating anther deflected in the opposite direction. Our microscopy imaging of Cyanella alba carpels revealed that stylar bending results from differential expansion in ovary wall regions. However, how mechanical forces influence such differential expansion remains unclear. Here, we combine data-driven modelling based on image recognition and biophysical modelling using a bead-spring formalism to investigate the mechanical forces guiding ovary wall growth and stylar bending. By optimising biophysical model parameters to best represent ovary morphological features identified through image recognition, we not only quantify the mechanical forces responsible for ovary expansion and style bending, but we also identify the stiffness of the style base as the primary factor driving stylar bending following differential expansion of the ovary walls. Our findings offer insights into the balance of forces necessary to break symmetry in plant organ development, shedding light on the mechanisms at play in symmetry breaking within biological systems.