A 3D Cellular Atlas of Ovule Development Reveals Altered Growth Patterns in the llp-1 Mutant

This master’s thesis investigates the cellular and tissue-level mechanisms underlying ovule curvature in Arabidopsis thaliana, with particular focus on the llp-1 mutant. Ovule bending is an essential morphogenetic process in plant reproductive development, yet the spatial growth patterns responsible for this 3D shape change are not fully understood. The study examines how altered growth coordination influences ovule form, with special attention to the chalaza region. To address this question, confocal microscopy, 3D cell segmentation using PlantSeg, and tissue annotation in MorphoGraphX were applied to generate a developmental atlas of llp-1 ovules across several stages of development. Quantitative parameters such as total cell number, tissue volume, cell volume, and kink angle were extracted and compared with wild-type reference data. In addition, the thesis includes adaptation of a whole-mount imaging protocol for Fagopyrum tataricum, extending the methodologica framework beyond Arabidopsis thaliana. The results show that llp-1 ovules are generally larger and contain more cells than wild-type ovules, while simultaneously displaying reduced curvature during development. Detailed analysis of the posterior chalaza revealed altered growth organization in the mutant, including reduced anisotropy and changes in spatial growth distribution. These findings indicate that normal ovule curvature depends on coordinated local growth asymmetries across multiple tissues rather than on overall tissue expansion alone. Overall, this thesis provides a quantitative characterization of ovule development in the llp-1 mutant and contributes to a better understanding of how spatial growth coordination shapes plant reproductive organs. It also offers a useful framework for future studies of ovule morphogenesis at cellular resolution.