Mechanics and growth: how physical forces shape plant development

Trozzi, Nicola (2025) Mechanics and growth: how physical forces shape plant development. Doctoral thesis, University of East Anglia.

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Abstract

A central question in plant biology is how genetic regulation and physical forces work together to shape growth. As cells expand, they generate stresses in their walls and tissues, which in turn influence cytoskeletal organization, wall remodeling, and developmental programs. This thesis examines such feedbacks across scales, from the cell wall to tissue geometry and evolutionary traits, using a combination of genetics, mechanical assays, imaging, and modeling. I developed CAMELOT (computer-automated micro-extensometer with low-cost optical tracking) and applied it in Arabidopsis thaliana to show how wall yielding thresholds and cytoskeletal feedback control growth. In onion (Allium cepa) epidermis, extensometry combined with finite element modeling revealed that cell shape contributes strongly to directional stiffness, but that walls themselves must also be mechanically anisotropic to match experimental data. In Marchantia polymorpha, confocal imaging and perturbations showed how oblique divisions and apical cell behavior generate thallus notches, with growth orientation linked to wall elasticity and microtubule alignment. In Arabidopsis endoreduplication mutants, reduced nuclear content shifted growth from expansion toward division, altering wall mechanics and weakening tissue robustness. In Capsella rubella, genetic and epigenetic regulation were studied in the context of mechanical constraints, showing how chromatin-based control interacts with stress feedback to shape fruits. Finally, a comparative survey of pavement cells in 327 species confirmed that puzzle cell formation is a widespread stress-relief mechanism across plants, sometimes replaced by alternative strategies, and demonstrated that the shape and orientation of lobes encode growth history, making it possible in principle to reconstruct how growth directions changed over time from final cell morphology. Together, these studies establish a multi-scale view of plant mechanics, demonstrating how physical forces and genetic regulation jointly shape cell behavior, tissue mechanics, and the evolution of plant form.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	13 May 2026 13:30
Last Modified:	13 May 2026 13:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/102995
DOI:

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