Sarah Robinson: Understanding the mechanical implications of cell division on plant development

Plants grow by cell expansion and cell division. Cell expansion requires a careful balance between the properties of the cell wall and the forces acting on it, which come from turgor pressure and the other cells. Cell division changes the size and shape of the cells altering the overall structure of the tissue and the forces acting on the walls. While cell division and cell expansion are key for plant growth, how they influence each other is less clear. We quantify these two factors to understand the driving forces of growth and how it is altered in changing environments. We take an interdisciplinary approach combining the automated confocal micro-extensometer, atomic force microscopy, timelapse imaging, quantitative solid-state NMR and single cell transcriptomics. Our results show that shifting the balance of cell division and cell expansion changes the response to environmentally induced growth changes. We also look at how cell division changes the cell wall biochemistry, mechanical properties of the tissue and the pattern of mechanical stress. By comparing tissues with different cell shapes we have been able to determine the contribution of cell wall changes versus cell geometry changes during growth. Ultimately, the different processes of expansion, cell division, and responses to mechanical stress are interconnected; understanding these relationships enables us to predict and modify plant development.