Freya Bottom

The relationship between molecular organization and mechanical properties in the leaf cell wall with a focus on infection

About me

Physics is always looking at the underlying mechanics and fundamental principles, and there is so much scope to apply this approach elsewhere. I obtained my MPhys with employment experience in Physics from the University of Sheffield. For my year in industry, I worked at CERN and thoroughly enjoyed the research environment I was immersed in. At university, my 3rd-year project was exploring Phase Contrast Microscopy techniques and my 4th-year project involved Atomic Force Microscopy (AFM) on bacterial cell walls, so a PhD using AFM and optical imaging felt like the perfect place to apply my experience. This particular PhD sparked my interest because I felt that applying my Physics background to a biological system would allow me to merge my interests. I studied biology up until university and had always enjoyed it, and missed it. This PhD topic allowed me to join my two interests by working on the structure and mechanics behind plant cell walls and infection.

My project

Plant cell walls are mechanically strong yet flexible and allow for growth of the plant. The cell wall is a complex mesh network of stiff cellulose fibres in a viscoelastic bed of hemicellulose and pectin. A great deal of work has been done to understand how the cell wall is able to bear the stresses of turgor pressure and cell growth, but a lot is still not fully understood. It is also known that callose is deposited at sites of attempted fungal penetration into the cell. This callose reinforces the cell wall and fills the nanopores, slowing infection by creating a barrier, but the intricate mechanics behind this are not fully understood.

My project intends to investigate the plant cell wall using AFM and super-resolution imaging techniques such as STORM. I will study the cell wall and its synthesis to further understand how each cell wall component bears the stresses present. This will require correlating mechanical data from AFM techniques with localisation of polysaccharides from STORM images. As well as aiming to explore the cell wall mechanics and function, the work undertaken will equally be focusing on plant infection. Using the same techniques, the role of callose will be explored to understand how infection causes cell wall architecture to be reshaped.