Identifying guidance mechanisms for plant immunity. Self Funded Biosciences PhD

Lead supervisor: Dr Mike Deeks, Department of Biosciences, College of Life and Environmental Sciences

Project description:
Phytopathogen contact with a plant triggers cell signalling that results in either the arrest of the pathogen or a disease-causing infection. During this process the plant cell delivers defensive material specifically to the pathogen interface. This targeted secretion occurs in response to a wide variety of potential pathogens and is suppressed by pathogens that are adapted to their hosts. Moreover, many of the components and cargoes of this process play critical roles in preventing pathogen entry.
We recently described the Arabidopsis thaliana protein FORMIN 4 as a connection between the cytoskeleton and pathogen targeted secretion (Sassmann et al. 2018, Current Biology). FORMIN 4 is an actin and microtubule-interacting protein that is membrane-integrated and transported through a secretory pathway using a ‘classic’ N terminus secretion signal peptide. The specificity of localisation of this protein is remarkable, with more than 80% of FORMIN 4 being deposited within an 11 micron radius of fungal appressoria. We have successfully used the N-terminus of FORMIN 4 to target a cargo of choice to fungal appressoria. The capability to target bespoke proteins precisely to fungal interaction sites holds great promise for synthetic biology approaches to augmenting the plant immune system.


This PhD project will use a variety of methods to isolate the key protein motifs responsible for FORMIN 4 targeting and will use a combination of quantitative live-cell imaging and image analysis to understand the contribution of each domain. This approach will be informed by a comparison to a control protein that shows similar expression control, domain architecture and transmembrane domain characteristics to FORMIN 4. We have already shown that this comparative protein is not recruited with the same specificity as FORMIN 4, despite the shared characteristics at the domain level. We will systematically swap domains and measure the impact on FORMIN 4 lateral membrane mobility, endocytic uptake and secretion focus. This approach will produce an instruction-set of key motifs for synthetic biology approaches to intercepting virulent pathogens at the plant surface.




Things to consider:

This project is self funded. Information about Exeter’s current fees can be found here: https://www.exeter.ac.uk/pg-research/money/fees/.

For information about possible funding sources: http://www.exeter.ac.uk/pg-research/money/alternativefunding/
For information about Doctoral Loans: http://www.exeter.ac.uk/pg-research/money/phdfunding/postgraduatedoctoralloans/