How does a pathogen hijack the host’s cell-to-cell communication system?

FAULKNER_J21DTP

Plant cells are connected to their neighbours via ‘tubes’ called plasmodesmata, creating an interconnected cytoplasm that joins cells within and between tissues and organs. Many molecules can move freely between cells through open plasmodesmata to carry information and resources. However, plasmodesmata can close and open in response to a range of environmental or developmental signals to control where, and how far, molecules can travel in the plant. It is critical for a plant to tightly control its plasmodesmata to enable execution of many different responses, including a full set of immune responses when it is being invaded by a pathogenic microbe.

We, and others, have observed that some pathogens can take control of plasmodesmata during infection, keeping them open when the host plant tries to shut them. This led us to ask how does a microbe (that doesn’t have plasmodesmata) control plasmodesmata function and why does the microbe benefit from keeping plasmodesmata open? This project will address these questions, taking advantage of a screen we performed for fungal proteins (effectors) that localise at plasmodesmata when they are produced in plant cells. These proteins are normally secreted from the fungus during infection and therefore we reason that they are candidate plasmodesmal regulators. The student will use these proteins to identify the host machinery at plasmodesmata that the fungus targets, the mechanisms by which these proteins works to control plasmodesmata function, and how this contributes to infection success. The project will also use synthetic biology approaches to control the plasmodesmata in order to explore the impact this has on a range of infection strategies.

References:

Cheval, C., Samwald, S., Johnston, M., Liu, X., Bellandi, A., Breakspear, A., Kadota, Y., Zipfel, C., Faulkner, C. (2020) Chitin perception in plasmodesmata characterizes submembrane immune-signaling specificity in plants. Proceedings of the National Academy of Science USA doi:10.1073/pnas.1907799117

Cheval, C., and Faulkner, C. (2018) Plasmodesmal regulation during plant-pathogen interactions. New Phytologist 217:62-67.

Xu, B., Cheval, C., Laohavisit, A., Hocking, B., Chiasson, D., Olsson, T.S.G., Shirasu, K., Faulkner, C., Gilliham, M.2 (2017) A calmodulin-like protein regulates plasmodesmal closure during bacterial immune responses. New Phytologist 215:77-84