Protein Processing in the Hypersensitive Response of Nicotiana benthamiana

Plant disease is a significant threat to food production, with currently 15% of pre-harvest crop losses attributed to pests. A key feature of plant immunity is the hypersensitive response (HR). This is a form of programmed cell death strictly occurring locally at the site of pathogen detection. Cell death at this stage prevents pathogens establishing disease and spreading throughout the plant tissue. HR is characterised by the production of a reactive oxygen species burst, the rupture of the vacuole and acidification of the cytosol, followed by DNA cleavage and plasma membrane rupture. The regulation of HR remains very poorly understood. Proteases are required for HR, in particular those exhibiting caspase-like activities. This is similar to animal programmed cell death, apoptosis, for which caspases are essential as both regulators and executioners of cell death. Two proteases, vacuolar processing enzyme (VPE) and cathepsin B (CTB), have been found to contribute to caspase-1-like and caspase-3-like activities respectively in HR. In this project we propose to generate an overview of proteolytic events in HR by taking a global proteomics approach using mass spectrometry to identify cleavage events in the early stages of HR progression. In addition, we will adopt a targeted approach to identify substrates specific to VPE and CTB in HR, and then perform assays to confirm the cleavage events occur and to determine the functional significance to HR regulation.

BBSRC priority areas:
Sustainably enhancing agricultural production
Global Food Security

AFS, ENWW