Keeping the leaves on: investigating disease threats to trees

Trees provide many ecosystem benefits, including for soil health, shelter, and food. Tree planting is often proposed as a method to sequester atmospheric carbon dioxide and thus mitigate climate change. As long-lived organisms, trees are threatened by disease throughout their lives, with the potential to limit their carbon capture potential. The destructive genus of plant pathogens, Phytophthora, is prevalent among disease agents of trees. These pathogens are emerging threats that are becoming more widespread due to human activity and climate change. The outward symptoms of tree disease caused by different Phytophthora species can be very similar, but our knowledge of the underlying mechanisms used by each species as they colonise and cause disease in trees is rudimentary. A deeper understanding of Phytophthora infection of trees is crucial to establishing whether breeding programmes to develop disease resistance are viable options.
Three lines of research can be followed in this project:
1. We are able to genetically transform Phytophthora species to express fluorescent markers. The aim in this objective is to generate tagged strains of different tree pathogenic Phytophthora species and follow infection of root, stem, and leaf tissue in the model plant Nicotiana benthamiana and in natural tree hosts. Confocal, or super-resolution microscopy can be used to determine how these pathogens enter and exit different tissue types as infection progresses.
2. The role of virulence proteins (called effectors) in tree disease is largely unknown, especially while the pathogen is colonising woody tissues. Proteomic analyses of Phytophthora proteins secreted into plant vascular tissue will be used to reveal candidate effectors that are common/distinct to tree colonisation by different Phytophthora species.
3. Candidate effector proteins can be either silenced, or knocked out using CRISPR-Cas, to determine their importance to Phytophthora infection of different tissue types in tree hosts. This objective will focus on effector candidates in common between different tree pathogenic Phytophthoras.
This research links with ongoing collaborative exchanges with New Zealand Phytophthora research laboratories, and there is scope for inter-lab travel during the PhD project. Many of these emerging disease threats are shared with New Zealand.
The project will provide training in a range of laboratory skills and techniques, including molecular biology, microbiology, plant transformation, cutting-edge microscopy, and cell biology. The student will be supported to present their work and encouraged to follow the literature and contribute to research discussions. Our group is collegiate, supportive, and covers a broad range of experience.