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Modelling plant host-pathogen interactions and spread for resilient biosecurity and planting policy


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Dr B Purse , Dr Daniel Chapman , Dr Louise Barwell No more applications being accepted Competition Funded PhD Project (Students Worldwide)

About the Project

Non-native plant pathogens are increasingly introduced into new areas through global trade and travel, with major consequences for agricultural, horticultural, forestry and natural ecosystems. Since many pathogens are unknown to science or only recently described at the point of emergence, comparative, cross-species approaches have investigated the factors that underpin pathogen invasiveness and host-pathogen interactions, to inform pathogen horizon-scanning and risk-assessment. These have revealed for example that pests and pathogens tend to be more likely to attack closely related plant species than species separated by greater evolutionary distances. For microbial taxa, biological traits such as spore morphology, optimum temperature for growth, the ability to disperse long distances, to reproduce both sexually and asexually and cold-tolerance have all been associated with greater invasiveness. These frameworks need to be further contextualised at national and landscape levels, to understand how pathogen traits influence invasion success in global and local transport and landscape-scale spread and how host traits, alongside pathogen traits, also underpin the likelihood and outcome of host-pathogen interactions.

More-over, against the backdrop of further climate change and forestry policies that promote extensive woodland expansion and planting of novel species, quantitative tools are required that inform biosecurity and planting policy by predicting which tree species are resilient or vulnerable to multiple important pathogens and climate change, whilst also delivering key ecosystem functions. This is particularly critical since movement of live plants is the commonest way by which plant pathogens have been introduced into new areas.


Using modelling approaches and strong engagement with decision-makers in biosecurity and experts in forest pathology and policy, the student will address the following questions:
(1) How do ecological traits and species relatedness predict which host species will be impacted by key pathogen species like Phytophthora and Xylella?
(2) How do the biological and distributional traits of pathogens and hosts determine the rates of pathogen arrival in the UK, and interact with landscape connectivity to determine the pathogen species spread from horticultural plant supply chains into the UK’s wider environment?
(3) How do the traits that determine tree host resilience to pathogens co-vary with those that underpin forest ecosystem functions and resilience to climate change and what are the consequences for biosecurity and tree planting policy?


Working alongside ecologists at UKCEH and University of Stirling and pathologists at Forest Research (Dr Sarah Green) and the James Hutton Institute (Dr David Cooke), the student will compile databases of traits, global occurrence and interactions for plant hosts and priority pathogens threatening UK forests (e.g. Phytophthoras, Xylella, Hymenoscyphus sp.). The student will develop phylogenetically-informed analyses to understand whether closely-related hosts share pathogen species (or closely-related pathogens share host species), whether host traits confer resilience or susceptibility to pathogens, or whether pathogens with particular traits impact a wider range of hosts. Using spatial Mixed Effect models, the student will analyse whether current patterns of spread of pathogens in the UK depend on pathogen and host traits or landscape connectivity. For native and non-native UK forestry species, the student examine their role in ecosystem functions, how these relate to traits and co-vary with resilience or susceptibility to pathogen infection to inform future planting policy.

Through strong stakeholder engagement, the PhD project is likely to develop tools that assist horticultural and forestry managers with assessing key biosecurity risks from planting and inform forestry managers about which hosts are more-or-less resilient to pathogens in different contexts. Policy context for the project will be provided by Alistair Yeomans from the Forestry Climate Change Working Group (FCCWG), that have been involved in developing the Plant Healthy Certification Scheme for nursery managers.

Training and supervision

The student will receive training in a breadth of skills including database compilation, cluster computing, manipulating large-scale ecological and environmental datasets using R, hierarchical mixed effects and occupancy modelling, environmental change impacts, comparative ecology, pathogen ecology and forest ecosystem functions, co-developing models with end-users to inform policy. They will benefit from working in an interdisciplinary, diverse and supportive supervisory team and engaging with plant health stakeholders including the Plant Health and Biosecurity Alliance.

Funding Notes

This studentship is funded as part of the IAPETUS2 Doctoral Training Programme, through which the student will benefit from further training and networking opportunities. Further information on eligibility, training and the application process for this DTP can be found at this link:


Chapman, D.S. et al (2017) Global trade networks determine the distribution of invasive non‐native species. Global Ecology and Biogeography 26, 907-917.

Gilbert GS, Briggs HM, Magarey R (2015) The Impact of Plant Enemies Shows a Phylogenetic Signal. PLoS ONE 10(4): e0123758.

Beales et al. (2019) Plant Diseases and Biosecurity, Oxford University Press, ISBN: 9780198827726
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