Non-native plant pathogens are increasingly being 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, the ability to reproduce both sexually and asexually and cold-tolerance have all been associated with greater invasiveness. These frameworks need to be further contextualised at the national and landscape level, 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 (the Forestry Climate Change Working Group, Plant Healthy Certification Scheme) and experts in forest pathology and policy (Forest Research, James Hutton Institute), 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?