Assessment of pathogen impacts on novel forestry species and provenances in the UK to aid understanding of future commercial potential

Over the last ten years, UK production forestry has found itself in a vulnerable position as epidemics of invasive pathogens such as Phytophthora ramorum on larches and Dothistroma septosporum on pines have narrowed the range of commercially viable timber species. This, added to the predicted direct effects of climate change, has raised serious doubts as to the level of 'future proofing' in UK production forestry. Alternative tree species may be suited to meeting timber utilization demands of UK forestry but the lack of information is a major barrier for informed species selection. Recent evidence shows that impacts of pathogenic agents is a key factor when assessing forest resilience.
Since 2012, Forest Research (FR) has developed several trials of emerging and native production forestry species planted at different locations across Britain to test performance and assess their potential suitability in face of 21st Century challenges. Preliminary health assessments indicate that species and provenances differ markedly in their responses to a broad range of endemic and invasive pathogens, some of which are shown to have significant health impacts, and that new pathogens may have been introduced on planting material from continental Europe.
This PhD project will identify the key pathogens affecting the health of alternative forestry species, the main biological factors influencing their impact, and practices that mitigate the risk of importing pathogens on exotic propagation material. Findings will be used to underpin decisions on future species suitability for commercial forestry and to inform nursery propagation best practice.
The objectives of the PhD project are to:
i) Identify the key pathogens causing damage in alternative forestry species trials planted across Britain, and the host and environment factors influencing pathogen impact.
ii) Further examine priority 'emerging' commercial forestry species/provenances for their phenotypic and genetic responses to the key pathogens identified in the field surveys.
iii) Work with two forest industry partners to determine which pathogens pose greatest risk to key forestry species/seed provenances in the forest and nursery and identify best nursery practices to avoid these pathogens occurring at seed collection, seedling or planted out stages.
Objective (i) will utilise the already established FR (24 species) trials and EU REINFFORCE project (30 species) trials planted between 2012 and 2015 and replicated at five locations in Britain varying in latitude and longitude allowing investigation of pathogen x environment interaction on each host. Each surveyed trial will be scored for damage indicators and samples will be collected to determine the causal agents of damage symptoms if field identification is not possible, by using a combination of morphological and molecular techniques. This work will result in a collection of isolates and associated genetic data as important project outputs. Statistical analyses will determine variation in susceptibility to key pathogens according to provenance and geographical location. Findings will be compared to national datasets and literature in the host source region.
For objective (ii), priority pathogen/host combinations will be investigated using greenhouse inoculation trials and molecular analyses to determine phenotypic and genetic factors influencing the outcome of infection. Molecular analyses such as RNA-Sequencing analyses, DNA methylation and determinations of secondary metabolite levels will be used to determine phenotypic differences and responses to inoculation. Provenance trials available in selected species will enable further analysis of genetic x environment interaction and DNA finger-printing will serve to assess the levels of genetic diversity among sources of provenance.
For objective (iii) the project sets out to work with two industry partners who both wish to gain a greater understanding of pathogen threats to