Adaptation to ash dieback disease in natural populations of European ash

Dario Galanti ¹, Connor Tyler ², Angela Biro ², Daniel Wood ², Richard Buggs ³, Richard Nichols ⁴, Laura Kelly ³

1 Plant Health and Adaptation, Royal Botanic Gardens, Kew, Richmond, UK. 2 School of Biological and Behavioural Sciences, Queen Mary University of London, Mile End Road, London, UK. ¹, 1 ², 1,2 ³, 2 ⁴

Natural tree populations are exposed to increasing threats from biotic and abiotic stressors. One recent case with large predicted ecological and economic consequences is ash dieback, a fungal disease currently decimating ash (Fraxinus excelsior) populations in the UK and northern Europe. Although there is some evidence that European ash populations are already adapting to the disease via selection on standing genetic variation, it is still unclear if this process will be fast enough to conserve populations. Also, it is unclear if novel genetic variation could be generated at a rate fast enough to make it available to selection. To investigate these questions and predict the future prospects for ash populations in northern Europe, we undertook a large whole genome sequencing effort to screen three UK populations (~930 trees) for genetic variants associated with resistance to the disease. We investigated this via Genome Wide Association, using different phenotypes such as visual assessments of disease damage and the quantification of fungal DNA load on the trees. Here we present these preliminary results and discuss comparisons with previous findings and plans for future investigations. Related to the latter, we assigned pedigrees including several parent-offspring pairs that will allow us to 1) look for alleles changing in frequency due to selection on standing genetic variation and 2) track the formation of de-novo variants since the arrival of the epidemic. In particular, we are interested in the role of novel Structural Variants (SVs), introduced by processes such as transposable element activity and recombination that have the potential to quickly generate large amounts of novel genetic variation. With this in mind, we are currently generating long read sequencing data from assigned parents and their offspring, to investigate SV formation and selection in the new generation of ash trees.

Main author career stage: Postdoc / Fellow

Contribution type: Talk

First choice session: 5. Genetics, genomics, and bioinformatics

Second choice session: 1. Systematics, phylogenetics, biogeography and evolution