Context

Silver birch (Betula pendula) is the second-most abundant broadleaved tree species in Britain by area, with the past 20 years seeing significant growth in the planting of birch for the creation of native woodlands and timber. However, a greater understanding of genetic adaptation is now required in order to plant trees that are resilient to climate change and dieback caused by native pathogens.

This interdisciplinary project brings together Forest Research expertise in forest genetics and tree health with genomic and bioinformatic skills at Kew. Forest Research holds well-designed provenance trials for silver birch in contrasting environments, which represent a comprehensive range of British populations. New assessments of performance and disease incidence or severity in these trials will be combined with innovative genomic approaches, to explore the genetic control of adaptive traits and prospects for adaptation to environmental change.

Research aims and objectives

Aims

This work aims to guide future planting of silver birch by providing an improved knowledge of:

• The distribution of adaptive variation (including disease susceptibility) in British silver birch populations and the climatic factors that drive genetic adaptation.
• The genomic control (the genetic component) of a range of adaptive traits in British silver birch including disease resistance.

Objectives

• This project will sequence the genomes of over 2000 silver birch trees from native British populations grown in three provenance trials planted in 2003. These trees have been periodically evaluated for growth and stem form over the past two decades and reveal a latitudinal pattern of variation for those traits in silver birch. In this study, we will gather new data on tree performance, such as stress tolerance, water use efficiency, and disease resistance, and seek associations between phenotype, genotype, and the environment.
• This will be by far the most comprehensive effort in genetically characterising a native tree species in the UK, and will support long-term efforts in tree improvement.
• Combining genomic analysis from provenance trials with those obtained from the genome-environment association (GEA) study conducted in the Centre for Forest Protection pilot year will allow us to cross-validate both approaches. This two-pronged methodology will generate an understanding of how natural selection operates on silver birch, the genetic basis of adaptation, and how silver birch may respond to environmental change.

Expected outcomes

• Peer reviewed papers linking environment, genotype, and phenotype.
• Publicly accessible genome-wide read data and single nucleotide polymorphism (SNP) data for silver birch.
• Popular article summarising factors influencing adaptation and choices of planting stock in silver birch.
• Outline plans for molecular-informed breeding of silver birch.