Conifer breeding, height, and cold tolerance

Selective breeding to accelerate tree growth may exacerbate future genetic trade-offs between growth and climate adaptation, complicating reforestation efforts for future climates, a study finds. Climate change has negative impacts on forest health, carbon sequestration, and timber production. However, relocating trees to cooler regions in anticipation of future warming may put the trees at greater short-term risk of frost damage. Ian MacLachlan and colleagues addressed this issue, focusing on the effects of selective breeding for rapid growth in natural lodgepole pine populations in different geographic regions of western Canada. The authors analyzed climatic data, seedling data, and approximately 50,000 genetic variants called single nucleotide polymorphisms (SNPs) associated with height, cold injury, and the timing of growth initiation and cessation. The results showed that growth and climate adaptation rely on variation in many genes. Regional differences in the genome-wide response to selective breeding were large, reflecting different climatic constraints on growth. Twenty-three SNPs from many genes were associated with all four traits and were highly responsive to selection, indicating potential sources of genetic trade-offs between growth and climate adaptation. According to the authors, historical climate adaptation is currently maintained, but strong genetic trade-offs among the identified genes could complicate future breeding programs, posing a challenge to planting healthy, productive forests that can tolerate changing climates.

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Article #20-16900: “Genome-wide shifts in climate-related variation underpin responses to selective breeding in a widespread conifer,” by Ian MacLachlan et al.

MEDIA CONTACT: Ian MacLachlan, University of British Columbia, Vancouver, CANADA; email: <

[email protected]

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