Abstract Detail

Hybrids and Hybridization

Worthing, Baxter [1], Phannareth, Tommy [2], Holliday, Jason [3], Keller, Stephen [4].

The Pan-genome Dynamics of Populus Hybrid Zones in Alaska and the Pacific Northwest.

Balsam poplar (Populus balsamifera) and its sister taxa, Populus trichocarpa, are recently diverged tree species that occupy distinct climatic niches. Populus balsamifera is adapted to continental climates with cold winters and hot summers, while P. trichocarpa is adapted to more moderate coastal climates. The two species naturally hybridize where their ranges overlap, facilitating introgression of genetic variants between species that may contribute to local adaptation along climatic and other environmental gradients.While P. trichocarpa, is an established model system for tree genomics, nearly all population genomic studies of P trichocarpa and P. balsamifera have mapped reads back to a single reference genome (Nisqually-1) to identify segregating genomic variation. This suggests that genomic sequences not present in Nisqually-1 (including those unique to P. balsamifera or hybrid zones) may have been overlooked by prior studies of climate adaptation in these species. Here, we produce long-read, de-novo genome assemblies for multiple samples of P. balsamifera, P. trichocarpa and admixed genotypes sampled from hybrid zones in Alaska and the Pacific Northwest. We use these de-novo assemblies to construct a pan-genome graph and examine the extent of presence/absence structural variants (SVs). This allows us to identify genomic sequences absent from the Nisqually-1 reference and study the dynamics of introgression between these species to search for potentially-novel genomic regions that may contribute to adaptive standing variation. Ultimately, we aim to apply our pan-genome approach to test the hypothesis hybrid zones form a bridge for introgression of SVs between species that helps them persist in challenging environments.

1 - University Of Vermont, Plant Biology, 63 Carrigan Drive, 111 Jeffords Hall, Burlington, VT, 05405, United States
2 - Virginia Tech., Department of Forest Resources and Environmental Conservation, 451 Latham Hall, Blacksburg, VA, 24061, USA
3 - Virginia Tech, Department of Forest Resources and Environmental Conservation, 451 Latham Hall, Blacksburg, VA, 24061, USA
4 - University Of Vermont, Department Of Plant Biology, 111 Jeffords Hall, 63 Carrigan Dr, Burlington, VT, 05405, United States

Keywords:
poplar
genomics
pan-genomics
molecular ecology
hybrids.

Presentation Type: Oral Paper
Number: HH1002
Abstract ID:769
Candidate for Awards:None