Abstract:
The Populus genus is one of the major plant model systems, but
genomic resources have thus far primarily been available for poplar
species, and primarily Populus trichocarpa (Torr. & Gray), which was
the first tree with a whole-genome assembly. To further advance
evolutionary and functional genomic analyses in Populus, we produced
genome assemblies and population genetics resources of
two aspen species, Populus tremula L. and Populus tremuloides
Michx. The two aspen species have distributions spanning the
Northern Hemisphere, where they are keystone species supporting
a wide variety of dependent communities and produce a diverse
array of secondary metabolites. Our analyses show that the two
aspens share a similar genome structure and a highly conserved
gene content with P. trichocarpa but display substantially higher
levels of heterozygosity. Based on population resequencing data,
we observed widespread positive and negative selection acting on
both coding and noncoding regions. Furthermore, patterns of genetic
diversity and molecular evolution in aspen are influenced by a
number of features, such as expression level, coexpression network
connectivity, and regulatory variation. To maximize the community
utility of these resources, we have integrated all presented data
within the PopGenIE web resource (PopGenIE.org).
