Abstract
Populus has a wide ecogeographical range spanning the Northern
Hemisphere, and exhibits abundant distinct species and hybrids globally.Populus tomentosa Carr. is widely distributed and cultivated in
the eastern region of Asia, where it plays multiple important roles in
forestry, agriculture, conservation, and urban horticulture. Reference
genomes are available for several Populus species, however, our
goals were to produce a very high quality de novo ,
chromosome-level genome assembly in P. tomentosa genome that
could serve as a reference for evolutionary and ecological studies of
hybrid speciation. Here, combining long-read sequencing and Hi-C
scaffolding, we present a high-quality, haplotype-resolved genome
assembly. The genome size was 740.2 Mb, with a contig N50 size of 5.47
Mb and a scaffold N50 size of 46.68 Mb, consisting of 38 chromosomes, as
expected with the known diploid chromosome number (2n=2x=38). A total of
59,124 protein-coding genes were identified. Phylogenomic analyses
revealed that P. tomentosa is comprised of two distinct
subgenomes, which we deomonstrate is likely to have resulted from
hybridization between Populus adenopoda as the female parent andPopulus alba var. pyramidalis as the male parent,
approximately 3.93 Mya. Although highly colinear, significant structural
variation was also found between the two subgenomes. Our study provides
a valuable resource for ecological genetics and forest biotechnology.