A nearly telomere-to-telomere diploid genome assembly of Firmiana kwangsiensis, a threatened species in China.

Firmiana kwangsiensis is a tree species of high ornamental value. The species is critically endangered in the wild, and is listed as a first-class national protected wild plant in China, and a Plant Species with Extremely Small Populations in need of urgent protection. We have assembled a chromosome-scale, haplotype-resolved genome for F. kwangsiensis using a combination of PacBio HiFi sequencing, ONT sequencing, and Hi-C sequencing. The final assembled genome is 2.3 G in size and comprises 2n = 40 chromosomes. All chromosomal ends contain telomeric characteristic motifs (TTTAGGG), and there are only 2 gaps within the rDNA regions, both close to a T2T genome assembly. Two complete sets of haplotypes are present, Haplotype A (1169.19 Mb) and Haplotype B (1157.87 Mb), with contig N50 lengths of 58.37 Mb and 57.27 Mb, respectively. The genome contains a total of 67,527 coding genes, with 62,351 genes functionally annotated here. This is the first report of the genome of F. kwangsiensis, and lays the foundation for future conservation genomics research into this species.