Chromosome-Level Genome Assembly of the Rare and Endangered Tropical Plant Speranskia yunnanensis (Euphorbiaceae)

Speranskia yunnanensis S. M. Hwang is an endangered shrub narrowly distributed in tropical regions, and its populations are gradually shrinking. We assembled and annotated the genome of S. yunnanensis at the chromosome level by combining Nanopore sequencing, Illumina HiSeq sequencing and Hi-C technology. The final genome assembly was similar to 417.65 Mb, with a contig N50 value of 12.52 Mb, and 408.62 Mb (97.84%) of which could be grouped into seven pseudochromosomes. Approximately 69.11% of the assembly was identified as repetitive elements, and 25,467 protein-coding genes were annotated. Based on the 1,517 single-copy orthologous genes, and 751 expanded and 1,645 contracted gene families among the 16,389 gene families in S. yunnanensis, a phylogenetic tree was further built. The high-quality, annotated, and chromosome-level genome of S. yunnanensis will present an important source of data for future research on the evolution of Euphorbiaceae genomes, and provide genomic resources toward studies on speciation, local adaptation, as well as conservation genomics of the ecologically important genus Speranskia.