Chromosome-level genome assembly and characterization of the Calophaca sinica genome.

Calophaca sinica is a rare plant endemic to northern China which belongs to the Fabaceae family and possesses rich nutritional value. To support the preservation of the genetic resources of this plant, we have successfully generated a high-quality genome of C. sinica (1.06 Gb). Notably, transposable elements (TEs) constituted ~73% of the genome, with long terminal repeat retrotransposons (LTR-RTs) dominating this group of elements (~54% of the genome). The average intron length of the C. sinica genome was noticeably longer than what has been observed for closely related species. The expansion of LTR-RTs and elongated introns emerged had the largest influence on the enlarged genome size of C. sinica in comparison to other Fabaceae species. The proliferation of TEs could be explained by certain modes of gene duplication, namely, whole genome duplication (WGD) and dispersed duplication (DSD). Gene family expansion, which was found to enhance genes associated with metabolism, genetic maintenance, and environmental stress resistance, was a result of transposed duplicated genes (TRD) and WGD. The presented genomic analysis sheds light on the genetic architecture of C. sinica, as well as provides a starting point for future evolutionary biology, ecology, and functional genomics studies centred around C. sinica and closely related species.

Genome Sequence of Elaeagnus mollis, the First Chromosome-Level Genome of the Family Elaeagnaceae.

Elaeagnus mollis Diels (Elaeagnaceae) is a species of shrubs and/or dwarf trees that produces highly nutritious nuts with abundant oil and pharmaceutical properties. It is endemic to China but endangered. Therefore, to facilitate the protection of its genetic resources and the development of its commercially attractive traits we generated a high-quality genome of E. mollis. The contig version of the genome (630.96 Mb long) was assembled into 14 chromosomes using Hi-C data, with contig and scaffold N50 values of 18.40 and 38.86 Mb, respectively. Further analyses identified 397.49 Mb (63.0%) of repetitive sequences and 27,130 protein-coding genes, of which 26,725 (98.5%) were functionally annotated. Benchmarking Universal Single-Copy Ortholog assessment indicated that 98.0% of highly conserved plant genes are completely present in the genome. This is the first reference genome for any species of Elaeagnaceae and should greatly facilitate future efforts to conserve, utilize, and elucidate the evolution of this endangered endemic species.