Chromosome-scale assembly of the wild cereal relative Elymus sibiricus

Elymus species, belonging to Triticeae tribe, is a tertiary gene pool for improvement of major cereal crops. Elymus sibiricus , a tetraploid with StH genome, is a typical species in the genus Elymus , which is widely utilized as a high-quality perennial forage grass in template regions. In this study, we report the construction of a chromosome-scale reference assembly of E. sibiricus line Gaomu No. 1 based on PacBio HiFi reads and chromosome conformation capture. Subgenome St and H were well phased by assisting with kmer and subgenome-specific repetitive sequence. The total assembly size was 6.929 Gb with a contig N50 of 49.518 Mb. In total, 89,800 protein-coding genes were predicted. The repetitive sequences accounted for 82.49% of the genome in E. sibiricus . Comparative genome analysis confirmed a major species-specific 4H/6H reciprocal translocation in E. sibiricus . The E. sibiricus assembly will be much helpful to exploit genetic resource of StH species in genus Elymus , and provides an important tool for E. sibiricus domestication.