Assembly and Annotation of the Tetraploid Salsola tragus (Russian Thistle) Genome

This report presents two phased chromosome-scale genome assemblies of allotetraploid Salsola tragus (2n = 4x = 36) and fills the current genomics resource gap for this species. Flow cytometry estimated 1C genome size was 1.319 Gb. PacBio HiFi reads were assembled and scaffolded with Hi-C chromatin contact mapping and Bionano optical mapping data. For annotation, a PacBio Iso-Seq library was generated from root, stem, leaf, and floral tissues followed by annotation using a modified Maker pipeline. The assembled haploid S. tragus genomes contained 18 chromosomes each, with 9 chromosomes assigned to subgenome A and 9 chromosomes to subgenome B. Each haplome assembly represented 95% of the total flow cytometry estimated genome size. Haplome 1 and haplome 2 contained 43,354 and 42,221 annotated genes, respectively. The availability of high-quality reference genomes for this economically important weed will facilitate future omics analysis of S. tragus and a better understanding of chenopod plants.