Chromosome-scale genome assembly and gene annotation in Lolium perenne

Here, we report a new chromosome-scale genome sequence assembly for perennial ryegrass, obtained by combining PacBio long-range sequencing, BioNano optical mapping and Hi-C scaffolding. More than 90% of the total genome size (approximately 2.55 Gbp) of perennial ryegrass is contained in seven pseudo-chromosomes that show high-level collinearity to the orthologous chromosomes of Brachypodium and barley. The transposon content of perennial ryegrass was relatively low, approximately 35% of the total genome content, which is less than half of the genome repeat content of cultivated cereal species. We predicted 54,629 high-confidence gene models, 10,287 long non-coding RNA genes and a total of 8,393 short non-coding RNAs in the perennial ryegrass genome.