Genome assembly and annotation of the terestrial microalgae Coccomyxa elongata SAG216-3B

Unicellular green algae of the genus Coccomyxa are recognized for their worldwide distribution and ecological versatility. Coccomyxa elongata is a freshwater species of the Coccomyxa simplex clade, which also includes lichen symbionts. To facilitate future molecular and phylogenomic studies of this versatile clade of algae, we generated a high-quality genome assembly for Coccomyxa elongata Chodat & Jaag SAG 216-3b. A combination of long-read PacBio HiFi and Oxford Nanopore Technologies with chromatin conformation capture (Hi-C) sequencing led to the assembly of the genome into 21 scaffolds with a total length of 51.4 Mb and an N50 of 2.8 Mb. Nineteen of the scaffolds represent full-length nuclear chromosomes delimited by telomeric repeats, while the two additional scaffolds represent the mitochondrial and plastid genomes. Transcriptome-guided gene annotation resulted in the identification of 14,811 protein-coding genes, of which 61% have annotated PFAM domains and 841 are predicted to be secreted. BUSCO analysis identified a total of 1,494 (98.4 %) complete gene models, suggesting a highly complete genome annotation.