Coccomyxa viridis Raw sequence reads. Coccomyxa viridis

Unicellular green algae of the genus Coccomyxa are recognized for their worldwide 21 distribution and ecological versatility. Most species described to date live in close association 22 with various host species, such as in lichen associations. However, little is known about the 23 molecular mechanisms that drive such symbiotic lifestyles. We generated a high-quality 24 genome assembly for the lichen photobiont Coccomyxa viridis SAG 216-4 (formerly C. 25 mucigena). Using long-read PacBio HiFi and Oxford Nanopore Technologies in combination 26 with chromatin conformation capture (Hi-C) sequencing, we assembled the genome into 21 27 scaffolds with a total length of 50.9 Mb, an N50 of 2.7 Mb and a BUSCO score of 98.6%. While 28 nineteen scaffolds represent full-length nuclear chromosomes, two additional scaffolds 29 represent the mitochondrial and plastid genomes. Transcriptome-guided gene annotation 30 resulted in the identification of 13,557 protein-coding genes, of which 68% have annotated 31 PFAM domains and 962 are predicted to be secreted.