First reference genomes for two mesophotic, reef-building coral species: Leptoseris cf. scabra and Montipora cf. grisea.

Coral mortality is occurring worldwide at an alarming rate. Despite the immense and underestimated biodiversity of reef-building corals, very few genomes are available. Further, almost all genomic resources originate from shallow water corals even though photosynthetic, symbiotic corals occur at mesophotic depths deeper than 30 m and even >100 m. We present annotated, de novo genomes for two mesophotic, scleractinian (reef-building) corals Montipora cf. grisea and Leptoseris cf. scabra from American Sāmoa, the latter being the first genome for the widespread genus Leptoseris. We used PacBio continuous long reads and Omni-C data to assemble chromosome-level reference genomes. For Montipora cf. grisea, the final genome size was 1.3 Gb with a completeness level (BUSCO) of 99.9% and 97.2% against the eukaryotic and metazoan databases, respectively. The M. cf. grisea genome had a N50 of 50.2 Mb and the annotation predicted 41,981 genes. For Leptoseris cf. scabra, the final genome size was 794 Mb with a BUSCO of 99.2% and 96.1% against the eukaryotic and metazoan databases, respectively. The L. cf. scabra genome had a N50 of 45.2 Mb and 35,741 predicted genes. These genomes serve as critical references for the analysis of coral gene expression responses to climate change such as ocean warming (i.e., coral bleaching) and ocean acidification impacts. The genomes can be used to investigate the genetic diversity and adaptive divergence of shallow vs. mesophotic coral populations to understand reef resilience and guide conservation strategies.