Coral reefs composed of stony corals are threatened by global marine environmental changes. However, soft coral communities of octocorallian species, appear more resilient. The genomes of several cnidarians species have been published, including from stony corals, sea anemones, and hydra. To fill the phylogenetic gap for octocoral species of cnidarians, we sequenced the octocoral, Dendronephthya gigantea, a non-symbiotic soft coral, commonly known as the carnation coral. The D. gigantea genome size is approximately 276?Mb. A high-quality genome assembly was constructed from PacBio long reads (29.85Gb with 108x coverage) and Illumina short paired-end reads (35.54Gb with 128x coverage) resulting in the highest N50 value (1.4?Mb) reported thus far among cnidarian genomes. About 12% of the genome is repetitive elements and contained 28,879 predicted protein-coding genes. This gene set is composed of 94% complete BUSCO ortholog benchmark genes, which is the second highest value among the cnidarians, indicating high quality. Based on molecular phylogenetic analysis, octocoral and hexacoral divergence times were estimated at 544 million years ago. There is a clear difference in Hox gene composition between these species: unlike hexacorals, the Antp superclass Evx gene was absent in D. gigantea. Here, we present the first genome assembly of a non-symbiotic octocoral, D. gigantea to aid in the comparative genomic analysis of cnidarians, including stony and soft corals, both symbiotic and non-symbiotic. The D. gigantea genome may also provide clues to mechanisms of differential coping between the soft and stony corals in response to scenarios of global warming.© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
Journal: Genome biology and evolution