Assembling a reference-quality genome for Solemya velum (Bivalvia: Protobranchia)

Dr. Vanessa González, PhD, Smithsonian

In order to facilitate Solemya velum (Bivalvia: Protobranchia) as an emerging model system to study symbiosis and adaptation, we generated a reference-quality genome. We tested emergent technologies for molluscan genome assembly by leveraging 10X Genomics, PacBio Long-reads and Hi-C data. Solemya velum is a member of the subclass Protobranchia, one of the poorest known molluscan groups. Protobranchia has diversified and colonized the deepest oceans, with numerous cosmopolitan species at abyssal depths. Of the ca. 750 protobranch species, most are deposit feeders in soft sediments, but two lineages host chemoautotrophic, sulfide-oxidizing bacteria, with concomitant reductions of the hosts’ alimentary system, including Solemya velum. Previous research has characterized and sequenced the symbiotic bacterial genomes associated and identified in Solemya velum (Russell et al. 2017) but genomic resources are still lacking for their host. Iterations and combinations of each data type have resulted in a 2.4GB reference genome with a scaffold N50 of 200 MB and a BUSCO completeness score of 93.7%. This first reference-quality Protobranch genome will enable us to test hypotheses about mollusc genome evolution and the evolution of symbiotic interactions in marine molluscs.