Abstract
The Asian Clam (Corbicula fluminea) is a valuable commercial and
medicinal bivalve that is widely distributed in East and Southeast Asia.
As a natural nutrient source, the clam is high in protein, amino acids,
and microelements. In China, C. fluminea plays an important role in the
diversity of freshwater ecosystems. The genome of C. fluminea has not
yet been characterized, therefore, genome-assisted breeding and
improvements cannot yet be implemented. In this work, we present a de
novo chromosome-scale genome assembly of C. fluminea using PacBio and
Hi-C sequencing technologies. The assembled genome comprised 4,728
contigs, with a contig N50 of 521.06 Kb, and 1,215 scaffolds with a
scaffold N50 of 70.62 Mb. More than 1.51 Gb (99.17%) of genomic
sequences were anchored to 18 chromosomes, of which 1.40 Gb (92.81%) of
genomic sequences were ordered and oriented. The genome contains 38,841
coding genes, 32,591 (83.91%) of which were annotated in at least one
functional database. Compared with related species, C. fluminea had 851
expanded gene families and 191 contracted gene families. The expanded
genes were significantly enriched in 9 terms associated with metabolite
synthesis. The phylogenetic tree showed that C. fluminea diverged from
the ancestors of marine bivalves ~492.00 million years
ago (Mya). Additionally, we identified two MITF genes in C. fluminea and
several core genes involved in vitamin B6 metabolic pathways. The
high-quality and chromosomal Asian Clam genome will be a valuable
resource for a range of development and breeding studies of C. fluminea
in future research.