A chromosome-level genome assembly for the Pacific oyster Crassostrea gigas

Carolina Penaloza, Alejandro Gutierrez Silva, Lel Eory, Shan Wang, Ximing Guo, Alan Archibald, Tim Bean, Ross Houston

Research output: Contribution to journalArticlepeer-review

Abstract

Background: The Pacific oyster (Crassostrea gigas) is a bivalve mollusc with vital roles in coastal ecosystems and aquaculture
globally. While extensive genomic tools are available for C. gigas, highly contiguous reference genomes are required to
support both fundamental and applied research. Herein we report the creation and annotation of a chromosome-level
assembly for C. gigas. Findings: High-coverage long- and short-read sequence data generated on Pacific Biosciences and
Illumina platforms were used to generate an initial assembly, which was then scaffolded into 10 pseudo-chromosomes
using both Hi-C sequencing and a high-density linkage map. The assembly has a scaffold N50 of 58.4 Mb and a contig N50 of 1.8 Mb, representing a step advance on the previously published C. gigas assembly. Annotation based on Pacific Biosciences Iso-Seq and Illumina RNA-Seq resulted in identification of ∼30,000 putative protein-coding genes. Annotation of putative repeat elements highlighted an enrichment of Helitron rolling-circle transposable elements, suggesting their potential role in shaping the evolution of the C. gigas genome. Conclusions: This new chromosome-level assembly will be an enabling resource for genetics and genomics studies to support fundamental insight into bivalve biology, as well as for selective breeding of C. gigas in aquaculture.
Original languageEnglish
JournalGigaScience
Volume10
Issue number3
Early online date25 Mar 2021
DOIs
Publication statusE-pub ahead of print - 25 Mar 2021

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