Draft genomes of female and male turbot Scophthalmus maximus

Xi-Wen Xu,Na Wang,Chang-Wei Shao,Ming Li,Hao Xu,Qian Zhou,Song-Lin Chen,Wen-Long Li,Feng You

doi:10.1038/s41597-020-0426-6

Abstract

Turbot (Scophthalmus maximus) is a commercially important flatfish species in aquaculture. It has a drastic sexual dimorphism, with females growing faster than males. In the present study, we sequenced and de novo assembled female and male turbot genomes. The assembled female genome was 568 Mb (scaffold N50, 6.2 Mb, BUSCO 97.4%), and the male genome was 584 Mb (scaffold N50, 5.9 Mb, BUSCO 96.6%). Using two genetic maps, we anchored female scaffolds representing 535 Mb onto 22 chromosomes. Annotation of the female anchored genome identified 87.8 Mb transposon elements and 20,134 genes. We identified 17,936 gene families, of which 369 gene families were flatfish specific. Phylogenetic analysis showed that the turbot, Japanese flounder and Chinese tongue sole form a clade that diverged from other teleosts approximately 78 Mya. This report of female and male turbot draft genomes and annotated genes provides a new resource for identifying sex determination genes, elucidating the evolution of adaptive traits in flatfish and developing genetic techniques to increase the sustainability of turbot aquaculture.

Highlights

Background & SummaryTurbot (Scophthalmus maximus) is an economically important flatfish with both eyes on the upper side of the body, and it is commonly found along the Atlantic coast of Europe
Understanding the genomic architecture of female and male turbot may enable screening for sex determination loci, improve understanding of the interactions between genetic and environmental factors in sex determination, and lead to the acquisition of genomic resources for molecular breeding
The physiological sex of each turbot was determined by paraffin sectioning and HE staining of its gonadal tissues (Fig. 1)

Summary

Introduction

Background & SummaryTurbot (Scophthalmus maximus) is an economically important flatfish with both eyes on the upper side of the body, and it is commonly found along the Atlantic coast of Europe. We sequenced, assembled and annotated the female and male turbot genomes, and conducted a phylogenetic analysis using the genome sequences of eight other closely related species. One female (ZW) and one male (ZZ) adult turbot were selected for whole genome shotgun sequencing and were temporarily maintained at 16 °C in laboratory facilities. We generated 99.5 Gb and 196.4 Gb of raw data for the female and male turbot, respectively.

Results

Conclusion