Complete mitochondrial genome of Stethojulis Strigiventer (Labriformes, Labridae): mitogenome characterization and phylogenetic analysis

Abstract

Stethojulis strigiventer is a tropical reef-associated marine fish belonging to the family Labridae. Herein, we report the first sequencing and assembly of the complete mitochondrial genome of S. strigiventer. The complete mitochondrial genome is 16,524 bp length and has the typical vertebrate mitochondrial gene arrangement, consisting of 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and a control region. Phylogenetic analysis using mitochondrial genomes of 11 species showed that Stethojulis strigiventer is clustered together with the genus Parajulis and Halichoeres and rooted with other Labridae species. This mitochondrial genome provides potentially important resources for addressing taxonomic issues of the Labriformes and studying conservation genetics.

Keywords:

• Mitochondrial genome
• Labriformes
• Labridae
• Stethojulis strigiventer

The family Labridae, the wrasses, inhabit the tropical and subtropical waters of the Atlantic, Indian, and Pacific Oceans, though some species live in temperate waters (Bernardi et al. 2004; Rocha et al. 2010). The three-ribbon wrasse, Stethojulis strigiventer (Labriformes: Labridae), is listed as Least Concern in IUCN Red List due to the collection for the aquarium trade and habitat degradation in southeast Asia (Cabanban 2010). Although previous studies for many sub-groups of the Labridae obtained high nodal support (Hanel et al. 2002; Clements et al. 2004; Barber and Bellwood 2005), interrelationships among other familes such as Carapidae, Scaridae, Caesionidae, and Microdesmidae in Percomorpha are largely unresolved (Betancur-R et al. 2017). This is the first study to determine the complete mitochondrial genome of S. strigiventer, and to analyze the phylogenetic relationship of this species with members of Labridae.

The S. strigiventer specimen was collected from Chuuk ST 1, Micronesia (7.27N, 151.54E). Total genomic DNA was extracted from tissue of the specimen, which has been deposited in the National Marine Biodiversity Institute of Korea (Voucher No. MABIK 0000617). The mitogenome was sequenced and assembled using Illumina Hiseq 4000 sequencing platform (Illumina, San Diego, CA) and SOAPdenovo assembler at Macrogen Inc. (Korea), respectively. The complete mitochondrial genome was annotated using MacClade ver. 4.08 (Maddison and Maddison 2005) and DNASIS ver 3.2 (Hitachi Software Engineering).

The complete mitochondrial genome of S. strigiventer (GenBank accession no. AP018523) is 16,524 bp length, and includes 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and a control region. The ND6 gene and eight tRNA genes are encoded on the light strand. The overall base composition of the heavy strand is 27.10% A, 28.83% C, 17.36% G, and 26.71% T. Similar to the mitogenomes of other vertebrates, the AT content is higher than the GC content (Saccone et al. 1999). All tRNA genes can fold into a typical cloverleaf structure, with lengths ranging from 66 to 74 bp. The 12S rRNA (952 bp) and 16S rRNA genes (1,693 bp) are located between tRNA^Phe and tRNA^Val and between tRNA^Val and tRNA^Leu(UUR), respectively. Of the 13 protein-coding genes, 11 begin with an ATG start codon; the exception being the COI and ATP6 gene, which start with GTG and TTG, respectively. The stop codon of the protein-coding genes is TAA in COI, ATP8 and ND4L; TAG in NDI and ND6; AGA in ND5; TA in ATP6 and COIII; and T in the remaining five genes. The control region (836 bp) is located between tRNA^Pro and tRNA^Phe.

Phylogenetic trees were constructed by the maximum-likelihood method using MEGA 7.0 software (Kumar et al. 2016) for the newly sequenced genome and a further 10 complete mitochondrial genome sequences downloaded from the National Center for Biotechnology Information. We confirmed that S. strigiventer is clustered with genus Parajulis and Halichoeres, and formed monophyletic group with other Labridae species (genus Pseudolabrus, Bodianus and Choerodon) with high statistical support (Figure 1). This mitochondrial genome provides important resources for addressing taxonomic issues and studying molecular evolution.

Figure 1. Phylogenetic position of Stethojulis strigiventer based on a comparison with the complete mitochondrial genome sequences of 10 species. The analysis was performed using MEGA 7.0 software. The accession number for each species is indicated after the scientific name.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Marine Biodiversity Institute Research Program [2018M00900] and the Marine Biotechnology Program [20170488] funded by the Ministry of Oceans and Fisheries, Korea.