Vol. 50 No. 5, 2011

Utility of tRNA Genes from the Complete Mitochondrial Genome of Psetta maxima for Implying a Possible Sister-group Relationship to the Pleuronectiformes

Wei Shi^1,2, Xiao-Yu Kong^1,*, Zhong-Ming Wang², and Jin-Xia Jiang²

¹Key Laboratory of Mariculture of Ministry of Education of China, Ocean Univ. of China, Qingdao 266003, China
²Key Laboratory of Marine Bio-resource Sustainable Utilization, Marine Biodiversity Collection, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China

Wei Shi, Xiao-Yu Kong, Zhong-Ming Wang, and Jin-Xia Jiang (2011) The complete sequence of the 17,583-nucleotide mitochondrial genome of Psetta maxima (Linnaeus, 1758) was determined, and it contains 13 protein-coding genes, 2 ribosomal (r)RNA genes (srRNA, lrRNA), 22 transfer (t)RNA genes, and a putative control region as do most other fish mitogenomes. A striking finding is that this genome contains a surprisingly long ND2 gene of 1100 bp, which turns out to be the longest one among 700 teleost mitogenomes sequenced so far. In order to better understand the phylogenetic relationship of the Pleuronectiformes, extensive and intensive phylogenetic analyses were conducted using maximum-likelihood and Bayesian inference based on data of the 1st and 2nd codon positions of 12 concatenated protein-coding genes plus 22 stem or complete tRNA genes from 41 teleostean mitochondrial genomes. The results showed that the Pleuronectiformes is a monophyletic group, and it shared a recent common ancestor with carangids, which provides evidence for lower-percoid origins. These conclusions disagree with the hypothesis that flatfishes were derived from an ancestor species closely related to the Clupeiformes, Zeiformes, or Beryciformes. Comparisons of phylogenetic analyses between tRNA genes and protein-coding genes indicated that tRNA genes, especially unpaired regions, can provide useful and specific information for inferring phylogenetic relationships. Therefore, we suggest that tRNA genes be included when mitochondrial genomic data are used for phylogenetic analyses. The results of this study should be able to increase our understanding of the possible sister-group of the Pleuronectiformes to some extent.

Key words: Phylogenetic relationship, Carangidae, tRNA gene, Mitogenome.

*Correspondence: Tel and Fax: 86-20-89023198. E-mail:xykong@scsio.ac.cn