Abstract
In this study, we cloned and sequenced the complete mitochondrial genome DNA of Chinese pig, the Meishan pig. The sample was taken from Yencheng City, Jiangsu province in China. The complete genome DNA is 16 708 bp in length. We also performed a comparative analysis of the Meishan pig mitochondrial to the mitogenome sequences of 21 pig breeds which have been deposited in GenBank. Phylogenetic analysis using neighbour-joining computational algorithms showed that the analyzed species are divided into four major clades; the results can be subsequently used to provide information for pig phylogenetic and insights into the evolution of genomes.
Keywords: Genome, Meishan pig, mitochondria, phylogeny
Meishan pig, a native breed from Taihu lake basin in China, is famous for its reproductive performance in the word. The litter size of Meishan pig can reach 42 piglets, which makes the Meishan pig to be the champion in reproductive performance in all of the domestic pig breeds. Studies in mtDNA showed that the single strand conformation polymorphism, natural selection and artificial selection may play a critical role in the high litter size of Meishan pig (Li et al. 2014). In this study, nested polymerase chain reaction was carried out to amplify the complete mitochondrial genome with 24 pairs of primers. The Meishan pig miDNA genome has been deposited in NCBI GenBank database with the accession number KM998967. The complete genome DNA is 16 708 bp in length, which contains a non-coding control region (D-loop), two rRNA genes, 13 protein-coding genes and 22 tRNA genes, the complete mitochondrial genome had the order A > C>T > G feature.
Figure 1.
Protein-based Phylogenetic relationships of Meishan pig and 21 other pig breeds based on 12 protein-coding genes using NJ method.
Phylogenetic analysis was performed using the complete mitochondrial DNA sequence of 23 pig breeds. Each of the sequence datasets was aligned by Clustal W in MEGA 5.0 (Kumar et al. 2008) and analyzed by neighbour-joining (N-J) in MEGA 5.0 with 1000 bootstrap replicates (Tamura et al. 2011). The N-J tree showed that the 18 native breed and Yorkshire pig, including Meishan pig, formed a monophyletic clade, Landrace and Duroc formed into another clade, the Java warty pig and Visayan warty pig formed into a clade, respectively. This can be explained by that pigs are independently domesticated in various regions of the world (Giuffra et al. 2000; Larson et al. 2005), and the results of researching on mtDNAs exhibited an independent origin of domestic pigs in Europe and Asia (Kijas & Andersson 2001).
Disclosure statement
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
Funding information
This study was financially supported by China Agriculture Research System (CARS-36) and Hunan Provincial Innovation Foundation for Postgraduate (CX2015B251).
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