Acta Veterinaria et Zootechnica Sinica ›› 2019, Vol. 50 ›› Issue (12): 2387-2399.doi: 10.11843/j.issn.0366-6964.2019.12.003

• ANIMAL GENETICS AND BREEDING • Previous Articles     Next Articles

Genetic Diversity of Tibetan Pig Mitochondrial DNA D-Loop in Ruoergai Area of A'ba Tibetan and Qiang Autonomous Prefecture

LI Zhengjie1, ZHOU Xiankun1, WANG Yichen1, CHEN Yuhui1, CHU Tianqi1, QIN Yujie1, TANG Kai2, LI Xuewei1, MA Jideng1*   

  1. 1. Farm Animal Genetic Resource Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China;
    2. Sichuan Lumingqiu Plateau Eco-agriculture Technology Limited Company, Ruoergai 624500, China
  • Received:2019-07-16 Online:2019-12-23 Published:2019-12-20

Abstract: The purpose of this study was to obtain and compare partial sequences of mtDNA D-Loop high variable region of Tibetan pig in Ruoergai area,so as to provide reference for the protection and utilization of Tibetan pig genetic resources. In this experiment,the ear samples of 80 Tibetan pig from 9 towns in Ruoergai area were collected. The primers were designed based on the sequence of mtDNA D-Loop region of Tibetan pig in Gannan. Eighty nucleotide sequences were obtained by PCR amplification and sequencing technology,and the data processing method of bioinformatics were used to analyze the sequences. The results showed that the A+T content (56.46%) of mtDNA D-Loop high variable region (435 bp) was obviously higher than G+C content (43.54%) of Tibetan pig in Ruoergai area,and representing base bias. Among the 80 sequences of 435 bp length,14 mutation sites and 17 haplotypes were identified. Haplotype diversity (Hd),nucleotide diversity (Pi) and average number of nucleotide difference (k) were 0.881,0.004 66 and 2.028,respectively. Hd,Pi and k were the highest in Tibetan pig populations from Jiangzha, and Pi and k were the lowest in Tibetan pig population from Zhanwa. There were 8 shared haplotypes and 9 specific haplotypes,and there was big difference in specific haplotype number among different Tibetan pig populations in Ruoergai area. The highest number of specific haplotypes were found in Tibetan pig population from Jiangzha,accounting for 17.65% (3/17) of the total haplotype number. The haplotypes of Hap_1 and Hap_15 were shared haplotypes by Tibetan pig populations from 4 townships (Jiangzha,Yiwa,Re'er and Donglie),indicating that there were two common maternal ancestry haplotypes in Tibetan pig populations from the 4 towns. The average genetic distance of Tibetan pigs in Ruoergai area was 0.004 66. The genetic distance between Tibetan pig populations from Jiangzha and Donglie was the highest of 0.006 90,and the genetic distance between Tibetan pig populations from Baozuo and Yiwa was the lowest of 0.002 16. The NJ molecular phylogenetic tree was constructed to divide the Tibetan pigs into two branches. After Chinese domestic pigs, wild boars and introduced pig breeds were introduced,the Tibetan pigs in Ruoergai area were more dispersed in the evolutionary tree,indicating that the maternal lineage of Tibetan pigs in this area was genetically complex and had many genetic exchanges. This study further confirmed that the Tibetan pigs in Ruoergai area had higher genetic diversity than that in Tibet Nyingchi,Shannan,Shigatse,Ganzi and A'ba Prefecture,and the intensity of artificial selection was lower, and the protection and utilization of Tibetan pig genetic resources should be strengthened in Ruoergai area.

Key words: Ruoergai area, Tibetan pig, mtDNA, D-Loop, haplotype, genetic diversity

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