Characterization Of Genetic Diversity Of Vietnamese And Chinese Pig Breeds Based On Mitochondrial Genome Variation

Vietnam is one of the well-known countries with rich biodiversity in Southeast Asian region. Although the studies on animal genetic resource have been carried out in recent years, the depth studies are very necessary to complete genetic data. Until now, there are very little data about previous or current genetic variation of local Vietnamese pigs based on whole mitochondrial genomes. Therefore, the objective of the current study is to investigate genetic diversity among Mong Cai pigs and Ban pigs as well as wild boars in Vietnam. Ear tissue samples of these pig breeds/species were collected from Son La province, Vietnam. The DNAs of these samples were extracted, and then the whole mitochondrial genomes of these pig breeds were sequenced, and compared with those of native Chinese pig breeds/species. The Neighbour-Joining and UPGMA methods were used to reconstruct phylogenetic trees of 7 pig mitochondrial genomes from Vietnam and 145 individuals from China, Taiwan, Korea, Japan and European region(downloaded from GenBank). The results of the study are summarized as follows:1. We systemically investigated two local Vietnam pig breeds, including 75 MongCai pigs and 40 Ban pigs. The coat color and reproductive traits were collected. In additions, samples from two wild pigs were also collected.2. The reproductive performance of Mong Cai pig ishigher than Ban pig. The number of nipples of Mong Cai pig is 13.47 and that of Ban pig is 11.35. The litter sizes of Mong Cai and Ban pigs are 11.80 and 7.66, respectively. The average weights of Mong Cainew-born piglets and weaning pigs are 0.54 kg and 5.57 kg, whereas those of Ban newborn piglets and weanling pigs are 0.44 kg and 4.46 kg, respectively.3. The whole mitochondrial genome characteristics of Mong Cai and Ban pigs as well as wild boar breeds areannotated clearly with 37 coding-genes including 2 ribosomal RNA genes, 22 transfer RNA genes, 13 protein-coding genes and 1 control region. The total length of mitochondrial genomes of these pig breeds rangesfrom 16.5 kb to 16.7 kb, with the base composition approximately of 34 % for A, 25 % for T, 26 % for C and 13 % for G, and rich feature in A+T(about 60%).4. The phylogenetic relationships between Vietnamese and Chinese pigs were analyzed. Specifically, Mong Cai pigs and Bama pigs have closed genetic distance, while Ban pigs and Banna mini pig as well as Diannan Small-eared pigs shared closerelationship. Curiously, Vietnamese wild boar shares common ancestors with Chinese pig breeds. The close geographical position and interaction of human and animals between the two countries could explain the close genetic distances of animals.5. The genetic distances between pig populations of countrieswithin Asian region were calculated. The results showed that the hereditary distances of pig groups in Asian countries weresmaller in comparison with European region. In which, the genetic distance between Chinese and Japanese pig breeds were smallest(0.0010).The current study provided essential genetic data for future studies.