China Animal Husbandry and Veterinary Medicine ›› 2021, Vol. 48 ›› Issue (5): 1647-1654.doi: 10.16431/j.cnki.1671-7236.2021.05.015

• Genetics and Breeding • Previous Articles     Next Articles

Genetic Difference Between Menyuan White Yaks and Tianzhu White Yaks Based on mtDNA D-loop Sequences

LI Guangzhen1, MA Zhijie1, CHEN Shengmei1, GA Buzang2, LI Ruizhe1   

  1. 1. Key Laboratory of Plateau Livestock Genetic Resources Protection and Innovative Utilization, Academy of Animal Science and Veterinary Medicine, Qinghai University, Xining 810016, China;
    2. Sujitan Veterinary Station of Menyuan County in Qinghai Province, Xining 810399, China
  • Received:2020-10-28 Online:2021-05-20 Published:2021-05-20

Abstract: In order to explore the maternal genetic difference between Menyuan White yaks in Qinghai province and Tianzhu White yaks in Gansu province,the mtDNA D-loop sequences of 31 Menyuan White yaks were sequenced in this study.Combined with 235 D-loop sequences of Tianzhu White yaks reported in GenBank,266 White yaks D-loop sequences were analyzed.The results showed that 80 polymorphic sites were detected in the 638 bp D-loop sequences,including 5 single polymorphic sites and 75 parsimony informative sites after excluding 64 InDel sites.A total of 56 haplotypes were identified according to the nucleotide sequence variations.Totally,Menyuan White yaks had 7 specific haplotypes and Tianzhu White yaks owned 43 specific haplotypes,but only 2 haplotypes were shared by them.The haplotypes of Menyuan White yaks belonged to A,B and C haplogroups,while the haplotypes of Tianzhu White yaks falled within A,B,C,D,E and F haplogroups and contained 4 Bos taurus haplotypes,which indicated that there was genetic introgression of Bos taurus in Tianzhu White yak breed.The haplotype diversity and nucleotide diversity of Menyuan White yaks were 0.862 and 0.007,respectively,while those of Tianzhu White yaks were 0.946 and 0.014,respectively,which showed that the level of genetic diversity of Tianzhu White yaks was higher than that of Menyuan White yaks.The genetic differentiation index (Fst) between two populations was 0.114,which indicated that the genetic differentiation between them was moderate.The result of phylogenetic analysis showed that the 56 haplotypes could be divided into two distinct lineages (Ⅰ and Ⅱ),indicating that White yaks had two maternal origins.In conclusion,both Menyuan White yaks and Tianzhu White yaks had rich maternal genetic diversity,but the latter had higher level of genetic diversity than the former.There was a moderate differentiation between two populations and Tianzhu White yaks had a certain degree of Bos taurus genetic introgression.Each White yak breed (population) was composed of two maternal lineages,suggesting that White yaks had two maternal origins.Considering the moderate genetic differentiation between two populations and the specific haplotypes owned by them,we suggested that they should be considered as independent "genetic unit"for genetic resource protection and then corresponding conservation and breeding practice would be carried out.

Key words: White yaks; mtDNA; D-loop region; genetic diversity; differentiation; maternal origin

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