囊谦青牦牛母系遗传多样性及遗传背景探析

Analysis of Maternal Genetic Diversity and Genetic Background of Nangqian Grey Yak Population

为从分子水平上揭示青海省囊谦青牦牛的母系遗传多样性、群体结构及遗传背景,对31头囊谦青牦牛mtDNA D-loop区序列进行PCR扩增、测序和序列比对分析,确定序列变异位点和单倍型数目,计算单倍型多样度和核苷酸多样度大小,并进行系统发育分析。结果表明,在囊谦青牦牛618 bp D-loop区序列分析中,共检测到34个多态位点,包括8个单一多态位点和26个简约信息位点。根据序列间核苷酸变异共确定了12种单倍型,单倍型多样度和核苷酸多样度分别为0.846±0.055和0.011±0.005。与野牦牛及我国其他18个家牦牛品种相比,囊谦青牦牛群体核苷酸多样度和单倍型多样度值均较低,表明囊谦青牦牛母系遗传多样性水平较低。以美洲野牛为外群构建的系统发育树结果显示,囊谦青牦牛群体的12种单倍型分布在3种单倍型组A、C、D中,且聚为2个大的分支,提示囊谦青牦牛由2个母系支系组成,拥有2个母系起源。综上,囊谦青牦牛群体母系遗传多样性较低,由2个母系支系组成,推测其有2个母系起源。

To reveal the maternal genetic diversity,population structure and genetic background of the Nangqian Grey yak population at molecular level in Qinghai province.The mtDNA D-loop sequences of 31 Nangqian Grey yaks were determined and analyzed by multiple sequence alignment to determine the sequence variation sites and the number of haplotypes and the corresponding indexes of haplotype diversity and nucleotide diversity were also calculated.Meanwhile,the phylogenetic analysis of Nangqian Grey yak was performed.The results showed that 34 polymorphic sites including 8 single polymorphic sites and 26 parsimony information sites were detected in the 618 bp D-loop region sequences analysis totally.According to the nucleotide variations among sequences,12 haplotypes were identified in Nangqian Grey yak.The haplotype diversity and nucleotide diversity of Nangqian Grey yak were 0.846±0.055 and 0.011±0.005,respectively.Compared with wild yak and other 18 domestic yak breeds/populations in China,the values of nucleotide diversity and haplotype diversity of Nangqian Grey yak were lower,indicating that the level of maternal genetic diversity of Nangqian Grey yak was lower.The results of the phylogenetic tree constructed with the Bison bison(GenBank No.EU177871)as the outgroup showed that the 12 haplotypes of the Nangqian Grey yak population were distributed in three haplotype groups A,C,and D,and clustered into two large branches.The haplotypes/haplogroups could be clustered into two maternal lineages,which indicated that Nangqian Grey yak had two maternal origins.In conclusion,Nangqian Grey yak population owned lower maternal genetic diversity,which was composed of three haplogroups(A,C and D)individuals distributed in two lineages with two maternal origins.