三江黄牛mtDNA D-Loop区遗传多样性及系统进化
Analysis of Genetic Diversity of mtDNA D-Loop Regions and Phylogenetic Evolution of Sanjiang Cattle

根据普通牛线粒体DNA 序列设计引物，扩增获得三江黄牛线粒体D-loop区全序列，并以绵羊为外属对牛亚科代表性品种（类群）（九龙牦牛、野牦牛、瘤牛、欧洲野牛、中国水牛、亚洲水牛、德国普通牛、秦川牛、南阳牛、晋南牛、蒙古牛、平武牛、川南牛、凉山牛、湘西牛和昭通牛）的mtDNA D-loop序列进行系统进化分析，以期了解三江黄牛的遗传多样性，分析三江黄牛数量急剧下降的原因并提出参考意见。结果表明，三江黄牛线粒体D-loop区序列长909~911 bp，T、C、A、G碱基的平均含量分别为29.08%、24.49%、32.72%和13.71%；三江黄牛共有16种单倍型，平均单倍型多样性（Hd）为0.875 7，平均核苷酸多样性（Pi）为0.022 92，遗传多样性较为丰富；三江黄牛与已知牛品种（类群）mtDNA D-loop序列比对结果表明，与凉山牛差异最小（0.11%），与欧洲野牛差异最大（32.63%）；系统进化分析显示三江黄牛是中国众多黄牛类群中的一支，与秦川牛、平武牛亲缘关系较近，推测其是由普通牛和瘤牛共同进化而来。
The Sanjiang cattle mitochondrial D-loop area was cloned using a specific primers design according to the mitochondrial DNA sequence of bovine,which was then used for phylogenetic analysis combined with the mtDNA D-loop sequence of bovine typical cattle(groups) and cattle breeds of China,including Jiulong yak,Poephagus mutusc,Poephagus mutusc,Bos indicus,Bison bonasus,Chinese water buffalo,Bubalus bubalis,German Bos taurus,Qinchuan cattle,Nanyang cattle,Jinnan cattle,Mongolian cattle,Pingwu cattle,Chuannan cattle,Liangshan cattle,Xiangxi cattle and Zhaotong cattle,with that sheep as the exogenous reference. These data may be beneficial for us to understand the genetic diversity of Sanjiang cattle,and we put forward the reasons and solution for the dramatic decline of Sanjiang cattle. The results showed that sequence length of Sanjiang cattle mitochondrial D-loop area was between 909-911 bp. T,C,A,G took the average content of 29.08%,24.49%,32.72% and 13.71%,respectively; the average haploid type diversity(Hd) of a total of 16 Sanjiang cattle haploid type was 0.875 7,the average nucleotide diversity(Pi) of 0.022 92 were identified; Sanjiang cattle sheared the minimum sequence difference with that of Liangshan cattle(0.11%),and hit the maximum difference on Bison bonasus(32.63%). Phylogenetic evolution analysis showed that Sanjiang cattle is an independent cattle breeds which obtaine the closest genetic relationship with Sanjiang cattle,Qinchuan cattle and Pingwu cattle,and presume to be co-evolved by the Bos taurus and Bos indicus.