Maternal genetic diversity, differentiation and phylogeny of three white yak breeds/populations in China.

White yak is a unique economic livestock animal on the Qilian Mountains of Qinghai-Tibet Plateau (QTP). Here, 369 mitochondrial D-loop sequences from three Chinese white yak breeds/populations (Tianzhu, Menyuan and Huzhu) were comprehensively analyzed to indicate their maternal genetic diversity, differentiation and phylogenetic relationship. Our results showed that the haplotype diversity (Hd) was found to be highest in Tianzhu white yak (Hd ± SD = 0.9501 ± 0.0058), while the lowest was recorded in Huzhu white yak (Hd ± SD = 0.7178 ± 0.0474). Totally, the haplotype and nucleotide diversities of white yak were 0.9407 ± 0.0069 and 0.0187 ± 0.0094, respectively, indicating an abundant maternal genetic diversity in white yak. Estimates of FST (Fixation Index) values showed a high genetic differentiation between Tianzhu and Menyuan populations (FST = 0.2928, p < 0.05) as well as that between Tianzhu and Huzhu populations (FST = 0.2721, p < 0.05), but a moderate genetic differentiation between Menyuan and Huzhu populations (FST = 0.1352, p > 0.05) was observed. Cluster analysis based on FST values among populations indicated that the genetic relationship between Menyuan and Huzhu white yak was closer, but they had a far genetic relationship with Tianzhu white yak. Maternal phylogenetic analysis revealed that white yak represented two maternal lineages (I and II), suggesting two maternal origins. In addition, it is notable that taurine mtDNA haplotypes were detected in Tianzhu and Huzhu white yak populations, indicating taurine genetic introgression to some extent. Our study would provide useful information for the conservation and utilization of white yak.

Mitogenome characterization and phylogeny of Huzhu white yak (Bos grunniens) in China.

White yak is a unique and precious economic livestock animal in the world. In this study, the mitogenome of Huzhu white yak was firstly sequenced using Illumina high-throughput sequencing technique and then the assembly was annotated. We also explored mitogenome characterization and phylogeny of Huzhu white yak. Our results showed that the mitogenome of Huzhu white yak is a circular molecule with 16,323bp length including a non-coding control region (D-loop), two ribosomal RNA genes (12S rRNA and 16S rRNA), 22 transfer RNA genes and 13 protein-coding genes. The contents of four nucleotides (A, G, C and T) were 33.71%, 13.21%, 25.80%, and 27.28%, respectively, yielding a lower GC content (39.01%) than AT (60.99%). Phylogenetic analysis suggested that Huzhu white yak possessed the closest relationships with Huanhu, Jiulong, Datong, Jinchuan, Sibu, Ashdan and Pali yak breeds, and closer to wild yak and Bazhou breed.