Genetic Diversity of mtDNA D-loop Region in Zhaotong Cattle

Purpose To clarify the genetic background information of Zhaotong cattle.

Methods The variations in mtDNA D-loop complete sequences from 98 samples of Zhaotong cattle were detected by direct sequencing of PCR products. Further, the data of Zhaotong cattle were analyzed jointly with the published mtDNA data of Yunnan indigenous cattle, including Wenshan cattle, Dehong humped cattle, Dianzhong cattle and Diqing cattle.

Results A total of 73 nucleotide substitution sites and three indels were found in the mtDNA D-loop sequence of Zhaotong cattle. The nucleotide substitutions found accounted for about 8.13% of the total nucleotide sites detected and base substitutions were mainly transitions, of which 18 were single informative sites, 55 were parsimony informative sites. A total of 36 haplotypes were identified in Zhaotong cattle, of which 38.78% belonged to the haplotypes H01-H09 derived from two mtDNA lineages of Bos indicus been found: I1 lineage accounted for 37.76% and I2 lineage accounted for 1.02%. And the remaining 61.22% of this cattle was distributed in haplotypes H10-H36, which were derived from the discovered mtDNA lineages of B. taurus, of which T2 lineage accounts for 5.10%, T3 lineage accounts for 43.88%, and T4 lineage accounts for 12.24%. The haplotype diversity of Zhaotong cattle was 0.880±0.027, the nucleotide diversity was 0.024 43±0.000 94, the genetic distance within population was 0.026±0.004, and the genetic diversity index within the population was 0.027±0.004. The genetic distance and genetic differentiation between Zhaotong cattle and Diqing cattle were the lowest, and that between Zhaotong cattle and Dehong humped cattle were the highest.

Conclusion The genetic diversity of Zhaotong cattle is rich, and this cattle has a certain degree of genetic differentiation with other indigenous cattle breeds in Yunnan. The cattle has mixed maternal origins of B. taurus and B. indicus, but it is greatly affected by B. taurus.