Comparative analysis of the genetic diversity of the neutral microsatellite loci and second exon of the goat MHC-DQB1 gene

Abstract

This study compared and analyzed the genetic diversity and population structure of exon 2 of the DQB1 gene and 13 autosomal neutral microsatellite markers from 14 Chinese goat breeds to explore the potential evolutionary mechanism of the major histocompatibility complex (MHC). A total of 287 haplotypes were constructed from MHC-DQB1 exon 2 from 14 populations, and 82 nucleotide polymorphic sites (SNPs, 31.78%) and 172 heterozygous individuals (79.12%) were identified. The F_ST values of the microsatellites and MHC-DQB ranged between 0.01831–0.26907 and 0.00892–0.38871, respectively. Furthermore, 14 goat populations showed rich genetic diversity in the microsatellite loci and MHC-DQB1 exon 2. However, the population structure and phylogenetic relationship represented by the two markers were different. Positive selection and Tajima’s D test results showed the occurrence of a diversified selection mechanism, which was primarily based on a positive and balancing selection in goat DQB. This study also found that the DQB sequences of bovines exhibited trans-species polymorphism (TSP) among species and families. In brief, this study indicated that positive and balancing selection played a major role in maintaining the genetic diversity of DQB, and TSP of MHC in bovines was common, which enhanced the understanding of the MHC evolution.

Keywords:

• Major histocompatibility complex (MHC)
• microsatellite markers
• goats
• genetic diversity
• selection

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by the Chongqing Research Program of Basic Research and Frontier Technology [cstc2018jcyjAX0153] and Fundamental Research Funds for the Central Universities [XDJK2018B014].