Genetic variant of the sheep E2F8 gene and its associations with litter size.

The economic efficiency of sheep breeding, aiming to enhance productivity, is a focal point for improvement of sheep breeding. Recent studies highlight the involvement of the Early Region 2 Binding Factor transcription factor 8 (E2F8) gene in female reproduction. Our group's recent genome-wide association study (GWAS) emphasizes the potential impact of the E2F8 gene on prolificacy traits in Australian White sheep (AUW). Herein, the purpose of this study was to assess the correlation of the E2F8 gene with litter size in AUW sheep breed. This work encompassed 659 AUW sheep, subject to genotyping through PCR-based genotyping technology. Furthermore, the results of PCR-based genotyping showed significant associations between the P1-del-32bp bp InDel and the fourth and fifth parities litter size in AUW sheep; the litter size of those with genotype ID were superior compared to those with DD and II genotypes. Thus, these results indicate that the P1-del-32bp InDel within the E2F8 gene can be useful in marker-assisted selection (MAS) in sheep.

Whole-genome resequencing reveals the genomic diversity and signatures of selection in Romanov sheep.

Romanov sheep are adapted to the extremely cold and harsh environment and display a distinctive grey color. Herein, we analyzed the population structure, genetic diversity, and selection signatures of Romanov sheep based on whole-genome sequencing data of 17 Romanov sheep, 114 individuals from other 10 European breeds. The results of PCA, ADMIXTURE, and NJ-tree showed that the Romanov sheep was closely related to other northern European breeds. A relative high level of genetic diversity, low inbreeding coefficient, and large effective population size was observed in Romanov sheep when compared with other European breeds. We then screened the genomic selection signatures of Romanov sheep using FST, XP-XLP, and XP-EHH methods. The most significant region under selection (CHR14:14.2 to 14.3 Mb) harbored a haplotype that contained MC1R gene. Furthermore, this haplotype was also found in other grey-body breeds including Gotland sheep, Grey Tronder Sheep, and German grey heath sheep, suggesting that it was associated with the unique coat color of these breeds. We also found one region (CHR10:40.8Mb- 41.0Mb) harboring PCDH9 gene which was potentially associated with cold environmental adaptation. In summary, this study identified candidate genes that were associated with the unique grey color and environmental adaptation in Romanov sheep, which provided a basis for understanding the genetic background and utilization of this breed.

Romanov sheep is one of the most famous sheep breeds in the word, characterized by adaptability to harsh environment, high fertility, and unique coat color. Understanding its genetic architecture and signatures is of great value for its conservation and utilization. In this study, we analyzed whole-genome sequences of Romanov sheep as compared with 11 other European breeds, to explore for the population structure, genetic diversity, and selection signatures. We discovered a series of candidate genes that likely play a role in the grey coat color and cold adaptation of the Romanov sheep. In particular, we identified MC1R as a strong candidate gene that determines the grey coat color.