RESUMO
Danzhou chicken (DZ) is a local breed in China noted for its strong adaptability, roughage resistance, strong wildness, and delicious taste, thus containing important genetic resources. In this study, genome re-sequencing data was generated from 200 DZ chickens. Combined with previously generated data from 72 additional chickens across six other exotic and local breeds, these data were used to systematically evaluate the germplasm characteristics of DZ chickens from a genomic perspective. Unlike exotic breeds, both DZ and southern local chicken varieties exhibited high genetic diversity, and the genetic distance between DZ and southern local chickens was smaller than the genetic distance between DZ and exotic chickens. A reconstructed Neighbor-Joining phylogenetic tree indicated that all sampled populations clustered into single independent populations, with DZ chickens showing clear evidence of intra-population differentiation, forming 2 subpopulations. Principal component analysis and ADMIXTURE analysis showed that DZ was significantly different from other breeds. These results indicate that DZ is a unique genetic resource that is different from other southern native and exotic chickens. The results of the study will improve our understanding of the genetic structure and current status of the DZ breed, which is of great significance in promoting the conservation of genetic resources of DZ chickens and fostering breed innovations and genetic improvement.
RESUMO
Tunchang pigs are an indigenous pig population in China known for their high tolerance to roughage, delicious meat, and fecundity. However, the number of Tunchang pigs has been declining due to the influence of commercial breeds and African swine fever, which could potentially lead to inbreeding. To assess the inbreeding level and the genetic basis of important traits in Tunchang pigs, our research investigated the patterns in "runs of homozygosity" (ROHs) using whole genome resequencing data from 32 Tunchang pigs. The study aimed to determine the length, number, coverage, and distribution model of ROHs in Tunchang pigs, as well as genomic regions with high ROH frequencies. The results of the study revealed that a total of 20,499,374 single-nucleotide polymorphisms (SNPs) and 1953 ROH fragments were recognized in 32 individuals. The ROH fragments in Tunchang pigs were predominantly short, ranging from 0.5 to 1 megabases (Mb) in length. Furthermore, the coverage of ROHs varied across chromosomes, with chromosome 3 having the highest coverage and chromosome 11 having the lowest coverage. The genetic diversity of Tunchang pigs was found to be relatively high based on the values of HE (expected heterozygosity), HO (observed heterozygosity), pi (nucleotide diversity), Ne (effective population size), and MAF (minor allele frequency). The average inbreeding coefficients of Tunchang pigs, as determined by three different methods (FHOM, FGRM, and FROH), were 0.019, 0.0138, and 0.0304, respectively. These values indicate that the level of inbreeding in Tunchang pigs is currently low. Additionally, the study identified a total of 13 ROH islands on all chromosomes, which in total contained 38,913 SNPs and 120 genes. These ROH islands included genes associated with economically important traits, including meat quality (GYS1, PHLPP1, SLC27A5, and CRTC1), growth and development (ANKS1A, TAF11, SPDEF, LHB, and PACSIN1), and environmental adaptation (SLC26A7). The findings of this research offer valuable perspectives on the present status of Tunchang pig resources and offer a reference for breeding conservation plans and the efficient utilization of Tunchang pigs in the future. By understanding the inbreeding level and genetic basis of important traits in Tunchang pigs, conservation efforts can be targeted towards maintaining genetic diversity and promoting the sustainable development of this indigenous pig population.
