Facial pigmentation is an important economic trait of chickens, especially for laying hens, which will affect the carcass appearance of eliminated layers. Therefore, identifying the genomic regions and exploring the function of this region that contributes to understanding the variation of skin color traits is significant for breeding. In the study, 291 pure-line Xinyang blue-shelled laying hens were selected, of which 75 were dark-faced chickens and 216 were white-faced chickens. The population was sequenced and typed by GBS genotyping technology. The obtained high-quality SNPs and pigmentation phenotypes were analyzed by a genome-wide association study (GWAS) and a F_ST scan. Based on the two analytical methods, we identified a same genomic region (10.70–11.60 Mb) on chromosome 20 with 68 significant SNPs (−log 10(P)>6), mapped to 10 known genes, including NPEPL1, EDN3, GNAS, C20orf85, VAPB, BMP7, TUBB1, ELMO2, DDX27, and NCOA5, which are associated with dermal hyperpigmentation.

Pigeon breed resources provide a genetic model for the study of phenomics. The pectoral muscles play a key role for the meat production performance of the meat pigeon and the athletic ability of the High flyers. Euro-pigeons and Silver King pigeons are commercial varieties that exhibit good meat production performance. In contrast to the domestication direction of meat pigeons, the traditional Chinese ornamental pigeon breed, High flyers, has a small and light body. Here, we investigate the molecular mechanism of the pectoral muscle development and function of pigeons using whole-genome and RNA sequencing data. The selective sweep analysis (F_ST and log2 (θπ ratio)) revealed 293 and 403 positive selection genes in Euro-pigeons and Silver King, respectively, of which 65 genes were shared. With the Silver King and Euro-pigeon as the control group, the High flyers were selected for 427 and 566 genes respectively. There were 673 differentially expressed genes in the breast muscle transcriptome between the commercial meat pigeons and ornamental pigeons. Pigeon genome selection signal combined with the breast muscle transcriptome revealed that six genes (SLC16A10, S100B, SYNE1, HECW2, CASQ2 and LOC110363470) from commercial varieties of pigeons and five genes (INSC, CALCB, ZBTB21, B2M and LOC110356506) from Chinese traditional ornamental pigeons were positively selected which were involved in pathways related to muscle development and function. This study provides new insights into the selection of different directions and the genetic mechanism related to muscle development in pigeons.

To meet human needs, domestic pigeons (Columba livia) with various phenotypes have been bred to provide genetic material for our research on artificial selection and local environmental adaptation. Seven pigeon breeds were resequenced and can be divided into commercial varieties (Euro‐pigeon, Shiqi, Shen King, Taishen, and Silver King), ornamental varieties (High Fliers), and local varieties (Tarim pigeon). Phylogenetic analysis based on population resequencing showed that one group contained local breeds and ornamental pigeons from China, whereas all commercial varieties were clustered together. It is revealed that the traditional Chinese ornamental pigeon is a branch of Tarim pigeon. Runs of homozygosity (ROH) and linkage disequilibrium (LD) analyses revealed significant differences in the genetic diversity of the three types of pigeons. Genome sweep analysis revealed that the selected genes of commercial breeds were related to body size, reproduction, and plumage color. The genomic imprinting genes left by the ornamental pigeon breeds were mostly related to special human facial features and muscular dystrophy. The Tarim pigeon has evolved genes related to chemical ion transport, photoreceptors, oxidative stress, organ development, and olfaction in order to adapt to local environmental stress. This research provides a molecular basis for pigeon genetic resource evaluation and genetic improvement and suggests that the understanding of adaptive evolution should integrate the effects of various natural environmental characteristics.

China has the largest population of pigeons globally, particularly for commercial meat production. Due to insufficient emphasis on bloodline preservation, there is a significant occurrence of breed hybridization, which presents challenges to the differentiation and identification of various pigeon breeds. In this study, a single-nucleotide polymorphism chip was developed to elucidate genomic relationships and genetic diversity among 10 pigeon breeds, encompassing meat, racing, and ornamental varieties. Principal component analysis revealed that this resource population could be classified into three major clusters: homing and Tarim pigeons; the Dianzi (DZ) and Xinjiang Roller (XR) varieties; and commercial meat pigeon breeds, including the Euro-pigeon (EP), Danish King (DK), Silver King (SK), Yellow Carneau (YC), Red Carneau (RC), and Taishen (TS) varieties. Phylogenetic tree analysis indicated that the HP, TR, DZ, and XR varieties clustered into a large group. Of these, the HP and TR groups and the DZ and XR group were closely genetically related. Other meat pigeon varieties clustered into a large group. The genetic relationship between the YC and RC pigeons was intertwined, suggesting that although there were differences in feather color, the genetic backgrounds are similar. The phylogenetic tree results also demonstrated that the DK and SK pigeons had a considerable genetic distance, indicating that although the feather color was similar, the birds belong to two distinct genetic groups. The Pigeon 5 K liquid chip can effectively discriminate among different pigeon populations and provides a method for the identification and evaluation of pigeon germplasm resources, especially for pure breed identification and exploration of new resources.

Background: Various morphological breeds of rock pigeons have emerged as a result of human domestication. Pigeon breed resources provide a genetic model for the study of phenomics. The pectoral muscles are play a key role for the meat production performance of the meat pigeon and the athletic ability of the High flyers. Euro-pigeons and Silver King are commercial varieties that exhibit good meat production performance. In contrast to the domestication direction of meat pigeons, the traditional Chinese ornamental pigeon breed, High flyers, has a small and light body. Here, we investigate the molecular mechanism of the pectoral muscle development and function of pigeons using whole-genome and RNA sequencing data Result: The selective sweep analysis (FST and log2 (θπ ratio)) revealed 293 and 403 positive selection genes in Euro-pigeons and Silver King, respectively, of which 65 genes were shared. With the Silver King and Euro-pigeon as the control group, the High flyers were selected for 427 and 566 genes respectively. There were 673 differentially expressed genes in the breast muscle transcriptome between the commercial meat pigeons and ornamental pigeons. Pigeon genome selection signal combined with the breast muscle transcriptome revealed that 6 genes from commercial varieties of pigeons and 5 genes from Chinese traditional ornamental pigeons were positively selected. These genes were involved in pathways related to muscle development and function. Conclusion: Integrated selection signal, transcriptome analysis, and functional annotation identified SYNE1 as a key gene enriched in the actin binding and muscle cell differentiation pathways. Moreover, SYNE1 gene mutations have been associated with human muscular dystrophy. The differential expression of this gene reveals that it has a negative regulatory role in the development and function of pigeon breast muscle.