A chromosome-level genome assembly for the Silkie chicken resolves complete sequences for key chicken metabolic, reproductive, and immunity genes

A set of high-quality pan-genomes would help identify important genes that are still hidden/incomplete in bird reference genomes. In an attempt to address these issues, we have assembled a de novo chromosome-level reference genome of the Silkie (Gallus gallus domesticus), which is an important avian model for unique traits, like fibromelanosis, with unclear genetic foundation. This Silkie genome includes the complete genomic sequences of well-known, but unresolved, evolutionarily, endocrinologically, and immunologically important genes, including leptin, ovocleidin-17, and tumor-necrosis factor-alpha. The gap-less and manually annotated MHC (major histocompatibility complex) region possesses 38 recently identified genes, with differentially regulated genes recovered in response to pathogen challenges. We also provide whole-genome methylation and genetic variation maps, and resolve a complex genetic region that may contribute to fibromelanosis in these animals. Finally, we experimentally show leptin binding to the identified leptin receptor in chicken, confirming an active leptin ligand-receptor system. The Silkie genome assembly not only provides a rich data resource for avian genome studies, but also lays a foundation for further functional validation of resolved genes. A chromosome-level genome for the Silkie chicken (Gallus gallus domesticus) provides insight into both the basis of fibromelanosis in these animals and, more broadly, unresolved genes in genome assemblies for related chicken subspecies.

Automated summary

This study assembled a chromosome-level reference genome of the Silkie chicken, which revealed the complete genomic sequences of important genes such as leptin, ovocleidin-17, and tumor-necrosis factor-alpha. It also provided annotation for the MHC region and gene expression information. Additionally, the study included whole-genome methylation and genetic variation maps, as well as the identification of a complex genetic region associated with fibromelanosis.