Single nucleotide polymorphism screening, molecular characterization, and evolutionary aspects of chicken Piwi genes

The P-element-induced wimpy testis (Piwi) gene is involved in germline stem cell self-renewal, meiosis, RNA silencing, and transcriptional regulation. Piwi genes are relatively well conserved in many species, but their function in poultry species is unclear. In this study, Piwi genes were sequenced using a target-sequence capture assay in quail and 28 breeds of chicken. Single nucleotide polymorphisms (SNPs) and evolutionary aspects of these chicken breeds were then analyzed. We found that SNP sites existed mainly in the introns of a few chicken breeds, and we selected an SNP on intron 4 for further verification by Sanger sequencing, the results of which were similar to those obtained by the target-capture sequencing assay. The evolutionary analysis revealed that there were more mutations in the Chahua and Leghorn breeds than in the other breeds, and that the phylogenetic tree was divided into four main categories that suggested that Piwi is evolutionarily conserved, and mutations in the introns might be associated with gametogenesis. The screened SNPs can be used as candidate markers for Piwi, and our results provide basic information for the further study of Piwi function in poultry.