Abstract
Naked-neck chickens are distributed across tropical and subtropical regions and exhibit notable resistance to heat stress. The naked-neck trait in chickens is an incompletely dominant characteristic determined by the Na gene, and significant differences in feather quantity and distribution have been observed between homozygous and heterozygous individuals. The Ake chicken, a native Chinese breed originating from southwestern Yunnan Province, is the only breed in China that possesses the naked-neck trait. The Ake chicken was developed in a relatively isolated mountain area, and the genetic basis for the determinants of the naked-neck trait in this breed remains unclear. In this study, we utilized Oxford Nanopore Technologies and next-generation sequencing to obtain genomic data from Ake chickens and other naked-neck chicken breeds from Iran and Egypt. Genome sequence alignments revealed that the mutation responsible for the naked-neck trait in Ake chickens was the same as that in naked-neck chickens from other regions, specifically, a 73-kb insertion at the end of chromosome 3. We further demonstrated that the insertion fragment was homologous to the intergenic region between the WNT11 and UVRAG genes at 198 Mb on chromosome 1. The original sequence on chr 1 remained intact without any mutation. This study provides a genetic foundation for the naked-neck trait in chickens and provides a reliable molecular marker for the future breeding of heat stress-resistant chicken breeds.