A cis-Regulatory Mutation of PDSS2 Causes Silky-Feather in Chickens

Abstract

Silky-feather has been selected and fixed in some breeds due to its unique appearance. This phenotype is caused by a single recessive gene (hookless, h). Here we map the silky-feather locus to chromosome 3 by linkage analysis and subsequently fine-map it to an 18.9 kb interval using the identical by descent (IBD) method. Further analysis reveals that a C to G transversion located upstream of the prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2) gene is causing silky-feather. All silky-feather birds are homozygous for the G allele. The silky-feather mutation significantly decreases the expression of PDSS2 during feather development in vivo. Consistent with the regulatory effect, the C to G transversion is shown to remarkably reduce PDSS2 promoter activity in vitro. We report a new example of feather structure variation associated with a spontaneous mutation and provide new insight into the PDSS2 function.

Genomic determinants of epidermal appendage patterning and structure in domestic birds

“…Silky-feather was first described by Marco Polo in the 13 th century and has since become fixed in several chicken breeds, including the modern Silkie breed (Feng et al, 2014). Classical genetics experiments demonstrate that silky-feather is caused by a single recessive allele at the hookless locus (Dunn and Jull, 1927).…”

“…Classical genetics experiments demonstrate that silky-feather is caused by a single recessive allele at the hookless locus (Dunn and Jull, 1927). In birds homozygous for hookless , silky-feather results from a failure in hooklet formation, the structure responsible for holding feather vane barbs together in pennaceous feathers (Feng et al, 2014). To determine the molecular basis of silky-feather, Feng et al (2014) employed SNP association mapping and identity-by-descent (IBD) analysis to refine a locus previously identified by QTL mapping.…”

“…In birds homozygous for hookless , silky-feather results from a failure in hooklet formation, the structure responsible for holding feather vane barbs together in pennaceous feathers (Feng et al, 2014). To determine the molecular basis of silky-feather, Feng et al (2014) employed SNP association mapping and identity-by-descent (IBD) analysis to refine a locus previously identified by QTL mapping. Additional whole-genome analyses of unrelated Silkie chickens identified a single shared 21.7-kb haplotype that overlapped completely with the candidate region in the F2 mapping population (Feng et al, 2014).…”

“…In his words, the chicken has “a variety of regionally distinctive integumentary derivatives” such as feathers and scales of different types (Saunders, 1958). For example, the pennaceous feathers of the White Leghorn (tightly linked feather barbs) and Silkie (fluffy due to missing hooklets on barbules; Feng et al, 2014) breeds are so different that he could use feather morphology as a marker in his embryonic tissue transplant experiments (Cairns and Saunders, 1954). Saunders also recognized the value of embryonic tissue transplants between fore- and hindlimb buds to study the roles of the mesoderm and ectoderm in limb-specific epidermal appendage patterning: whichever tissue(s) conferred forelimb epidermal identity should predictably produce feathers when transplanted, and tissues bearing the hindlimb signal should produce scales (Cairns and Saunders, 1954).…”

High-Throughput Sequencing Reveals miRNAs Affecting Follicle Development in Chicken

“…The feather is one of the most complex integumentary appendages due to the extensive diversity in shape, size, arrangement and pigmentation, and is therefore an excellent model for evolutionary and developmental biology as variations can occur at each step of development and differentiation [10][11][12][13]. The Kirin chicken can adapt to high-temperature environment because of unique frizzled feather branching structure characteristic, rachis stout and outwardly curved, barbs short sparse, feather hook can't connect with the back edge of the adjacent twig lead to pinna can not closed.…”