# Characterisation of the Ovine KRTAP36-1 Gene in Chinese Tan Lambs and Its Impact on Selected Wool Traits

## TL;DR

This study explores how the KRTAP36-1 gene influences wool traits in Chinese Tan lambs, particularly the curvature of fine wool fibers.

## Contribution

The study identifies associations between KRTAP36-1 gene alleles and fiber curvature in fine wool, but not in heterotypic hair fibers.

## Key findings

- Allele C of KRTAP36-1 is associated with mean fiber curvature in fine wool of Chinese Tan lambs.
- The gene's effect is not observed in heterotypic hair fibers with larger diameters.
- Three alleles (A, B, C) of KRTAP36-1 were identified in Hardy–Weinberg Equilibrium in the lamb population.

## Abstract

Found predominantly in the Ningxia Hui Autonomous Region, Tan sheep are a dual-purpose breed unique to China. Their population is believed to number in the millions, and they are renowned and valued by the Chinese for their meat and distinctive curly fleece at approximately one month of age. There are limits to our knowledge of the genetic mechanisms that underpin their fibre development and that contribute to their fleece characteristics. To better understand the formation of curly fibres, this study focused on the wool keratin-associated protein gene KRTAP36-1 in Tan lambs. Sequence variation in this gene was found to be associated with mean fibre curvature in the fine wool fibres of the breed, but not in the heterotypic hair fibres which have a larger fibre diameter.

Wool has distinctive biological, physical, and chemical properties that contribute to its value both for the sheep and in global fibre and textile markets. Its fibres are primarily composed of proteins, principally keratin and keratin-associated proteins (KAPs). To better comprehend the genes that underpin key wool traits, this study examined the keratin-associated protein 36-1 gene (KRTAP36-1) in Chinese Tan lambs. We identified three previously reported alleles of the gene (named A, B and C) that were present in the lambs studied, with genotype frequencies as follows: 2.0% (n = 5; AA), 6.9% (n = 17; AB), 13.8% (n = 34; AC), 8.9% (n = 22; BB), 33.4% (n = 82; BC) and 35.0% (n = 86; CC). The frequencies of the individual alleles in the Chinese Tan lambs were 12.4%, 29.1% and 58.5% for alleles A, B and C, respectively. The three alleles were in Hardy–Weinberg Equilibrium. In an association analysis, it was revealed that allele C was associated with variation in the mean fibre curvature of the fine wool of the Chinese Tan lambs, but this association was not observed in their heterotypic hair fibres. This finding suggests that KRTAP36-1 might be differentially expressed in the wool follicles that produce the two fibre types, and that along with other KRTAP genes, it may be involved in determining fibre curvature and the distinctive curly coat of the lambs.