The Mean Staple Length of Wool Fibre Is Associated with Variation in the Ovine Keratin-Associated Protein 21-2 Gene

• Main Authors: Shaobin Li, Huitong Zhou, Hua Gong, Fangfang Zhao, Jiqing Wang, Xiu Liu, Jiang Hu, Yuzhu Luo, Jon G.H. Hickford
• Format: Article
• Language: English
• Published: MDPI AG 2020-01-01
• Series: Genes
• Subjects: kap21-2 gene (<i>krtap21-2</i>); mean staple length; wool traits; sheep
• Online Access: https://www.mdpi.com/2073-4425/11/2/148

Wool and hair fibres consist of a variety of proteins, including the keratin-associated proteins (KAPs). In this study, a putative ovine homologue of the human KAP21-2 gene (<i>KRTAP21-2</i>) was identified. It was located on chromosome 1 as a 201-bp open reading frame (ORF) in the ovine genome assembly from a Texel sheep (v.4 NC_019458.2: nt122932727 to 122932927). A polymerase chain reaction- single strand conformation polymorphism (PCR-SSCP) analysis of this ORF, and subsequent DNA sequencing, identified five sequences (named <i>A</i>-<i>E</i>). The putative amino acid sequences that would be produced, shared some identity with each other and with other KAPs, but they were most similar to ovine KAP21-1, and phylogenetically related to human KAP21-2. The location of the ovine <i>KRTAP21-2</i> sequence was consistent with the location of human <i>KRTAP21-2,</i> and this suggests they represent different variant forms of ovine <i>KRTAP21</i>-2. Variation in this gene was investigated in 389 Merino (sire) &#215; Southdown-cross (ewe) lambs. These were derived from four independent sire-lines. The sequence variation was found to be associated with variation in five wool traits: including mean staple length (MSL), mean fibre diameter (MFD), fibre diameter standard deviation (FDSD), prickle factor (PF), and greasy fleece weight (GFW). The most persistent effect of <i>KRTAP21-2</i> variation was with variation in MSL; with the MSL of sheep of genotype <i>AC</i> being 12.5% greater than those of genotype <i>CE</i>. A similar effect was observed from individual variant absence/presence models. This suggests that <i>KRTAP21-2</i> should be further investigated as a possible gene-marker for improving MSL.