National Germplasm Center of Domestic Animal Resources, Ministry of Technology, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China; National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; Key Laboratory of Livestock and Poultry Resources (Cattle) Evaluation and Utilization, Ministry of Agriculture and Rural Affairs, China.
National Germplasm Center of Domestic Animal Resources, Ministry of Technology, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China; Key Laboratory of Livestock and Poultry Resources (Cattle) Evaluation and Utilization, Ministry of Agriculture and Rural Affairs, China.
J Adv Res. 2024 Mar;57:1-13. doi: 10.1016/j.jare.2023.04.012. Epub 2023 May 1.
Fine-wool sheep are the most common breed used by the wool industry worldwide. Fine-wool sheep have over a three-fold higher follicle density and a 50% smaller fiber diameter than coarse-wool sheep.
This study aims to clarify the underlying genetic basis for the denser and finer wool phenotype in fine-wool breeds.
Whole-genome sequences of 140 samples, Ovine HD630K SNP array data of 385 samples, including fine, semi-fine, and coarse wool sheep, as well as skin transcriptomes of nine samples were integrated for genomic selection signature analysis.
Two loci at keratin 74 (KRT74) and ectodysplasin receptor (EDAR) were revealed. Fine-scale analysis in 250 fine/semi-fine and 198 coarse wool sheep narrowed this association to one C/A missense variant of KRT74 (OAR3:133,486,008, P = 1.02E-67) and one T/C SNP in the regulatory region upstream of EDAR (OAR3:61,927,840, P = 2.50E-43). Cellular over-expression and ovine skin section staining assays confirmed that C-KRT74 activated the KRT74 protein and specifically enlarged cell size at the Huxley's layer of the inner root sheath (P < 0.01). This structure enhancement shapes the growing hair shaft into the finer wool than the wild type. Luciferase assays validated that the C-to-T mutation upregulated EDAR mRNA expression via a newly created SOX2 binding site and potentially led to the formation of more hair placodes.
Two functional mutations driving finer and denser wool production were characterized and offered new targets for genetic breeding during wool sheep selection. This study not only provides a theoretical basis for future selection of fine wool sheep breeds but also contributes to improving the value of wool commodities.
细毛绵羊是全球羊毛产业最常用的品种。细毛绵羊的毛囊密度比粗毛绵羊高三倍以上，纤维直径小 50%。
本研究旨在阐明细毛绵羊品种中更密、更细羊毛表型的潜在遗传基础。
整合了 140 个样本的全基因组序列、385 个样本的绵羊 HD630K SNP 阵列数据，包括细毛、半细毛和粗毛绵羊，以及 9 个样本的皮肤转录组，用于基因组选择特征分析。
揭示了角蛋白 74（KRT74）和外胚层发育不良受体（EDAR）两个基因座。在 250 只细毛/半细毛和 198 只粗毛绵羊中进行精细分析，将这种关联缩小到 KRT74 的一个 C/A 错义变异（OAR3：133486008，P=1.02E-67）和 EDAR 上游调控区的一个 T/C SNP（OAR3：61927840，P=2.50E-43）。细胞过表达和绵羊皮肤切片染色试验证实，C-KRT74 激活了 KRT74 蛋白，并特异性地增大了内根鞘 Huxley 层的细胞大小（P<0.01）。这种结构增强将生长中的毛干塑造成比野生型更细的羊毛。荧光素酶试验验证了 C 到 T 的突变通过一个新创建的 SOX2 结合位点上调了 EDAR mRNA 的表达，并可能导致更多的毛胚形成。
两个驱动更细和更密羊毛生产的功能突变被鉴定出来，为羊毛绵羊选择中的遗传育种提供了新的目标。本研究不仅为未来的细毛绵羊品种选择提供了理论基础，也为提高羊毛商品的价值做出了贡献。
