van Son Maren, Kent Matthew P, Grove Harald, Agarwal Rahul, Hamland Hanne, Lien Sigbjørn, Grindflek Eli
Topigs Norsvin, Storhamargata 44, 2317, Hamar, Norway.
Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, P. O. Box 5003, 1432, Ås, Norway.
BMC Genet. 2017 Oct 11;18(1):85. doi: 10.1186/s12863-017-0549-8.
Previous studies in the Norwegian pig breeds Landrace and Duroc have revealed a QTL for levels of skatole located in the region 74.7-80.5 Mb on SSC7. Skatole is one of the main components causing boar taint, which gives an undesirable smell and taste to the pig meat when heated. Surgical castration of boars is a common practice to reduce the risk of boar taint, however, a selection for boars genetically predisposed for low levels of taint would help eliminating the need for castration and be advantageous for both economic and welfare reasons. In order to identify the causal mutation(s) for the QTL and/or identify genetic markers for selection purposes we performed a fine mapping of the SSC7 skatole QTL region.
A dense set of markers on SSC7 was obtained by whole genome re-sequencing of 24 Norwegian Landrace and 23 Duroc boars. Subsets of 126 and 157 SNPs were used for association analyses in Landrace and Duroc, respectively. Significant single markers associated with skatole spanned a large 4.4 Mb region from 75.9-80.3 Mb in Landrace, with the highest test scores found in a region between the genes NOVA1 and TGM1 (p < 0.001). The same QTL was obtained in Duroc and, although less significant, with associated SNPs spanning a 1.2 Mb region from 78.9-80.1 Mb (p < 0.01). The highest test scores in Duroc were found in genes of the granzyme family (GZMB and GZMH-like) and STXBP6. Haplotypes associated with levels of skatole were identified in Landrace but not in Duroc, and a haplotype block was found to explain 2.3% of the phenotypic variation for skatole. The SNPs in this region were not associated with levels of sex steroids.
Fine mapping of a QTL for skatole on SSC7 confirmed associations of this region with skatole levels in pigs. The QTL region was narrowed down to 4.4 Mb in Landrace and haplotypes explaining 2.3% of the phenotypic variance for skatole levels were identified. Results confirmed that sex steroids are not affected by this QTL region, making these markers attractive for selection against boar taint.
先前对挪威猪品种长白猪和杜洛克猪的研究表明，位于猪7号染色体（SSC7）上74.7 - 80.5 Mb区域存在一个与粪臭素水平相关的数量性状基因座（QTL）。粪臭素是导致公猪异味的主要成分之一，加热时会使猪肉产生不良气味和味道。对公猪进行手术阉割是降低公猪异味风险的常见做法，然而，选择遗传上倾向于低异味水平的公猪将有助于消除阉割的必要性，并且出于经济和福利原因都具有优势。为了确定该QTL的因果突变和/或鉴定用于选择目的的遗传标记，我们对SSC7粪臭素QTL区域进行了精细定位。
通过对24头挪威长白猪和23头杜洛克公猪进行全基因组重测序，获得了SSC7上一组密集的标记。分别使用126个和157个单核苷酸多态性（SNP）子集对长白猪和杜洛克猪进行关联分析。在长白猪中，与粪臭素相关的显著单标记跨越了从75.9 - 80.3 Mb的大片4.4 Mb区域，在基因NOVA1和TGM1之间的一个区域发现了最高测试分数（p < 0.001）。在杜洛克猪中也获得了相同的QTL，尽管显著性较低，相关SNP跨越了从78.9 - 80.1 Mb的1.2 Mb区域（p < 0.01）。在杜洛克猪中，最高测试分数出现在颗粒酶家族（GZMB和GZMH样）和STXBP6基因中。在长白猪中鉴定出了与粪臭素水平相关的单倍型，但在杜洛克猪中未鉴定出，并且发现一个单倍型块可解释粪臭素表型变异的2.3%。该区域的SNP与性类固醇水平无关。
对SSC7上粪臭素QTL的精细定位证实了该区域与猪粪臭素水平的关联。在长白猪中，QTL区域缩小到4.4 Mb，并鉴定出了解释粪臭素水平表型变异2.3%的单倍型。结果证实性类固醇不受该QTL区域影响，使得这些标记对于选择抗公猪异味具有吸引力。
