影响中-欧猪种系 SSC2p 背膘厚的 QTL 的数量和遗传方式。

Number and mode of inheritance of QTL influencing backfat thickness on SSC2p in Sino-European pig pedigrees.

机构信息

INRA, UMR 0444 Génétique Cellulaire, F-31326 Castanet-Tolosan, France.

出版信息

Genet Sel Evol. 2011 Mar 6;43(1):11. doi: 10.1186/1297-9686-43-11.

DOI:10.1186/1297-9686-43-11

PMID:21375775

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC3073881/

Abstract

BACKGROUND

In the pig, multiple QTL associated with growth and fatness traits have been mapped to chromosome 2 (SSC2) and among these, at least one shows paternal expression due to the IGF2-intron3-G3072A substitution. Previously published results on the position and imprinting status of this QTL disagree between analyses from French and Dutch F2 crossbred pig populations obtained with the same breeds (Meishan crossed with Large White or Landrace).

METHODS

To study the role of paternal and maternal alleles at the IGF2 locus and to test the hypothesis of a second QTL affecting backfat thickness on the short arm of SSC2 (SSC2p), a QTL mapping analysis was carried out on a combined pedigree including both the French and Dutch F2 populations, on the progeny of F1 males that were heterozygous (A/G) and homozygous (G/G) at the IGF2 locus. Simulations were performed to clarify the relations between the two QTL and to understand to what extent they can explain the discrepancies previously reported.

RESULTS

The QTL analyses showed the segregation of at least two QTL on chromosome 2 in both pedigrees, i.e. the IGF2 locus and a second QTL segregating at least in the G/G F1 males and located between positions 30 and 51 cM. Statistical analyses highlighted that the maternally inherited allele at the IGF2 locus had a significant effect but simulation studies showed that this is probably a spurious effect due to the segregation of the second QTL.

CONCLUSIONS

Our results show that two QTL on SSC2p affect backfat thickness. Differences in the pedigree structures and in the number of heterozygous females at the IGF2 locus result in different imprinting statuses in the two pedigrees studied. The spurious effect observed when a maternally allele is present at the IGF2 locus, is in fact due to the presence of a second closely located QTL. This work confirms that pig chromosome 2 is a major region associated with fattening traits.

摘要

背景

在猪中，多个与生长和脂肪性状相关的 QTL 已被映射到染色体 2（SSC2）上，其中至少有一个表现出父系表达，这是由于 IGF2 内含子 3-G3072A 取代所致。之前关于该 QTL 位置和印迹状态的研究结果在使用相同品种（梅山猪与长白猪或大约克夏猪杂交）获得的法荷 F2 杂交猪群体的分析中存在分歧。

方法

为了研究 IGF2 基因座上父系和母系等位基因的作用，并检验影响 SSC2 短臂背脂厚度的第二个 QTL（SSC2p）的假设，对包括法荷 F2 群体在内的联合系谱进行了 QTL 作图分析，该系谱包括 IGF2 基因座杂合子（A/G）和纯合子（G/G）的 F1 雄性的后代。进行模拟以澄清两个 QTL 之间的关系，并了解它们在多大程度上可以解释先前报道的差异。

结果

QTL 分析表明，两个系谱中至少在染色体 2 上分离出两个 QTL，即 IGF2 基因座和第二个 QTL，至少在 G/G F1 雄性中分离，位于 30 到 51 cM 之间。统计分析强调 IGF2 基因座上母系遗传等位基因有显著影响，但模拟研究表明，这可能是由于第二个 QTL 分离而产生的虚假效应。

结论

我们的结果表明，SSC2p 上的两个 QTL 影响背脂厚度。在 IGF2 基因座上杂合雌性数量的系谱结构差异导致了两个研究系谱中不同的印迹状态。当 IGF2 基因座上存在母系等位基因时观察到的虚假效应实际上是由于存在紧密相邻的第二个 QTL 所致。这项工作证实了猪染色体 2 是与育肥性状相关的主要区域。