Abstract
ObjectiveThe aim of this study is to identify genomic regions or genes controlling growth traits in pigs.MethodsUsing a panel of 54,148 single nucleotide polymorphisms (SNPs), we performed a genome-wide Association (GWA) study in 562 pure Yorshire pigs with four growth traits: average daily gain from 30 kg to 100 kg or 115 kg, and days to 100 kg or 115 kg. Fixed and random model Circulating Probability Unification method was used to identify the associations between 54,148 SNPs and these four traits. SNP annotations were performed through the Sus scrofa data set from Ensembl. Bioinformatics analysis, including gene ontology analysis, pathway analysis and network analysis, was used to identify the candidate genes.ResultsWe detected 6 significant and 12 suggestive SNPs, and identified 9 candidate genes in close proximity to them (suppressor of glucose by autophagy [SOGA1], R-Spondin 2 [RSPO2], mitogen activated protein kinase kinase 6 [MAP2K6], phospholipase C beta 1 [PLCB1], rho GTPASE activating protein 24 [ARHGAP24], cytoplasmic polyadenylation element binding protein 4 [CPEB4], GLI family zinc finger 2 [GLI2], neuronal tyrosine-phosphorylated phosphoinositide-3-kinase adaptor 2 [NYAP2], and zinc finger protein multitype 2 [ZFPM2]). Gene ontology analysis and literature mining indicated that the candidate genes are involved in bone, muscle, fat, and lung development. Pathway analysis revealed that PLCB1 and MAP2K6 participate in the gonadotropin signaling pathway and suggests that these two genes contribute to growth at the onset of puberty.ConclusionOur results provide new clues for understanding the genetic mechanisms underlying growth traits, and may help improve these traits in future breeding programs.
Highlights
Growth rate is an important factor in pig breeding programs as it is directly associated with economic benefits [1]
GWAS has been performed to identify candidate genes for traits related to production [2], body composition [6], reproduction [17], and immunity [18]
GWAS was performed for four growth traits (ADG100, ADG115, D100, and D115), for which 6 genome-wide significant and 12 genome-wide suggestive single nucleotide polymorphisms (SNPs) were identified
Summary
Growth rate is an important factor in pig breeding programs as it is directly associated with economic benefits [1]. Growth rate is typically represented by traits such as average daily gain (ADG) and days to 100 or 115 kg (D100 or D115). In order to design better breeding programs and to improve production efficiency, it is important to understand the genetic determinants controlling these traits [2]. 1315 QTLs are associated with growth traits, including 563 QTLs for ADG and 18 QTLs for days to different body weights (http://www.animalgenome.org/cgi-bin/QTLdb/SS/index, Apr 29, 2016). QTL data suggests that growth traits are controlled by many loci [1], but the causative genes or single nucleotide polymorphisms (SNPs) are difficult to identify due to the low resolution and complex architecture of most QTLs [4,5]. Because of the availability of high-throughput genotyping platforms for SNPs, genome-wide www.ajas.info
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