Abstract
BackgroundOur initial genome-wide association study (GWAS) identified 20 promising candidate genes for milk fatty acid (FA) traits in a Chinese Holstein population, including PRLR, MOGAT1, MINPP1 and CHUK genes. In this study, we performed whether they had significant genetic effects on milk FA traits in Chinese Holstein.ResultsWe re-sequenced the entire exons and 3000 bp of the 5′ and 3′ flanking regions, and identified 11 single nucleotide polymorphisms (SNPs), containing four in PRLR, two in MOGAT1, two in MINPP1, and three in CHUK. The SNP-based association analyses showed that all the 11 SNPs were significantly associated with at least one milk FA trait (P = 0.0456 ~ < 0.0001), and none of them had association with C11:0, C13:0, C15:0 and C16:0 (P > 0.05). By the linkage disequilibrium (LD) analyses, we found two, one, one, and one haplotype blocks in PRLR, MOGAT1, MINPP1, and CHUK, respectively, and each haplotype block was significantly associated with at least one milk FA trait (P = 0.0456 ~ < 0.0001). Further, g.38949011G > A in PRLR, and g.111599360A > G and g.111601747 T > A in MOGAT1 were predicted to alter the transcription factor binding sites (TFBSs). A missense mutation, g.39115344G > A, could change the PRLR protein structure. The g.20966385C > G of CHUK varied the binding sequences for microRNAs. Therefore, we deduced the five SNPs as the potential functional mutations.ConclusionIn summary, we first detected the genetic effects of PRLR, MOGAT1, MINPP1 and CHUK genes on milk FA traits, and researched the potential functional mutations. These data provided the basis for further investigation on function validation of the four genes in Chinese Holstein.
Highlights
Our initial genome-wide association study (GWAS) identified 20 promising candidate genes for milk fatty acid (FA) traits in a Chinese Holstein population, including Prolactin receptor (PRLR), Monoacylglycerol O-acyltransferase 1 (MOGAT1), Multiple inositol-polyphosphate phosphatase 1 (MINPP1) and Conserved helix-loop-helix ubiquitous kinase (CHUK) genes
By haplotype-based association analyses (Additional file 5: Table S5), we found that the block 1 in PRLR was significantly associated with C6:0 (P = 0.0389); block 2 in PRLR was significantly associated with C6:0, C14:0, C17:1, C17index, Saturated fatty acids (SFA) and Unsaturated fatty acids (UFA) (P = 0.0392 ~ 0.0001); block 3 in MOGAT1 had significant associations with C8:0, C16:1, C18: 0 and C17index (P = 0.0364 ~ < 0.0001); block 4 in MINPP1 had strong associations with C6:0, C8:0, C10:0, C18:1cis-9, C20:0, C17index, and UFA (P = 0.0306 ~ < 0.0001); and block 5 in CHUK was strongly associated with C6:0, C8:0, C10:0, C14:0, C16:1, C17:0, C18:0, C18:1cis-9, C18index, C20:0, C14index, C16index, C17index, SFA, UFA, and SFA/UFA (P = 0.0256 ~ < 0.0001)
The PRLR, MOGAT1, MINPP1 and CHUK genes were considered as the promising candidates for milk FA traits in our previous GWAS [12], and their polymorphisms and genetic effects were determinated in this study
Summary
Our initial genome-wide association study (GWAS) identified 20 promising candidate genes for milk fatty acid (FA) traits in a Chinese Holstein population, including PRLR, MOGAT1, MINPP1 and CHUK genes. We performed whether they had significant genetic effects on milk FA traits in Chinese Holstein. Fatty acids (FAs) are the important components of milk fat, and the milk fat contains 70% of saturated fatty acids (SFAs) and 30% unsaturated fatty acids (UFAs) [1]. The ideal nutritional milk fat contain 10% polyunsaturated fatty acids, 82% monounsaturated fatty acids and 8% SFAs, that can not be accomplished by modifying diets of lactating cows [2]. There is a growing number of genome-wide association studies (GWASs) on milk FA traits, and many candidate genes were identified [8,9,10,11,12].
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