崂山奶山羊硬脂酰-CoA去饱和酶基因(SCD)多态性及其与泌乳性状的相关分析

摘要

The current study was aimed to analyze the association of exon 3 of stearoyl-CoAdesaturase gene (stearoyl-CoA desaturase,SCD) with milk traits in Laoshan dairy goat (Capra hircus).Direct sequencing was applied to identify SNPs in exon 3 and its flanking regions of SCD gene in Laoshan dairy goat population containing 174 samples,and least square method was performed to evaluate the association of polymorphism in SCD with milk traits.Four SNPs havebeen identified as followed,E315 E/e and E368H/h in exon3,I346 R/r and I355Q/q in in eron3 of SCD gene.The distribution of alleles and genotypes in this group were all under Hardy-Weinberg equilibrium.And the alleles and genotypes distribution of E315 were consistent with that of I355,so the two sites were linked sites.The difference between genotypes EE/QQ and ee/qq was statistically significant for all milk ingredients (P＜0.05 or P＜0.01).And the difference between genotypes EE/QQ and Ee/Qq was significant for protein rate,milk density (P＜0.05).Allele E/ Q had positive effects on all milk ingredients,in which the additive effects were highly significant (P＜0.01) and the dominant effects were not significant (P＞0.05).The difference between genotype hh with genotypes HH and Hh was statistically significant for all milk ingredients (P＜ 0.05 or P＜0.01).Meanwhile the allele h had positive effects on all milk ingredients.The additive effects and the dominant effects of allele on all milk ingredients were both highly significant (P＜0.01).The milk yield of genotype rr was significantly higher than that of RR (P＜0.01).Allele r had positive effect on milk yield,while it had no significant effect on milk ingredients (P ＞0.05).Then we analyzed the association of polymorphisms in SCD gene with milk traits in Group F and Group P respectively.The difference among genotypes were very low on milk traits in Group F,while that was higher in Group P.Four SNPs have been identified in exon 3 and its flanking regions of SCD gene,E315 E/e,E368H/h I355Q/q and I346 R/r,in which I346 R/r had not yet been found in other domestic dairy goats.Alleles E/h/Q had positive effects on all milk ingredients and allele r had positive effect on milk yield.The effects of SCD gene on milk traits of Laoshan dairy goats mainly be owing to the influence of Group P.%利用直接测序法检测了174只崂山奶山羊泌乳母羊的硬脂酰-CoA去饱和酶基因(stearoyl-CoA desaturase,SCD)外显子3及侧翼序列多态性.采用最小二乘方法分析其在崂山奶山羊(Capra hircus)群体中的多态性及其与泌乳性状之间的关联效应.结果如下:在SCD基因外显子3及侧翼区检测到4个SNPs,即E315 E/e、E368 H/h,内含子3的I346 R/r和I355 Q/q,其等位基因和基因型频率在样本群中均处于Hardy-Weinberg平衡状态(P ＞0.05).其中E315 E/e和I355 Q/q的分布情况一致,呈紧密连锁关系.SCD基因E315和I355位点的EE/QQ 基因型与基因型ee/qq的所有乳成分性状差异显著(P＜0.05)或极显著(P＜0.01),EE/QQ与Ee/Qq基因型的乳蛋白率、乳密度差异显著(P＜0.05),等位基因E/Q为乳成分性状的有利等位基因；各乳成分性状的基因加性效应极显著(P＜0.01),显性效应不显著(P＞0.05).E368位点hh基因型与HH和Hh基因型的所有乳成分性状差异显著(P＜0.05)或极显著(P＜0.01),等位基因h为乳成分性状的有利等位基因；所有乳成分的基因加性效应和显性效应极显著(P＜0.01).I346位点rr基因型的300 d产奶量极显著(P＜0.01)高于RR基因型,等位基因r为300 d产奶量的有利等位基因,但其对乳成分性状的影响不显著(P＞0.05).在不同试验群体中分析SCD基因多态性与泌乳性状的关系,发现F群体中,各突变位点的不同基因型在泌乳性状上的差异显著性较低；而P群体中不同基因型间所有乳成分性状的差异显著较高.本研究表明:SCD基因外显子3及侧翼区检测到4个SNPs,即E315 E/e、E368 H/h、I355 Q/q和I346 R/r,其中I346 R/r在国内其它奶山羊中尚未发现.等位基因E、h和Q分别为乳成分性状的有利基因,等位基因r为300 d产奶量的有利基因,SCD基因在崂山奶山羊样本群中对泌乳性状的效应主要来源于对P育种群的影响.