Abstract: A structural variation measuring 89 bp，designated as DKK2‐I1‐sv89，was identified in intron 1 of the DKK2 gene of pigs through preliminary genomic analysis.To investigate the polymorphism distribution of this structural variation（SV）and its potential impact on gene expression，specific primers targeting the SV sequence were designed for this study.The population distribution of DKK2‐I1‐sv89 was subsequently evaluated using polymerase chain reaction（PCR）across four Guizhou indigenous pig breeds（Xiang pig，Qianbeihei pig，Kele pig，and Jiangkouluobo pig）and one European pig breed（Large White pig）.The gene expression difference of DKK2 among the various genotypes was determined by using real time quantitative PCR（RT‐qPCR）.Additionally，bioinformatics analyses were employed to assess the functional elements within the structural variation region of DKK2‐I1‐sv89. The findings demonstrated that in the Xiang pig and Qianbeihei pig，three genotypes（insertional genotype II，heterozygous genotype DI，and wild‐type genotype DD）were found，while only one genotype（DD）was found in Large White pig，however in Kele pig and Jiangkouluobo pig，two genotypes（DI and DD）were found.Comparative analysis across the five breeds demonstrated that the four Guizhou local pig breeds（including Xiang pig，Qianbeihei pig，Kele pig，and Jiangkouluobo pig） had a higher frequency of the insertional allele（I allele） compared to the Large White pig. Bioinformatics analysis revealed that the DKK2‐I1‐sv89 contained one intronic splicing enhancer（ISE） and 13 RNA binding protein（RBP） binding sites.Quantitative trait locus（QTL）analysis demonstrated that the QTL at this SV locus was associated with reproduction，meat quality，and health‐related traits. Further analysis of DKK2 gene expression in ovarian tissues of Xiang pigs with different genotypes（II，DI，and DD）revealed that II genotype pigs exhibited significantly higher expression levels compared to both the DI and DD genotypes.The results indicated a notable difference in the distribution frequency of this polymorphism between Large White pig and Guizhou local pigs.Additionally，the SV was found to be beneficial for the expression of DKK2 gene in the ovary and could serve as an early molecular marker for distinguishing between Large White pig and Guizhou local pigs.

Key words: Pig, DKK2 gene, Structural variation, Polymorphism, Gene expression

摘要： 前期基因组学分析结果表明，猪Dickkopf-2（DKK2）基因内含子1中存在一个结构变异（89 bp，DKK2-I1-sv89），为探究该结构变异（SV）在不同猪品种中多态性分布以及对基因表达的影响，针对该SV序列设计特异性引物，通过PCR验证DKK2-I1-sv89在贵州地方猪种（香猪、黔北黑猪、柯乐猪、江口萝卜猪）和欧洲猪种（大白猪）共5个猪品种中的群体分布；采用实时荧光定量PCR（RT-qPCR）检测不同基因型之间香猪卵巢组织中DKK2 基因的表达差异；采用生物信息学分析DKK2-I1-sv89结构变异区存在的功能元件。结果表明，香猪和黔北黑猪检测到3种基因型（插入型II、杂合型DI与野生型DD），大白猪仅检测到1种基因型（DD），柯乐猪、黔北黑猪检测到2种基因型（DI和DD）。5个猪种比较，4个贵州地方猪种的插入型等位基因（I等位基因）频率均高于大白猪。生物信息学分析结果显示，DKK2-I1-sv89结构变异区含有1个内含子剪接增强子（ISE）和13个RNA结合蛋白（RBP）结合位点，定量性状位点（QTL）分析显示，该SV位点的QTL与繁殖、肉质和健康性状相关。进一步检测了II型、DI型和DD型香猪卵巢组织中DKK2 基因表达量，结果显示，II型基因型极显著高于DI型和DD型，DI型和DD型无统计学差异。综上，DKK2-I1-sv89的多态性分布频率在贵州地方猪品种和欧洲猪种中有差异，且该SV的插入有利于DKK2基因在卵巢中的表达，可作为区分欧洲猪种和贵州地方猪种的分子标记。

关键词: 猪, DKK2基因, 结构变异, 多态性, 基因表达