保幼带是新生野猪的一种天然保护色，杜洛克新生仔猪偶尔也会出现，从而影响杜洛克种猪的销售。目前对保幼带形成的遗传机制及其自然消褪的分子机理还不清楚。项目组所在的团队利用F2群体，通过全基因组关联分析，把控制保幼带的基因位点定位在6号染色体2.05Mb（MC1R所在区域）和8号染色体44.93Mb（KIT所在区域）处。本项目拟在已有的F2、嵌合和巴里3个群体中进行Meta和染色体同源分析，对这两个基因位点进行精细定位。然后对5头有保幼带和5头无保幼带的公猪进行目标区域重测序，获取该区域内的多态位点，并在上述群体中检测与保幼带表型相吻合的多态位点，寻找最强关联的多态位点。根据最强关联位点所在单倍型框，锚定因果基因，并在真皮细胞系中构建相应的表达载体对其功能进行验证。最后通过转录组测序，比较因果基因在有保幼带和无保幼带个体之间的表达差异，并探究因果基因表达量随日龄的变化与保幼带自然消褪的分子机理。

Juvenile longitudinal stripe is a natural protective color of new-born wild boars, and it also occurs occassionally in Duroc new-born piglets result in decreasing the sale of Duroc breeding pigs. Until now, it is still unclear of the juvenile longitudinal stripe formation and its natural disappearance. The applicants have performed a genome-wide association analysis of the juvenile longitudinal stripe and mapped two genetic loci in an F2 resource population, one at 2.05 Mb (near MC1R) on chromosome 6 and the other at 44.93 Mb (close to KIT) on chromosome 8. The aims of this project is to fine mapping the genetic loci by meta-analysis and identical by descent (IBD) analysis in F2, Mosaic and Bali (Berkshire boars cross to Licha black pig sows) populations. Then five boars with and five boars without juvenile longitudinal stripe were sequenced to search the polymorphic loci in the target region, and polymorphic loci matching to the juvenile longitudinal stripe were genotyped in the three populations to find the strongest associated polymorphic locus. After the hypolotypes having been constructed, the causative gene could be anchored according to the IBD block of the top locus, and its functions will be verified by constructing a relevant expression vector in a dermal cell line. Finally, transcriptome sequencing by RNA-Seq is used to compare the expression of causal genes in pigs with juvenile longitudinal stripe to pigs without it, and the molecular mechanism of the natural disappearance of juvenile longitudinal stripe will be explored.