Study On Genes Related Four-nipple Trait Of Hu Sheep Based On Whole Gene Resequencing

Some sheep have four or more nipples,but few studies had been reported on genetic mechanisms of this trait.In order to explore the genetic differences between the sheep with four nipples and sheep with two nipples,whole genome re-sequencing was used to screen the candidate genes related to the four-nipple trait of Hu sheep in this study.1、Blood samples of sheep with four-nipple（test group）and sheep with two-nipple（control group）were collected.The blood genome DNA were extracted for sequencing,the date was compared with the sheep reference genome（Ovis aries Oar₃.1）,and the results were showed as following:（1）The GATK algorithm was used to find the mutant locus in sequence date of the Hu sheep genome.There were 42,001 SNP / InDel sites shared in the test group and 50,010 SNP / InDel sites shared in the control group in CDS region of genes.（2）39 SNP / InDel sites special were found for test group by Venn Analysis of mutations of two groups,which suggestted that these mutations were potentially related with the four-nipple trait.（3）The 39 SNP / InDel sites special to the test group were annotated with 21 genes,and these genes were involved material metabolism,immune response,cell growth,body development and signal pathway and other functions by GO enrichment analysis and KEGG pathway analysis.2、33 SNP sites in the test group were tested by Sanger method and SNaPshot technique,the main results were showed as following:（1）18 of 33 mutations with no base change comparing with the reference genome,and the 15 sites had base change.There was a high mutation rate in sheep13-32879407 of ZEB1 gene and the sheep15-61871375 of DEPDC7 gene comparing with control group.The mutation rate of the sheep13-32879407G>C in the test group was 91%,while 30% in the control group;the mutation rate of the sheep15-61871375G> C site in the group test was 72%,while 29% in the control group.（2）Correlation analysis of the sheep13-32879407G> C site of the ZEB1 gene with the four-nipple grade of Hu sheep showed that the genotype CC and GC had higher four-nipple grade（P <0.01）than genotype GG individuals in total population.Genotype CC and GC had higher four-nipple grade（P <0.05）than genotype GG individual in the four-nipple sheep population,which indicated that the supernumerary nipples of individual of genotype CC and GC developed better.Correlation analysis of the sheep15-61871375A> C site of the DEPDC7 gene with the four-nipple grade of Hu sheep,the genotype CC and AC had higher four-nipple grade（P <0.01）than genotype GG individuals in total population,indicating that the genotype CC and AC had more developed supernumerary nipples.In summary,ZEB1 and DEPDC7 were candidate genes for four-nipple traits of Hu sheep.