Genetic Diversity And Tissue Expression Analysis Of MSTN,MC4R And POMC Genes In Domestic Donkey

The domestic donkey is an economic animal with both skin and meat.Due to its slow growth and development,people are not very motivated to raise it.In recent years,the number of livestock has dropped sharply.In order to explore the molecular genetic markers related to the growth and development of domestic donkeys,this study carried out research from two aspects.First,14 domestic donkey breeds in China were selected as the research objects,and MSTN,MC4 R and POMC genes related to growth and development were selected as candidate genes,and the population genetic diversity was analyzed by PCR-SSCP technology.The second is to take Yangyuan donkey as the research object to analyze the differences in body size indicators(body height,body length and chest circumference)among individuals with different haplotypes of MSTN,MC4 R and POMC genes,and use q RT-PCR technology to detect the difference in the Yangyuan donkey.Expression levels in tissues(longissimus Dorsi,heart,liver,spleen,lung and kidney).The result is as follows:1.Two incompletely linked SNP loci,g.-386T→C and g.708 T→C in the first intron region of MSTN gene,were screened out from 14 breeds of domestic donkey populations in China,and 4 species were constructed.Haplotypes(T1-T4).Two completely linked SNP sites,g.1407G→A and g.1468G→A,were constructed in the first exon of MC4 R gene,and two haplotypes(R1-R2)were constructed.Two completely linked SNP sites were found in POMC gene,g.148C→T in the first intron region and g.368 G → T in the CDS region,and two haplotypes(C1-C2)were constructed.The gene frequency and genotype frequency distribution of MSTN,MC4 R and POMC gene SNP loci had no obvious regularity among species,but they all belonged to moderate polymorphism and Hardy-Weinberg disequilibrium.The results of haplotype Tajima’s D showed that MSTN,MC4 R and POMC genes were overall balanced selection.Genetic variation analysis found that MSTN,MC4 R and POMC gene mutations were mainly derived from individuals,and were less affected by type and breed.2.Yangyuan donkey MSTN,MC4 R and POMC genes had significant differences in body size among different haplotypes.The body height of MSTN gene haplotypes T1 and T2 was significantly higher than that of T4(P<0.05),the body length of T2 was significantly higher than that of T4(P<0.05),and the chest circumference of T1,T2 and T3 were significantly higher than those of T4 haplotype(P<0.05).The body length and chest circumference of MC4 R gene haplotype R1 were significantly higher than those of R2(P<0.05).The body height of POMC gene haplotype C2 was significantly higher than that of C1(P<0.05).3.MSTN,MC4 R and POMC genes were expressed in different tissues of Yangyuan donkey.The expression level of MSTN gene was highest in the longissimus Dorsi muscle,and the expression levels in other tissues were as follows:lung>spleen>kidney>liver>heart.The expression levels of MC4 R and POMC genes were the highest in the spleen,and the expression levels in other tissues were as follows:spleen>lung>kidney>liver>heart>longissimus Dorsi.Therefore,it is speculated that the donkey MSTN gene mainly acts on the skeletal muscle,and the MC4R and POMC genes mainly act on the spleen.