Polymorphism Of Three Candidate Genes And Their Association With Reproductive Traits In Ningxiang Pigs

Reproductive traits of sows are very important to the production efficiency and economic benefits of the pig industry.In recent years,candidate genes and molecular markers of reproductive traits of sows have attracted much attention.In this study,170 Ningxiang pigs were selected as the research object.Three candidate genes related to pig reproductive traits were selected by the research group through microarraysequencing and Genome-wide Association Study(GWAS)screening.Transcription factor 23(TCF23),Placenta specific 8(PLAC8)and Heparanase(HPSE)genes,PCR-RFLP(Restriction Fragment Length Polymorphism)and DNA sequencing were used to detect Ningxiang pig TCF23 2 exon,PLAC8 exon 5 and HPSE exon 12,and determine the genotype of each body through the results of enzyme digestion and sequencing peak maps,and statistically analyze the survival rate of each genotype and newborn piglets Number of deaths,total number of litters and number of live litters.The research results are as follows:1.The PCR-SmaⅠ-RFLP results of the second exon of TCF23 gene of Ningxiang pigs showed three genotypes: GG genotype,AG genotype and AA genotype,their genotype frequencies were 0.824,0.13 and 0.045,etc.Allele frequency G(0.89)is greater than A(0.11).PIC=0.17,belonging to low polymorphism,He=0.195,the degree of genetic variation is low,Ne=1.243,indicating that the genotype at G387 A locus of TCF23 gene is unevenly distributed in the Ningxiang pig population,χ2 =17.78(P<0.05)Proved that the population deviated from Hardy-Weinberg law as a non-equilibrium population.At G387 A locus of Ningxiang pig TCF23 gene,the total litter size of the three genotypes was AA>AG>GG genotype,and the total number of AA genotypes The number of litters were significantly correlated with AG genotype and AA genotype(P<0.05),while the survival rate,number of live births and number of live births at this locus were not significant(P>0.05).2.The first exon and the 12 th exon of Ningxiang pig HPSE gene were detected by PCR-RFLP,and the results of enzyme digestion showed that no polymorphism was found.The 12 th exon of HPSE gene was selected for DNA sequencing and it was found that there are three genotypes at T264G: TT genotype,AG genotype and GG genotype.Their genotype frequencies are 0.514,0.346 and 0.14,respectively,alleles Gene T(0.687)>A(0.323),PIC=0.325,belongs to moderate polymorphism,He=0.423,the degree of genetic variation is at a medium level,Ne=1.735,indicating that the HPSE gene T264 G locus is distributed in the Ningxiang pig population Relatively uniform,2=4.03(p>0.05),in line with Hardy-Weinberg law(P>0.05),it is a balanced population.The results of association analysis show that this locus has no significant effect on the reproductive traits of Ningxiang pigs(P>0.05).3.The first exon,the second exon,the third exon and the fifth exon of Ningxiang pig PLAC8 gene were tested by PCR-RFLP.The enzyme digestion results showed that no polymorphism was found.The 5th exon of PLAC8 was selected for DNA sequencing,and it was found that there are three genotypes at site A257G: AA genotype,AG genotype and GG.Their genotype frequencies are 0.35,0.291 and 0.404,respectively,and the allele frequency G(0.55)>A(0.45),PIC=0.372,belonging to moderate polymorphism,He=0.495,the degree of genetic variation is at a moderate level,Ne=1.98,indicating that the PLAC8 gene A257 G locus is relatively evenly distributed in the Ningxiang pig population,2 =25.56(P<0.05),which deviated from Hardy-Weinberg’s law as an unbalanced group.In Ningxiang pig PLAC8 gene A257 G locus,the survival rate of the three genotypes is GG>AG>AA genotype.Among them,the survival rate of piglets of GG genotype and AG genotype is significantly higher than that of AA genotype(P <0.05);In terms of the number of deaths of newborn piglets,AA>AG>GG genotype,GG genotype was significantly lower than AA genotype(P<0.05),and the total litter size and the number of live litters at this locus were both Not significant(P>0.05)In summary,the PLAC8 gene A257 G locus has a significant impact on the survival rate of piglets and the number of newborn piglets in Ningxiang pigs,and the G387 A locus of TCF23 gene has a significant impact on the total litter size of Ningxiang pigs.As a genetic marker for high-producing sows.However,whether the gene at this locus can be used as a candidate gene related to the number of litters in Ningxiang pigs requires further verification of its function.There is no significant difference between the HPSE gene T264 G locus and the reproductive traits of Ningxiang pigs and cannot be used as a genetic marker for this trait.Whether HPSE gene affects the reproductive traits of Ningxiang pigs needs further research.