| Qira black sheep is one of the Excellent local lambskin sheep breeds in China,Which also has the characteristic of high fecundity.However,the molecular mechanism of lambing and growth traits of this variety is still unclear,which influences the molecular selection process of this variety.Therefore,The discovery of key candidate genes for the lambing and growth traits of Ceres black sheep will help speed up the molecular breeding process of this breed and improve the economic benefits of local farmers.In view of the multi-lamb traits of Qira black sheep,Two multi-lamb major genes(BMP15 and GDF9)existing in Chinese sheep breeds were selected for SNP sequencing,correlation analysis between candidate genes and the number of lambing trait were conducted subsequently.In this study,81 Qira black sheep with lambing records were divided into single-lamb group(L)and multi-lamb group(H)according to the number of lambings.Blood was collected from the jugular vein,DNA was extracted,and complete Long sequencing were conducted for BMP15 and GDF9 genes.The results showed that there were a total of 16 SNPs loci in the two significant candidate genes.The GDF9 gene had 7 SNPs,which were g.41769976A>G,g.41769833G>A,g.41769723C>T,g.41769898A>G,g.41769246A>G,g.41769008C>T and g.41769002A>G.Among them,Compared with AA type located in g.41769976A>G,The average number of litter size of GG type is 0.31 more,g.41769833G>A locus AA type is 0.22 more than GG type,g.41769723C>T locus Type TT is 0.19 more than type CC,and these three SNPs are significantly correlated with litter size(P<0.05),while the other 4 mutation sites had no significant correlation with litter size(P>0.05).There are 9 mutation sites in the BMP15 gene: g.50986052C>A,g.50985229A>G,g.50985162T>C,g.50985071C>T,g.50983056C>G,g.50982538T>C,g.50981129A>G,G.50980656T>C and g.50981170T>C.But these 9 SNPs loci showed no significant correlation with litter size(P>0.05).Aiming at the growth traits of Qira black sheep,the Affymetrix 630 K SNP chip was used to detect the typing of 188 Qira black sheeps with body size and appearance records in this study.The analysis of GWAS results based on literature reports showed that RXFP2 gene could be used as a horn-type candidate gene of Qira black sheep.A total of 13 candidate genes related to body type were screened,Which included: FAM19A2 and DISP1(weight candidate genes),KIF1 C gene(body height candidate gene),PDGFD,S1PR3 and RUNX1T1 genes(chest depth candidate genes),S1PR1,TBC1D4 and CXCL12 genes(breast width candidate genes),MFAP1 gene(chest circumference candidate genes),DIAPH3 gene(body oblique length candidate genes),ZSCAN4 and ADGRB3 genes(tail length candidate genes).Subsequently,the runs of consecutive homozygous fragments(ROHs)in the data were analyzed and 9261 ROHs were found,where there were totally 3927 ROH overlapping pools.A total of 28 ROH high-frequency regions were identified in this study,of which 10 regions on chromosome 1,17 regions on chromosome 3 and 1 region on chromosome 6.Combined with literature reports,SOX2,KLHL24,TNS2 and FGD6 genes could be used as significant candidate genes of growth traits for further study. |
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