Study On The Relationships Between Polymorphisms Of MyoD Gene And Weight Traits In Liangshan Semi-wool Sheep

The polymorphisms of MyoD gene were detected by PCR-SSCP method among 386 Liangshan semi-wool sheep from 9 populations developed by Liangshan prefecture.Based on the detection of polymorphisms,the effects of different genotypes on weight traits were analyzed,attemptting to provide sheep breeding molecular markers.The results are as follows:Designed five pairs of primers in 5' flanking region and exon 1 region,and identified two locuses,they were G126T and A657G.Analysised the hehedity polymorphism of MyoD gene,the results of the trial showed that:the nine families were all belong to midrange polymorphism,The distribution of MyoD genotype in L3,L4 strain strayed offthe Hardy-Weinberg equilibrium(0.01＜P＜0.05),but all the other populations were in Hardy-Weinberg equilibrium(P＞0.05).Through the least-squares analysis and significant test,discovered that the MyoD gene locus 1 each genotype on the slaughter of the weaning weight(WW),weaning daily gain(WDG),1.5-year weight(18MW) and 3.0-year weight(30MW) reached a significant level(P＜0.05),the allele gene A had the addictive effects to the weight traits.It had no significant influence to the birth weight(BW).MyoD gene locus 2 only influenced the 1.5-year weight(18MW) in significantly (P＜0.05),and it had no significant influence to the other weight traits.To the birth weight(BW) and 2.5-year weight(30MW),the allele gene C had the addictive effects to the weight traits,and mainly had the positive additive effect of increasing 0.29 and 1.03.Through the haplotype analyzed of MyoD gene by PHASE software,the highest frequence ofhaplotype H1 was 49.71%.The haplotype H1 and H3 had the advantage. The results by LSM(least square means)analysis and significant test showed that each genotype of the MyoD had significant difference with the weaning weight(WW), weaning daily gain(WDG),1.5-yeal weight(18MW) and 2.5-year weight(30MW)(P＜0.05).But it had no significant influence to the birth weight(BW).The weaning weight(WW),weaning daily gain(WDG),1.5-yeal weight(18MW) and 2.5-year weight(30MW) of H1H2 had markedly difference with H1H1,H1H3,H4H4(P＜0.05).These results showed that MyoD gene and the Weight traits in Liangshan Semi-wool Sheep were correlative.The results showed that the effect of family,year and genotype influence the weight traits on different degree.The effect of year and family influenced the birth weight(BW),weaning weight(WW),weaning daily gain(WDG),1.5-year weight (18MW) and 2.5-year weight(30MW) in very significantly(P＜0.01).The effect of genotype in primer 1 influenced the weaning weight(WW),weaning daily gain (WDG),1.5-year weight(18MW) and 2.5-year weight(30MW) in very significantly(P＜0.01).The effect of genotype in primer 2 only influenced the 1.5-year weight(18MW) in very significantly(P＜0.01).The effect of sex had no significant influence to the five weight traits(P＞0.05).