| The bioinformatics, DNA sequencing, DNA sequence analysis, PCR-SSCP techniques were applied to analyze the genetic variations of key function gene and their association with economic traits in 260 goat, which comprised of two breed, namely XinongSannen dairy goat and Boer goat. The four key function gene included PRLR gene (intron1,2,exon 10), PRL gene (5'UTR), GHR(exon9,10), LHβgene(5'UTR,exon2,exon3) .The economic traits comprised of milk yield and little size . The association between genetic variations economic traits were analyzed by using general linear model (GLM) or adjusted linear model, as well as population genetic structure and distribution of genotype and allele were calculated by chi-square and quantitative genetic method. These will benefit for the protection, development and application of goat genetic resource ,application of DNA marker related to economic traits on marker-assist-selection(MSA), and improvement and promotion of goat. The important results were in the following:1 Association of genetic variation of PRLR gene with economic traits in goat1.1 Association of genetic variation of intron1and 2 with economic traits in goatTwo pairs of primer were designed to amplify intron1 and 2, of PRLR gene , The results showed that the products amplified by primer P1 didn't display polymorphisms; the polymorphism of P2 locus was resulted by 3 mutation. In this locus ,the genotyp GG,GH,HH were detected in analyzed populations and the predominant GG genotype in two breed. It was not significantly found that the distribution of genotypes and alleles associated with milk yield and litter size of Xinong Sannen dairy goat. But the correlations were observed between this and litter size of Boer goat: the fifth litter size of individuals with genotype GH were significant higher than that of genotype GG(P<0.01), the third litter size of individuals with genotype GH were significant higher than that of genotype GG(P<0.05). 1.2 Association of genetic variation of exon10 with economic traits in goatFour pairs of primers were designed to detect single nucleotide polymorphisms of exon 10 of PRLR gene by PCR-SSCP. The results showed that only the products amplified by primer P3 didn't display polymorphisms. For primer P4, two genotypes (AA and AB) were detected in two breed. Sequencing revealed two mutations of PRLR gene in the genotype AA in comparison to the genotype AB, The mutation of27C→T did not cause any amino acid change, The deletion of 189th result in two amino acid changes of His→Tyr and Thr. The difference of the least squares means (LSM) for milk yield between AA and AB was significant (P<0.05) in Saanen dairy goat, the third lactation milk yield of individuals with genotype AA was higher than that of genotype AB(P<0.05).For primer P5, three genotypes(CC,CD,DD) was detected in Saanen dairy goat and Boer goat. Sequencing revealed two mutations(103C→A and 106T→C) of PRLR gene in the genotype CC in comparison to the genotype DD. The former mutation resulted in an amino acid change of Lys→Thr, and the later mutation resulted in an anino acid change Thr→Ile. The difference of LSM for milk yield among CC,CD and DD was non-significant(P>0.05). the correlations were observed between this and litter size of Boer goat and Xinong Sannen : the third litter size of individuals with genotype CC were significant higher than that of genotype DD(P<0.05).For primer P6, two genotypes(EE and EF) were detected in Saanen dairy goat. Sequencing revealed one mutation(114A→G) of PRLR gene in the EE in comparison to the genotype EF ,and this mutation resulted in an amino acid change of Met→Val. he difference of the LSM for milk yield between EE and EF was significant (P<0.05) in Saanen dairy goat, The milk yield of individuals with genotype EE was higher than that with genotype EF in third, fourth lactation milk yield and average milk yield (P<0.05).Based on these results ,it was indicated that PRLR gene had significant positive effects on milk performance of dairy goats.2 Association of genetic variation of GHR gene with economic traits in goatThe 241G→T produced the polymorphism of exon9 of goat GHR gene. In analyzed populations ,two genotypes was observed and PIC values was low(PIC<0.25). It was significantly found that the distribution of genotypes and alleles associated with milk yield and litter size of Xinong Sannen dairy goat: the milk yield of individuals with genotype NN was higher than that with genotype NT in third, fourth lactation milk yield and average milk yield (P<0.05).The correlations were observed between this and litter size of Boer goat : the third litter size of individuals with genotype NN were significant higher than that of genotype NT(P<0.05).3 Association of genetic variation of LHβgene with economic traits in goatApplying the PCR-SSCP technique and sequence to analyze the polymorphism of LHβgene, the results show that P1-153C→A and P564T→C were found in the populations ,respectively. The associations of the mutation with litter size were observed: for primer P1, genotype PP were significant higher than that of genotype PQ(P<0.01)in Boer goat and . genotype PP were significant higher than that of genotype PQ(P<0.01)in the third and the fourth litter size of individuals of Boer goat and in the fifth and the fourth litter size of individuals of Xinong Sannen dairy goat. For primer P5, the correlations were observed between the polymorphism and litter size of two breed: the fifth litter size of individuals with genotype LL were significant higher than that of genotype LM(P<0.01), the fourth litter size of individuals with genotype LL were significant higher than that of genotype GG(P<0.05). |
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