Cloning, SNPs Of Porcine TMOD1, MKK3 And MKK6 Genes And Their Association With Production Traits

With the development of the molecular biology theory and technology in the past two decades,a number of molecular markers and candidate genes have been identified and then applied on breeding of animals and plants,which have greatly contributed to the improvement of animal and plant production.Marker assisted selection(MAS) can help researchers and farmers select animals on DNA level and improve the selection accuracy.In the last decade,the selection on swine production traits has made great achievements,owing to the utilization of conventional breeding and molecular breeding approaches.In this study,three important genes including TMOD1,MKK3 and MKK6,which were highly expressed in porcine skeletal muscle,have been investigated as the candidate genes associated with production traits in the pig.The findings of the study are as follows,1) The partial cDNA seqence of porcine TMOD1 gene was obtained.The intron 7 of MKK3 gene and of intron 4 and intron 9 of porcine MKK6 gene were obtained.2) Genetic variants discovery was implemented in the obtained sequences of above three genes.One SNP within exon 7 of TMOD1 gene was identified and this mutation site could be distinguished by MvaI,One SNP within intron 7 of MKK3 gene and two SNPs within intron 4 and intron 9 of MKK6 gene respectively were founded.3) The PCR-RFLP techniques were developed for genotyping of the identified SNPs.Large scale SNP genotyping were carried out in two different pig populations and then the association analyses between the genotypes and the traits were completed.According to the association analysis results from a experimental pig population including Toncheng(n=38),Landrace(n=25),Yorkshire(n=22), Landrace×Yorkshire×Toncheng(LYT)(n=34),Yorkshire×Landrace×Tnonche ng(YLT)(n=38),which was developed by our lab in collaboration with Tnoncheng county,Hubei province.SNP-A134G of porcine TMOD1 gene was significantly associated(p＜0.05) with loin pH.SNP-C439T of porcine MKK3 gene is significantly associated with length.SNP-C208T of MKK6 gene is significantly associated with marbling.(4) The association analysis results from the Iowa State University Berkshire×Yorkshire pig resource family showed,SNP-A134G of porcine TMOD1 gene was significantly associated with loin eye muscle area,average back fat, back fat at the lumbar,at 10th rib and at last rib,ham pH and lab loin pH. SNP-C439T of porcine MKK3 gene was significantly associated with loin eye area and firmness.SNP-A324G of porcine MKK6 gene was significantly associated with water holding capactiy and average glycolytic potential. SNP-C208T of MKK6 gene was significantly associated with average daily gain on test and birth weight.In conclusion,TMOD1,MKK3 and MKK6 gene are significantly associated with the production traits in pigs,which may be three important genes affecting production traits in pig.