Study On Molecular Genetic Marker Of Coat Color Of Rongchang Pig

In order to provide the base of the genetic mechanism for the genesis of white coat color in Rongchang pig, KIT gene and TYR gene were selected as candidated genes and their polymorphisms and the relationship between the polymorphisms and the diversity of coat color were studied by PCR-SSCP in Rongchang pigs in the research. Some representative coat color breeds, such as Landerace, Large pig, Durco and Neijiang pig were also studied as controlling groups.1 Polymorphic detection and sequencing of KIT geneThe polymorphisms of KIT gene were detected by PCR-SSCP in Rongchang pigs(including white and other coat color), Druco, Landrance and Large pigs and KIT gene in a Rongchang pig with white coat color was sequenced. The results of polymorphisms of KIT gene showed that the genotypes of KIT gene were specific among the breeds. In the same breed, all detected dividuals have the same genotypes of KIT gene. Among breeds, Landerace and Large pig have an identical genotype of KIT gene and Rongchang pig and Druco have another identical genotype of KIT gene. The result of sequencing KIT gene in a Rongchang pig with white coat color showed that the mutatins of KIT gene of Landerace and Large pig( G→A and the deletion of AGTT) were not found in Rongchang Pig with the same coat color, which was against that white coat color was controlled by tranditinal dominated white aelle gene Therefore,the conclusion was attained that the phenotype of white coat color in Rongchang pig was not controlled by tranditinal dominated white allele. In addition, the genotypes of KIT gene were same entirely between other coat color Rongchang pig and Druco.They were both the genotype of ii. Therefore,the form of other coat color phenotypes in Rongchang pig was possiblely associated with the E gene locus. 2 Clone, sequencing and sequences analysis of TYR gene in Rongchang pigThree new DNA sequences of exon 2, 3, 4 of TYR gene in pig were cloned and sequenced. The similarity of DNA sequences and amino acid sequences respectively arrived at 83%, 88% at leeast among four species: pig, human, cattle and mouse. The result showed that the sequences of TYR gene were very conservative among the species: pig, human, cattle and mouse.Two Rongchang pigs with white coat color, a Rongchang pig with big black-head coat color and a Neijiang pig with uniform black were selected as experimental animals. The sequences of exon1 of TYR were sequenced and analysed. The result showed that the sequences of exon1 of TYR gene of the two Rongchang pigs with white coat color were same entirely. Comparing with the sequences of exon1 of TYR gene of the two Rongchang pigs with white coat color, two new mutations (319C→T and 551A→G) were observed in the Rongchang pig with big black-head coat color though the sequence of exon1 of TYR gene of a Neijiang pig with uniform black was same entirely. The two mutations observed belonged to synonymou mutations. Comparing with the sequences of exon1 of TYR gene from GenBank, a new insert mutation was observed in all sequences sequenced. The insert of C base exited between the 539th base the 540 th base. 3 Polymorphic detecting and sequencing of TYR geneIn this research, 24 Rongchang pigs (including all kinds of coat color) were selected as experimemtal animals and the polymorphisms of TYR gene were detected. The result revealed that exon 1 was polymorphic and other three exons were monmorphic. And the polymorphism of exon1 of TYR gene came from a single nuclotide substitution: G→A at the 46 th nucleotide upstream the start code.