Analysis of polymorphisms in exon 14 in porcine Mx1 gene and identification of new mutation points

By the PCR-RFLP method, the polymorphisms of exon 14 of Mx1 gene were detected in 7 native and foreign pig breeds. Taken together with the analysis of restriction enzyme Hin6 I digestion, there were 6 genotypes and 3 alleles. And, all individuals of Duroc exhibited the AA genotype but the Sutai pigs exhibited all three kinds of genotypes. The BB genotype was detected only in Meishan pigs and their derivate Sutai pigs. Among all pig breeds, the allele B only appeared in Chinese indigenous pig breeds and developed pig breed in this study, and the allele A was dominant allele in all pig breeds except for Songliao black pig. The results of Chi Square test showed that there were abundant polymorphisms in all pig breeds. The gene frequency of Meishan pig and Songliao black pig showed greatly significant difference to other pig breeds (P<0.01), Sutai pig showed greatly significant difference (P<0.01) to other pig breeds except for Pietrain; and Huai pig showed greatly significant differences (P<0.01) with Pietrain and other indigenous Chinese pig breeds, but no difference with Duroc and Yorkshire (P>0.05). Three new mutation points in three genotypes were identified by sequencing comparison analysis of PCR products, two of which resulted in Thr-->Ala and Glu-->Arg respectively, the last one was a silence mutation, the Glu-->Arg mutation point and this silence mutation point only appeared in the individuals with the BB genotype.