白色基因座(I)在中国地方猪种毛色遗传中的作用研究

通过利用PCR—RFLP和PCR—SSCP技术对中国地方猪种KIT基因内含子17、18的序列进行多态性分析。结果表明：内含子17上的替换突变(G→A)发生于毛色为白色的个体——白色五指山猪、大白猪、长白猪上，其基因型(AB型)频率分别为1、1和0．8；其他中国地方猪种的此基因型频率均为0。内含子18上的缺失突变(AGTT)也同样发生在上述3个猪种的白色个体中，其基因型(AA型)频率分别为1、1和0．93；而且同样在其他的地方品种中其基因型频率均为0。这充分证明KIT基因对于猪的白毛色有重要的调控作用，而且I基因座对于其他的经典遗传基因座有上位作用。另一方面，中国地方猪种荣昌猪虽然在表型上与引入猪种大白猪、长白猪相似(白毛色)，但是在KIT基因上发生的突变完全不同，推测它们分别属于不同的毛色遗传体系。

Effect Study of White Locus (I) on Coat Color Inheritance in Chinese Native Pig Breeds

The classical White (I) locus is one of the important pig coat color hereditable loci,which is homologous to KIT gene.In this study,PCR-RFLP and PCR-SSCP analysis were commanded on the Intron 17 and 18 nucleotide sequences of KIT gene.The tested results showed that the substitution mutation (G→A) of Intron 17 was found in white pigs,including Wuzhishan pigs(white),Landrace and Large White,and its genotype (AB) frequency was 1,1 and 0.8 respectively.The genotype frequency was uniformly 0 in the other native pig breeds.Similarly,the deleted mutation (AGTT) of Intron 18 was also found in the same white pigs,its genotype (AA) frequency was 1,1 and 0.93 separately,while in the other native pig breeds was 0.Accordingly it was considered that KIT gene was an important factor regulating the white coat color genotype,and the classical I locus (KIT gene) was epistatic to the other genetic coat color loci.On the other hand,although the native pig breed Rongchang Pig is similar to Landrace and Large White in phenotype (white coat color),the mutation status found in them was absolutely distinct.So it is presumed that the coat color genetic system of Chinese native pig breeds was different from that of imported breeds.