利用微卫星DNA标记分析槟榔江水牛群体遗传特征

Unfolding of Genetic Characterization of Binglangjiang Buffalo by Microsatellite DNA Markers

槟榔江水牛是近年在我国云南西部发现的第一个本土河流型水牛。为了揭示其群体遗传多样性、群体遗传组成、其与河流型和沼泽型水牛的遗传关系及沼泽型水牛对该水牛的基因渗入等重要遗传背景信息,本研究采用30个微卫星DNA标记对141份槟榔江水牛样品和对照群体24份河流型水牛(摩拉水牛)样品、41份沼泽型水牛(滇东南水牛)样品进行了检测分析。结果,在槟榔江水牛群体中共检测到253个等位基因,其中,54个为3个群体所共享的等位基因,58个为只在槟榔江水牛与摩拉水牛间共享的等位基因,73个为只在槟榔江水牛与滇东南水牛间共享的等位基因,其余68个等位基因为该群体所独有。槟榔江水牛平均等位基因数、平均表观杂合度、平均期望杂合度和多态信息含量等参数均显著高于对照组群体,分别为8.433 3、0.640 5、0.600 9和0.594 7。该水牛群体近交系数FIS值为0.061 9。槟榔江水牛与摩拉水牛间的DA遗传距离为最小(0.114 4),在NJ树上聚为一支;而滇东南水牛与槟榔江水牛和摩拉水牛间的遗传距离较大(分别为0.382 9和0.555 3),其在NJ树上单独聚为一支。群体遗传结构分析显示,槟榔江水牛遗传组分为河流型与沼泽型2种类型水牛混合的模式(当K=2时),整个群体中有相当数量的个体存在沼泽型水牛的遗传渗入(群体中沼泽型水牛遗传组分为0.067 2)。结果揭示,槟榔江水牛遗传资源独特,群体遗传多样性丰富,但该群体杂合子缺乏,且存在一定沼泽型水牛的基因渗入。

Binglangjiang buffalo is the first indigenous river type buffalo which has been found in western Yunnan province of China in recent years.In order to elucidate genetic background information on its genetic diversity,genetic composition,genetic relationship with typical river and swamp buffalo,and the gene introgression from swamp buffalo,141 random samples from Binglangjiang buffalo population and 24 samples from control river buffalo population（Murrah） and 41 samples from control swamp buffalo population（Diandongnan buffalo） were genotyped by employing 30 microsatellite DNA markers.The result showed that a total of 253 alleles were identified in Binglangjiang buffalo（including 54 alleles shared among the three populations assayed,58 alleles only shared between Binglangjiang and Murrah buffalo,73 alleles only shared between Binglangjiang and Diandongnan buffalo,and 68 alleles unique to Binglangjiang buffalo）.The genetic diversity parameters in Binglangjiang buffalo were much higher than that in the control groups,its mean number of alleles per locus,mean observed heterozygosity,mean expected heterozygosity and polymorphism information content（PIC） were 8.433 3,0.640 5,0.600 9 and 0.594 7,respectively.Inbreeding coefficient（FIS） in Binglangjiang buffalo was 0.061 9.Genetic distance（DA） between Binglangjiang and Murrah buffalo was the lowest（0.114 4）,while genetic distance（DA） between Diandongnan and Binglangjian buffalo（0.382 9） or between Diandongnan and Murrah buffalo（0.555 3） was much larger than that between the two formers,which make Binglangjiang buffalo and Murrah buffalo,grouped together and Diandongnan independently clustered in the NJ tree.Structure analysis revealed that Binglangjiang buffalo displayed a genetic mixed pattern by river buffalo and swamp buffalo,most of the individuals having some proportion of swamp buffalo component（membership coefficients =0.067 2）.The results indicate that Binglangjiang buffalo is of high degree of genetic diversity and is unique genetic resource,but this buffalo is under the conditions of heterozygote deficit and genetic mixture with swamp buffalo.