利用微卫星DNA多态性预测引进肉用绵羊品种杂种优势

Forecast of Heterosis of Imported Meat Sheep by Genetic Polymorphism of Microsatellite DNA

旨在利用微卫星DNA在不同绵羊群体中的多态性预测引进肉用绵羊品种与地方绵羊品种的杂种优势。利用23个微卫星基因座对4个国外引进肉羊品种及3个地方绵羊品种的群体多态信息含量、有效等位基因数、杂合度和遗传距离进行遗传检测,并测定引进肉羊与地方肉羊品种的杂交效果。结果,23个微卫星座位在7个绵羊群体中均呈现高度多态,共检测到348个等位基因,平均每个座位等位基因数为15个;多态信息含量在0.532 1~0.936 1,有效等位基因数在2.572 8~9.345 8,平均杂合度在0.549 2~0.936 0,品种平均杂合度在0.714 2~0.829 5,可以用于绵羊遗传多样性的评估。从不同品种看,无角陶赛特的遗传变异最大,而小尾寒羊的遗传变异相对较小;经遗传关系分析,在引进的4个肉羊品种中,与小尾寒羊、蒙古羊及滩羊杂交优势由大到小依次为白萨福克、波德代、无角陶赛特、特克赛尔,与实际杂种优势测定结果一致。利用微卫星DNA多态性预测引进肉用绵羊品种与小尾寒羊、蒙古羊及滩羊的杂种优势是可行的,这将对今后绵羊育种具有重要的应用价值和指导意义。

The polymorphisms of microsatellite DNA in different sheep breeds were detected to forecast the heterosis of local breed crossed with imported mutton sheep.Polymorphism information contents,number of effective alleles,heterozygosity and genetic distances were analyzed in four introduced mutton sheep and three local sheep breeds by 23 microsatellite loci,the crossing effects of three local sheep breeds and four imported mutton sheep breeds were tested respectively.The results indicated that there were abundant genetic polymorphisms at 23 microsatellite loci in seven sheep breeds,348 alleles were detected in total,the average allele number of one locus was 15,the polymorphism information content of different loci was from 0.532 1 to 0.936 1,the number of effective alleles was from 2.572 8 to 9.345 8,the average heterozygosity was from 0.549 2 to 0.936 0,and the average heterozygosity of breeds was from 0.714 2 to 0.829 5.23 microsatellite loci could be used for genetic diversity evaluation in sheep breeds.Among different breeds,the genetic variability of Poll Dorset was highest,while Small-tail Han sheep was lowest in seven sheep breeds.By the analysis of genetic correlationship,four imported mutton sheep mated with Small-tail Han sheep and Mongolian sheep and Tan sheep,respectively,the order of heterosis degree was White-Suffolk,Borderdale,Poll Dorset and Texel in turn,which accorded with testing results of actual heterosis.It is feasible to forecast the heterosis of Small-tail Han sheep,Mongolian sheep and Tan sheep respectively crossing with imported mutton sheep by genetic polymorphism of microsatellite DNA,and the results will have an important applied value and directive significance for sheep breeding in future.