山东省地方绵羊品种的mtDNA D-loop序列多态性及系统进化研究

为了进一步了解山东省绵羊起源、群体遗传结构、群体遗传关系,利用线粒体DNA(mtDNA)分析了小尾寒羊、大尾寒羊、洼地绵羊3个地方绵羊品种(群体)的遗传多样性和起源进化。通过PCR和测序技术测定了3个绵羊群体82个个体的线粒体D-loop 1182 bp全序列,采用DnaSP 5.0进行多态性分析,并利用MEGA 5.05的邻接法(NJ)构建系统发育树。结果显示,3个绵羊群体mtDNA D-loop碱基组成:A、T、G、C平均含量分别为32.88%、29.33%1、8.28%、19.50%,A+T含量明显高于G+C含量;碱基突变以转换为主,说明绵羊线粒体碱基替换存在转换偏倚现象。mtDNA D-loop区的核苷酸多样度分别为0.03240、0.02455和0.03172;单倍型多样度分别为0.9710、.728和0.932,表明小尾寒羊和洼地绵羊mtDNA D-loop区具有较高的多态性,遗传资源相当丰富,大尾寒羊相对较低,需要加强资源保护。构建的NJ系统发育树表明3,个绵羊品种内、品种间存在基因交流,品种间存在共同的起源。

Study on Sequence Polymorphism and Phylogeny of mtDNA D - loop Regions in Three Sheep Breeds of Shandong Province

To explore the origin,genetic structure and relationship of sheep breeds in Shandong Province,the complete 1 182 bp mitochondrial D-loop regions of 82 sheep individuals from 3 domestic breeds including Small-tail Han,Large-tail Han and Wadi sheep were cloned and sequenced.The sequences were analyzed by DnaSP 5.0 and the NJ tree was constructed by MEGA 5.05 software.The results showed that the average compositon of A,T,G and C was 32.88%,29.33%,18.28% and 19.50% respectively.The content of A+T was obviously higher than that of G+C.Among base mutation,the majority was transition,which suggested that transition bias was present in sheep mitochondria.The nucleotide diversity of three sheep breeds were 0.03240,0.02455 and 0.03172 respectively,and their haplotype diversity were 0.971,0.728 and 0.932 respectively.The results indicated that there were higher polymorphism in mtDNA D-loop region of Small-tail Han sheep and Wadi sheep,but there was lower in the Large-tail Han sheep,so it needed to be protected.The NJ tree showed that the three breeds had the same origin,and there was gene infiltration within them.