庆阳驴mtDNA D-loop区遗传多样性及起源分析

Genetic Diversity and Origin Evolution Analysis of Qingyang Donkey Based on mtDNA D-loop Region Sequence

[目的]研究庆阳驴养殖群体的遗传多样性与母系起源,了解其遗传信息,为保护庆阳驴种质资源、选育和遗传改良工作提供理论依据。[方法]随机选取133头庆阳驴,对其线粒体DNA(mitochondrial DNA,mtDNA)D-loop区序列进行PCR扩增、测序及比对,并探讨庆阳驴的遗传多样性与母系起源。[结果]在获得的520 bp D-loop碱基序列中,AT含量(57.3%)高于GC含量(42.8%),表现出碱基的偏倚性;检测到38个变异位点,包含8个碱基对的转换;其核苷酸多样性(Pi)、单倍型多样性(Hd)、平均核苷酸差异(K)分别为0.01591、0.895和8.274,与欧洲家驴和中国家驴研究的平均值相比较低,说明该驴品种核苷酸变异较为贫乏。庆阳驴mtDNA D-loop区存在35个单倍型,单倍型之间的遗传距离为0.002~0.042。系统进化结果显示,庆阳驴存在2个线粒体支系,表明其具有2个母系起源,且遗传距离表明,庆阳驴与克罗地亚家驴之间的遗传距离较近。[结论]本研究从分子水平初步揭示庆阳驴核苷酸变异比较贫乏,杂交程度高,mtDNA遗传多态性正逐步丧失,应加强庆阳驴品种的遗传资源保护工作。

[Objective]This study was aimed to explore the genetic diversity and maternal origin of Qingyang donkey breeding population,understand its genetic information,and provide theoretical basis for protecting germplasm resources,breeding,and genetic improvement in Qingyang donkey.[Method]133 Qingyang donkeys were randomly selected,the mitochondrial DNA(mtDNA)D-loop region sequences were analyzed by PCR amplification,sequencing and alignment,and the genetic diversity and maternal origin of Qingyang donkey were explored.[Result]520 bp D-loop base sequence were obtained,the AT content(57.3%)was higher than GC content(42.8%),indicating there was bias in base composition.There were 38 SNPs of D-loop region,including 8 conversions.The nucleotide diversity(Pi),haplotype diversity(Hd)and average nucleotide difference(K)were 0.01591,0.895 and 8.274,respectively,which was lower than the average of European and Chinese domestic donkey studies,indicating that the nucleotide variation of Qingyang donkey breed was relatively poor.The genetic distances of 35 haplotypes of D-loop region in Qingyang donkey ranged from 0.002 to 0.042.Phylogenetic results showed that there were two mitochondrial lineages,indicating that there were two mitochondrial maternal origins,and the genetic distance between Qingyang donkey and Croatian domestic donkey was relatively close.[Conclusion]The experiment preliminarily revealed the nucleotide variation of Qingyang donkey was poor from the molecular level,the degree of hybridization was high,and the mtDNA genetic polymorphism was gradually lost,so the protection of genetic resources of Qingyang donkey breed should be strengthened.