魁蚶3个群体及杂交子代遗传多样性分析

Genetic Diversity Analysis of 3 Populations and Their Hybrid Progenies in Blood Clam Scapharca broughtonii

为探明魁蚶不同群体间遗传多样性差异,以魁蚶中国群体、韩国群体和杂交子一代群体为研究对象,利用线粒体基因(16S rRNA和COⅠ)和核糖体内部转录间隔区(ITS-1)对5个魁蚶群体共150个样本进行遗传多样性分析。结果显示,魁蚶16S rRNA、COⅠ和ITS-1同源序列片段长度分别为605、766 bp和419 bp,其中16S rRNA和COⅠ基因片段A+T含量均高于G+C含量,ITS-1片段A+T含量均低于G+C含量。16S rRNA和COⅠ基因分别定义了4个和14个单倍型,主体单倍型所占频率分别为81.58%和61.43%,ITS-1定义了24种单倍型,主体单倍型所占频率为50.67%。单倍型邻接关系树结果显示,16S rRNA和COⅠ基因均为4个子一代群体聚为1支,即墨群体独有的单倍型为1支,而ITS-1的分支无明显群体特征。16S rRNA和COⅠ的遗传分化结果均表明,即墨群体与其他4个群体间遗传分化较大,其他4个群体间不存在分化;ITS-1的结果显示,5个群体间的遗传分化指数值均小于0.25,遗传分化不明显。试验结果表明,在进行魁蚶种内遗传进化研究时,线粒体基因的敏感性高于核糖体基因,即墨群体的遗传多样性明显高于4个子一代群体。

In order to explore the differences in genetic diversity between different populations of blood clam Scapharca broughtonii,genetic diversities were investigated in 150 samples from 5 blood clam populations including the wild blood clam populations in the Changdao and Jimo waters of Yantai,Shandong Province,the wild populations in the waters of Busan,Republic of Korea,and the hybrids of China ♀× Republic of Korea ♂,Republic of Korea♀×China♂,and inbred generations of China ♀× China ♂ and Republic of Korea ♀×Republic of Korea ♂ by mitochondrial genes(16S rRNA and COⅠ and ribosomal internal transcriptional spacer(ITS-1).Fragments with 605 bp of the partial 16S rRNA gene,766 bp of the partial COⅠ gene and 419 bp of the partial ITS-1 sequences were obtained after alignment and emendation.There were the maximal values of nucleotide differences and nucleotide diversity in the wild Jimo population based on 16S rRNA and COⅠ gene,and the maximal values of nucleotide differences and nucleotide diversity in ZH population based on ITS-1.Four and 14 haplotypes were defined among 16S rRNA and COⅠ from five populations respectively,and a total of 24 haplotypes were defined in ITS-1 from five populations.The neighbor-joining phylogenetic tree of haplotypes showed that the unique haplotypes of Jimo population were converged into a single branch based on 16S rRNA and COⅠ gene,without population characteristics based on ITS-1.The maximum genetic difference was found between Jimo population and other four populations on account of 16S rRNA and COⅠ gene,without genetic difference among five populations based on ITS-1.The findings indicated that the sensitivity of mtDNA was higher than that of rDNA genes in the study of intraspecific genetic evolution of S.broughtonii,and the genetic diversity of Jimo population was significantly higher than that of the 4 hybrids generation in China and Republic of Korea.