漠斑牙鲆微卫星标记筛选及美国群体遗传结构分析

摘要

A repeat-enriched genomic library was constructed from southern flounder Paralich-thys lethostigma in order to evaluate the level of genetic diversity and population structure. In the first batch, 45 positive clones were successfully sequenced and 43 sequences were found to contain repeat motifs. According to Weber(1990) classification rules, the sequences were divided into three categories; 26 perfect repeat sequences without interruptions in the runs of CA or GA dinucleotides (60.5%), 14 imperfect repeat sequences with one or more interruptions in the run of repeats (32. 6%) , and 3 compound repeat sequences with adjacent tandem simple repeats of a different sequence (6. 9%). Fourteen pairs of microsatellite primers were selected and used to analyze the polymorphism and genetic structure of the wild and cultured population of southern flounder from America. The results were shown as follows: two loci were monomorphic, and 12 loci were polymorphic, inwhich 7 loci showed high polymorphic levels judged by PIC value (Pic>0. 5). The averages of observed and expected heterozygosities of the 12 polymorphic loci were 0. 36 and 0. 57, respectively. In addition, a total of 90 alleles (50 effective alleles) were detected at 12 loci in total samples. The Hardy-Weinberg equilibrium ( HWE) analysis showed that 9 loci deviated from genetic equilibrium to different extent in the two populations and heterozygote deficiency occurred in total samples (Fzs>0). The level of genetic diversity in the wild population was significantly higher than that of the cultured population, and the genetic distance between two populations was 0.111 5, which indicated that the genetic differentiation between two populations was quiet weak. Twelve polymorphic microsatellites were identified in this study, and these microsatellite loci would be usful to analyze genetic diversity, and protect germ plasm resource of southern flounder.%采用磁珠富集法筛选适合漠斑牙鲆遗传多样性分析的微卫星分子标记.筛选共获得43条序列,其中完美型26个,占60.5％；非完美型14个,占32.6％；复合型3个,占6.9％.选取其中14对特异性好且扩增效率高的微卫星引物,对采自美国北卡罗来纳州沿海的漠斑牙鲆野生群体和养殖群体进行遗传多样性及遗传结构比较分析.研究结果表明,12对引物的扩增产物具有多态性,其中7个位点为高度多态(PIC＞0.5).两个群体中共检测到90个等位基因.12个多态性微卫星位点在两个群体中的平均观察杂合度(Ho)和期望杂合度(He)分别为0.36和0.57.9个位点在整个群体中呈现出不同程度的偏离遗传平衡(P＜0.05),且偏离平衡的位点均表现为杂合子缺失(Fis＞0).野生群体和养殖群体间的遗传距离为0.111 5,群体间的遗传分化微弱(Fst=0.043 8).