泥东风螺EST-SSR开发及其群体遗传多样性分析

Development and Genetic Diversity Analysis of Babylonia lutosa with EST-SSR Markers

本研究采用MISA软件分析泥东风螺(Babylonia lutosa)转录组中微卫星信息。结果显示,从转录组中共获得16324个SSR,共有181种重复基元;泥东风螺转录组中不同类型微卫星的重复基元具有不同的分布特征,其中,二核苷酸重复基元中AC/GT(70.58%)重复基元以重复6次出现频率占优;长度为12~20 bp的SSR占63.95%,长度为21~25 bp的SSR占9.14%,总体的平均长度为18.4 bp。随机选取其中50条序列设计引物,通过对福建野生泥东风螺群体(WP)DNA样本进行PCR扩增和分型,结果获得23个多态性位点,等位基因数目为2~7个不等,期望杂合度(Ne)为0.190~0.937,观察杂合度(No)为0.065~0.936,多态性信息含量(PIC)为0.061~0.777,有4个位点显著偏离哈迪温伯格平衡(Hardy-Weinberg equilibrium,HWE)(P<0.05)。对野生群体和养殖群体(BP)遗传多样性分析显示,野生群体和养殖群体的平均Ne分别为0.491和0.544,平均No分别为0.477和0.564,平均PIC分别为0.541和0.407。Fis结果显示,野生群体和养殖群体分别有13个和9个位点杂合子过剩。群体间遗传分化指数(Fst)为0.001~0.655,平均值为0.053(0.05<Fst<0.15),属于中等程度分化。群体间的基因流值(Nm)为0.132~543.787,平均为4.450。两群体间的遗传距离为0.892,表明群体间的遗传分化小。本研究结果表明,泥东风螺野生群体和养殖群体均具有较高的遗传多样性,具有很大的选育潜力,开发的泥东风螺SSR标记对泥东风螺的群体遗传结构、图谱构建、增殖放流效果评估和分子辅助育种等研究方面具有重要意义。

Babylonia lutosa is a marine shellfish that has high economic values.In recent decades,the natural resource of B.lutosa has declined due to the environment destruction and overfishing.To further understand the level of genetic diversity and population genetic structure of B.lutosa,we have evaluated the information characteristics of B.lutosa’s microsatellites,after obtaining transcriptome sequences using MISA software.The results show that a total of 16342 microsatellites and 181 nucleotide repeat motifs were identified.Different types of repeat microsatellites had considerably different distribution characteristics.Mononucleotide and dinucleotide microsatellite repeating units were the most abundant in the B.lutosa transcriptome,in which 6 repeats of AC/GT(70.58%)were the dominant repeating dinucleotide units.The length of the dominant repeating units was 12~20 bp(63.95%)and 21~25 bp(9.14%),respectively,and the average length was 18.4 bp.Among the 50 designed primer pairs,23 proved to be polymorphic microsatellite markers in the B.lutosa wild populations(WP).The results showed that the allele number of these microsatellites ranged from 2 to 7.The expected heterozygosity(He)and observed heterozygosity(Ho)ranged from 0.190 to 0.937,and 0.065 to 0.936,respectively.The polymorphism information content(PIC)ranged from 0.061 to 0.777.The He values of the WP and breeding population(BP)were 0.491 and 0.544,respectively.The Ho values of the WP and BP populations were 0.477 and 0.564,respectively.The PIC values for WP and BP were 0.541 and 0.407,respectively.There were 13 population loci that were heterozygote excesses in WP,and 13 population loci in BP.The genetic differentiation index(Fst)ranged from 0.001 to 0.655,with an average value of 0.053(0.05<Fst<0.15),and the gene flow value(Nm)ranged from 0.132 to 543.787,with an average value of 4.450.The genetic distance between the WP and BP was 0.892,which indicated that the two populations had little genetic differentiation.The results above show that the BP still has high genetic diversity after selection,and that it could still potentially be used as breeding material.The EST-SSR in this study will facilitate further studies on the population genetic structure,genetic mapping,evaluation artificial releasing and molecular assisted breeding of B.lutosa.