3个尖塘鳢引进群体繁育后代的遗传多样性分析

Genetic diversity analysis among offspring stocks of three imported Oxyeleotris populations by microsatellite markers

【目的】分析3个尖塘鳢引进群体繁育后代的遗传多样性和遗传结构,为尖塘鳢亲本管理和资源可持续利用提供基础资料,同时为尖塘鳢的遗传改良及新品种培育打下基础。【方法】采用微卫星分子标记分析2000年引进的线纹尖塘鳢群体繁育后代(AZ1)、2005年引进的线纹尖塘鳢群体繁育后代(AZ2)及1986年引进的云斑尖塘鳢群体繁育后代(TG)的遗传多样性,运用PopGene32、CERVUS 3.0、Arlequin 3.1计算3个尖塘鳢群体的等位基因数(Na)、期望杂合度(He)、多态信息含量(PIC)及遗传分化系数(Fst)等遗传参数,基于Nei氏遗传距离利用MEGA 7.0中的非加权组平均法(UPGMA)构建系统发育进化树,并以Structure 2.3分析群体间的遗传结构。【结果】12个微卫星分子标记在3个尖塘鳢群体中扩增得到32个等位基因。AZ1群体、AZ2群体和TG群体的平均Na分别为1.33、1.92和2.33,平均He分别为0.034、0.180和0.214,平均PIC分别为0.031、0.155和0.191。3个尖塘鳢群体间的Fst为0.077~0.384、遗传相似度为0.926~0.950、遗传距离为0.052~0.077。3个尖塘鳢群体有22.54%的变异来自于群体间,77.46%的遗传变异来自群体内。基于Nei氏遗传距离构建的UPGM系统发育进化树显示,AZ1群体和AZ2群体先聚类为一支,然后与TG群体聚类在一起。【结论】3个尖塘鳢引进群体繁殖后代遗传多样性水平较低,尤其是AZ1群体近交程度较高,因此相关引种单位或繁殖场需尽快采取相应的选育手段提高现有杂交鳢群体遗传多样性,避免近交衰退带来的风险,也可通过引进新的种质资源提高杂交鳢遗传多样性。此外,3个杂交鳢群体尚未出现种质混杂和杂交情况,仍可作为杂交鳢遗传育种奠基种群。

【Objective】The genetic diversity and genetic structure of offspring stocks of three imported Oxyeleotris populations in Guangdong were analyzed,in order to provide basic data for the management of the parent fish and the sustainable utilization of the Oxyeleotris resources,and to lay the foundation for genetic improvement and new variety breeding of Oxyeleotris.【Method】Microsatellite markers were used to analyze the 90 offspring samples from the imported O.lineolatus populations AZ1 and AZ2(introduced in 2000 and 2005 respectively)and the imported O.marmoratus population in 1986(TG).The genetic parameters,including number of alleles(Na),expected heterozygosity(He),polymorphism information content(PIC)and genetic differentiation coefficient(Fst)of the three populations were calculated by PopGene32,CERVUS 3.0 and Arlequin 3.1 software.The phylogenetic tree was constructed by UPGMA of Mega 7.0 program based on Nei’s genetic distance,and the genetic structure was calculated by Structure 2.3 software.【Result】The results showed that a total of 32 alleles were identified in the three populations by using of 12 microsatellite markers.The number of average Na of the offspring samples for AZ1,AZ2 and TG populations were 1.33,1.92,and 2.33 respectively;average He values were 0.034,0.180,and 0.214;and average PIC were 0.031,0.155,and 0.191,respectively.The Fst values ranged from 0.077 to 0.384,the genetic similarity values ranged from 0.926 to 0.950,and the genetic distance(Da)values ranged from 0.052 to 0.077.AMOVA analysis of the genetic variation revealed that only 22.54%of the genetic variation came from the inter-populations,and 77.46%genetic variation was from intra-populations among the three populations.UPGMA phylogenetic analysis based on Nei’s genetic distance showed that AZ1 and AZ2 populations first clustered together,and then clustered with TG population.【Conclusion】The results indicate that the genetic diversity of the offspring stocks of three imported Oxyeleotris populations is low,and the inbreeding degree of AZ1 population is the high.It is urgent to carry out genetic improvement of Oxyeleotris as soon as possible and increase the number of parents by imported Oxyeleotris from different sources to increase the genetic diversity of the culture populations and avoid inbreeding decline risks.In addition,the three hybrid populations have not been mixed and hybridized,and can still be used as the foundation population of hybrid breeding.