基于SSR-seq技术评估中间球海胆多代选育群体和普通养殖群体的遗传多样性

Evaluation of the genetic diversity and genetic structure of multiple generation selection populations and unselected common population of sea urchin(Strongylocentrotus intermedius)using SSR-seq

为明确不同选育群体中间球海胆的遗传多样性和遗传结构,利用SSR-seq技术和15个微卫星位点,对1个家系选育群体(FP)、1个群体选育群体(IP)和1个未经选育的普通养殖群体(CP)的遗传多样性及遗传结构进行了分析。结果显示,15个微卫星位点共检测出112个等位基因,FP、IP、CP 3个群体的平均观测等位基因数(N_(a))分别为5.077、5.133和6.133个,平均有效等位基因(N_(e))分别为2.816、2.873和3.638个,平均观测杂合度(H_(o))分别为0.522、0.441和0.501,平均期望杂合度(H_(e))分别为0.595、0.599和0.667,平均多态性信息含量(PIC)分别为0.546、0.543和0.623。家系选育群体(FP)H_(e)与H_(o)的差值(0.073)低于IP(0.158)和CP(0.166),平均固定指数(F)(0.115)低于IP(0.248)和CP(0.246)。3个群体间遗传分化系数(F_(st))介于0.018~0.176,为中低等程度的遗传分化。分子方差分析(AMOVA)结果显示,3个群体的遗传变异主要源于个体间。主成分分析(PCoA)和聚类进化树结果均显示,3个群体之间的亲缘关系较近,其中IP群体遗传分化程度最高。研究表明,3个中间球海胆群体均具有较高的遗传多样性,多代家系选育和群体选育均未明显降低群体的遗传多样性,家系选育更有利于保持群体的杂合度和控制群体的近交水平,群体选育则会提升群体的遗传分化程度。

The sea urchin Strongylocentrotus intermedius was originally found off the coast from Hokkaido,Japan and Far East Russia and was introduced from Japan to China in 1989.Now,is one of the most commercially important cultured sea urchin species in China.Family selection and individual selection have been used to genetically improve its economic traits.In order to clarify the genetic diversity and genetic structure of different breeding populations of S.intermedius,the genetic diversity and genetic structure of a family selection population(FP),an individual selection population,and a unselected common population(CP)were analyzed using SSR-seq technology and 15 microsatellite loci.The results showed that a total of 112 alleles were detected at 15 microsatellite loci,and the average number of alleles(N_(a))observed in FP,IP and CP were 5.077,5.133 and 6.133,respectively,with mean effective alleles(N_(e))of 2.816,2.873 and 3.638,respectively.The mean observed heterozygosities(H_(o))in FP,IP and CP were 0.522,0.441 and 0.501,respectively,and the mean expected heterozygosities(H_(e))were 0.595,0.599 and 0.667,respectively.The mean polymorphic information contents(PIC)in FP,IP and CP were0.546,0.543 and 0.623,respectively.The difference between H_(e) and H_(o) in FP(0.073)was lower than that in IP(0.158)or CP(0.166).The mean fixation index(F)in FP(0.115)was also lower than that in IP(0.248)or CP(0.246).The coefficients of genetic differentiation(F_(st))among the three populations ranged between 0.018 and 0.176,indicating a low-to-medium degree of genetic differentiation.The analysis of molecular variance(AMOVA)results showed that the genetic variation of the three populations mainly come from individuals.Both principal component analysis(PCoA)and clustering phylogenetic tree showed that the three populations were closely related,and the IP population had the highest degree of genetic differentiation.In summary,our results suggest that the three sea urchin populations have high genetic diversity,and multiple generations of family selection and individual selection did not reduce genetic diversity dramatically.Family selection is more beneficial in maintaining population heterozygosity and controlling inbreeding levels.This research can lay a foundation for the evaluation and development of germplasm resources of the sea urchin S.intermedius.