刺参(Apostichopus japonicus)野生及两代选育群体间遗传变异的微卫星标记研究

GENETIC VARIATIONS OF WILD AND SELECTIVELY BRED POPULATIONS OF A SEA CUCUMBER APOSTICHOPUS JAPONICUS

应用微卫星DNA技术对野生刺参和两代选育刺参群体遗传多样性进行了研究。9对微卫星引物在三个刺参群体中共扩增获得43个等位基因,每个微卫星座位检测到的等位基因数为2—7个。三个群体的观测杂合度的平均值分别为0.6556、0.6704和0.6148,多态信息含量平均值分别为0.6654、0.5929和0.5275。结果表明,与野生群体相比,选育刺参两代群体存在杂合度降低,遗传多样性下降的现象。Hardy-Weinberg平衡的卡方检验及F-检验数据显示3个群体在某些位点都出现了杂合子缺失,偏离平衡的位点逐代增加,相邻世代之间遗传分化系数逐代减小,人工累代选育已经使群体的遗传结构发生了变化。FST平均值0.0443提示出选育群体处在较弱的分化水平,说明遗传变异主要来自于群体内个体间。遗传距离及遗传相似性结果显示随着选育世代的增加,世代之间遗传距离越来越小,遗传相似性越来越大,但与理论值仍有差距,选育群体刺参仍具育种潜力。

Genetic diversities of a wild and two generations of selectively bred populations of the sea cucumber, Apostichopusjaponicas, were examined using the microsatellite DNA techniques. 43 bands of alleles amplified using 9 primers were obtained from these three populations and 2-7 alleles were detected from each microsatellite locus. Average observed heterozygosities （Ho） of these populations were 0.7164, 0.6486 and 0.5968, respectively; and the average values of polymorphism information content were 0.6654, 0.5929 and 0.5275, respectively. The results showed that the heterozygosities of two generations of selectively bred A. japonicus were reduced, compared with the wild population, and genetic diversity declined as the breeding generations increased. Hardy-Weinberg equilibrium chi-square test and F-test data showed that selective breeding had changed the genetic structure of the populations, including decreased heterozygous sites, increased loci deviated from the equilibrium, and decreased coefficient of genetic differentiation between the adjacent generations. Fsr value （0.0443） suggested the breeding population had weak genetic differentiation and illustrated that the main genetic variation existed among individuals within population rather than between populations. Genetic distance and genetic identity indicated that divergence became smaller with increasing breeding generations and the genetic similarity between the adjacent generations became greater, even though they had not reached the theoretical value, thus it was still suitable for further selective breeding.