牙鲆连续两代减数分裂雌核发育家系的遗传特征

Analysis of homozygosity and genetic similarity between two succes-sive generations in a meiogynogenetic Japanese flounder family

对牙鲆(Paralichthys olivaceus)减数分裂雌核发育二倍体(Meio-G1)再次诱导减数分裂雌核发育,获得连续两代雌核发育二倍体家系(Meio-G2),以Meio-G1亲本与1尾普通牙鲆雄鱼人工授精获得的家系作为对照组(control)。利用15个微卫星标记对3个家系进行遗传特征分析。结果显示,15个微卫星位点在Meio-G1、Meio-G2和对照组3个家系中,分别扩增到30、28、50个等位基因,平均等位基因数为2.0、1.9、3.3,平均观测杂合度(Ho)分别为0.875 3、0.774 2、0.908 3,平均纯合度分别为0.124 7、0.221 5、0.091 7。3个家系个体间的平均遗传相似系数分别为0.891 7、0.923 8、0.520 2,亲代与子代之间的平均相似系数分别为0.916 6、0.930 4、0.560 3。高重组率的Poli9-8tuf、Poli18tuf、Poli107tuf 3个位点在Meio-G1和Meio-G2中观测杂合度均为1.0,低重组率的Poli33tuf、Poli24MHFS两个位点在Meio-G1和Meio-G2中均全部纯合,观测杂合度为0。结果表明,Meio-G2的纯合度、个体间平均相似系数以及亲子之间的平均相似度均略高于Meio-G1,显著高于对照组家系,证明连续两代诱导减数分裂雌核发育,能提高鱼类纯合度和遗传相似度,具有固定母本遗传性状的作用。

The artificial induction of gynogenesis is a form of chromosome manipulation that has several applica- tions, including the rapid establishment of inbred lines or strains. The technique offers a high degree of homozy- gosity, sex-control, and accelerated elimination of recessive deleterious genes from a cultured population. We produced two meiotic gynogenetic Japanese flounder （Paralichthys olivaceus） family lines： meio-G1 （the first generation） and meio-G2 （the second generation）. We evaluated the efficacy of artificial meiotic gynogenesis for producing pure inbred lines by quantifying the homozygosity and genetic similarity of meio-G1 and meio-G2 us- ing microsatellite markers The average homozygosity among 15 loci was 0.124 7 for meio-G1 and 0.221 5 for meio-G2, which was higher than that in the natural mating family （0.091 7）. The average similarity indices among individuals within meio-G1 and meio-G2 were 0.891 7 and 0.923 8, which were higher than within the natural mating family （0.5603）. The average similarity in meio-G2 was slightly higher than in meio-G1. The observed heterozygosity in meio-G1 and meio-G2 was 1 at the Poli9-8tuf, Poli18tuf, PolilO7tufloci, all of which were lo- cated at some distance from the centromere （i.e., had high recombination frequencies）. The loci （Poli33tuf, Poli24MHFS） closest to the centromere （i.e., with a low recombination frequency） were homozygous in meio-G1 and meio-G2. Our results suggest that artificially induced meiotic gynogenesis is an efficient method for inbreed- ing to purify the genome, increase genetic similarity, and fix maternal genetic traits in the Japanese flounder. The meiogynogenetic families cultured in our study may be used in further selective breeding research.