基于18S-ITS1-5.8S序列的吉富罗非鱼群体遗传多样性分析

Genetic Diversity of GIFT Strains of Oreochromis niloticus Based on 18S-ITS1-5.8S Sequence

运用PCR技术扩增吉富罗非鱼选育群体第20和21世代18S-ITS1-5.8S序列,分析二序列的遗传变异。结果表明,18S-ITS1-5.8S序列中,18S、内转录间隔区(ITS)1和5.8S序列分别为156、483~540、64 bp,主要变异位点位于ITS1中;基于ITS1序列的第20代吉富罗非鱼(17尾)群体内遗传距离为0.001,保守位点530个,变异位点10个,单倍型4个,单倍型多样性为0.331±0.143,核苷酸多样性为0.002,平均核苷酸差异为1.279;基于ITS1的第21代吉富罗非鱼(42尾)群体内遗传距离为0.015,6个个体存在严重碱基缺失现象,保守位点492个,变异位点49个,单倍型12个,单倍型多样性为0.638±0.083,核苷酸多样性为0.014,平均核苷酸差异为6.945。ITS序列在该两吉富罗非鱼群体中变异较小,基于ITS1序列分析的两代群体遗传多样性水平较低。

18S-ITS1-5.8S sequences of the GIFT strains of Oreochromis niloticus were amplified by PCR. The result was used to analyze the genetic variation of the 20 th and 21 st generation. The study showed that the sequences of 18 S, ITS1, 5.8 S were 156, 483-540, and 64 bp, respectively, and the main variable sites were located in ITS1. Based on ITS1 sequences, the 20 th generation（17 individuals） genetic distance was 0.001. It contained 530 conservative sites, 10 variable sites, 4 haploid types. The haplotype diversity was 0.331±0.143, and nucleotide diversity was 0.002, and the average nucleotide difference was 1.279. The 21 th generation（42 individuals） genetic distance was 0.015, and some nucleotides have severely been lost in 6 individuals. It contained 492 conservative sites, 49 variable sites and 12 haploid types. It haplotype diversity was 0.638±0.083, nucleotide diversity was 0.014, and the average nucleotide difference was 6.945. The results indicated that the variation of ITS1 sequences were relatively small and genetic diversity was at a low level in the two generations of GIFT strains of Oreochromis niloticus.