基于线粒体DNA Cyt b、12S rRNA和D-loop序列的铜鱼养殖群体遗传多样性分析OA

[Objective]In this study,the genetic diversity of the cultured Coreius heterodon population was analyzed by using the sequences of mitochondrial DNA Cyt b,12S rRNA and displacement loop region(D-Loop),and the genetic diversity and genetic structure were preliminarily understood.[Methods]PCR amp-lification and Sanger sequencing were performed using previously designed primers targeting the mitochondrial Cyt b,12S rRNA,and D-Loop regions.The genetic diversity parameters were calculated by DNASP 6.12 soft-ware.The MEGA 11.0 software was used to analyze the base composition and variable sites of the DNA se-quences.The genetic distances among haplotypes were calculated by the Kimura two-parameter model.The haplotype phylogenetic trees based on complete sequences of the mitochondrial DNA control region were con-structed by neighbor-joining(NJ)method and the maximum likelihood(ML)method.[Results]The sequences of mitochondrial DNA Cyt b,12S rRNA,and D-loop used for analysis were 1 110−1 147 bp,425−445 bp,and 972−1 023 bp,with average lengths 1 122.77,430.00,and 1 000.47 bp,and median lengths of 1 122,429,and 1 001 bp,respectively.A total of 8,1,14 variable sites,and 22,19,30 haplotypes were identified in the mitochon-drial DNA Cyt b,12S rRNA and D-loop,respectively,with genetic distance between haplotypes ranging from 0 to 0.004,0 to 0.005,and 0 to 0.007,respectively.The average haplotype diversities based on mitochondrial DNA Cyt b,12S rRNA,and D-loop were 0.547±0.010 5,0.186±0.007 8,and 0.885±0.001 3,respectively;the average nucleotide diversities were 0.000 76,0.000 44,and 0.002 58,respectively;and the average number of nucleotide differences was 0.830,0.186,and 2.432,respectively.Mismatch-distribution showed a unimodal pat-tern,and Tajima's D value was negative(D=−1.04,P>0.01)in the neutrality test,but the statistical result was not significant.[Conclusion]The genetic diversity of the cultured C.heterodon population is relatively low,and there is extensive gene flow between haplotypes,with no genetic differentiation of the population,but the cultured C.heterodon population has undergone a population decline.Therefore,establishing a broodstock pop-ulation with rich genetic diversity for artificial breeding of C.heterodon,solving the problem of broodstock cul-tivation,and continuously expanding the scale of C.heterodon farming population is the primary task.