| In order to research the germplasm resource status of Siniperca scherzeri in Qingshuijiang River(QR),the study was investigated by means of gene labeling technique and microsatellite marker technology aimed at mitochondrial DNA D-loop region and Cytb gene.The study was mainly on the genetic structure and genetic diversity of S.scherzeri population(185 tail)sampled from Kaili,Jianhe,Jinping,Yuankou,Taipan,Nanshao,Sanjiang and Datong total 8 sites.Main results were as follows:1.Genetic analysis based on mitochondrial DNA D-loop region.The results reflected that the QR population’s A,T,C and G average content was 33.9%,29.9%,20.3% and 15.8% respectively;The terminating sequence area was the most active mutation site in the 3 parts of D-loop with 31 heterotopic points(70.45%);A total of35 haplotypes were defined in 185 sample gene sequences,44 base substitution sites were detected,no base insertion/deletion,and the conversion/bounce ratio was 4.5.The distribution of the haplotypes in these populations was that the main stream more than the tributaries and the middle reaches more than the upstream and downstream;Hap 1,Hap 7 and Hap 16 represented 83 individuals(44.9% of the total number of individuals),it was the dominant and the widest distribution population in QR;Although a few individuals have been differentiated into unique type,but there was no strict haplotype geographical distribution in the whole basin.Genetic distance,genetic differentiation coefficient and nucleotide diversity index showed that thepopulation of Kaili in the upstream had the highest genetic variation and genetic diversity,and Jinping Sanbanxi population in the middle reaches were the lowest.The comprehensive analysis reveals that QR population can be regarded as an effective population with no haplotype geographical distribution,low genetic variation,rich genetic diversity,no population expansion history,stable population structure.2.Genetic analysis based on mitochondrial DNA Cytb gene.Preliminary results showed that the average content of A,T,C and G was 24.3%,27.44%,15.34% and39.32% in the 8 populations in QR,and there was no difference between groups;The average content of A+T and C+G was 51.74% and 48.26%,which had obvious bias.In all,24 haplotypes were defined in the 185 sequences,with a total of 24 polymorphic sites;Among those sites,there were 17 simple information loci,7 single mutation loci,21 non synonymous mutations,and 3 synonymous mutations.Interval sampling points or between basins,the distribution of the haplotype was also the main stream higher than the tributaries,the middle reaches higher than the upper and lower reaches.Hap6 was the most widely distributed and represented the individuals most,followed by Hap4,Hap5,Hap7 and Hap8,which together form the dominant haplotype population of QR.The genetic variation between or in population was at the same level,and the genetic variation rate was much lower than of the above-mentioned control area and there was no obvious genetic divergence.The results showed that the Cytb gene of QR S.scherzeri population had no haplotype geographical distribution,genetic variation was not high,low nucleotide diversity was poor,and no population expanded history.3.Research based on microsatellite(SSR)markers.The study was carried on the12 selected polymorphic microsatellite loci by non denaturing polyacrylamide gel electrophoresis(PAGE)and Hardy-Weinberg equilibrium test.The experimental results indicated that the 8 S.scherzeri populations in QR was a random mating population.The polymorphism information content of various groups was Kaili0.6506,Jianhe 0.6700,Jinping 0.6957,Yuankou 0.6957,Taipan 0.6643,Nanshao0.6080,Sanjiang 0.4373,Datong 0.4644;The average observation heterozygosity of the whole population in QR was 0.2605,the average expected heterozygosity was0.7798,Shannon index was 1.6466,the average allele was 4.6269,and the average number of effective allele was 3.6179.According to the above genetic diversity parameters,the population of QR had a higher genetic diversity.To summarize,there was no geographical isolation and no serious genetic divergence among the population of S.scherzeri in the QR.Among the populations,there was rich genetic diversity without population expansion history.Therefore,it belongs to an effective population with diverse genetic composition,abundant genetic diversity and stable population structure. |
