“全红”瓯江彩鲤不同世代间的遗传结构及遗传分化初步分析

PRELIMINARY ANALYSIS OF GENETIC STRUCTURE AND DIFFERENTIATION AMONG THE SELECTED POPULATIONS OF "WHOLE RED" PATTERNS OF CYPRINUS CARPIO VAR.COLOR

利用ISSR技术对"全红"瓯江彩鲤(Cyprinus car pio var. color)4个世代群体的遗传结构及其分化进行了分析。筛选的15个ISSR引物从4个世代群体中分别扩增到120、118、101和110条扩增谱带,全部扩增片段长度在200—2500bp之间。根据扩增结果,利用POPGENE version 1.31进行分析,结果表明:4个群体的多态位点比例(P)为51.49%—67.80%,Shannon信息指数(Ho)为0.2176—0.2745之间,并随着世代的增加,选育群体的遗传多样性呈现下降趋势。有70%的遗传变异来自于群体内;结合遗传分化指数Gst、UPGMA聚类分析,证实"全红"瓯江彩鲤4个世代间存在一定程度的遗传分化,即任意两个群体间的遗传分化达到较大的水平(Gst均为0.1588—0.2766)。

Oujiang color common carp is the important species for freshwater culture due to their commercial value and ornamental value of fishery industry, which distribute over Lishui city, Longquan city, Qingtian country and Oujiang river basin in Zhejiang Province, China. It has several color patterns, such as completely red, red with scattered black spots, completely white, white with scattered black spots. Its culture can be traced back for 1200 years in local paddies, but no scientific studies have been undertaken until 2000. Since 2000, some domestic aquaculture scientists have carried out studies on the genetic diversity and exploitation and utility of Oujiang color common carp. Although several generations of “whole red” pattern of Oujiang color common carp have been selected and the offspring’s body color isozygoty degree have been reached 90%, or so, little is know about the genetic structure and genetic differentiation of different generations. In this paper, ISSR technique was applied to investigate the genetic diversity among four generations of “whole red” patterns of C. carpio var. color, which were collected from the provincial farm of Oujiang color common carp, Longquan, Zhejiang Province. ISSR analysis was carried out according to previously established standard ISSR reaction system for Steed barbel with a slight modification. In brief, a 25μL of reaction system involved 2.5μL 10×PCR buffer containing Mg^2＋, 20 ng DNA template, 0.2 mM dNTPs, 0.6 U Taq DNA polymerase, 0.2m M primers and 0.5μL deionized formanide. ISSR-PCR reaction procedure was as follows： pre-denaturing at 94℃ for 5min followed by 5 cycles： denaturing at 94℃ for 30s, annealing at 55℃ for 45s, 1 ℃ decreased for each cycle, elongation at 72℃ for 1.5min, sequently 35 cycles were included： 94℃ for 30s, 50℃ for 45s, 72℃ for 1.5min with a elongation at 72℃ for 7min after cycle. PCR products were electrophoresed on a 1.5% agarose gel with ethidium bromide using DNA Marker-G as standard molecular weight control and photographed on UV imaging system BIO-RAD. Fifteen ISSR primers （screened out of 60 primers） were employed to scan the genomic DNA in 18 individuals of four populations, 120, 118, 101 and 110 fragments ranging from 200 to 2500 bp were amplified from the above four stocks respectively. The experimental data were analyzed with Popgene version 1.31. As analyzed, the proportions of polymorphic loci in Oujiang color common carp ranged from 51.49% to 67.80%; the Shannon’s information index （Ho） varied from 0.2176 to 0.2745 among stocks. With the increasing of selected generations, the selected populations showed a reduction in genetic diversity. H0 revealed that 70% variation occurred with populations. To test the genetic differentiation among four populations, genetic difference value （Gst）, cluster analysis through UPGMA were also performed. The result revealed that the differentiation has taken place to some extent among “whole red” patterns of Oujiang color common carp, which the differentiations were large （Gst from 0.1588 to 0.2766） between the arbitrary two populations. The knowledge of their genetic structure and variation could be used to assist the selection of better ornamental carp, especially Oujiang color common carp in China.