基于微卫星标记的洞庭青鲫倍性鉴定

Ploidy identification for Carassius auratus var. dongting based on microsatellites

洞庭青鲫产于湖南省澧县北民湖,因个体大且背部青灰而得名,其快速生长的特性和异于普通鲫的体型令作者怀疑前人报道的“二倍体群体”结果。为此,从银鲫微卫星文库中筛选9个位点构建微卫星鲫倍性鉴定体系,同时采用流式细胞术和染色体核型分析完成了洞庭青鲫倍性鉴定。结果显示,建立的微卫星鲫倍性鉴定体系能够100%区分二倍体、三倍体和四倍体鲫,微卫星基因分型结果显示136尾洞庭青鲫均为三倍体,各位点的等位基因数为1~3,样本基因型包括AAA、AAB/ABB、ABC 3种类型;洞庭青鲫血细胞DNA平均含量为159.42±5.64,与二倍体红鲫的血细胞DNA平均含量(102.43±3.54)比值(DI)为1.56∶1;流式细胞术与微卫星体系判定结果匹配度100%;染色体核型分析显示洞庭青鲫染色体数为3n=156±,核型公式为3n=39m+36sm+81sta,NF=231。建立了适用于鲫倍性鉴定的微卫星标记体系,且系统地证实了洞庭青鲫为三倍体鲫品种。

Carassius auratus var. dongting originates from Beimin Lake, Hunan. Compared to other Carassius spp., C. auratus var. dongting had a higher growth rate and larger body size, and we therefore hypothesized that these growth advantages were related to polyploidization. To verify this hypothesis, a 9 microsatellite ploidy identification method was developed to examine the ploidy level of C. auratus var. dongting, and flow cytometry assays and chromosome karyotype assays were used to further confirm the findings. The results showed that 9 microsatellites could completely distinguish 37 ploidy-known specimens. The genotyping results showed that all the 136 ploidy-unknown individuals were triploid, all three genotypes (AAA, AAB/ABB, and ABC) were observed in this population. The mean DNA content of blood cells in C. auratus var. dongting (159.42±5.64) was 1.5 times that of blood cells in C. auratus var. red (102.43±3.54), and the results from microsatellite markers were totally concordant with those from flow cytometry analysis. The karyotype analysis revealed that the number of chromosomes was 3n=156± and the karyotypic formula was 3n=39m+36sm+81sta, NF=231. This study not only established a microsatellite-based system for ploidy identification of C. auratus, but also systematically confirmed that C. auratus var. dongting is triploid.