基于SSR标记的长江下游原良种场鳙亲本和后备亲本种质资源现状分析

分析长江下游原良种场鳙(Aristichthys nobilis)亲本和后备亲本的遗传多样性和遗传结构,评估鳙育种群体的种质资源现状,可为鳙的种质资源管理和活体资源库建设提供科学的参考依据。本研究利用已发表的10对SSR荧光引物结合毛细管电泳技术,对7个亲本群体和1个后备亲本群体共638份DNA进行基因分型。主要应用GenAlEx 6.501、Cervus 3.0和Structure 2.3.4等软件进行遗传多样性参数计算和群体遗传结构分析。结果表明,8个群体总体遗传多样性水平较高,但存在一定程度的近亲繁殖风险。其平均等位基因数(N_a)为14.83±1.45,观测杂合度(H_o)和期望杂合度(H_e)分别为0.76±0.05、0.82±0.02,Shannon's信息指数(I)为2.08±0.09,近交系数(F)为0.08±0.05。各亲本群体之间遗传多样性水平存在差异,后备亲本遗传多样性水平最高。鳙的贝叶斯群体遗传结构分析图(Structure)与主坐标分析(PCoA)结果具有一致性,将所有样本划分为两个类群,大部分亲本群体之间并无明显的遗传分化,而后备亲本和亲本之间则表现明显的遗传分化。分子方差分析(AMOVA)显示,11%的遗传变异来自群体间,群体间的遗传分化处于中等水平,而89%的遗传变异来自群体内。本研究探究了鳙亲本和后备亲本的遗传差异性,对野生原种引进和保护提供了建议,以期为构建健康负责的增殖放流种苗繁育体系提供理论支持和数据参考。

Current germplasm situation of bighead carp (Aristichthys nobilis) candidate parent and parent from hatchery in the lower reaches of Changjiang River based on SSR markers

This study aimed to assess stock enhancement of the bighead carp ( is a fish of ecological and scientific significance, inhabiting most of Chinese freshwaters. Moreover, it is one of the most released species in the lower reaches of the Changjiang River. The primary focus of stock enhancement was to release juveniles into natural environments and enhance the stocks of interest. However, the genetic quality of large-scale stock fish is difficult to quantify. Consequently, it is essential to examine the genetic quality of the brood stocks in the hatchery, in order to provide a scientific reference for genetic resource management as well as living resources database construction of brood stocks in the lower reaches of the Changjiang River. During our study, the genetic diversity and population structure of 8 populations were studied using SSR markers. A total of 638 individuals from 7 parent populations and 1 candidate parent population were assayed by 10 pairs of SSR primers. Genetic diversity parameters, principal coordinate analysis (PCoA), and analysis of molecular variance (AMOVA) were generated using Cervus 3.0, GenAlEx 6.501 and Arlequin 3.1 software. Structure and CLUMP software were used to analyze the genetic structure of the populations. The results revealed that the genetic diversity was superior despite inbreeding risk within populations. The average number of alleles was 14.83±1.45, expected heterozygosity and observed heterozygosity were 0.82±0.02 and 0.76±0.05, respectively, while Shannon information index was 2.08±0.09, and inbreeding coefficient was 0.08±0.05. The highest level of genetic diversity was in the candidate parent population. Furthermore, the genetic diversity of parent populations was different. According to structure and PCoA, all individuals could be divided into two genetic clusters, which showed that the genetic differentiation among parent populations were not significantly different, in addition the genetic differentiation between parent and candidate parent populations was significantly different. AMOVA analysis showed that 11% of genetic variation was among the populations and 89% of genetic variation was within populations. The genetic differences between candidate parent and the parent of bighead carp suggest the importance for the introduction and protection of natural germplasm. The results from this study further suggest that it is possible to improve hatchery practices and mitigate the negative effects on wild stocks. However, theoretical support and data reference are required for constructing a healthy and sustainable stock enhancement strategy.