| 摘要: |
| 罗非鱼“粤闽1号”是用尼罗罗非鱼(Oreochromis niloticus)和奥利亚罗非鱼(O. aureus)培育的全雄罗非鱼新品种。采用同工酶电泳技术和线粒体DNA控制区序列分析方法，对罗非鱼“粤闽1号”及其繁育群体的遗传多样性、遗传结构及群体之间的遗传关系进行研究。同工酶电泳结果显示，酯酶(EST)和乳酸脱氢酶(LDH)的酶谱具有组织和群体特异性。肌肉和脾脏中的EST表达量极低，而肝脏中的EST表达量较高，LDH在3种组织中均有较高表达，但酶谱存在差异。在罗非鱼“粤闽1号”及其繁育群体中，共检测到10条EST酶带和5条LDH酶带，多态性位点比例(P)为12.50%~71.43%，平均观测杂合度(Ho)为0.0417~0.6143，Hardy-Weinberg遗传偏离指数(D)为‒0.2347~0.9072。线粒体DNA控制区序列分析结果显示，mtDNA D-loop区的碱基组成无显著差异，均呈现出A+T碱基偏向性(63.39%)。在罗非鱼“粤闽1号”及其繁育群体中，共发现20种单倍型，核苷酸多样性指数(Pi)为0~0.0519，奥尼罗非鱼雌鱼(WY1)、尼罗罗非鱼雌鱼(XX)、尼罗罗非鱼雄鱼(XY)和罗非鱼“粤闽1号”(XY2)群体的Pi值(0.0440~0.0519)明显高于超雄尼罗罗非鱼(YY1)、超雄奥尼罗非鱼(YY2)和奥利亚罗非鱼雌鱼(WZ)群体的Pi值(0~0.0009)。各群体之间的遗传分化指数(FST)为‒0.0115~0.9963，XY2与WY1群体之间、XX与XY群体之间以及WZ和YY2群体之间的遗传分化不显著(FST<0.05, P>0.05)。XY2群体与尼罗罗非鱼群体(XX群体和XY群体)和奥利亚罗非鱼群体(WZ群体)之间的平均遗传距离分别为0.0639和0.0695。在NJ系统进化树中，XX、XY、YY1和XY2群体聚为一支，WY1、WZ和YY2群体聚为另一支。本研究揭示了罗非鱼“粤闽1号”的生化和分子遗传特征，为其种质鉴定、繁育群体的构建和优良性状的稳定遗传提供理论基础。 |
| 关键词: 罗非鱼“粤闽1号” 同工酶 线粒体DNA控制区 遗传多样性 遗传关系 |
| DOI： |
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| Genetic Diversity and Genetic Relationship Analysis of Tilapia “Yuemin No.1” and Its Breeding Populations |
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LIU Zhigang, LU Maixin, CAO Jianmeng, GAO Fengying
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Pearl River Fisheries Research Institute, Chinese Academy of Fisheries Science, Key Laboratory of Tropical & Subtropical Fishery Resource Application & Cultivation, Ministry of Agriculture and Rural Affairs, Guangzhou 510380
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| Abstract: |
| “Yuemin No.1” is a novel holandric species of tilapia, which was bred with Oreochromis niloticus and O. aureus. In order to reveal the genetic characteristics of tilapia “Yuemin No.1,” the genetic diversity, genetic structure, and genetic relationships among groups of tilapia “Yuemin No.1” and its breeding populations were studied by isozyme electrophoresis and sequence analysis of the D-loop region of mtDNA. The results of isozyme electrophoresis showed that the zymogram of esterase (EST) and lactate dehydrogenase (LDH) were population- and tissue-specific in tilapia. The expression level of EST in the muscle and spleen was extremely low, whereas that in the liver was high. LDH was highly expressed in all the tissues, as revealed by the different zymograms. Ten bands of EST and five of LDH were detected in tilapia “Yuemin No.1” and its breeding populations. The proportion of polymorphic loci (P) ranged from 12.50% to 71.43%, the average observed heterozygosity (Ho) ranged from 0.0417 to 0.6143, and the Hardy-Weinberg genetic deviation index (D) ranged from ‒0.2347 to 0.9072. The result of sequence analysis of the D-loop region of mtDNA revealed that no significant difference occurred in base composition, and that A+T content (63.39%) bias was widespread in all the populations. There were 20 haplotypes in tilapia “Yuemin No.1” and its breeding populations. The nucleotide diversity index (Pi) ranged from 0 to 0.0519. The Pi value of WY1, XX, XY2, and XY populations (0.0440~0.0519) were significantly higher than that of YY1, YY2, and WZ populations (0~0.0009). The genetic differentiation index (FST) among populations ranged from ‒0.0115 to 0.9963. There was no significant genetic differentiation (FST<0.05, P>0.01) between the XY2 and WY1, XX and XY, and WZ and YY2 populations. The average genetic distance between XY2 population and O. niloticus (XX and XY populations) was 0.0639, whereas that between the XY2 population and O. aureus (WZ population) was 0.0695. Cluster analysis revealed two clusters; one cluster included XY, XX, YY1, and XY2 populations, and the other cluster included WY1, WZ, and YY2 populations. This study revealed the biochemical and molecular genetic features of tilapia “Yuemin No.1,” and provide research data for germplasm identification, establishment of breeding populations, and maintainence of stable inheritance of desirable traits. |
| Key words: Tilapia “Yuemin No.1” Isozyme Mitochondrial DNA control region Genetic diversity Genetic relationship |
