Li Si-Fa, Tang Shou-Jie, Cai Wan-Qi
Key Laboratory of Aquatic Genetic Resources and Utilizations, Ministry of Agriculture, Shanghai Ocean University , Shanghai 201306, China.
Dongwuxue Yanjiu. 2010 Apr;31(2):147-54. doi: 10.3724/SP.J.1141.2010.02147.
The NEW GIFT Nile tilapia (Oreochromis niloticus niloticus L.) is a nationally certificated new strain selected over 14 years and 9 generations from the base strain of GIFT Nile tilapia, introduced in 1994. This new variety has been extended in most of areas of China. The management of genetically improved strains, including the genetic markers for identification is needed urgently. RAPD analysis was conducted and their conversion to SCAR markers was developed. From NEW GIFT Nile tilapia, two strain-specific RAPD bands, S(304 )(624 bp ) and S(36 )(568 bp ) were identified. The strain-specific RAPD bands were gel-purified, cloned, and sequenced. Locus-specific primers were then designed to amplify the strain-specific bands. PCR amplification was conducted to test the variations in allele frequencies of two converted SCAR markers among the NEW GIFT Nile tilapia and its base strains, as well as 7 additional farmed strains worldwide. The frequency of SCAR marker I (553 bp) was 85.7% in NEW GIFT Nile tilapia, but 16.7% in the base strain. The frequency of SCAR marker II (558 bp) was 91.4% in NEW GIFT Nile tilapia, but 0% - 70% in the 7 other strains. In order to confirm the utility of these two markers, an examination was conducted for a wild population from Egypt, resulted the frequency of SCAR I and II was 10% and 70%, respectively, much lower than that of New GIFT strain. The increase in allele frequency of these two SCAR markers suggests that these markers might be genetically linked to the quantitative trait loci (QTL) underlining the performance traits by long term selection, and indicate the bright potential of SCAR marker technology for tracking generations during selection progress and for distinguishing among genetically improved strain and other strains.
吉富尼罗罗非鱼（Oreochromis niloticus niloticus L.）是一个经过国家认证的新品系，它是从1994年引进的吉富尼罗罗非鱼基础群体中历经14年9代选育而成。这个新品种已在中国大部分地区推广。目前迫切需要对遗传改良品系进行管理，包括用于鉴定的遗传标记。为此开展了随机扩增多态性DNA（RAPD）分析，并将其转化为序列特异性扩增区域（SCAR）标记。从吉富尼罗罗非鱼中鉴定出两条品系特异性RAPD条带，即S(304)(624 bp)和S(36)(568 bp)。对这两条品系特异性RAPD条带进行凝胶纯化、克隆和测序，然后设计位点特异性引物来扩增品系特异性条带。通过聚合酶链反应（PCR）扩增来检测这两个转化后的SCAR标记在吉富尼罗罗非鱼及其基础群体，以及全球另外7个养殖品系中等位基因频率的差异。SCAR标记I（553 bp）在吉富尼罗罗非鱼中的频率为85.7%，而在基础群体中为16.7%。SCAR标记II（558 bp）在吉富尼罗罗非鱼中的频率为91.4%，而在其他7个品系中的频率为0% - 70%。为了验证这两个标记的实用性，对来自埃及的野生群体进行了检测，结果显示SCAR I和II的频率分别为10%和70%，远低于吉富新品系。这两个SCAR标记等位基因频率的增加表明，这些标记可能与长期选择下决定生产性能的数量性状位点（QTL）存在遗传连锁，这也显示了SCAR标记技术在选育过程中追踪世代以及区分遗传改良品系和其他品系方面具有广阔的应用潜力。
