鲤科鲌属药用鱼类线粒体COI基因的DNA条形码研究

目的:采用线粒体COI基因序列研究我国长江流域不同地区鲤科鲌属药用鱼类的遗传特征,探讨利用该基因片段作为鲌属药用鱼类鉴定条形码的适用性.方法:扩增鲌属药用鱼类的线粒体COI基因序列5′端并进行测序,分析不同药用鱼类种内和种间的遗传变异,构建聚类树,探讨该序列片段在鲌属药用鱼类中进行鉴定的可行性.结果:鲌属药用鱼类COI基因片段的碱基组成中A+T碱基量明显高于G+C量,96％的遗传变异均发生在编码区密码子第3位点,但所有翻译后氨基酸组成均相同,表明COI基因编码在鲌属鱼类中的保守性;鲌属药用鱼类的种内遗传距离均小于1％,种间遗传距离大于10倍的种内距离;NJ聚类树显示所有鲌属鱼类聚成独立的一支,其属内不同鱼种的个体又分别聚成独立的分支,不同分支具有较高的节点支持率.结论:鲌属4种药用鱼类的DNA分类与形态学分类结果一致,COI条形码序列能够对鲌属鱼类进行有效的区分.

DNA barcoding application of mitochondrial COI gene sequence in medicinal fish of Culter (Pisces: Cyprinidae)

The sequence variation of medicinal fish of Culter (Pisces: Cyprinidae) was analyzed by using cytochrome c oxidase subunit I (COI) sequencing collected from different regions of the Yangtze River basin, and we examine whether barcoding of COI can be used to discriminate medicinal fish of Culter. The AT content in the COI region of medicinal fish of Culter was higher than that of GC, which was similar with other species of Cypriniformes. Ninty-six percent of nucleotide changes were observed at the 3rd codon position of COI sequence, but the amino acid compositions translated by COI sequences of all Culter fish stayed the same. It is suggested that most synonymous mutations might occur at the 3rd position. The average Kimura-2-parameter (K2P) distance within-species was lower than 1%,and the K2P distance of pairwise-species was 10 times as much as that of within-species. The phylogenetic tree estimated by Neighbour-joining method indicated that species within genera invariably clustered, and generally so did individuals within species. Individuals from operational taxonomic units designated as different Culter species, supporting morphological evidence for each of these being separate species. It is suggested that the COI barcoding can be used to identify medicinal fish species of Culter.