一株分离自胶州湾的裸甲藻形态相似种的分子系统学研究

摘要

对一株分离自胶州湾的裸甲藻形态相似种(Gymnodinium sp.ZX)进行了分子水平的分类鉴定.提取基因组DNA后扩增核糖体小亚基和转录间隔区序列,经纯化、克隆并测序.将获得的序列分别进行Blastn同源性分析,并下载相关序列构建系统进化树,结果表明,该藻与共生藻(Symbiodinium)亲缘关系较近,而与裸甲藻(Gymnodinium)等其他甲藻亲缘关系较远,因此初步鉴定该藻为一种共生藻.用核糖体小亚基和转录间隔区序列分别对共生藻属构建系统进化树,分析各类群之间的关系,初步鉴定本藻属于共生藻属E类群.该藻分离自胶州湾,在f/2培养液中生长良好,表明胶州湾可能存在营自由生活的共生藻.%A strain of microalgae that was isolated from the Jiaozhou Bay and primarily identified as Gymnodinium-like based on the morphological features (named as Gymnodinium sp. ZX) was further distinguished with molecular phylogenetic methods. After the processes of DNA extraction, amplification and purification, the nuclear-encoded small subunit ribosomal DNA (SSU rDNA) and internal transcribed spacer (ITS) regions were cloned and sequenced. Sequences homologous to SSU rDNA and ITS regions of Gymnodinium sp. ZX were searched with Blastn from the GenBank. The phylogenetic trees were reconstructed with the neighbor-joining (NJ) method. The results show that Gymnodinium sp. ZX has a close genetic relationship with Symbiodinium rather than Gymnodinium. Therefore, Gymnodinium sp. ZX was judged as a strain of Symbiodinium sp. Then the phylogenetic trees were reconstructed based on the SSU rDNA and ITS sequences of genus Symbiodinium respectively, the relationship among the various clades was analyzed, and Gymnodinium sp. ZX belonged to clade E. The Gymnodinium sp. ZX was isolated from the Jiaozhou Bay, and grew well in the f/2 medium, therefore, it was inferred that the free-living species of genus Symbiodinium probably existed in the Jiaozhou Bay.