4株扁藻属微藻5.8S rDNA和转录间隔区(ITS)的序列分析

The Sequence Analysis of 5.8S rDNA and ITS Region from Four Strains of Tetraselmis

为确定种质库4株微藻(库存号为C73、C74、C151、C152)的亲缘关系及确切种类,本研究采用PCR技术扩增其核糖体5.8S rDNA和转录间隔区(ITS)序列,结果在4株微藻上获得大小分别为593 bp、632 bp、596 bp、591 bp的序列。与GenBank中高相似度的瑞典四爿藻(T.suecica)和另一四爿藻属的微藻T.stiata比较发现,4株微藻与瑞典四爿藻和T.stia-ta5.8S rDNA的碱基序列完全相同,而2个间隔区(ITS1和ITS2)碱基序列存在一定差异,其中4株微藻ITS1变异位点占到总位点数的26.7%,ITS2变异位点占到总位点数的28%。系统进化分析表明,4株微藻与瑞典四爿藻聚集为同一群,其中C73和C152与瑞典四爿藻完全聚为一支(获得100%的支持率),而C74和C151彼此间距离仅为0.074,而与瑞典四爿藻的距离在0.2以上,结果说明,C73和C152是瑞典四爿藻的不同株系,C74和C152可能属于同一个有待确认的种。

Ribosome 5.8S rDNA and the internal transcribed spaces (ITS) of four microalgae(C73,C74,C151 and C152) were amplified by PCR and sequenced.The sequence lengths of the four microalgae were 593 bp,632 bp,596 bp and 591 bp,respectively,which had the highest level of similarity with T.suecica(AY574382.1) from GenBank.The 5.8S rDNA sequences from the amplified four microalgae were the same as those from T.suecica and T.striata while the ITS1 and ITS2 sequences from the four microalgae had evident difference from that of T.suecica,the percentage of variance sites of ITS1 sequences from the four microalgae was 26.7%,and that of the ITS2 sequences was 28%.The evolutionary tree was established and our result indicated that the investigated four microalgae and T.suecica clustered in one clade,two microalgae(C73 and C152) were close to T.suecica(BP=100%),which implies both C73 and C152 belong to T.suecica,and the distances between the other two microalgae(C74 and C151) and T.suecica were more than 0.2 and the distance between C74 and C151 was only 0.074,which implies that C74 and C151 may belong to other unknown species.