长松藻ITS序列特征及其系统进化分析

CHARACTERIZATION OF ITS SEQUENCE AND THE PHYLOGENETIC ANALYSIS OF CODIUM CYLINDRICUM(CODIACEAE,CHLOROPHYTA)

采用PCR扩增的方法获得了第一个松藻目物种长松藻(Codium cylindricum)的ITS序列,长松藻ITS全长515bp,其中ITS1的长度为74bp,5.8S序列长163bp,ITS2的长度为278bp。与已知的绿藻门其它5个目8个属物种的ITS序列的系统发育分析结果表明,绿藻门物种分为三大支,其中团藻目藻类为一支,松藻目和刚毛藻目藻类为一支,石莼目、顶管藻目和丝藻目藻类构成一大支;长松藻与刚毛藻目的刚毛藻属和硬毛藻属物种同为多核藻体,在系统发生上表现出更近的亲缘关系;不同绿藻目海藻的聚类关系表明,其能够准确地反映出其在单核与多核、单细胞与多细胞等生物结构特性方面的差异与水平。

The internal transcribed spacer （ITS） region of Codiurn cylindricum （Codiales） was firstly se- quenced by PCR method. The sequence length of ITS region was 515bp including ITS1 （74bp）, 5.8S ribosomal DNA （163bp） and ITS2 （278bp）. Compared to the ITS sequences of other species from eight genera of five orders of Chlorophyta downloaded from GenBank database, the phylogenetic relationship of Chlorophyta based on ITS region was explored. The phylogenetic results indicated that Chlorophyta algae were grouped into three main clades： Volvocales clustered as a single clade; Codiales and Cladophorales fell into the same clade; Ulvales, Acrosiphoniales and Ulotrichales formed another main clade. Codium cylindricurn has the same characteristic of algal multi nuclei with species from Cladopho- rales, and showed closer phylogenetic relationship with Cladophora and Chaetomorpha. The phyloge- netic analysis of different orders of Chlorophyta algae could exactly reflect the difference on biological characteristics from single nucleus to multi nuclei and from single cells to multicellular organisms.