Molecular Phylogeny of Laminariales (Phaeophyceae) deduced from rRNA gene sequences

对海带目（Laminariales）的以下几个种的18S rRNA基因序列和rRNA基因的ITS区序列进行了分析，以阐明原始海带目（Laminariales）成员：Pseudochorda nagaii、Pseudochorda gracilis（Pseudochordaceae）、Chorda filum（Chordaceae）和裙带菜（Undaria pinnatifida（Alariaceae））的系统发育关系。对作为外类群的单纯髓腔菌（Myelophycussimplex）的18SrDNA序列进行了研究，其系统学位置尚存在争议。两种拟脊索动物（P.nagaii和P.gracilis）尽管在配子体形态上存在差异，但它们在生殖遗传上非常接近。裙带菜属（Undaria）与海带科（Laminariaceae）的Costaria亲缘关系较近，而脊索属（Chorda filum）与伪脊索属（Pseudochorda spp.）Undaria和Costaria。这些结果与孢子体形态学分类相一致，其性质为性引诱剂。

Gene sequences of 18S rRNA gene and the ITS region of rRNA gene were studied in the following species of the Laminariales, in order to clarify the phylogenetic relationships among the members of primitive Laminariales (kelps) : Pseudochorda nagaii, Pseudochorda gracilis (Pseudochordaceae) ; Chorda filum (Chordaceae) ; Undaria pinnatifida (Alariaceae). 18S rDNA sequence was also studied in Myelophycus simplex as an out group, whose ordinal systematic position is in question. Two species of Pseudochorda (P.nagaii and P.gracilis) were shown to be phylogenetically very close in spite of their differences in the gametophyte morphology. Undaria and Costaria (Laminariaceae) showed close relationship and Chorda filum showed rather distant position from Pseudochorda spp., Undaria and Costaria. These results agree with the taxonomy based on their sporophyte morphology and the nature is sexual attractants.