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

通过对海带属(Laminariales)3个种的18S rRNA基因序列和rRNA基因ITS区序列的研究，探讨了原始海带属(海带)成员间的系统发育关系：海带属(Pseudochorda Nagaii)、细长假藻属(Pseudochorda Gracilis)、脊索科(Chordaceae)、裙带菜属(Unaria Pinnatifida)。18S rDNA序列也作为一个OUT类群在单纯脊椎动物中进行了研究，其有序分类地位尚存疑问。Nagaii和P.gracilis两个种虽然在配子体形态上存在差异，但在系统发育上非常接近。裙带菜和裙带菜(海带科)亲缘关系较近，而丝状索与假丝藻、裙带菜和Costaria的位置较远。这些结果与基于孢子体形态的分类一致，其本质是性引诱剂。

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.