A molecular phylogenetic analysis of the fucalean brown algae based on RFLPs of chloroplast DNA.

虽然最初的计划是研究叶绿体DNA的RFLPs，但我们已经将其改为核编码基因的DNA测序分析，因为测序技术在项目开始之前才可用。作为项目的起点，我们开发了一种从褐藻组织中提取PCR友好DNA的技术，这通常被认为是困难的。我们以雄花托为来源，成功地提取了PCR质量的总DNA。为了验证日本岩藻分科系统的有效性，利用18SrDNA序列对岩藻目各属的系统发育关系进行了研究。调查了该目7属10种。这些包括墨角藻、盆腔藻（岩藻科）、囊藻、尾藻、Myagropsis（囊藻科）、马尾藻和Hizikia（马尾藻科）。结果表明，囊藻科成员Myagropsis是马尾藻/Hizikia分支（马尾藻科）的姐妹群，具有较高的bootstrap支持。因此，将马尾草科与囊藻科区分开来的形态学特征（分支模式）并不能反映系统发育关系。相反，卵子在卵原内的发育模式被发现反映了从18SrDNA序列推断出的系统发育关系。利用ITS2序列对马尾草科植物的系统发育关系进行了研究。结果表明，Hizikia属的自主性是可疑的。我们在马尾藻/Hizikia分支中发现了几个分支。然而，这些分支不对应于任何当前的分类群，如马尾藻属的亚属。形态学研究表明北海道的马尾藻属（Sargassum confusum-like sp.）为新种，命名为S.boreale sp.nov。

Although original plan was to investigate RFLPs of the chloroplast DNA,we have changed it to DNA sequencing analyzes of nuclear encoded genes, because the sequencing techniques became available just before start of the project. As the starting point of the project, we have developed a technique to extract PCR friendly DNA from the brown algal tissue, which is generally said to be difficult. We have successfully extract the total DNA of the PCR quality by using male receptacles as a source.In order to test the validity of the classification system of the Japanese fucalean algae which recognize three families based on morphological grounds, we have investigated phylogenetic relationship of the genera in the order Fucales based on 18SrDNA sequence data. Ten species belonging to 7 genera in the order were investigated. These include Fucus, Pelvetia (Fucaceae), Cystoseira, Coccophora, Myagropsis (Cystoseiraceae) Sargassum and Hizikia (Sargassaceae). The results revealed that the member of the Cystoseiraceae, Myagropsis come to the position sister group to the Sargassum/Hizikia clade (Sargassaceae) with high bootstrap support. Therefore, the morphological character (mode of branching) which separates the Cystoseiraceae from the Sargassaceae was found not to reflect phylogenetic relationship. Instead, the mode of egg development within a oogonium was found to reflect phylogenetic relationship deduced from the 18SrDNA sequences.The phylogenetic relationship within the family Sargassaceae was investigated using ITS2 sequences. The results revealed that autonomy of the genus Hizikia is dubious. We have recognized a few clades within a Sargassum/Hizikia clade. However, these clades do not correspond to any of the current taxa, such as subgenera within the genus Sargassum.Morphological study revealed that a species refereed Sargassum confusum-like sp.from Hokkaido was a new species and we described it as S.boreale sp.nov.