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RFLP，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前就已经可用。作为该项目的起点，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。以雄性托为材料，成功地提取了PCR质量的总DNA，为了验证基于形态学的3科分类系统的有效性，我们基于18 SrDNA序列数据对岩藻目（Fucales）各属的系统发育关系进行了研究。调查了该目7属10种。这些包括墨角藻属、Pelvetia（墨角藻科）、囊塞藻属、椰子属、Myagropsis（囊塞藻科）、马尾藻属和Hizikia（马尾藻科）。结果表明，囊绥菌科的Myagropsis与马尾藻科的Sargassum/Hizikia分支处于姐妹群的位置，具有较高的自举支持率。因此，形态特征（模式的分支），分离的囊绒藻科马尾藻科被发现不反映系统发育关系。相反，卵原细胞内的卵发育模式被发现，反映了系统发育关系推断的18 SrDNA序列。结果表明，Hizikia属的自主性是可疑的。我们已经认识到几个分支内的马尾藻/Hizikia分支。形态学研究表明，产于北海道的一个种为一新种，命名为Sargassum confusum-like sp.，并将其命名为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.