| Research Abstract |
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.
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