The Study On Phylogenetic Relationships Of Filamentous Cyanobacteria

The paper studied the stability and the reliability of traditional morphologic charactersof cyanobacteria by using a species of Hapalosipnon sp. which belongs to theStigonematales and cultured in seven different medium. The results indicate thatHapalosiphon sp. has distinctly different morphological characters in different culturemedium. The influences of different nutrition ingredient and concentration to themorphogenesis construction of Haposlisipn sp. are very great. The branches' length and theshapes of cells' are not stable and it's inappropriate applying in the classification researchin Cyanobacteria. Only the branches' style of cyanobacteria is a stable character in ourresearch. This result indicated that the traditional morphological characters can't be used tostudy cyanobacteria classification. That means the cyanobacteria taxonomy study needsome new and stable standards.In order to determine phylogenetic position of stigonematales and the phylogeneticrelationships of filamentous cyanobacteria, the experiment constructed MP, ML and NJtree based on part sequences of 16S rRNA gene of 29 species of filamentous cyanobacteriawith sequence analysis software PAUP(4.0b4a). The results are mostly consistent with thetraditional taxonomic method that the filamentous cyanobacteria are divided into threeorders widely used internationally. The research indicates that the Stigonematales ispolyphyletic origin and it belongs to the evolutiver group in filamentous cyanobacteria.The oscillatoriatales is the most primal group and it is the phylogenetic origin. TheNostocales is the most advanced group which is also polyphyletic origins.