16S rRNA 분석에 의한 Subsection IV cyanobacteria 균주들의 다계통성 기원의 증거

Abstract

Unicellular cyanobacterial strains of Subsections Ⅰ and Ⅱ and filamentous cyanobacterial strains of Subsection Ⅲ have been shown to be polyphyletic, heterocystous strains of Subsections Ⅳ and Ⅴ, both of which were previously reported to be monophyletic. In this study, the small subunit ribosomal RNA (16S rRNA) sequences of 13 strains of cyanobacteria - one strain, Oscillatoria nigro-viridis PCC7112, of the Subsection Ⅲ, 6 strains including genus Anabaena, Nostoc, Tolypothrix, Calothrix and Scytonema of the Subsection Ⅳ, and 6 strains including genus Hapalosiphon, Fischerella and Chlorogloeopsis of the Subsection Ⅴ - were determined. The phylogenetic analysis of cyanobacteria was carried out using the 16S rRNA sequences. The results of the phylogenetic analyses of 16S rRNA sequences, based on Neighbour-joining, maximum-parsimony, and maximum-likelihood methods, indicated that the members of Subsection Ⅳ were not monophyletic but polyphyletic. In addition, the phylogenetic results strongly indicated that the genus Scytonema in Subsection Ⅳ could be a common ancestor of heterocystous cyanobacteria in Subsection Ⅳ and Ⅴ. Furthermore, the phylogenetic analyses revealed that the genus Anabaena could be phylogenetically diverse and that cyanobacterial strains in Subsection Ⅳ might be polyphyletic, whereas those in Subsection Ⅴ could be monophyletic, as reported before. The results for the genus Anabaena indicate that it should be reclassified.