The phylogenetic relationships of cyanobacteria inferred from 16S rRNA, gyrB, rpoC1 and rpoD1 gene sequences.

Phylogenetic analysis of cyanobacteria was carried out using the small subunit rRNA (16S rRNA), DNA gyrase subunit B (gyrB), DNA-dependent RNA polymerase gamma subunit (rpoC1) and a principal sigma factor of E. coli sigma(70) type for DNA-dependent RNA polymerase (rpoD1) gene sequences of 24 strains which contained 5 subgroups of cyanobacteria-3 strains of the Chroococcales, 5 strains of the Pluerocapsales, 7 strains of the Oscillatoriales, 7 strains of the Nostocales and 2 strains of the Stigonematales. Degenerated PCR primers of gyrB, rpoC1 and rpoD1 genes were designed using consensus amino acid sequences registered in GenBank. The phylogenetic positions of cyanobacteria were resolved through phylogenetic analysis based on 16S rDNA, gyrB, rpoC1 and rpoD1 gene sequences. Phylogenies of gyrB, rpoC1 and rpoD1 support 16S rRNA-based classification of cyanobacteria. Interestingly, phylogenies from amino acid sequences deduced from gyrB and combined amino acid sequences deduced from rpoC1 and rpoD1 genes strongly support that of 16S rRNA, but the branching pattens of the trees based on 16S rDNA, GyrB, rpoC1, rpoD1 and combined amino acid sequences deduced from rpoC1 and rpoD1 were not congruent. In this study, we showed the correlation among phylogenetic relationships of 16S rDNA, gyrB, rpoC1 and rpoD1 genes. The phylogenetic trees based on the sequences of 16S rDNA, GyrB, rpoC1, rpoD1 and the combined amino acid sequences deduced from rpoC1 and rpoD1 showed that the lateral gene transfer of rRNA might be suspected for Synechocystis sp. PCC 6803.