Phylogeny of the genus Pseudomonas: intrageneric structure reconstructed from the nucleotide sequences of gyrB and rpoD genes

Phylogenetic analysis of the genus Pseudomonas was conducted by using the c ombined gyrB and rpoD nucleotide sequences of 31 validly described species of Pseudomonas (a total of 125 strains). Pseudomonas strains diverged into two major clusters designated intrageneric cluster I (IGC I) and intragener ic cluster II (IGC II). IGC I was further split into two subclusters, the ' P. aeruginosa complex', which included P. aeruginosa, P. alcaligenes, P. ci tronellolis, P. mendocina, P. oleovorans and P. pseudoalcaligenes, and the 'P. stutzeri complex', which included P. balearica and P. stutzeri. IGC II was further split into three subclusters that were designated the 'P. putid a complex', the 'P. syringae complex' and the 'P. fluorescens complex'. The 'P. putida complex' included P. putida and P. fulva. The 'P. syringae comp lex' was the cluster of phytopathogens including P. amygdali, P. caricapapa yae, P. cichorii, P. ficuserectae, P. viridiflava and the pathovars of P. s avastanoi and P. syringae. The 'P. fluorescens complex' was further divided into two subpopulations, the 'P. fluorescens lineage' and the 'P. chlorora phis lineage'. The 'P. fluorescens lineage' contained P. fluorescens biotyp es A, B and C, P. azotoformans, P. marginalis pathovars, P. mucidolens, P. synxantha and P. tolaasii, while the 'P. chlororaphis lineage' included P. chlororaphis, P. agarici, P. asplenii, P. corrugata, P. fluorescens biotype s B and G and P, putida biovar B. The strains of P. fluorescens biotypes fo rmed a polyphyletic group within the 'P. fluorescens complex'.