Phytopathogenic “Pseudomonas” Species: a Taxonomic Overview

Abstract

Over the past two decades, the original genus Pseudomonas has been thoroughly revised and reorganised following the discovery of its heterogeneity on the basis of DNA:rRNA hybridisation. Only the nucleus of species around P. fluorescens and P. aeruginosa (rRNA group 1) in the gamma-Proteobacteria has been retained in Pseudomonas sensu stricto. Other species have been reallocated to other genera in the alfa-, beta- and gamma-Proteobacteria. This taxonomic overview will cover the phytopathogenic ex-Pseudomonas species of rRNA groups II and III. These organisms have been reallocated to Burkholderia, Ralstonia, Herbaspirillum and Acidovorax, all in the beta-Proteobacteria. They include: P. caryophylli, P. cepacia, P. gladioli, P. glumae, P. plantarii, P. andropogonis, and P. stizolobii, all now in Burkholderia; P. solanacearum, now in Ralstonia; P. rubrisubalbicans, now in Herbaspirillum; and P. avenae, P. rubrilineans, P. cattleyae, P. pseudoalcaligenes subsp. citrulli and subsp. konjaci, now in Acidovorax. Acidovorax anthurii has been described more recently. In addition to these phytopathogenic species, these four genera contain non-phytopathogenic species as well as clinical isolates. Recent findings reported in literature are summarised and discussed.