Pseudomonas syringae is a rod-shaped,
Gram-negative bacterium with polar
flagella. As a
plant pathogen, it can infect a wide range of species, and exists as over 50 different
pathovars, all of which are available to researchers from international culture collections such as the
NCPPB,
ICMP, and others. It is unclear whether these pathovars represent a single
species.