Identification of two serological flagellar types (H1 and H2) in Pseudomonas syringae pathovars

Flagellar antigen specificity was studied for the species Pseudomonas syringae, P. viridiflava and P. cichorii. After checking their motility, bacteria were reacted against six polyclonal antisera containing anti-O (LPS) and anti-H (flagellar) antibodies by indirect immunofluorescent staining. Two distinct flagellar serotypes (H1 and H2) were described. The distribution of H1 and H2 serotypes was then determined for a collection of 88 phytopathogenic Pseudomonas strains. Serotype H1 was possessed by P. syringae pv. aptata (12 strains), P. s. pv. helianthi (2), P. s. pv. pisi (11), and P. s. pv. syringne (13). Serotype H2 was possessed by P. cichorii (2), P. s. pv. delphinii (1), P. s. pv. glycinea (4), P. s. pv. lacrymans (1), P. s. pv. mori (1), P. s. pv. morsprunorum (10), P. s. pv. persicae (1), P. s. pv. phaseolicola (8), P. s. pv. tabaci (10) and P. s. pv. tomato (1). P. viridiflava (5) revealed HI, H2 and untyped flagella. The following isolates were untypable by the H1/H2 system: P. corrugata (3), P. fluorescens (2), P. tolaasii (1). H1/H2 serotypes distribution is not linked to P. syringae O-serogroups. On the other hand, H1/H2 distribution seems remarkably linked to the new genospecies of the P. syringae group.