Serological and molecular size characterization of flagellins of Pseudomonas syringae pathovars and related bacteria

Flagella from a total of 118 strains representing mostly pathovars of the phytopathogenic group Pseudomonas syringae, but also P. chlororaphis, P. cichorii, P. corrugata, P. fluorescens, P. fuscovaginae, P. stutzeri, P. viridiflava, as well as related phytopathogenic genera (Burkholderia cepacia and Ralstonia solanacearum) were characterized by immuno-fluorescent staining, SDS-PAGE, and immunoblotting. Eighty-six strains of the P. syringae group pathovars, P. cichorii and P. viridiflava were shown to possess flagella of serotypes H1 or H2, composed of a unique flagellin, whose molecular size varied between 31 and 31.5 kDa. Similarities between the P. syringae flagellin and a 31 kDa surface protein involved in pathogenicity are pointed out. The distribution of H1 and H2 antigens in the nine recently described genomospecies of P. syringae-P. viridiflava group suggested that flagellin would represent a phylogenetic marker within the arginin-dihydrolase-negative fluorescent pseudomonads. The characterization of flagellin was proposed as an identification tool at a level situated between genus and species.