Phylogeny of P. agglomerans sensu stricto strains of diverse origin based on partial sequencing the hrcN gene, coding for the type III secretion system-specific ATPase. A total of 32 P. agglomerans or nearly related strains (e.g., SC-1 or LMG 5343) were tested for the presence of a T3SS using primers hrcN-4r and hrcN-5rR, which were designed on the basis of the alignment of the hrcN genes of E. amylovora and Pseudomonas syringae. A positive amplification was obtained as expected in two known plant pathogens (P. agglomerans pv. gypsophilae CFBP 4342 and P. agglomerans pv. gypsophilae ATCC 43348) and in seven more strains, including four environmental strains (CIP 82.100, LMG 2557, P3SAA and P7NSW), one clinical isolate (VA21971) and two biocontrol strains (Eh239 and CPA-2). Sequence analysis revealed that the hrcN gene found in the latter seven strains is more similar to that of biocontrol P. fluorescens and is not closely related to P. agglomerans pv. gypsophilae or other plant pathogenic bacteria, indicating a divergent function. GenBank accession numbers of reference sequences not obtained in this work are indicated between square brackets.