The HrpZ proteins of Pseudomonas syringae pvs. syringae, glycinea, and tomato are encoded by an operon containing Yersinia ysc homologs and elicit the hypersensitive response in tomato but not soybean. - Preston, G; Huang, H; He, S; Collmer, A (Molecular plant-microbe interactions : MPMI, 1995)