Figure 1.

The cluster of Psy 61 genes carried on pHIR11 that enables nonphytopathogenic bacteria to elicit the HR in tobacco. hopPsyA (checkered) encodes an effector protein that apparently is delivered into plant cells. Other genes encode regulatory factors (shaded), Hrc components associated with export across the inner membrane (diagonal hatching) or outer membrane (cross hatching), extracellular Hrp proteins (stippled), or proteins with unknown function (open boxes). Squares on arrows denote the presence of HrpL-activated promoters (55).