RRS1 and infection: Although both AvrRps4 and PopP2 are recognized by RPS4 and RRS1, a thorough comparison of immune responses, particularly of early transcriptional changes, has been difficult due to the distinct infection modes of the bacterial pathogens from which AvrRps4 (Pseudomonas syringae) and PopP2 (Ralstonia solanacearum) originate.