FIG. 2.

A model for the role of PRX33/34 in PAMP-triggered immunity (PTI) signaling. (A) In unchallenged cells, PRX33/34 activity and presumably low-level apoplastic ROIs appear to maintain low-level expression of pathogen-associated molecular pattern (PAMP)-activated genes through an unknown mechanism. This possibly serves to pre-prime plant defenses for rapid activation after PAMP recognition. (B) Pathogen infection and PAMP recognition by pattern recognition receptors (PRRs) both activate intracellular signaling leading to PTI and also trigger the apoplastic production of ROIs by PRX33/34. This appears to positively regulate the expression of PAMP-activated genes and contributes to the establishment of PTI.