Figure 1.

Proposed model depicting the components and events of PAMP triggered immunity. According to the to date literature, there are two PAMPs perception models. One is BAK1/SERK3 dependent (left) and the other one is BAK1/SERK3 independent perception (right). All PAMPs shown in the leftmost table are perceived in BAK1/SERK3 dependent manner. Ca²⁺ ion influx is among the earliest events of PAMP perception followed by opening up the membrane transporters for the influx of H⁺ and efflux of K⁺, Cl⁻, and ${\text{NO}}_3^{-}$ that leads to changes in extracellular pH and depolarization of plasma membrane. ROS burst is reported to occur within minutes of PAMP perception. Ca²⁺-dependent or Ca²⁺independent phosphorylated RBOHD generates ROS that leads to further increase in cytosolic Ca²⁺ concentrations. Calcium, MAPK, and hormonal signaling are all reported to be involved in receptor mediated perception of Phytophthora spp. PAMPs. PAMPs induce defense responses include; ROS burst, callose deposition, hypersensitive response (HR), expression of defense genes, accumulation of antimicrobial secondary metabolites and systemic acquired resistance (SAR).