A bacterial effector targets the master immune regulator NPR1 ($)

Pathogenic microbes translocate effector molecules into plant cells that subvert host immune responses and promote disease. In a recent article published in Cell Host & Microbe, Chen et al. (2017) describe an exciting new interaction between the Pseudomonas syringae effector AvrPtoB and its cognate host target: the master immune regulator NPR1. Intriguingly, the authors show that the plant defense hormone salicylic acid (SA) promotes the AvrPtoB-NPR1 interaction, which subsequently leads to the poly-ubiquitination and proteasomal degradation of NPR1. This effectively suppresses NPR1’s function in SA signalling, ultimately leading to enhanced microbial growth in the now immunocompromised host plant. (Summary by Philip Carella) Cell Host Microb. 10.1016/j.chom.2017.10.019