A Bacterial Type III Effector Targets the Master Regulator of Salicylic Acid Signaling, NPR1, to Subvert Plant
Huan Chen1, Jian Chen1, Min Li2
1Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210014, P. R. China; Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA.
Abstract:
Most plant bacterial pathogens rely on type III effectors to cause diseases. Although it is well known that the plant hormone salicylic acid (SA) plays an essential role in defense, whether the master regulator of SA signaling, NPR1, is targeted by any plant pathogen effectors is unknown. SA facilitates the reduction of cytosolic NPR1 oligomers into monomers, which enter the nucleus and function as transcriptional coactivators of plant defense genes. We show that SA promotes the interaction between the Pseudomonas syringae type III effector AvrPtoB and NPR1. In the presence of SA, AvrPtoB mediates the degradation of NPR1 via the host 26S proteasome in a manner dependent on AvrPtoB's E3 ligase activity. Intriguingly, we found that NPR1 plays an important role in MAMP-triggered immunity (MTI), inducing the expression of MTI marker genes. Thus, this work uncovers a strategy in which AvrPtoB targets NPR1 and represses NPR1-dependent SA signaling, thereby subverting plant innate immunity.
Related Concept Videos
Cell Signaling in Plants
Defenses Against Pathogens and Herbivores
Gene Regulation in Microbial Communities: Quorum Sensing
Riboswitches
The aptamer has high specificity for a particular metabolite which allows riboswitches to specifically regulate...
Gene Regulation During Sporulation
Stringent Response in E. coli


