The Phytophthora RXLR effector AVR3a12 suppresses ER-mediated plant immunity (Mol. Plant)

The pathogenic oomycete Phytophthora capsici secretes RXLR effector proteins into plant cells to subvert host cell machinery and facilitate disease. Several RXLR effector proteins have been characterized to date, however, Phytophthora species encode a vast array of effector molecules that likely target different cellular compartments during infection. In a recent article in Molecular Plant, Fan et al. (2018) characterize the role of a Phytophthora capsici RXLR effector (PcAVR3a12) during infection in Arabidopsis thaliana. The authors discovered that PcAVR3a12 specifically targets the ER-localized peptidyl-prolyl cis-trans isomerase (PPIase) FKBP15-2. Disease assays and expression studies using knockout and overexpression lines demonstrated a pivotal role for FKBP15-2 in the positive regulation of plant immunity via an ER-stress sensing network involving bZIP transcription factors. Taken together, the data presented by Fan et al. provide further support for an important stress sensory system in the plant endoplasmic reticulum whose function is subverted by a pathogen effector in order to promote microbial fitness in planta. (Summary by Phil Carella) Mol. Plant 10.1016/j.molp.2018.05.009