A Phytophthora capsici RXLR Effector Targets and Inhibits a Plant PPIase to Suppress Endoplasmic Reticulum-Mediated Immunity

Abstract

Phytophthora pathogens secrete a large arsenal of effectors that manipulate host processes to create an environment conducive to pathogen colonization. However, the underlying mechanisms by which Phytophthora effectors manipulate host plant cells still remain largely unclear. In this study, we report that PcAvr3a12, a Phytophthora capsici RXLR effector and a member of the Avr3a effector family, suppresses plant immunity by targeting and inhibiting host plant peptidyl-prolyl cis-trans isomerase (PPIase). Overexpression of PcAvr3a12 in Arabidopsis thaliana enhanced plant susceptibility to P. capsici. FKBP15-2, an endoplasmic reticulum (ER)-localized protein, was identified as a host target of PcAvr3a12 during early P. capsici infection. Analyses of A. thaliana T-DNA insertion mutant (fkbp15-2), RNAi, and overexpression lines consistently showed that FKBP15-2 positively regulates plant immunity in response to Phytophthora infection. FKBP15-2 possesses PPIase activity essential for its contribution to immunity but is directly suppressed by PcAvr3a12. Interestingly, we found that FKBP15-2 is involved in ER stress sensing and is required for ER stress-mediated plant immunity. Taken together, these results suggest that P. capsici deploys an RXLR effector, PcAvr3a12, to facilitate infection by targeting and suppressing a novel ER-localized PPIase, FKBP15-2, which is required for ER stress-mediated plant immunity.

An RXLR effector PlAvh142 from Peronophythora litchii triggers plant cell death and contributes to virulence

“…RXLR effectors have become a focus for studying plant–pathogen interaction in the past decade, with numerous effector genes identified and characterized in Phytophthora and downy mildew species (Tyler et al , ; Haas et al , ; Baxter et al , ; Yin et al , ). Many studies have reported that RXLR effectors are involved in the suppression of PTI and/or ETI (Wang et al , ; Kong et al , ; Fan et al , ) Additionally, some of them can trigger immune response‐related cell death, for example Phytophthora sojae Avh238 (Yang et al , ), Phytophthora capsici Avh1 (Chen et al , ), and Plasmopara viticola RXLR16 (Xiang et al , ).…”

Subtractive hybridization-assisted screening and characterization of genes involved in the rice-Magnaporthe oryzae interaction

“…Moreover, multiple candidate proteins or their closely related orthologs have been shown implicated in diverse plant-microbe interactions. Rice chitinase 11 is a PR protein strongly induced by pathogen infection, and overexpression of the protein in transgenic rice plants enhances the resistance against sheath blight disease (Grover 2012;Kumar et al 2018); whereas the PPIases, which mediate protein folding in the endoplasmic reticulum, are targeted by pathogens to subdue plant defenses (Kromina et al 2008;Fan et al 2018). In contrast, OsWRKY28 has been identified as a negative regulator of immunity and can enhance susceptibility to blast disease when overexpressed in transgenic plants (Chujo et al 2013;Chen et al 2017); likewise, overexpression of the Arabidopsis heat shock cognate 70 (HSC70), sharing over 90% of sequence identity with the candidate rice heat shock cognate protein 2 found in this study, disables resistance to virulent pathogen strains including Hyaloperonospora parasitica Noco2 and Pseudomonas syringae pv tomato DC3000 (Noël et al 2007).…”

AtRTP5 negatively regulates plant resistance to Phytophthora pathogens by modulating the biosynthesis of endogenous jasmonic acid and salicylic acid

“…Agrobacterium-mediated transient expression assay by infiltration was performed as described previously (Fan et al, 2018). Briefly, constructs were transformed into A. tumefaciens strain GV3101 (Rossi et al, 1993) by electroporation.…”