The Powdery Mildew Effector CSEP0027 Interacts With Barley Catalase to Regulate Host Immunity

Abstract

Powdery mildew is one of the most important fungal pathogen diseases. The genome of barley mildew fungus, Blumeria graminis f. sp. hordei (Bgh), encodes a large number of candidate secreted effector proteins (CSEPs). So far, the function and mechanism of most CSEPs remain largely unknown. Here, we identify a Bgh effector CSEP0027, a member of family 41, triggering cell death in Nicotiana benthamiana. CSEP0027 contains a functional signal peptide (SP), verified by yeast secretion assay. We show that CSEP0027 promotes Bgh virulence in barley infection using transient gene expression and host-induced gene silencing (HIGS). Barley catalase HvCAT1 is identified as a CSEP0027 interactor by yeast two-hybrid (Y2H) screening, and the interaction is verified in yeast, in vitro and in vivo. The coexpression of CSEP0027 and HvCAT1 in barley cells results in altered localization of HvCAT1 from the peroxisome to the nucleus. Barley stripe mosaic virus (BSMV)-silencing and transiently-induced gene silencing (TIGS) assays reveal that HvCAT1 is required for barley immunity against Bgh. We propose that CSEP0027 interacts with barley HvCAT1 to regulate the host immunity and likely reactive oxygen species (ROS) homeostasis to promote fungal virulence during barley infection.

Infection Strategies and Pathogenicity of Biotrophic Plant Fungal Pathogens

“…Moreover, the effectors of biotrophic fungi camouflage the host as modulators, leading to the diversion of the metabolic flux of many compounds, resulting in a deficiency of precursors or compounds responsible for host defense ( Tanaka et al, 2014 ; van der Linde and Göhre, 2021 ). Some well-known other examples are: CSEP0055 ( Zhang et al, 2012 ), BEC3, BEC4 ( Schmidt et al, 2014 ), CSEP0105, CSEP0162 ( Ahmed et al, 2015 ), BEC1054 ( Pennington et al, 2016 ), BEC1019 ( Zhang et al, 2019 ), CSEP0027 ( Yuan et al, 2021 ), CSEP0139 and CSEP0182 ( Li et al, 2021 ) from Bgh and AvrPm3 a 1/ f 1 from Bgt ( Bourras et al, 2015 ; Parlange et al, 2015 ). The effector protein PNPi of Pt acts directly on wheat TaNPR1 to inhibit resistance of wheat to leaf rust ( Bi et al, 2020 ).…”

Deciphering the genome of Simplicillium aogashimaense to understand its mechanisms against the wheat powdery mildew fungus Blumeria graminis f. sp. tritici

“…Therefore, these two genes, which putatively code for effectors, may play crucial roles in mycoparasitic interactions. Effectors are reported to play crucial roles in phytopathogen-host and mycoparasitic agentphytopathogen systems (Laur et al 2018;Li et al 2021;Yuan et al 2021). However, the effectors and their mechanisms in the interaction between S. aogashimaense and Bgt have not been elucidated.…”

Protein-protein interactions in plant antioxidant defense

“…PTMs, such as phosphorylation, glycation, Tyr-nitration, acetylation, S-nitrosation regulate CATs functions ( Zou et al., 2015 ; Palma et al., 2020 ; Zhang et al., 2020 ). Notably, CATs are frequently bound and inhibited by pathogen effectors leading to pathogen spread and mitigation of host immunity ( Murota et al., 2017 ; Sun et al., 2017 ; Jiao et al., 2021 ; Yuan et al., 2021 ).…”