title: The bacterial effector HopM1 suppresses PAMP-triggered oxidative burst and stomatal immunity.
abstract: Successful pathogens counter immunity at multiple levels, mostly through the action of effectors. Pseudomonas syringae secretes c. 30 effectors, some of which have been shown to inhibit plant immunity triggered upon perception of conserved pathogen-associated molecular patterns (PAMPs). One of these is HopM1, which impairs late immune responses through targeting the vesicle trafficking-related AtMIN7 for degradation. Here, we report that in planta expressed HopM1 suppresses two early PAMP-triggered responses, the oxidative burst and stomatal immunity, both of which seem to require proteasomal function but are independent of AtMIN7. Notably, a 14-3-3 protein, GRF8/AtMIN10, was found previously to be a target of HopM1 in vivo, and expression of HopM1 mimics the effect of chemically and genetically disrupting 14-3-3 function. Our data further show that the function of 14-3-3 proteins is required for PAMP-triggered oxidative burst and stomatal immunity, and chemical-mediated disruption of the 14-3-3 interactions with their client proteins restores virulence of a HopM1-deficient P. syringae mutant, providing a link between HopM1 and the involvement of 14-3-3 proteins in plant immunity. Taken together, these results unveil the impact of HopM1 on the PAMP-triggered oxidative burst and stomatal immunity in an AtMIN7-independent manner, most likely acting at the function of (a) 14-3-3 protein(s).
authors.affiliation: The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Rosa
authors.initials: R
authors.lastname: Lozano-Durán
authors.affiliation: The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Gildas
authors.initials: G
authors.lastname: Bourdais
authors.affiliation: Department of Energy Plant Research Laboratory, Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Michigan State University, East Lansing, MI, 48824, USA.
authors.forename: Sheng Yang
authors.initials: SY
authors.lastname: He
authors.affiliation: The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Silke
authors.initials: S
authors.lastname: Robatzek
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D017360:Arabidopsis / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects; D005408:Flagellin / Q000494:pharmacology; D055785:Gene Knockdown Techniques; D007976:Leupeptins / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000378:metabolism; D057865:Plant Immunity; D054046:Plant Stomata / Q000276:immunology* / Q000382:microbiology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D044224:Pseudomonas syringae / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D051192:Receptors, Pattern Recognition / Q000378:metabolism*; D016897:Respiratory Burst; D014026:Nicotiana / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D007976:Leupeptins; D017382:Reactive Oxygen Species; D051192:Receptors, Pattern Recognition; D005408:Flagellin; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde
keywords: 14-3-3; HopM1; PAMP/MAMP; TFT1; effector; immunity; oxidative burst; stomata