title: GmRIN4 protein family members function nonredundantly in soybean race-specific resistance against Pseudomonas syringae.
abstract: The Pseudomonas syringae effector AvrB interacts with four related soybean (Glycine max) proteins (GmRIN4a-d), three (GmRIN4b, c, d) of which also interact with the cognate resistance (R) protein, Rpg1-b. Here, we investigated the specific requirements for the GmRIN4 proteins in R-mediated resistance and examined the mechanism of Rpg1-b activation. Using virus-induced gene silencing, we show that only GmRIN4a and b are required for Rpg1-b-mediated resistance. In planta binding assays show that GmRIN4a can associate with Rpg1-b indirectly via GmRIN4b. Pathogen-delivered AvrB induces the phosphorylation of GmRIN4b alone, and prevents interactions between GmRIN4b and Rpg1-b or GmRIN4a. Consistent with this result, a phosphomimic derivative of GmRIN4b (pm4b) fails to bind Rpg1-b and GmRIN4a. Conversely, a phosphodeficient derivative of GmRIN4b (pd4b) continues to bind the R protein and GmRIN4a, in the presence of AvrB. Coexpression of Rpg1-b with pm4b, but not GmRIN4b or pd4b, induces cell death and ion leakage in the heterologous Nicotiana benthamiana. Our data suggest that the AvrB-induced phosphorylation of GmRIN4b, and the subsequent inhibition of interaction among GmRIN4b, GmRIN4a and Rpg1-b, might activate the R protein. Furthermore, even though GmRIN4c and d are not required for Rpg1-b-derived resistance, they do function in resistance derived from other R loci.
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY, 40546, USA.
authors.forename: Devarshi
authors.initials: D
authors.lastname: Selote
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY, 40546, USA.
authors.forename: Guillaume P
authors.initials: GP
authors.lastname: Robin
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY, 40546, USA.
authors.forename: Aardra
authors.initials: A
authors.lastname: Kachroo
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D060467:Disease Resistance / Q000235:genetics*; D010766:Phosphorylation; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D044224:Pseudomonas syringae / Q000276:immunology*; D013025:Glycine max / Q000235:genetics* / Q000382:microbiology
chemical_list: C100931:AvrB protein, Pseudomonas syringae; D001426:Bacterial Proteins; D010940:Plant Proteins