Plant response to bacterial TypeIII effectors Lihua

Plant responses to pathogens  Susceptibility: host-pathogens  Resistance: non-host pathogens Basal defense: first line defense PAMP-triggered immunity(PTI): common pathogen-associated moleculars (lipopolysaccharides, flagellin, elongation factor and peptidoglycans) Hypersensive response(HR): Avirulence protein-R protein interaction Effector-triggered immunity(ETI): Type III effetors (T3Es)

Structural class of R proteins Kruijt M et al. Molecular plant pathology 2005,6( 1 ),85–97

Avirulence and Virulence activity of effectors Block A et al. Current Opinion in Plant Biology 2008, 11:396–403

Effectors R proteins Host Targets Guard Hypothesis Response to its action instead of Effector itself 1.A R protein could response to two or more unrelated type III effectors targeting the same host machinery. 2. A host protein complex that is a common target of various effctors might be guarded by more than one R protein. Indirect interaction of Avr-R

Effectors R proteins Host Targets One Example AvrRpm1 AvrB AvrRpt2 RIN4 Rps2 Rpm1 Induce HR Couples: AvrB/AvrRpm1-Rpm1 AvrRpt2-Rps2

Yeast two-hybrid and coimmunoprecipitation data shows that: RIN4 directly interacts with AvrB, AvrRpm1 and RPM1 RIN4 is required for the HR induced by RPM1 Col-0: as positive control Rpm1/rps2: double mutant of two R proteins as negative control rin4-as : homozygous rin4 with normal morphology Key Experimental Test Mackey D et al. Cell : 743–754

AvrRpm1 or AvrB Induces RPM1-indepentdent Phosphorylation of RIN4 Key Experimental Test Mackey D et al. Cell : 743–754

AvrRpt2 induces disappearance of RIN4 Key Experimental Test Mackey D et al. Cell : 379–389 What does the disappearance do to the interaction of AvrRpt2-RPS2?

Overexpression of RIN4 suppresses RPS2-induced HR Key Experimental Test Elimination of RIN4 Activates RPS2: T-DNA insertion into the RIN4 gene is protein null and seedling lethal, while rin4/rps2 double mutants survive Mackey D et al. Cell : 379–389

Key Experimental Test AvrRpt2 is sufficient to induce degradation of RIN4 AvrRpt2 could block the function of RPM1 By reducing RIN4 Mackey D et al. Cell : 379–389 Protein mRNA avrRpm1-RIN4-Rpm1 avrRps2-RIN4-Rps2

Conclusion RIN4 is required for the HR induced by both RPM1 and RPS2 AvrRpm1 or AvrB Induces RPM1-indepentdent Phosphorylation of RIN4, and RPM1 recognizes the phosphorylation to induce HR AvrRpt2 induces disappearance of RIN4, and RPS2 induce HR by the recognization of disappearance

Weak point: 1. Need more convincing evidence from mass spectrometer about the phsophorylation of RIN4 since some other modification may exist; 2. Also need RIN4 in Col-0 treated with CIP as a control in following figure a 3.Need pattern of the expression level of RIN4 at different hours without inoculation of effectors in figure b. a b

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