Plant response to bacterial TypeIII effectors

1. Plant response to bacterial TypeIII effectors Lihua 12.3.08

2. 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)

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

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

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

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

7. Key Experimental Test 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 Mackey D et al. Cell 2002. 108: 743–754

8. Key Experimental Test AvrRpm1 or AvrB Induces RPM1-indepentdent Phosphorylation of RIN4 Mackey D et al. Cell 2002. 108: 743–754

9. Key Experimental Test AvrRpt2 induces disappearance of RIN4 What does the disappearance do to the interaction of AvrRpt2-RPS2? Mackey D et al. Cell 2003. 112: 379–389

10. Key Experimental Test Elimination of RIN4 Activates RPS2: T-DNA insertion into the RIN4 gene is protein null and seedling lethal, whilerin4/rps2 double mutants survive Overexpression of RIN4 suppresses RPS2-induced HR Mackey D et al. Cell 2003. 112: 379–389

11. Key Experimental Test AvrRpt2 is sufficient to induce degradation of RIN4 Protein mRNA avrRpm1-RIN4-Rpm1 avrRps2-RIN4-Rps2 AvrRpt2 could block the function of RPM1 By reducing RIN4 Mackey D et al. Cell 2003. 112: 379–389

12. 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 phosphorylationto induce HR AvrRpt2 induces disappearance of RIN4, and RPS2 induce HR by the recognization of disappearance

13. 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 a b 3.Need pattern of the expression level of RIN4 at different hours without inoculation of effectors in figure b.

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