Phytophthora infestans effector AVR3a is essential for virulence and manipulates plant immunity by stabilizing host E3 ligase CMPG1
- 10 May 2010
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 107 (21), 9909-9914
- https://doi.org/10.1073/pnas.0914408107
Abstract
Fungal and oomycete plant pathogens translocate effector proteins into host cells to establish infection. However, virulence targets and modes of action of their effectors are unknown. Effector AVR3a from potato blight pathogen Phytophthora infestans is translocated into host cells and occurs in two forms: AVR3aKI, which is detected by potato resistance protein R3a, strongly suppresses infestin 1 (INF1)-triggered cell death (ICD), whereas AVR3aEM, which evades recognition by R3a, weakly suppresses host ICD. Here we show that AVR3a interacts with and stabilizes host U-box E3 ligase CMPG1, which is required for ICD. In contrast, AVR3aKI/Y147del, a mutant with a deleted C-terminal tyrosine residue that fails to suppress ICD, cannot interact with or stabilize CMPG1. CMPG1 is stabilized by the inhibitors MG132 and epoxomicin, indicating that it is degraded by the 26S proteasome. CMPG1 is degraded during ICD. However, it is stabilized by mutations in the U-box that prevent its E3 ligase activity. In stabilizing CMPG1, AVR3a thus modifies its normal activity. Remarkably, given the potential for hundreds of effector genes in the P. infestans genome, silencing Avr3a compromises P. infestans pathogenicity, suggesting that AVR3a is essential for virulence. Interestingly, Avr3a silencing can be complemented by in planta expression of Avr3aKI or Avr3aEM but not the Avr3aKI/Y147del mutant. Our data provide genetic evidence that AVR3a is an essential virulence factor that targets and stabilizes the plant E3 ligase CMPG1, potentially to prevent host cell death during the biotrophic phase of infection.Keywords
This publication has 34 references indexed in Scilit:
- Phytopathogen type III effector weaponry and their plant targetsCurrent Opinion in Plant Biology, 2008
- RXLR-Mediated Entry of Phytophthora sojae Effector Avr1b into Soybean Cells Does Not Require Pathogen-Encoded MachineryPlant Cell, 2008
- Oomycete RXLR effectors: delivery, functional redundancy and durable disease resistanceCurrent Opinion in Plant Biology, 2008
- A translocation signal for delivery of oomycete effector proteins into host plant cellsNature, 2007
- Groovy times: filamentous pathogen effectors revealedCurrent Opinion in Plant Biology, 2007
- The plant immune systemNature, 2006
- Subterfuge and Manipulation: Type III Effector Proteins of Phytopathogenic BacteriaAnnual Review of Microbiology, 2006
- A Catalogue of the Effector Secretome of Plant Pathogenic OomycetesAnnual Review of Phytopathology, 2006
- Host-Microbe Interactions: Shaping the Evolution of the Plant Immune ResponseCell, 2006
- Trafficking arms: oomycete effectors enter host plant cellsTrends in Microbiology, 2006