Back to Search
Start Over
Arabidopsis Actin-Depolymerizing Factor AtADF4 Mediates Defense Signal Transduction Triggered by the Pseudomonas syringae Effector AvrPphB
- Source :
- Plant Physiology. 150:815-824
- Publication Year :
- 2009
- Publisher :
- Oxford University Press (OUP), 2009.
-
Abstract
- The actin cytoskeleton has been implicated in plant defenses against pathogenic fungi and oomycetes with limited, indirect evidence. To date, there are no reports linking actin with resistance against phytopathogenic bacteria. The dynamic behavior of actin filaments is regulated by a diverse array of actin-binding proteins, among which is the Actin-Depolymerizing Factor (ADF) family of proteins. Here, we demonstrate that actin dynamics play a role in the activation of gene-for-gene resistance in Arabidopsis (Arabidopsis thaliana) following inoculation with the phytopathogenic bacterium Pseudomonas syringae pv tomato. Using a reverse genetics approach, we explored the roles of Arabidopsis ADFs in plant defenses. AtADF4 was identified as being specifically required for resistance triggered by the effector AvrPphB but not AvrRpt2 or AvrB. Recombinant AtADF4 bound to monomeric actin (G-actin) with a marked preference for the ADP-loaded form and inhibited the rate of nucleotide exchange on G-actin, indicating that AtADF4 is a bona fide actin-depolymerizing factor. Exogenous application of the actin-disrupting agent cytochalasin D partially rescued the Atadf4 mutant in the AvrPphB-mediated hypersensitive response, demonstrating that AtADF4 mediates defense signaling through modification of the actin cytoskeleton. Unlike the mechanism by which the actin cytoskeleton confers resistance against fungi and oomycetes, AtADF4 is not involved in resistance against pathogen entry. Collectively, this study identifies AtADF4 as a novel component of the plant defense signaling pathway and provides strong evidence for actin dynamics as a primary component that orchestrates plant defenses against P. syringae.
- Subjects :
- Hypersensitive response
Cytochalasin D
DNA, Plant
Physiology
Arabidopsis
Pseudomonas syringae
macromolecular substances
Plant Science
Microbiology
Bacterial Proteins
Gene Expression Regulation, Plant
Genetics
Animals
Arabidopsis thaliana
Gene Silencing
RNA, Messenger
Cytoskeleton
Actin
Plant Diseases
biology
Arabidopsis Proteins
Effector
Genetic Complementation Test
biology.organism_classification
Actin cytoskeleton
Actins
Immunity, Innate
Cell biology
Adenosine Diphosphate
Plant Leaves
Protein Transport
Destrin
Actin Depolymerizing Factors
Actin depolymerizing factor
Mutation
Rabbits
Protein Binding
Signal Transduction
Research Article
Subjects
Details
- ISSN :
- 15322548
- Volume :
- 150
- Database :
- OpenAIRE
- Journal :
- Plant Physiology
- Accession number :
- edsair.doi.dedup.....b8b6164663eaa4764b0f3bc7fa56aaad