Perturbation of plant immunity and engagement of the plant cellular stress response by the core Xanthomonas type III effector protein XopX
Abstract/Contents
- Abstract
- Many of the most dangerous bacterial pathogens that cause disease in plants and animals utilize a common strategy to promote their survival during infection: via the type III secretion system (T3SS), they deliver effector proteins (T3Es) directly into their host's cells. The goal of this work was to identify the function of the uncharacterized Xanthomonas T3E XopX in the plant cell during bacterial pathogenesis. XopX was originally identified as a Xanthomonas euvesicatoria (Xe) factor that elicited plant cell death in the Xe non-host, Nicotiana benthamiana. XopX is a "core" Xanthomonas T3E and is required for full Xe growth and symptom development in the natural Xe hosts, tomato and pepper. However, it is unclear how XopX contributes to Xe pathogenesis. I investigated the role of XopX in suppressing plant immunity. Although XopX suppressed a flagellin-induced reactive oxygen species burst when expressed in N. benthamiana, the primary phenotypes associated with XopX in tomato were transcription of plant defense genes, accumulation of ethylene, and activation of host cell death. These phenotypes are indicative of a weak plant defense response to XopX and may account for XopX's role in promoting Xe symptoms in infected tomato. XopX interacted directly with plant Class I DnaJ proteins, and an RNA-seq analysis of the tomato transcriptome in Xe-treated leaves indicated that XopX elicited a stress response in tomato leaves, including the transcription of several tomato genes that encode molecular chaperones. These results indicate that XopX engaged the plant cell stress response, but it is unclear whether this engagement is linked to XopX virulence activity or elicitation of plant defense. Taken together, the results of this work are consistent with a previously described "default to death and defense" model of plant immunity, in which XopX interferes with a basic host cell process (protein folding) to promote pathogenesis, but prolonged interference with this process by XopX is detected by the host cell and activates a death and defense response.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2014 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Stork, William Francis James |
|---|---|
| Associated with | Stanford University, Department of Biology. |
| Primary advisor | Mudgett, Mary Beth, 1967- |
| Thesis advisor | Mudgett, Mary Beth, 1967- |
| Thesis advisor | Bergmann, Dominique |
| Thesis advisor | Long, Sharon |
| Advisor | Bergmann, Dominique |
| Advisor | Long, Sharon |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | William Francis James Stork. |
|---|---|
| Note | Submitted to the Department of Biology. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2014. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2014 by William Stork
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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