Elucidating the early transcriptional response to the systemic acquired resistance-activating metabolite N-hydroxy-pipecolic acid in arabidopsis
Abstract/Contents
- Abstract
- Systemic acquired resistance (SAR) is a robust immune response in plants that confers long-lasting and broad-spectrum disease resistance throughout the body of a plant. Establishment of SAR begins at the site of an initial pathogen infection where mobile signals are sent out from infected tissue to uninfected tissue, initiating the priming of systemic immune responses. In part, this priming is carried out through accumulation of the defense hormone salicylic acid (SA) and through substantial transcriptional reprogramming to prioritize defense. N-hydroxy-pipecolic acid (NHP) has emerged as a powerful mobile signal required for the initiation and amplification of SAR. In the model plant Arabidopsis thaliana (Arabidopsis), exogenous NHP is sufficient to activate SAR-like immune responses, including SA accumulation and transcriptional changes. Previous studies have tracked these changes 1-2 days after an initial NHP treatment, when such responses could be detected in untreated, distal tissues. As a result, little was known about the very early phase of NHP signaling including the immediate transcriptional changes and physiological events that occur once NHP levels increase in tissues and how these impact the development of SAR. Furthermore, key players that orchestrate NHP signaling and the impact of SA accumulation on early NHP signaling were unknown. Here, I show that NHP induces genome-wide transcriptional changes in Arabidopsis seedlings within minutes of treatment and these distinct patterns of expression, over the course of minutes to hours, provide evidence toward the primary and secondary targets of NHP-driven signaling. My findings indicate that members of the WRKY transcription factor family are among the primary targets of NHP signaling, these in turn act as executors of secondary NHP transcriptional reprogramming. Additionally, through study into the early NHP transcriptomic response in the SA accumulation deficient mutant (sid2), I identified NHP responsive genes which are SA-independent and partially SA-independent, revealing that NHP can drive early signaling in a low-SA environment. Unexpectedly, I also uncovered preliminary evidence suggesting the relationship between early NHP and SA signaling is not only synergistic but also antagonistic in certain conditions. Using this transcriptomic dataset, I performed a reverse genetic screen to identify early NHP responsive genes. This screen revealed that the transcription factor WRKY70 is required for full NHP-elicited SAR. Overall, my thesis work is first to investigate and characterize the early time frame of NHP-induced transcriptional reprogramming. My research has helped to elucidate the progression of NHP signaling in the absence and presence of accumulating SA levels and provides a strong foundation for the discovery of key players involved in NHP signal transduction pathways important to the establishment of immune priming.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2023; ©2023 |
| Publication date | 2023; 2023 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Foret, Jessica Nicole |
|---|---|
| Degree supervisor | Mudgett, Mary Beth |
| Thesis advisor | Mudgett, Mary Beth |
| Thesis advisor | Bergmann, Dominique |
| Thesis advisor | Long, Sharon |
| Degree committee member | Bergmann, Dominique |
| Degree committee member | Long, Sharon |
| Associated with | Stanford University, School of Humanities and Sciences |
| Associated with | Stanford University, Department of Biology |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Jessica N. Foret. |
|---|---|
| Note | Submitted to the Department of Biology. |
| Thesis | Thesis Ph.D. Stanford University 2023. |
| Location | https://purl.stanford.edu/rr340fd7230 |
Access conditions
- Copyright
- © 2023 by Jessica Nicole Foret
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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