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Updated: Apr 17, 2026
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Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production
Published on: March 2, 2014
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PsAvh109 suppresses SA-triggered immunity by mimicking TPL function to disrupt mediator complex assembly.
Xinwei Tan1, Yujing Sun1, Zhaomei Qi1
1Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Taian, China.
Nature Communications
|April 15, 2026
Summary
Pathogen effectors mimic host repressors to disrupt plant immunity. Phytophthora sojae
Area of Science:
- Plant-pathogen interactions
- Molecular plant-pathology
- Eukaryotic transcription regulation
Background:
- Pathogens manipulate host transcriptional machinery to evade immunity.
- Spatiotemporal mechanisms of pathogen-mediated transcriptional suppression are poorly understood.
- Plant immune responses involve complex signaling networks, including salicylic acid (SA).
Purpose of the Study:
- To elucidate the molecular mechanisms by which Phytophthora sojae nuclear effectors interfere with host transcriptional regulation.
- To investigate the role of the Mediator complex in pathogen-induced immune suppression.
- To understand how pathogen effectors exploit host signaling dynamics.
Main Methods:
- Investigated the interaction of Phytophthora sojae nuclear effector PsAvh109 with the host Mediator complex.
- Utilized biochemical assays to demonstrate PsAvh109's mimicry of the host repressor TOPLESS (TPL).
- Analyzed the effect of PsAvh109 on salicylic acid (SA)-responsive genes and plant defense.
Main Results:
- Phytophthora sojae effector PsAvh109 directly targets the host Mediator complex.
- PsAvh109 functionally mimics the host repressor TOPLESS (TPL) by binding to MED21 and inhibiting MED21-MED6 interactions.
- This interaction represses SA-responsive defense genes, and PsAvh109 expression is induced by SA, enabling pathogen evasion during host defense activation.
Conclusions:
- Pathogens employ sophisticated strategies to subvert host immunity by manipulating core transcriptional machinery.
- Phytophthora sojae utilizes effector PsAvh109 to mimic host repressors, targeting the Mediator complex to silence defense genes.
- Pathogens exploit host signaling rhythms, releasing effectors during critical vulnerability windows to ensure sustained immune suppression.
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