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Published on: March 17, 2010
The maize cystatin CC9 interacts with apoplastic cysteine proteases
Karina van der Linde1, André N Mueller, Christoph Hemetsberger
1Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
Plant Signaling & Behavior
|September 11, 2012
Summary
Corn cystatin9 (CC9) is a novel maize protein that prevents the biotrophic smut fungus Ustilago maydis from activating plant defenses. CC9 inhibits proteases, suppressing Ustilago maydis infection and ensuring compatibility.
Area of Science:
- Plant-pathogen interactions
- Molecular plant pathology
- Biochemistry
Background:
- Biotrophic fungi like Ustilago maydis require host compatibility factors for successful infection.
- Plant immune responses, including salicylic acid (SA) signaling and PR-gene expression, can be triggered by specific proteases.
- Apoplastic papain-like cysteine proteases are implicated in plant defense activation.
Purpose of the Study:
- To investigate the role of corn cystatin9 (CC9) as a compatibility factor in the Ustilago maydis-maize interaction.
- To elucidate the mechanism by which CC9 suppresses maize host immunity.
- To analyze plant cystatin-protease interactions in silico.
Main Methods:
- Transcriptional analysis of CC9 during U. maydis infection.
- Localization studies of CC9 in the maize apoplast.
- Biochemical assays to determine CC9's inhibition of apoplastic cysteine proteases.
- In silico analysis of plant cystatins and apoplastic cysteine proteases.
Main Results:
- CC9 is transcriptionally induced during compatible U. maydis-maize interactions.
- CC9 localizes to the maize apoplast and inhibits apoplastic papain-like cysteine proteases.
- Inhibition of these proteases by CC9 prevents SA signaling and PR-gene expression.
- Experimental and in silico data support the cysteine protease-cystatin interaction.
Conclusions:
- Corn cystatin9 (CC9) is a crucial compatibility factor for Ustilago maydis.
- CC9 suppresses maize immunity by inhibiting apoplastic cysteine proteases, thereby preventing salicylic acid-mediated defense.
- Understanding CC9's mechanism provides insights into plant-pathogen interactions and potential strategies for disease management.
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