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N-Glycosylation Mediates Smut Effector Adaptation Toward a Host Pectin Methylesterase Inhibitor
Chibbhi Bhaskar1,2,3, Ee Yang Teoh1, Minh-Quang Chau1,2,3
1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
The Plant Cell
|August 10, 2026
Summary
Smut fungi overcome plant defenses by using N-glycosylation on their effector Nge1. This modification allows Nge1 to disable host pectin methylesterase inhibitors (PMEIs), weakening plant cell walls for pathogen colonization.
Area of Science:
- Plant-pathogen interactions
- Molecular plant pathology
- Biochemistry of cell walls
Background:
- Pectin methylesterases (PMEs) and inhibitors (PMEIs) regulate plant cell wall pectin demethylation.
- PMEIs strengthen plant walls against pathogens, but how biotrophic pathogens overcome this is unknown.
Purpose of the Study:
- Investigate how smut fungi, specifically Ustilago maydis, overcome host PMEI defenses.
- Determine the role of post-translational modifications in effector function.
Main Methods:
- Identified and characterized the N-glycosylated effector Nge1 from Ustilago maydis.
- Assessed Nge1 interaction with host PMEI45 and PMEI46.
- Engineered N-glycosylation sites into Nge1 orthologs.
- Complemented U. maydis Δnge1 mutant with engineered Nge1.
Main Results:
- Nge1 interacts with host PMEI45 and PMEI46 to suppress their inhibitory activity.
- N-glycosylation of Nge1 is crucial for PMEI45 interaction, enabling pectin demethylation and wall loosening.
- Engineered N-glycosylation restored Nge1 function, confirming its role in overcoming PMEI defenses.
Conclusions:
- Smut fungi employ N-glycosylation as a post-translational mechanism to adapt effectors for host PMEI interaction.
- This glycan modification allows pathogens to manipulate plant cell wall dynamics for successful colonization.