Fungal Effector Protein Protects Wheat Pathogen from Competing Bacteria
Researchers discovered that AvrStb6, an effector protein from the wheat fungal pathogen Zymoseptoria tritici, protects the fungus from antagonistic bacteria in the plant microbiota rather than directly attacking bacteria as previously hypothesized. The protein associates with the fungal cell wall and reduces the fungus's sensitivity to bacterial competitors like Pseudomonas and Pantoea species. This finding expands understanding of how fungal effectors function beyond triggering plant immune responses, suggesting they play roles in microbial competition within plants.
A bioRxiv preprint reports that AvrStb6, a secreted effector protein from Zymoseptoria tritici (the fungus causing Septoria tritici blotch in wheat), has an unexpected biological function: protecting the pathogen from antagonistic bacteria in the plant microbiota. Researchers initially hypothesized the protein functioned as an antimicrobial agent based on its predicted structure, but in vitro assays showed it does not directly inhibit bacterial growth. Instead, microbiome analyses revealed that AvrStb6 alters bacterial community composition in wheat plants. Confrontation assays demonstrated that fungal strains lacking AvrStb6 became more sensitive to Pseudomonas and Pantoea bacteria, a phenotype consistent across multiple fungal genetic backgrounds. Biochemical work showed AvrStb6 associates with the fungal cell wall, distinguishing it from other secreted effectors. The findings suggest fungal effectors contribute to ecological adaptation and microbial competition within plants, beyond their known roles in triggering plant immune recognition.
What's missing
The study does not discuss the evolutionary origins of this protective function or whether similar mechanisms exist in other fungal pathogens. The practical implications for disease management or breeding strategies are not addressed. The preprint status means peer review findings are not yet available.
What different sources said
- bioRxivCenter
An effector protein that protects a fungal pathogen from the plant microbiota during host colonisation
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