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mRNA Inventory of Extracellular Vesicles from Ustilago maydis
Seomun Kwon1, Oliver Rupp2, Andreas Brachmann3
1Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.
Abstract:
Extracellular vesicles (EVs) can transfer diverse RNA cargo for intercellular communication. EV-associated RNAs have been found in diverse fungi and were proposed to be relevant for pathogenesis in animal hosts. In plant-pathogen interactions, small RNAs are exchanged in a cross-kingdom RNAi warfare and EVs were considered to be a delivery mechanism. To extend the search for EV-associated molecules involved in plant-pathogen communication, we have characterised the repertoire of EV-associated mRNAs secreted by the maize smut pathogen, Ustilago maydis. For this initial survey, we examined EV-enriched fractions from axenic filamentous cultures that mimic infectious hyphae. EV-associated RNAs were resistant to degradation by RNases and the presence of intact mRNAs was evident. The set of mRNAs enriched inside EVs relative to the fungal cells are functionally distinct from those that are depleted from EVs. mRNAs encoding metabolic enzymes are particularly enriched. Intriguingly, mRNAs of some known effectors and other proteins linked to virulence were also found in EVs. Furthermore, several mRNAs enriched in EVs are also upregulated during infection, suggesting that EV-associated mRNAs may participate in plant-pathogen interactions.
Insights
Extracellular vesicles (EVs) from the maize smut pathogen Ustilago maydis carry messenger RNAs (mRNAs). These EV-associated mRNAs may play a role in plant-pathogen communication and virulence.
Area of Science:
- Plant pathology
- Mycology
- Molecular biology
Background:
- Extracellular vesicles (EVs) mediate intercellular communication by transferring RNA cargo.
- EV-associated RNAs are found in fungi and may contribute to pathogenesis.
- Cross-kingdom RNA exchange via EVs is implicated in plant-pathogen interactions.
Purpose of the Study:
- To characterize messenger RNA (mRNA) repertoires within EVs secreted by the maize smut pathogen, Ustilago maydis.
- To investigate the potential role of EV-associated mRNAs in plant-pathogen communication.
- To identify specific mRNAs enriched in EVs during conditions mimicking infection.
Main Methods:
- Isolation and characterization of EV-enriched fractions from axenic filamentous cultures of Ustilago maydis.
- Assessment of RNA integrity and resistance to RNase degradation within EVs.
- Comparative analysis of mRNA content inside EVs versus fungal cells.
Main Results:
- EV-associated RNAs, including intact mRNAs, were resistant to RNase degradation.
- EV-enriched mRNAs were functionally distinct from those depleted in EVs.
- mRNAs encoding metabolic enzymes, virulence factors, and effectors were enriched in EVs.
- Several EV-enriched mRNAs were also upregulated during host infection.
Conclusions:
- Ustilago maydis secretes EVs containing a distinct repertoire of mRNAs.
- EV-associated mRNAs, particularly those linked to virulence, may be transferred to host plants.
- These findings suggest a novel mechanism of intercellular communication and potential virulence strategy in plant-pathogen interactions.
