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Concurrent Session

Session: Concurrent Session: RNA on the move: Advances in Cross-Species Communication & Translational Research

Extracellular proteins facilitate fungal EV entry into plant cells to induce cross-kingdom RNA interference

Tuesday, July 15, 2025
12:10 - 12:30  
Location: Room P+Q

Abstract Text:

The fungal pathogen Botrytis cinerea delivers small RNAs (Bc-sRNAs) into plant hosts via extracellular vesicles (BcEVs) to induce cross-kingdom RNA interference (ckRNAi). However, the underlying mechanisms by which EVs can pass through cellular barriers, such as the rigid plant cell wall, remain elusive. Here, we provide new evidence for BcEV-induced ckRNAi and that fungal secreted proteins are essential for Bc-sRNA delivery. We isolated BcEVs containing Bc-sRNAs that can induce ckRNAi in the host plant Arabidopsis. Using a GFP reporter system, we visualized the dynamics of BcEV-induced gene silencing in planta by live-cell imaging. Strikingly, BcEVs purified via size-exclusion chromatography (SEC) failed to induce ckRNAi, indicating that BcEVs require additional molecular factors to deliver Bc-sRNAs into plants. We performed comparative proteomics of crude versus SEC-purified BcEVs and identified several fungal cell wall remodeling enzymes (CWREs) and other secreted proteins that were enriched in the crude BcEVs. Combining the SEC protein fraction with the purified BcEVs reactivated ckRNAi, while crude BcEVs, upon protein degradation, lost their activity. Taken together, these findings suggest that fungal secreted proteins are essential to trigger ckRNAi in plants. We are currently testing whether CWREs are one key factor in loosening the plant cell wall for BcEV delivery.