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Poster

Session: Session 1 Presenting Authors at Posters (Odds)

P-257 - Role of small RNA production and mobility in viral symptom recovery

Monday, July 14, 2025
13:30 - 15:15  
Location: Confex Hall 3
Plant-virus Interactions (incl. Viromes, Evolution & Vectors)
Plants in natural ecosystems tolerate viral infections, allowing replication and movement while maintaining fitness and reproduction. In Arabidopsis thaliana, tolerance varies among ecotypes and viruses, making it a key model for studying the underlying mechanisms. Col-0 tolerates Tobacco mosaic virus (TMV) but develops disease upon infection with Oilseed rape mosaic virus (ORMV). Interestingly, ORMV-infected plants can recover from symptoms despite continued replication. This “induced tolerance” correlates with the inactivation of the viral suppressor of RNA silencing (VSR) and requires key components of post-transcriptional and transcriptional gene silencing (PTGS/TGS), such as RDR2 and RDR6, DCL2 and DCL4, and also RNA polymerase IV (Pol IV). Moreover, recovery is linked to the accumulation of virus-derived siRNAs (vsiRNAs) and host siRNAs, including virus-activated (vasiRNAs) and Pol IV-dependent siRNAs. We propose that these siRNAs, are produced in symptomatic tissues, and move systemically, saturating VSR activity, thus blocking miRNA sequestration by this protein and enabling recovery. This study highlights the interplay between viral VSRs and mobile siRNAs in determining the outcome of infection.