RNA molecules are generally known for their instability. Yet, certain higher plants can be infected by pathogens composed solely of small, circular RNA molecules that are both naked and highly stable. These pathogens, known as viroids, do not encode any proteins. Viroids replicate either in the nucleus or in the chloroplasts of plant cells. But how do these naked RNA molecules achieve such remarkable stability? Could RNA modifications play a role?
A research team led by Hana Cahová from IOCB Prague, in collaboration with colleagues from the Institute for Sustainable Plant Protection in Italy, investigated RNA modifications in two viroid species. Surprisingly, they did not find any modification in chloroplastic family of viroids, but they identified the presence of the 6-methyladenosine (m6A) modification in the citrus exocortis viroid (CEVd), which replicates in the nucleus of plant cells. Furthermore, they proposed two specific positions where this methylation might occur.
Further studies could clarify the functional role of the m6A modification at these positions and its impact on the viroid's infectious cycle.
Read the paper: Vopálenský, P.; Škríba, A.; Chiumenti, M.; Ďuričeková, L.; Šimonová, A.; Lukšan, O.; di Serio, F.; Navarro, B.; Cahová, H. Exploring RNA Modifications in Infectious Non-Coding Circular RNAs. RNA Biol. 2025. https://doi.org/10.1080/15476286.2025.2459039
