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Poster

Session: Session 1 Presenting Authors at Posters (Odds)

P-229 - A Tomato RNase H1 Enzyme Modulates PepMV Infection and May Influence R-Loop Homeostasis

Monday, July 14, 2025
13:30 - 15:15  
Location: Confex Hall 3
Plant-virus Interactions (incl. Viromes, Evolution & Vectors)
Type 1 RNases H are conserved enzymes across all organisms that degrade the RNA strand of RNA/DNA hybrids, playing a key role in nucleic acid metabolism and R-loop regulation. R-loops are widespread structures across genomes formed by an RNA/DNA duplex and the displaced single-stranded DNA. They have been well studied in animals, acting as mediators/modulators of different processes such as gene transcription and genome stability. Although studies in plants are scarce, evidence suggests that R-loops might act as regulators of plant development and stress responses. In this study, we identified members of a family of tomato RNase H proteins that affect pepino mosaic virus (PepMV, species Potexvirus pepini) infection. RNaseH1A1 interacts with the CP and the TGB1 viral proteins and relocalizes to viral replication organelles, as observed by confocal microscopy following transient expression in Nicotiana benthamiana. CRISPR/Cas9-generated double knockout tomato mutants for RNaseH1A1 and its paralog RNaseH1B1 exhibited increased viral accumulation compared with wild-type plants. Transcriptomic analysis of the mutant revealed differential expression of genes involved in defense perception and signalling, suggesting a potential alteration of its immune responses. We are currently investigating the genome-wide distribution of R-lopps in healthy and PepMV-infected tomato plants to explore their possible connection to RNaseH1A1 function and virus susceptibility.