Mobile virus-derived siRNAs drive plant antiviral silencing through reiterated 3-4 cell immunization.

VsiRNAs drive plant antiviral immunity through reiterated 3-4 cell immunization events, even when intracellular RNAi is suppressed by TuYV infection.

• Why it matters: Understanding how plants defend against viruses is crucial for improving crop resistance, but the specific role of mobile vsiRNAs in immunity remains unclear due to the challenge of separating their movement from viral spread.
• What they did: Researchers examined the phloem-restricted infection of turnip yellows virus in Arabidopsis roots at cellular resolution, revealing complex mechanisms in both vsiRNA-emitting and -receiving cells that promote repeated short-range immunization.
• The result: Non-cell-autonomous vsiRNA immunization mainly accounts for controlling viral titers and tissue invasion, and it also spatially confines unrelated viruses over 3-4 cells, highlighting a key component of plant antiviral defense.