Plant virus-derived siRNAs stay a step ahead of viral short-range spread.

Plant virus-derived siRNAs establish an AGO1-dependent immune zone in uninfected short-range cells, with viral suppressors of RNA silencing affecting this pre-immunization.

• Why it matters: Understanding if mobile siRNAs can pre-immunize uninfected tissues addresses a key question in plant immune defense mechanisms and virus spread prevention.
• What they did: Albertini et al. used experimental approaches to show that virus-derived siRNAs create an immune zone in adjacent uninfected cells, which depends on AGO1 and is influenced by viral suppressors.
• The result: This finding suggests that mobile siRNAs can pre-emptively protect plant tissues from viral spread, highlighting a dynamic aspect of plant antiviral immunity.