Movement of Arabidopsis thaliana inverted repeat small RNA between leaves vascular and epidermis tissues

We aimed at characterizing the identity of the silencing signal i.e. siRNA or longer dsRNA precursor thereof. We used transgenic dsRNA, endogenous dsRNA or virus infection as sources of siRNAs combined to sophisticated immunoprecipitation-based procedures coupled to deep-sequencing. We found that siRNAs populations are highly similar between incipient and recipient cells in the three systems. Additionally, a significant depletion of 5’U and 5’A content in the recipient cells suggested Argonaute-loading dependent depletion of these siRNAs during their movement over multiple cell layers. Using the PAZ-domain mutants ago1-18 and ago1-42 confirmed that the observed depletion of mobile siRNAs is the result of RISC loading. The results advocate movement of individual siRNA duplexes as opposed to their precursors and that loading into Argonaut proteins renders those small RNAs cell-autonomous. small RNA from vasculature and epidermis tissus from Arabidopsis thaliana Col0 leaves (2 replicates for each) . RNA-seq from Arabidopsis thaliana epidermis in Col0 WT plants or ir71 mutant (2 replicates for each).