GSE133411
FIERY1 promotes microRNA accumulation by suppressing rRNA-derived small interfering RNAs in Arabidopsis [RNA-seq]
Plant  microRNAs (miRNAs) associate with ARGONAUTE1 (AGO1) to direct post-transcriptional gene silencing and regulate numerous biological processes. Although AGO1 predominantly binds miRNAs in vivo, AGO1 also associates with endogenous small interfering RNAs (siRNAs). It is unclear whether the miRNA/siRNA balance affects miRNA activities. Here we report that FIERY1 (FRY1), which is involved in 5'-3' RNA degradation, regulates miRNA abundance and function by suppressing the biogenesis of ribosomal RNA-derived siRNAs (risiRNAs). In mutants of FRY1 and the nuclear 5'-3' exonuclease genes XRN2 and XRN3, we found that a large number of 21-nt risiRNAs were generated through an endogenous siRNA biogenesis pathway. The production of risiRNAs correlated with pre-rRNA processing defects in these mutants. We also show that these risiRNAs were loaded into AGO1, causing reduced loading of miRNAs. This study reveals a previously unknown link between rRNA processing and miRNA accumulation. Overall design: RNA-seq in WT, fry1-6, fry1-6 rdr6-11, and fry1-6 rdr1-1, each with 2 biological replicates