Cytosine DNA methylation is an epigenetic modification that regulates gene expression, represses transposable elements (TEs), and maintains genome integrity.The establishment of DNA methylation in all sequence contexts is mediated by 24-nucleotide (nt) small interfering RNAs (siRNAs) through a specialized RNA interference (RNAi) pathway referred to as RNA-directed DNA methylation (RdDM).Twenty-four-nt siRNAs are known to be processed from double-stranded RNAs by Dicer-like 3 (DCL3) and loaded into the effector Argonaute 4 (AGO4).In my talk, I will present our recent findings with regard to an alternative route for siRNA biogenesis and discuss its role in the initiation of RdDM.