The cellular RNA-dependent RNA polymerases in plants.

RNA-dependent RNA Polymerases (RdRPs) synthesize double-stranded RNA (dsRNA) from a single-stranded RNA (ssRNA) template. In plants, dsRNAs produced by RdRPs can be further processed into small interfering RNA (siRNAs) with different lengths, ranging from 21 to 24 nucleotides (nt). These siRNAs play a pivotal role in various biological processes, including antiviral responses, transposable elements silencing, DNA methylation, and the regulation of plant reproduction and development. Recent research has reported significant progress in uncovering the molecular mechanisms of plant RNA-DEPENDENT RNA POLYMERASE 2 (RDR2), a representative RdRP involved in the RNA-directed DNA methylation (RdDM) pathway. These discoveries provide a molecular basis underlying the principles of RdRP function and offer insights into potential advancements in crop breeding and antiviral defense strategies.

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