The article by Mette et al. (2000) investigates the role of double-stranded RNA (dsRNA) in triggering transcriptional gene silencing (TGS) and promoter methylation in plants. The authors demonstrate that dsRNA containing promoter sequences can induce TGS and de novo methylation of target promoters, similar to the process of RNA interference (RNAi) in other organisms. They show that the dsRNA produced in the nucleus is partially cleaved into small interfering RNAs (siRNAs) of approximately 23 nucleotides, which are involved in both TGS and DNA methylation. The study also explores various constructs designed to produce dsRNA in different ways and evaluates their effectiveness in inducing gene silencing in tobacco and Arabidopsis. The results indicate that RNA hairpins transcribed from inverted DNA repeats are the most effective trans-acting silencing signals. The findings suggest that dsRNA plays a crucial role in directing DNA methylation and could be a useful tool for downregulating genes in various plants.The article by Mette et al. (2000) investigates the role of double-stranded RNA (dsRNA) in triggering transcriptional gene silencing (TGS) and promoter methylation in plants. The authors demonstrate that dsRNA containing promoter sequences can induce TGS and de novo methylation of target promoters, similar to the process of RNA interference (RNAi) in other organisms. They show that the dsRNA produced in the nucleus is partially cleaved into small interfering RNAs (siRNAs) of approximately 23 nucleotides, which are involved in both TGS and DNA methylation. The study also explores various constructs designed to produce dsRNA in different ways and evaluates their effectiveness in inducing gene silencing in tobacco and Arabidopsis. The results indicate that RNA hairpins transcribed from inverted DNA repeats are the most effective trans-acting silencing signals. The findings suggest that dsRNA plays a crucial role in directing DNA methylation and could be a useful tool for downregulating genes in various plants.