New article published in New Phytologist


Temperature modulates virus-induced transcriptional gene silencing via secondary small RNAs

Yue Fei, Douglas E. Pyott, Attila Molnar


Different molecular mechanisms of virus induced posttranscriptional gene silencing (ViPTGS) and virus induced transcriptional gene silencing (ViTGS). At 22°C, in ViPTGS, primary siRNAs derived from tobacco rattle viruses (TRV)-GFP mediate GFP mRNA cleavage resulting posttranscriptional gene silencing (PTGS) of GFP. The cleavage of GFP mRNA can further trigger the amplification of secondary siRNAs from the plant-derived GFP transcript. The production of secondary siRNAs enhances PTGS of GFP in Nicotiana benthamiana 16c plants. In ViTGS, primary siRNAs derived from TRV-35S direct DNA methylation at the target 35S promoter sequence resulting transcriptional gene silencing (TGS) of GFP. ViTGS does not trigger secondary siRNAs amplification, but mainly depends on virus-derived primary siRNAs. At the higher temperature of 29°C, plants exhibit effective antiviral RNA silencing responses to clear viral RNAs. This limits the production of virus-derived primary siRNAs. Unlike ViPTGS, ViTGS is not able to produce a large number of secondary siRNAs and only depends on its primary siRNAs resulting the loss of silencing phenotype at later times of the infection process. Solid and dotted arrows indicate full and reduced flux, respectively