[ES] RNA silencing is a sequence specific gene regulation system that is highly preserved in eucalariots. In plants, this mechanism plays a very important role vis-à-vis exogenous nucleic acids such as transgenes or viral agents. Viruses generate, at some stage of their replication cycle, dual chain RNA (dsRNA) that activates this type of process. These dsRNA are recognised by enzymes with RNasa III activity, known as DCL (Dicer-like), the action of which generates small RNA (small RNA) of between 20 and 24 nt. Then, one of the channels of these SRNA is incorporated into a multiprotein complex known as RISC (RNA-induced silencing complex), the effective molecule of which is an endonuclease of the Argonautas family (AGO). Once activated, RISC is led by the SRNA to a complementary sequential RNA, promoting its degradation or suppressing translation. To counter this defensive barrel, plant viruses encode proteins known as viral RNA silencing suppressors (SRVs), whose mechanisms of action are diverse and complex and are often not fully understood. This work analysed the possible suppressive activity of the P0 protein of yellow veins of pepper 5 (Pepper vein yellows virus 5, PeVYV-5), a member of the genus Polerovirus (Luteoviridae family) that has been detected in our country and which poses a significant threat to pepper cultivation. The results obtained confirmed that the P0 protein of PeVYV-5 is capable of inhibiting silencing by RNA, consistent with that observed in other poleroviruses. Additional studies have shown that this protein is found in cytoplasma, nucleus and nucleole and forms homodymers in vivo. As the P0 protein of some poleroviruses has recently been described as capable of interacting with and inducing degradation with AGO1, it was decided to assess whether P0 of PeVYV-5 also interferes with this RISC component. Bimolecular fluorescse complementation (BiFC) tests did not detect interaction of P0 with AGO1 or AGO4, also included in these tests. However, an analysis of the accumulation of AGO proteins in the presence of the PeVYV-5 P0 protein indicated that this protein could be inducing degradation of different AGOs, which could explain the lack of detection of interactions in the BiFC assay. Additional experiments will confirm or refute whether the PeVYV-5 P0 protein is indeed capable of interacting and inducing degradation not only of AGO1, as proposed for P0 proteins of some members of the genus Polerovirus, but also of other AGO proteins. Bustos Valdearenas, M. (2021). Analysis of the suppressive RNA silencing protein of the yellow vein virus of pepper 5 (PeVYV-5). Universitat Politèca de València. http://hdl.handle.net/10251/168647