Conventional PCR primers for the detection of grapevine pathogens disseminated by propagating material

Polymerase chain reaction driven by sequence specific primers has become the most widely used diagnostic method to detect andidentify plant pathogens. The sensitive and cost-effective pathogen detection is exceptionally important in the production of propagatingmaterial. In this paper we have collected primer sequence data from the literature for the detection of the most important grapevine pathogensdisseminated by propagating stocks by conventional polymerase chain reaction. Basic protocols to obtain template nucleic acids have alsobeen briefly rewieved

Polerovirus protein P0 prevents the assembly of small RNA-containing RISC complexes and leads to degradation of ARGONAUTE1

RNA silencing plays an important role in plants in defence against viruses. To overcome this defence, plant viruses encode suppressors of RNA silencing. The most common mode of silencing suppression is sequestration of double-stranded RNAs involved in the antiviral silencing pathways. Viral suppressors can also overcome silencing responses through protein-protein interaction. The poleroviral P0 silencing suppressor protein targets ARGONAUTE (AGO) proteins for degradation. AGO proteins are the core component of the RNA-induced silencing complex (RISC). We found that P0 does not interfere with the slicer activity of pre-programmed siRNA/miRNA containing AGO1, but prevents de novo formation of siRNA/miRNA containing AGO1. We show that the AGO1 protein is part of a high-molecular-weight complex, suggesting the existence of a multi-protein RISC in plants. We propose that P0 prevents RISC assembly by interacting with one of its protein components, thus inhibiting formation of siRNA/miRNA-RISC, and ultimately leading to AGO1 degradation. Our findings also suggest that siRNAs enhance the stability of co-expressed AGO1 in both the presence and absence of P0. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Ltd