HETEROLOGOUS RNA-RNA INTERACTIONS INVOLVED IN THE PRESERVATION OF BEET NECROTIC YELLOW VEIN VIRUS GENOME INTEGRITY

Multipartite phytoviruses are characterized by having two or more genomic segments packaged in independent particles. To ensure a productive infection, such heterogeneous group of viruses has to preserve their genome as a functional unit ensuring the presence of at least one of each viral segment in the target cell. Such condition implies a mechanism that elude the biological costs of having its own genome split in physically separated components. The high level of multiplicity of infection (MOI) together with the physical constrains that a multipartite virus faces during its journey in the host vascular tissues, make, in fact, the uncoordinated trafficking of viral particles an unrealistic model of viral movement across the plant. We therefore hypothesized a model for multipartite phytoviruses ssRNA(+) whereby each genomic RNA is specifically recognized by a network of RNA/RNA interaction and packaged in a modular ribonucleoprotein (RNP) complex. Beet necrotic yellow vein virus (BNYVV) possess the higher number of genomic segments (RNA1 to 5) within ssRNA(+) viruses. Among them RNA1 together with RNA2 is sufficient for viral replication and long distant movement in susceptible hosts. Consequently, we decided to investigate the existence of specific heterologous interactions between these RNAs evaluating their role in the formation of genome complexes. By Electro Mobility Gel Shift Assays (EMSA) and reverse genetic approaches we identified specific interaction domains in each RNAs possibly involved in the BNYVV infectivity.