Soil-borne plasmodiophorid-transmitted plant viruses are causing economically important diseases on major crops such as wheat, rice, potato, sugar beet and groundnut. If much is known now about the virus genomes and the interaction with the plants, challenges are still ahead to fully understand how the viruses are transmitted by their zoosporic vector. Furthermore, the emergence of resistance-breaking virus isolates has triggered attention to these viruses.
Several soil-borne virus models will be presented before focusing on rhizomania, one of the major sugar beet diseases, caused by the Beet necrotic yellow vein virus, and often associated with Beet soil-borne virus and Beet virus Q, two pomoviruses. Complementary to reverse genetic approaches, data gathered at the field level will be displayed, focusing on the spatial and temporal virus diversity. The evidence for divergent microevolution of the virus as shown by next generation 454 deep sequencing of targeted virus genes, and linked with dependence on the sugar beet cultivars, will be discussed.