Résumé
The Rice stripe necrosis virus (RSNV) is a Benyvirus spread across South America and re-emerging in West Africa, causing damages to rice crops (Lozano and Morales, 2009; Bagayoko et al., 2021). It is transmitted by the plasmodiophorid Polymyxa graminis f. sp. colombiana (Pgcol), a rice root obligate endoparasite. However, the extent of host ranges for both the virus and Pgcol is still largely unknown. This presentation aims to unravel the host range of RSNV and its vector, examining whether they are restricted to rice or capable of infecting other cereals. Host range assays in controlled conditions for the RSNV and its vector on various cereals and sugar beet suggest larger host ranges than previously reported. Moreover, detection of RSNV without its vector on sorghum indicates that the penetration of the vector in root cells without further development could be sufficient for RSNV transmission, as previously reported for the Peanut clump virus transmitted by Polymyxa graminis f. sp. tropicalis (Dieryck et al., 2011). Comparison of Pgcol incubation and multiplication rates, phenotype and its colonization capacity on different hosts will allow the characterization of specificity levels between Pgcol and its hosts. Additionally, the first genome sequencing of Pgcol will be presented, uncovering conserved genomic regions shared with Polymyxa betae that could be linked to the transmission of benyviruses. This will provide a foundation for understanding the molecular mechanisms behind Polymyxa-benyviruses interactions. Finally, a review of current phylogeny of Polymyxa species, including new sequences from isolates from Europe, North America, South America, and Africa and several new genes offers valuable insights into the evolution and geographic distribution of this genus of plant roots endoparasites.