Résumé
Viral diseases transmitted by Polymyxa are complex pathosystems involving three actors: a plant host, an obligate ndoparasitic protist vector (Polymyxa spp.) and a virus. These pathosystems involve major crops such as wheat, rice, sugar beets, etc. and a large diversity of viruses belonging to the Furovirus, Benyvirus, Pomovirus, Bymovirus and Pecluvirus genera, in temperate and tropical areas. Despite the vast distribution of these pathosystems, only a few genomic and transcriptomic studies involving the vector Polymyxa are available. The obligate endoparasitic nature of the vector – which complicates its multiplication and prevents its isolation from the host – is largely the reason why the first Polymyxa betae (Pb) genome was only recently sequenced. This also explains why almost no genomic data is available for Polymyxa graminis (Pg). This lack of data is an obstacle to further understanding host-Pg-virus interactions, as the sequencing of Pg is key to characterize the parasitic lifestyle of this vector and to develop molecular tools to study Pg under controlled conditions. Ourresearch aims to provide new Pg genomic and transcriptomic data, starting with the first sequencing of Pg f.sp. colombiana (Pgcol) genome. Methods developed for Pgcol multiplication in rice roots, quantification, sequencing, and data analysis are presented, as well as the preliminary results of the first sequencing. These results are a first step to improve the understanding of host-Polymyxa-virus interactions, in particular (1) reviewing of the Polymyxa spp. phylogeny with new genomic data, (2) studying the host-Polymyxa-virus compatible and non-compatible interaction based on the identification of Pg effectors and transcriptomic analyses, and finally, (3) studying the virus-vector acquisition and transmission mechanism