Abstract :
[en] Among cereal pathogens, Barley yellow dwarf virus (BYDV; genus Luteovirus, family Luteoviridae) is the most damaging virus, infecting both wild and cultivated species. BYDV is a single-stranded, positive-sense RNA virus. Therefore, it shows a high mutation rate and a small genome size, allowing its fast evolution. In the field, the presence of different host plant species can impact strongly the probability of epidemic outbreaks. The latter can be due, for instance, to viral mutations showing pleiotropic effects on different hosts. In this context, our goal was to study the impact of both cultivated and wild Poaceae species on BYDV evolution.
Four cultivated (Triticum aestivum, Avena sativa, Hordeum vulgare and Hordeum hexastichum) and two wild (Poa annua and Lolium perenne) Poaceae species were used in order to perform experimental evolution. An initial viral population composed of both BYDV-PAV and BYDV-PAS species has been used to inoculate all plants, using Rhopalosiphum padi L. aphid as a vector. During four months, the viral populations have been serially passaged on the same host species. Then, the viral populations coming from cultivated species have been passed on wild species and vice versa for three more months. The viral accumulation has been used as a proxy of the viral population fitness and has been measured at different time points of the experiment using quantitative ELISA. Using high throughput sequencing of total RNA, the change in the structure of the viral populations over time was also investigated. Finally, haplotype reconstructions of BYDV have been performed using PEHaplo de novo assembly tool. The analysis revealed that the bottlenecks associated with aphid transmission have a strong impact on the evolution of the viral population. A strong effect of the plant type (i.e. cultivated or wild) and species has also been observed.
