The ecology of multipartite plant viruses: insight into genome plasticity from experimental investigation and metagenomics

Summary

Plant viruses are ubiquitous in plant ecosystems. They have diverse genome organisation strategies: they can be monopartite, segmented, or multipartite. A multipartite genome organization, where multiple viral genome segments are packaged into separate virus particles, comes at an evolutionary cost. One recent hypothesis proposes that multipartite viruses benefit from a unique type of genome plasticity, where the abundance of each segment varies and depends on the environment. This PhD thesis aims to integrate this hypothesis into ecology by examining the impact of mixed infections on virus accumulation, and the influence of land use changes on plant virome composition, richness and virus accumulation. Results indicate that mixed viral infections constrain the variability of the viral segment abundance. Additionally, a field study reveals associations between plant virus community composition and sites of similar age. The research also highlights variability in segment abundance for specific multipartite viruses and suggests future experiments to understand how environmental factors influence these differences. Overall, the thesis contributes insights into the ecological aspects of multipartite plant viruses.