Diverse soil RNA viral communities have the potential to influence grassland ecosystems across multiple trophic levels

Grassland ecosystems form 30-40%1 of total land cover and provide essential ecosystem services, including food production, flood mitigation and carbon storage2. Their productivity is closely related to soil microbial communities3, yet the role of viruses within these critical ecosystems is currently undercharacterised4 and in particular, our knowledge of soil RNA viruses is significantly limited5. Here, we applied viromics6 to characterise soil RNA viral communities along an altitudinal productivity gradient of peat, managed grassland and coastal soils. We identified 3,462 viral operational taxonomic units (vOTUs) and assessed their spatial distribution, phylogenetic diversity and potential host ranges. Soil types exhibited showed minimal similarity in viral community composition, but with >10-fold more vOTUs shared between managed grassland soils when compared with peat or coastal soils. Phylogenetic analyses of viral sequences predicted broad host ranges including bacteria, plants, fungi, vertebrates and invertebrates, contrasting with soil DNA viromes which are typically dominated by bacteriophages7. RNA viral communities therefore likely have the ability to influence soil ecosystems across multiple trophic levels. Our study represents an important step towards the characterisation of terrestrial RNA viral communities and the intricate interactions with their hosts, which will provide a more holistic view of the biology of economically and ecologically important terrestrial ecosystems.