Diversity and ecological roles of RNA viral communities in the cryosphere of the Tibetan Plateau

RNA viruses play crucial roles in modulating host communities, but their diversity and ecological roles in the cryosphere are poorly understood. We investigated the RNA virome from the cryosphere of the Tibetan Plateau (TPC), the largest area of the cryosphere in the mid-low latitude regions, which includes 79 metatranscriptomes from ecosystems including glaciers, proglacial lake sediments, permafrost wetland and upland soils. We obtained 8,799 RNA-dependent RNA polymerase encoding contigs, which clustered into 5,333 viral species, adding more than 4,900 new RNA viral species to the global RNA virome database. The recovered RNA viruses primarily infect prokaryotes, distinctively different from the dominance of eukaryotic RNA viruses in oceanic ecosystems. In addition to the known taxa such as Leviviricetes, we identified novel clades of putative prokaryotic RNA viruses, which greatly extended our understanding of their diversity. We further expanded the host of RNA virus by 20 additional prokaryotic phylum- or class-level taxonomic groups. Moreover, the TPC RNA viruses encoded dozens of auxiliary metabolic genes that could reprogram the metabolisms of diverse hosts, including photosynthesis in glacier eukaryotic algae and cyanobacteria, which may exert great impacts on glacier dynamics through modulating host adaptation. Furthermore, we identified potential pathogenic RNA viruses in various cryosphere environments, though their overall risks are low. This study provides the first comprehensive view of cryosphere RNA virome, highlighting their high diversity, vital ecological functions, and potential health impacts.