Distance to the water table shapes the diversity and activity of DNA and RNA viruses in a subalpine peatland

Peatlands are essential reservoirs of carbon and critical zones for the cycling of greenhouse gases on Earth. Their ecological functions are primarily governed by the microbial communities inhabiting them, which vary with hydrological conditions. However, the roles of viruses in peatland ecosystems remain poorly understood despite their abundance and ubiquity. To address this gap, viral communities, their ecological roles, and their responses to environmental factors were explored using viromics, metatranscriptomics, and physicochemical property analyses of nine peat sediments collected from various layers of three profiles with different water table levels in the Dajiuhu Peatland, central China. This study revealed that the distance to the water table (DWT) significantly influenced the composition and function of viral communities by altering the levels of redox potential and total organic carbon, which in turn affected methane (CH₄) concentrations in pore water. Furthermore, a notable abundance of putative auxiliary metabolic genes associated with methane, nitrogen, and sulfur metabolism was identified in peatland DNA viruses, with their community composition strongly regulated by DWT. Additionally, functional genes related to oxidative phosphorylation and cysteine synthesis were detected for the first time in peatland RNA viruses. This study advances our comprehension of how hydrological conditions affect viral communities in peatlands, provides new insights into the impact of viruses on the CH₄ cycle, and serves as a crucial reference for future investigations into the ecological roles of viruses.