# Identification of shared viral sequences in peat moss metagenomes reveals elements of a possible Sphagnum core virome

## TL;DR

This study identifies shared viral sequences in peat moss, suggesting the presence of a core virome that may influence the moss's microbiome and carbon storage role.

## Contribution

The study presents the first evidence of a possible core virome in Sphagnum mosses through shared viral sequences across multiple samples.

## Key findings

- Only a small percentage of viral contigs were shared among all Sphagnum samples, indicating a potential core virome.
- Shared viral sequences included phage, nucleocytoplasmic large DNA viruses, and RNA viruses with diverse phylogenetic origins.
- Putative phage-like contigs were linked to bacterial taxa in the Sphagnum core microbiome, suggesting temperate phage or prophage origins.

## Abstract

Viruses are an understudied component of plant microbiomes. Identifying viruses that are shared between individual plants, or members of the “core virome”, could reveal stable viral populations with the potential to modulate the composition and function of the microbiome. Here, we examined the virome associated with Sphagnum mosses, a keystone species that has direct influence over the fate of peatland carbon stores. We analyzed bulk metagenomes and metatranscriptomes generated from Sphagnum field samples collected over a ten-month period to identify virus-like sequences shared among plants.

Individual Sphagnum samples harbored distinct DNA and RNA viromes where only a small percentage (< 1%) of the total number of identified viral contigs were shared among all samples. Based on taxonomic classification, the shared viral contigs represent bacterial viruses, or phage (Caudoviricetes), as well as viruses of eukaryotes, namely nucleocytoplasmic large DNA viruses (Nucleocytoviricota) and RNA viruses (Riboviria). We linked the shared phage-like contigs to viral regions within sequenced genomes of bacterial taxa that are members of the Sphagnum core microbiome, suggesting that these contigs represent temperate phage or degraded prophage. The putative nucleocytoplasmic large DNA viruses and RNA viruses were phylogenetically diverse and showed sequence similarity to viruses associated with a broad range of hosts and environmental sources.

The identification of shared viral contigs suggested that, despite the compositional heterogeneity between samples, Sphagnum mosses may harbor a core virome. Future work validating the presence of the core virome is warranted as it may aid in understanding how persistent viruses impact microbiome ecology and symbiont evolution within this climatically relevant keystone species.

The online version contains supplementary material available at 10.1186/s40793-025-00719-0.