Elevation-structured viral ecological strategies along glacier-fed rivers on the Qinghai-Tibet Plateau.

The Qinghai-Tibet Plateau, a climate-vulnerable source of Asia's major rivers, harbors underexplored viral communities critical to ecosystem functions. By integrating 597 metagenomes from the Yangtze, Yellow, Lancang, and Yarlung Tsangpo rivers with 85 public available glacial metagenomes (Tibetan Glacier Genome and Gene catalog), we built the Glacier-to-River Virome Catalogue, encompassing 36,358 vOTUs and 897,250 viral protein clusters, to decode viral adaptation and ecological influence across elevation gradients. Our results reveal that high-altitude conditions favor viruses with elevated Guanine-Cytosine content, larger genomes and more cold-adaptation genes. A central finding is a systematic viral lifestyle shift from temperate in glaciated regions to lytic viruses downstream, accompanied with decline of pathogens carrying antibiotic resistance genes along the glacier-to-river gradients. Further, viral auxiliary metabolic genes transition from glacier nutrient scavenging (e.g., nitrogen and sulfur transporters) to downstream mineralization processes (e.g., denitrification) in plains highlights their role in biogeochemical cycling. These findings position viruses as pivotal regulators of microbial community structural and functional dynamics to glacier-to-river gradient change and biogeochemistry in the Qinghai-Tibet Plateau, providing critical insights into climate response in vulnerable Asian water towers.