For Grassland Soil Viruses, Precipitation Shapes Diversity, Abundance, and Function

The Science

Viruses are abundant in soil, but scientists do not fully understand how climate change affects them. In this study, scientists analyzed DNA viruses (viruses that use DNA for replication) in three grassland soils. These grasslands had historical differences in average annual precipitation. The study included soils with low precipitation from eastern Washington, intermediate precipitation from Kansas, and high precipitation from Iowa. The researchers identified thousands of viruses, including 14 complete viral genomes. They found that viruses were more diverse and more common in drier soil. This understanding of the relationships between soil viruses and historical precipitation will help scientists predict how viruses will respond to future climate change.

The Impact

Climate change is shifting global precipitation patterns, bringing drought to some areas and increased rainfall to others. This study showed that soils with differing degrees of historical precipitation have different types of soil viruses. These findings are important because soil viruses influence soil ecology. For example, soil viruses control bacterial population levels and their functional activities in soil.

Summary

Soil viruses are abundant, but scientists have a poor understanding of how they respond to the environment and climate. This study addressed this gap by comparing the diversity, abundance, lifestyle, and metabolic potential of DNA viruses in three grassland soils with historical differences in average annual precipitation: low in eastern Washington, intermediate in Kansas, and high in Iowa. Bioinformatics analyses identified a total of 2,631 viral contigs, including 14 complete viral genomes from three deep metagenomes. The viruses were primarily bacteriophages targeting dominant bacterial taxa. The most significant differences among the three sampled locations were found in arid eastern Washington. Viral abundance in the low-precipitation Washington sample was significantly higher than in the other two locations. The diversity of viral and host bacteria was also higher in the Washington sample. The data also suggested that more infection cycles occur in the historically drier soil. Overall, the observed and predicted relationships between soil viruses and various biotic and abiotic variables can help predict viral responses to environmental change.

Funding

Funding was provided by the Department of Energy (DOE) Office of Science, Office of Biological and Environmental Research. The research is part of the DOE Scientific Focus Area, “Phenotypic response of the soil microbiome to environmental perturbations.”