Response of Soil Phage Communities and Prokaryote–Phage Interactions to Long-Term Drought

Soil moisture is a fundamental factor affecting terrestrial ecosystem functions. In this study, microscopic enumeration and joint metaviromic and metagenomic sequencing were employed together to investigate the impact of prolonged drought on soil phage communities and their interactions with prokaryotes in a subtropical evergreen forest. Our findings revealed a marked reduction in the abundances of prokaryotic and viral-like particles, by 73.1% and 75.2%, respectively, and significantly altered the structure of prokaryotic and phage communities under drought. Meanwhile, drought substantially increased the fraction of prokaryotic communities containing lysogenic phages by 163%, as well as the proportion of temperate phages. Nonetheless, drought likely amplified negative prokaryote-phage interactions given the nearly doubled proportion of negative links in the prokaryote-phage co-occurrence network, as well as the higher frequency and diversity of antiphage defense systems found in prokaryotic genomes. Under drought, soil phages exerted greater top-down control on typical soil <i>k</i>-strategists including <i>Acidobacteria</i> and <i>Chloroflexi</i>. Moreover, phage-encoded auxiliary metabolic genes may impact host metabolism in biosynthesis-related functions. Collectively, the findings of this study underscore the profound impact of drought on soil phages and prokaryote-phage interactions. These results also emphasize the importance of managing soil moisture levels during soil amendment and microbiome manipulation to account for the influence of soil phages.