Phage-Encoded Metabolic Bypass Drives Herbicide Resistance in Soil Microbiomes

Phages reshape microbial community functions through auxiliary metabolic genes (AMGs) and are increasingly recognized as active drivers of microbial adaptation. Although herbicides such as glufosinate significantly inhibit soil microbes, these communities exhibit striking resilience; however, the role of phages in facilitating this rapid adaptation remains poorly understood. Here, we dissect the temporal dynamics (days 0, 15, 30, and 60) of phage-host interactions under two contrasting stressors: the microbially toxic glufosinate and the nontoxic dicamba. We find that glufosinate transiently suppresses microbial diversity, followed by a robust recovery on day 60. This successional shift coincides with an elevated proportion of putative temperate phages (74.1%) and a strategic attenuation of bacterial antiviral systems, signaling a transition from antagonistic predation to mutualistic lysogeny. Metagenomic analyses across 23 regions in China corroborate that this temperate phage recruitment is a generalized response to field-relevant glufosinate exposure. Selection for temperate phage infections arises from asymmetric fitness costs (burdening virulent phage-susceptible hosts) and prophage integration of AMGs like gdhA. Specifically, coevolution assays reveal that glufosinate selectively penalizes virulent phage-sensitive hosts, favoring the recruitment of temperate phage infections. Furthermore, in vitro validation confirms that phage-encoded gdhA provides a compensatory metabolic bypass for ammonia detoxification, directly mitigating herbicide toxicity. Collectively, these findings delineate a phage-mediated mechanism for herbicide resistance evolution in soil microbiomes, emphasizing the need for a microbiome-informed agrochemical design to manage long-term ecological resilience.