Fusarium oxysporum f. sp. niveum invasion promotes Pseudomonas-driven antibiotic resistance gene enrichment.

The dissemination of antibiotic resistance genes (ARGs) in agricultural soils poses a growing threat to ecosystem health and food security, highlighting the need to identify key environmental drivers. Although soil-borne phytopathogens disrupt microbial communities, their specific impact on ARG dynamics remains poorly understood. In this study, we examined how Fusarium oxysporum f. sp. niveum (FON) invasion changes soil ARG profiles. Our results indicate that increasing FON loads heighten the abundances of soil ARGs, virulence factor genes (VFGs), and mobile genetic elements (MGEs). This invasion significantly transformed rhizosphere bacterial communities by enriching Pseudomonas populations. We further identified Pseudomonas-driven mechanisms that involve functional adaptations such as SOS response activation and enhanced biofilm formation. Genomic features, including vertically inherited ARGs (e.g., mexF/T/W, bacA) and horizontal gene transfer (HGT) elements tnpA transpositions, along with ecological interactions such as growth-supporting metabolic exchanges, collectively fueled ARG enrichment and dissemination. Pseudomonas strains exhibited prevalent multidrug resistance (MDR) and further promoted the enrichment of antibiotic-resistant bacteria (ARB) through growth - supporting metabolic interactions. An analysis of 689 Pseudomonas genomes from diverse habitats revealed that nearly all genomes contain multiple ARGs, VFGs, and MGEs, suggesting that Pseudomonas proliferation significantly contributes to ARG dissemination. Our findings establish FON load as a critical driver of resistome dissemination by selectively enriching multi-resistant Pseudomonas reservoirs and activating key resistance-enhancing mechanisms within these reservoirs. These results offer mechanistic insights for managing antimicrobial resistance risks in agroecosystems.