Metagenomic profiling of antibiotic resistance genes in terrestrial ecosystems across China

Soil represents a significant reservoir of antibiotic resistance genes (ARGs), yet their distribution across diverse terrestrial ecosystems remains poorly characterized. To address this knowledge gap, we conducted a large-scale, cross-regional soil survey spanning 4300 km in China, collecting samples at 42 intervals across six distinct terrestrial ecosystems. High diversity (18 ARG types and 129 ARG subtypes) and abundance (mean value: 724.9 [coverage, ×/Gb]) of ARGs were observed in the topsoil (0-20 cm depth) across the six terrestrial ecosystems, with tetracycline resistance and efflux pump being the prevailing class and resistance mechanism respectively. Notably, only aac (6')-I ranked among the highest-risk ARGs (Rank I), indicating that merely 0.78 % of detected ARGs pose a severe pathogenic threat. Meanwhile, horizontal gene transfer (HGT) is likely the primary transmission mechanism for ARGs in these soils. While most ARGs currently present minimal direct public health risks, their high transmission potential warrants attention. Furthermore, stochastic processes dominate the spread of soil ARGs, though both stochastic and deterministic processes contribute to the spread of their hosts. Collectively, these results provide timely insights into the resistance mode of soil ARGs in terrestrial ecosystems.