Evaluating the Impact of Biochar Amendment on Antibiotic Resistance Genes and Microbiome Dynamics in Soil, Rhizosphere, and Endosphere at Field Scale

Biochar amendment is a promising strategy for mitigating antibiotic resistance genes(ARGs) in soil and plants, but its effects on ARGs at field scale are not fullyunderstood. Here, field trials were executed utilizing two plant varieties, Brassicajuncea and Lolium multiflorum, with four types of biochar to investigate changes inARGs and microbiome in soil, rhizosphere, root endophytes, and leaf endophytes.Results showed that biochar altered ARG distribution in soil and plant, and restrainedtheir transmission from soil and rhizosphere to endophytes. A reduction of 1.2-2.2orders of magnitude in the quantity of ARGs was observed in root and leaf endophytesfollowing biochar addition, while no significant changes were observed in soil andrhizosphere samples. Procrustes and network analyses revealed significantcorrelations between microbial communities and mobile genetic elements (MGEs) withARGs (P bacterial communities may play a dominant role in shaping the ARGs profile,contributing to 43% of the variation observed in ARGs. These field results suggest thatbiochar amendment alone may not fully alleviate ARGs in soil, but it has a significantbeneficial impact on food safety and human health by effectively reducing ARGs inplant endophytes.