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 < 0.05). Besides, redundancy and variation partitioning analysis indicated thatbacterial 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.

生物炭改良是缓解土壤与植物中抗生素抗性基因（antibiotic resistance genes, ARGs）的极具潜力的策略，但目前学界对其在田间尺度下对ARGs的影响尚未完全明晰。本研究依托两种植物品种——芥菜型油菜（Brassica juncea）与多花黑麦草（Lolium multiflorum），搭配四种生物炭开展田间试验，以探究土壤、根际、根系内生菌及叶片内生菌中ARGs与微生物组的变化规律。研究结果表明，生物炭改变了土壤与植物体内ARGs的分布格局，并抑制了ARGs从土壤及根际向内生菌的传播过程。施加生物炭后，根系与叶片内生菌中的ARGs丰度降低了1.2~2.2个数量级，而土壤与根际样本中的ARGs丰度未出现显著变化。普氏分析（Procrustes）与网络分析结果显示，微生物群落、可移动遗传元件（mobile genetic elements, MGEs）与ARGs之间存在显著相关性（P < 0.05）。此外，冗余分析与变异分割分析结果表明，细菌群落在塑造ARGs特征方面发挥主导作用，可解释ARGs变异的43%。本田间试验结果显示，仅通过生物炭改良或无法完全缓解土壤中的ARGs，但通过有效降低植物内生菌中的ARGs丰度，其可对食品安全与人类健康产生显著的积极影响。