Antibiotic resistance and heavy metal contamination are two worldwide environmental concerns. Especially in soil, the interaction between these two pollutants may exacerbate the problem of antibiotic resistance genes (ARGs) entering the food chain, which can have severe consequences on the environment and the wellness of humankind. This study investigated the influences of cadmium (Cd) and copper (Cu) pollution on ARG profiles in the soil rhizosphere and endogenous microbiome of roots and leaves in pakchoi. We further determined the impact of these heavy metals and various environmental factors on the accumulation of ARGs in leaves and discussed the possible transfer pathways of ARGs in the soil-plant system. Our results showed that Cd–Cu stress increased the relative abundance of most target genes in the samples, especially the sulfonamide resistance genes and , the quinolone resistance gene , and the Class 1 integron integrase gene . Variance partitioning analysis indicated that the Cd–Cu contents primarily contributed (45.7%) to ARG variations in leaves. Cadmium and Cu led to a pollution-induced community tolerance phenomenon in microbial communities, enriching Cd- and Cu-tolerant bacteria. ARGs were highly correlated with mobile genetic elements (e.g., ) and metal resistance genes, increasing the co-selection of metals on ARGs. Structural equation modeling showed that metal resistance genes and in leaves had significant direct positive effects on the relative abundances of ARGs ( < 0.05). Higher Cu concentrations facilitated the migration of most target ARGs from soil to leaves.

中文翻译：

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镉铜胁迫对土壤和小白菜叶片抗生素抗性基因积累的影响

抗生素耐药性和重金属污染是世界范围内的两个环境问题。特别是在土壤中，这两种污染物之间的相互作用可能会加剧抗生素抗性基因（ARG）进入食物链的问题，这可能对环境和人类健康造成严重后果。本研究探讨了镉（Cd）和铜（Cu）污染对小白菜根际土壤ARG谱和根叶内源微生物组的影响。我们进一步确定了这些重金属和各种环境因素对叶片中ARGs积累的影响，并讨论了ARGs在土壤-植物系统中可能的转移途径。我们的结果表明，Cd-Cu胁迫增加了样品中大多数靶基因的相对丰度，特别是磺酰胺抗性基因、喹诺酮抗性基因和1类整合子整合酶基因。方差分配分析表明，Cd-Cu 含量主要影响 (45.7%) 叶片中 ARG 的变化。镉和铜导致微生物群落出现污染诱导的群落耐受现象，丰富了耐镉和耐铜的细菌。ARG 与移动遗传元件（例如 ）和金属抗性基因高度相关，增加了 ARG 上金属的共选择。结构方程模型表明，叶片中的金属抗性基因对 ARG 的相对丰度具有显着的直接正向影响（< 0.05）。较高的 Cu 浓度有利于大多数目标 ARGs 从土壤迁移到叶子。