摘要
      化学熏蒸剂和有机肥料通常用于设施农业，以控制土传疾病并促进土壤健康。然而，缺乏证据表明非抗生素熏蒸剂对植物根际土壤中抗生素抗性基因（ARGs）分布的影响。在这里，使用高通量定量PCR方法，研究了西瓜根际土壤中广谱ARGs和可移动遗传元素（MGE）在其分枝、开花和结果生长阶段对咪唑熏蒸实践的反应。我们的研究结果表明，土壤熏蒸结合施用有机肥显著增加了西瓜根际土壤中ARGs和MGEs的相对丰度。ARGs的相对丰度与MGEs之间的正相关性表明，土壤熏蒸可能会增加ARGs水平基因转移（HGT）的潜力。熏蒸处理网络中ARG和MGE亚型之间增强的相关性进一步证实了这一结果。此外，ARGs/MGE与微生物群落（细菌和真菌）之间的二分关联显示，在熏蒸土壤中，MGE和微生物类群之间的联系比例更高。结构方程模型分析进一步表明，熏蒸和施用有机肥后抗生素耐药性的增加主要是由MGE和真菌群落驱动的。总之，我们的研究结果提供了重要的证据，证明在塑料棚中结合有机肥的达佐米熏蒸过程具有促进ARGs在根际传播的巨大潜力，并提醒人们注意土传真菌病原体的获得抗性和ARGs沿土壤-植物连续体的潜在传播。
Abstract
Chemical fumigants and organic fertilizer are commonly used in facility agriculture to control soil-borne diseases and promote soil health. However, there is a lack of evidence for the effect of non-antibiotic fumigants on the distribution of antibiotic resistance genes (ARGs) in plant rhizosphere soils. Here, the response of a wide spectrum of ARGs and mobile genetic elements (MGEs) to dazomet fumigation practice in the rhizosphere soil of watermelon was investigated along its branching, flowering and fruiting growth stages in plastic shelters using high-throughput quantitative PCR approach. Our results indicated that soil fumigation combined with organic fertilizer application significantly increased the relative abundance of ARGs and MGEs in the rhizosphere soil of watermelon plant. The positive correlations between the relative abundance of ARGs and MGEs suggested that soil fumigation might increase the horizontal gene transfer (HGT) potential of ARGs. This result was further confirmed by the enhanced associations between ARG and MGE subtypes in the networks of fumigation treatments. Moreover, bipartite associations between ARGs/MGEs and microbial communities (bacteria and fungi) revealed a higher percentage of linkage between MGEs and microbial taxa in the fumigated soils. Structural equation model analysis further suggested that the increases in antibiotic resistance after fumigation and organic fertilizer application were mainly driven by MGEs and fungal community. Together, our results provide vital evidence that dazomet fumigation process combined with organic fertilizer in plastic shelters has the great potential to promote ARGs' dissemination in the rhizosphere, and raise cautions of the acquired resistance by soil-borne fungal pathogen and the potential spreading of ARGs along soil-plant continuum.

https://www.sciencedirect.com/science/article/abs/pii/S0048969721055030