摘要
      在过去的几十年里，抗生素耐药性基因（ARGs）的传播对人类健康构成了重大威胁。尽管叶层是一个重要的微生物库，但人们对ARGs在人类干扰较少的自然栖息地的分布和驱动因素知之甚少。为了最大限度地减少环境因素的影响，我们在2km内的主要植被演替序列中收集了早期、中期和晚期演替阶段的叶片样本，以研究叶层ARGs是如何在自然栖息地中发育的。使用高通量定量PCR测定了Phyllosphere ARGs。还测量了细菌群落和叶片养分含量，以评估它们对叶层ARGs的贡献。共鉴定出151种独特的ARGs，几乎涵盖了所有公认的主要抗生素类别。我们进一步发现，在植物群落演替过程中，由于叶层生境的波动和植物个体的特定选择效应，存在一些随机和核心的叶层ARGs。在植物群落演替过程中，由于叶层细菌多样性、群落复杂性和叶片养分含量的降低，ARG丰度显著降低。而土壤和落叶之间的紧密联系导致落叶中的ARG丰度高于新鲜叶片。总之，我们的研究表明，叶层在自然环境中含有广泛的ARGs。这些叶层ARG是由各种环境因素驱动的，包括植物群落组成、寄主叶片特性和叶层微生物组。
Abstract
The spread of antibiotic-resistance genes (ARGs) has posed a significant threat to human health over the past decades. Despite the fact that the phyllosphere represents a crucial pool of microorganisms, little is known about the profile and drivers of ARGs in less human interference natural habitats. In order to minimize the influence of environmental factors, here we collected leaf samples from the early-, middle- and late-successional stages across a primary vegetation successional sequence within 2 km, to investigate how the phyllosphere ARGs develop in natural habitats. Phyllosphere ARGs were determined using high-throughput quantitative PCR. Bacterial community and leaf nutrient content were also measured to assess their contribution to the phyllosphere ARGs. A total of 151 unique ARGs were identified, covering almost all recognized major antibiotic classes. We further found that there was some stochastic and a core set of the phyllosphere ARGs during the plant community succession process, due to the fluctuant phyllosphere habitat and specific selection effect of plant individuals. The ARG abundance significantly decreased due to the reduction of the phyllosphere bacterial diversity, community complexity, and leaf nutrient content during the plant community succession process. While the closer links between soil and fallen leaf resulted in a higher ARG abundance in leaf litter than in fresh leaf. In summary, our study reveals that the phyllosphere harbors a broad spectrum of ARGs in the natural environment. These phyllosphere ARGs are driven by various environmental factors, including the plant community composition, host leaf properties, and the phyllosphere microbiome.

https://www.sciencedirect.com/science/article/pii/S0160412023001769