摘要
      大量细菌存在于土壤和植物中，其中一些细菌携带抗生素抗性基因（ARGs）。当细菌聚集在土壤颗粒的界面或植物根表面时，这些ARG可以通过结合在细菌之间转移，导致形成威胁人类健康的抗生素耐药性病原体。植物生长调节剂广泛应用于农业生产，促进植物生长，提高作物产量。然而，到目前为止，关于PGRs对ARGs水平基因转移（HGT）的影响的信息还很少。本研究以大肠杆菌DH5α（携带含有TetR、AmpR、KanR的RP4质粒）为供体，以大肠杆菌HB101为受体，通过质粒介导的偶联实验，研究了吲哚乙酸（IAA）、乙烯（ETH）和赤霉素（GA3）对ARGs HGT的影响。此外，还澄清了所涉及的机制。结果表明，所有三种PGR都通过诱导细胞内活性氧（ROS）的形成、改变细胞膜通透性以及调节质粒RP4中traA、traL、trfAp、trbBp、kilA和korA的基因转录来影响ARG的转移频率。具体而言，50–100 mg·L−1 IAA、20–50 mg·L–1 ETH和1500–2500 mg·L-1 GA3都显著促进了ARG的结合。这项研究表明，PGRs在农业生产中的广泛使用可能通过质粒介导的结合影响ARG的HGT，并且应用合理浓度的PGRs可以减少ARG在土壤环境和植物中的传播。
Abstract
A vast number of bacteria occur in both soil and plants, with some of them harboring antibiotic resistance genes (ARGs). When bacteria congregate on the interface of soil particles or on plant root surfaces, these ARGs can be transferred between bacteria via conjugation, leading to the formation of antibiotic-resistant pathogens that threaten human health. Plant growth regulators (PGRs) are widely used in agricultural production, promoting plant growth and increasing crop yields. However, until now, little information has been known about the effects of PGRs on the horizontal gene transfer (HGT) of ARGs. In this study, with Escherichia coli DH5α (carrying RP4 plasmid with TetR, AmpR, KanR) as the donor and E. coli HB101 as the recipient, a series of diparental conjugation experiments were conducted to investigate the effects of indoleacetic acid (IAA), ethel (ETH) and gibberellin (GA3) on HGT of ARGs via plasmid-mediated conjugation. Furthermore, the mechanisms involved were also clarified. The results showed that all three PGRs affected the ARG transfer frequency by inducing the intracellular reactive oxygen species (ROS) formation, changing the cell membrane permeability, and regulating the gene transcription of traA, traL, trfAp, trbBp, kilA, and korA in plasmid RP4. In detail, 50–100 mg⋅L−1 IAA, 20–50 mg⋅L−1 ETH and 1500–2500 mg⋅L−1 GA3 all significantly promoted the ARG conjugation. This study indicated that widespread use of PGRs in agricultural production could affect the HGT of ARGs via plasmid-mediated conjugation, and the application of reasonable concentrations of PGRs could reduce the ARG transmission in both soil environments and plants.

https://www.sciencedirect.com/science/article/abs/pii/S0045653523002643