Effects and mechanisms of plant growth regulators on horizontal transfer of antibiotic resistance genes through plasmid-mediated conjugation. (March 2023)

• Record Type: Journal Article
• Authors: Zhao, Hui; Liu, Xiangyu; Sun, Yulong; Liu, Juan; Waigi, Michael Gatheru
• Is Part Of: Chemosphere. Volume 318(2023)
• Publication Date: 2023-03
• Subjects: Plant growth regulators -- Antibiotic resistance genes -- Diparental conjugation -- Membrane permeability -- Regulatory genes; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2023.137997
• Languages: English
• ISSNs: 0045-6535

Abstract

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 Tet R, Amp R, Kan R ) 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. Graphical abstract: Image 1 Highlights: All the tested plant growth regulators affected the antibiotic resistance gene transfer via plasmid-mediated conjugation. 50–100 mg⋅L −1 indoleacetic acid, 20–50 mg⋅L −1 ethethel and 1500–2500 mg⋅L −1 gibberellin acid all promoted RP4 conjugation. Indoleacetic acid, ethethel and gibberellin acid could all expand the cell membrane permeability. All the tested plant growth regulators could regulate the gene transcription involved in conjugation in plasmid RP4.