Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
J Hazard Mater. 2024 Nov 5;479:135639. doi: 10.1016/j.jhazmat.2024.135639. Epub 2024 Aug 23.
Chlormequat (CCC) is widely used in agricultural production to increase the crop yield. However, the effects of CCC on transfer of ARGs in agricultural system are still unclear. In this study, using E.coli DH5α (carrying RP4 plasmid with Amp, Tet, Kan) as the donor bacterium, E.coli HB101, endophytic Pseudomonas sp. Ph6 or rhizosphere Pseudomonas putida KT2440 as the recipient strain, three conjugative systems were designed to investigate the effects of CCC on ARG transfer. Meanwhile, hydroponics experiments were designed to study the ARG spread in the rice-nutrient solution system after CCC application. The results showed that CCC significantly promoted the RP4 conjugation by expanding cell membrane permeability and improving the relative transcription levels of trfAp, trbBp, traA and traL genes in RP4. Furthermore, the conjugation frequency between E. coli and Pseudomonas was much higher than that between E. coli cells. Compared with spraying foliage with 2500 mg·L of CCC, soaking seeds with 250 mg·L of CCC was more beneficial to the colonization of ARB in rice, and also increased the abundance of ARGs in rice cultivation system. These results remind that the use of CCC in agricultural production might promote the ARG transmission in agro-ecosystems; however, foliage spraying with 2500 mg·L of CCC could control its spread.
矮壮素（CCC）在农业生产中被广泛用于提高作物产量。然而，CCC 对农业系统中 ARGs 转移的影响尚不清楚。在本研究中，我们使用 E. coli DH5α（携带带有 Amp、Tet、Kan 的 RP4 质粒）作为供体菌，E. coli HB101、内生假单胞菌 Ph6 或根际假单胞菌 P. putida KT2440 作为受体菌，设计了三个共转移系统来研究 CCC 对 ARG 转移的影响。同时，我们设计了水培实验来研究 CCC 应用后水稻-营养液系统中 ARG 的传播。结果表明，CCC 通过扩大细胞膜通透性和提高 RP4 中 trfAp、trbBp、traA 和 traL 基因的相对转录水平，显著促进了 RP4 的共转移。此外，E. coli 和假单胞菌之间的共转移频率远高于 E. coli 细胞之间的共转移频率。与叶面喷施 2500 mg·L 的 CCC 相比，浸种 250 mg·L 的 CCC 更有利于 ARB 在水稻中的定殖，也增加了水稻种植系统中 ARGs 的丰度。这些结果提醒我们，农业生产中 CCC 的使用可能会促进 agro-ecosystems 中 ARG 的传播；然而，叶面喷施 2500 mg·L 的 CCC 可以控制其传播。
