Revisiting Metabolic Adaptation in Plants during Uptake and Dealkylation of Enrofloxacin from the Perspective of In Vivo Metabolomics

The widespread presence of enrofloxacin (ENRO) in reclaimed water and biosolids poses potential risks to agricultural systems. Although ENRO primarily undergoes dealkylation as its main biotransformation pathway, the effects of this process on plants remain insufficiently understood. In this study, an in vivo solid-phase microextraction (SPME) method was developed to monitor ENRO dealkylation and associated metabolomic changes in living plants at different exposure concentrations. The accumulation trends of ENRO and dealkylated product ciprofloxacin were influenced by exposure levels. Meanwhile, activation of different metabolic pathways helped plants survive acute high ENRO stress, promoting the key processes of enhanced energy production, structural maintenance, detoxification, antioxidant defense, and membrane repair and then regain balance during prolonged exposure. Additionally, there existed a threshold for self-repair and antioxidation in plants, which employed only mild adaptation and detoxification at low ENRO concentrations. These findings offered novel insights into the regulatory mechanisms involved in ENRO dealkylation. Based on these results, we assessed the implications of using reclaimed water and biosolids containing ENRO for agricultural irrigation and fertilization. This study advances in vivo SPME-based metabolomics and provides valuable insight into plant adaptation during ENRO dealkylation, contributing to the risk assessment of wastewater reuse in agriculture.