Phytoremediation is an effective solution to treat pollution with antibiotic compounds in aquatic environments; however, the underlying mechanisms for plants to cope with antibiotic pollutants are obscure. Here we used cell suspension culture to investigate the distribution and transformation of ciprofloxacin (CIP) in common reed (Phragmites australis) plants, as well as the accompanying phenotypic and metabolic responses of plants. By means of radioactive isotope labelling, we found that in total 68 % of CIP was transformed via intracellular Phase I transformation (reduction and methylation), Phase Ⅱ conjugation (glycosylation), and Phase Ⅲ compartmentalization (cell-bound residue formation mainly in cell walls, 23 %). The reduction and glycosylation products were secreted by the cells. To mitigate stress induced by CIP and its transformation products, the cells activated the defense system by up-regulating both intra- and extra-cellular antioxidant metabolites (e.g., catechin, l-cystine, and dehydroascorbic acid), anti-C/N metabolism disorder metabolites (e.g., succinic acid), secreting signaling (e.g., nicotinic acid), and anti-stress (e.g., allantoin) metabolites. Notably, the metabolic reprogramming could be involved in the CIP transformation process (e.g., glycosylation). Our findings reveal the strategy of wetland plants to cope with the stress from CIP by transforming the xenobiotic compound and reprogramming metabolism, and provide novel insights into the fate of antibiotics and plant defense mechanisms during phytoremediation.

中文翻译：

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揭示普通芦苇 （Phragmites australis） 悬浮细胞对环丙沙星的植物修复机制：异种生物转化和代谢重编程


植物修复是处理水生环境中抗生素化合物污染的有效解决方案;然而，植物应对抗生素污染物的潜在机制尚不清楚。在这里，我们使用细胞悬浮培养来研究环丙沙星 （CIP） 在芦苇 （Phragmites australis） 植物中的分布和转化，以及伴随的植物表型和代谢反应。通过放射性同位素标记，我们发现总共 68% 的 CIP 通过细胞内 I 期转化（还原和甲基化）、II. 期偶联（糖基化）和 III. 期区室化（细胞结合残基主要在细胞壁中形成，23%）转化。还原和糖基化产物由细胞分泌。为了减轻 CIP 及其转化产物诱导的压力，细胞通过上调细胞内和细胞外抗氧化代谢物（例如儿茶素、l-胱氨酸和脱氢抗坏血酸）、抗 C/N 代谢紊乱代谢物（例如琥珀酸）、分泌信号传导（例如烟酸）和抗应激（例如尿囊素）代谢物来激活防御系统。值得注意的是，代谢重编程可能参与 CIP 转化过程（例如，糖基化）。我们的研究结果揭示了湿地植物通过转化外源性化合物和重编程代谢来应对 CIP 压力的策略，并为抗生素的命运和植物修复过程中的植物防御机制提供了新的见解。