Oxytetracycline on the Wetland Macrophyte Bidens laevis L. Seedlings: Uptake, Bioaccumulation, Translocation and Biochemical Stress Responses

Oxytetracycline (OTC) is a widely used veterinary antibiotic worldwide due to its extensive use in livestock production. However, information regarding its uptake, biochemical and physiological effects in macrophytes remains limited. This study evaluated OTC uptake, bioaccumulation, translocation, and associated biochemical and physiological responses in seedlings of the wetland macrophyte Bidens laevis, exposed for 48 h to environmentally relevant concentrations (0, 0.05, 0.5, 5, 10 and 100 µg L−1). OTC accumulated in the roots and shoots, with bioaccumulation factors exceeding 1 in all treatments. At low concentrations, OTC was translocated to the shoots, whereas root retention predominated at 100 µg L−1. Antioxidant enzyme activities in shoots generally decreased with increasing OTC concentrations, while root responses remained comparatively stable. Chlorophyll contents increased with exposure, whereas lipid peroxidation showed limited variation. Multivariate analyses revealed contrasting effects of exposure concentration and organ accumulation on plant responses. Overall, B. laevis exhibited a high capacity to accumulate OTC and tolerate environmentally relevant concentrations, supporting its potential use in phytoremediation strategies.