Lead (Pb) accumulation and genotoxic responses in Ludwigia repens J.R. Forst.: a physiological and molecular approach

In this study, the potential genotoxic effects and phytoremediation capacity of Ludwigia repens J.R. Forst. were evaluated under lead (Pb) stress in contaminated aquatic environments. To achieve this, clonal L. repens plants were used to investigate their ability to remove Pb from freshwater systems and the experimental setup was established in controlled aquarium conditions. The plants were exposed to 0, 10, 25, 50 and 100 micromolar (μM) concentrations of Pb(NO₃)₂ in a 0.2% Hoagland nutrient solution for a period of ten days. Experimental results showed that Pb accumulated in both stems and leaves of L. repens. Although Pb levels did not meet hyperaccumulator criteria, the bioaccumulation index (BAI), bioconcentration factor (BCF) and translocation factor (TF) values revealed that the plant was capable of accumulating noteworthy amounts of Pb. In parallel, band profile analysis revealed new band appearances only with the UBC 812 primer, while no band loss or new band formation was detected with the other primers (UBC 808, UBC 826, UBC 833 and UBC 834). Instead, only changes in band intensities were observed, indicating a low polymorphism rate and a high level of genomic template stability (GTS). The findings also indicate that L. repens exhibits notable tolerance to Pb stress, as supported by high BAI, BCF and TF values in the absence of visible phytotoxic symptoms. Additionally, the consistent and progressive decline in mineral nutrient levels across Pb treatments, together with the moderate decline in total chlorophyll content, further supports the existence of a coordinated physiological adjustment, potentially reflecting a tolerance mechanism aimed at maintaining ionic balance under heavy metal stress. Moreover, low polymorphism rates and high genomic template stability (GTS) values derived from molecular analyses suggest that this species may serve as a genetically stable and physiologically resilient aquatic plant. These combined traits highlight its potential to contribute effectively to phytoremediation applications, particularly when co-cultivated with established Pb hyperaccumulator species.