Molecular, biochemical, and physiological analyses of Scaevola plumieri subjected to copper and zinc contamination: implications for the phytoremediation of coastal environments.
Name: LUCAS PIMENTEL PEREIRA
Publication date: 17/12/2025
Examining board:
Name |
Role |
|---|---|
| DEBORA DUMMER MEIRA | Examinador Interno |
| DIOLINA MOURA SILVA | Presidente |
| EUGENIA JACIRA BOLACEL BRAGA | Examinador Externo |
Summary: Contamination by trace elements in coastal ecosystems compromises the biodiversity and functional stability of Restinga environments. In this context, plants of Scaevola plumieri were evaluated for their molecular, biochemical and physiological responses to exposure to the trace elements copper (Cu), zinc (Zn) and the combination Cu+Zn, aiming to understand their tolerance mechanisms and potential as a phytoremediator. The experiment was conducted in a completely randomized design, with different concentrations of the trace elements (Control), (Cu 25 M), (Cu 50 M), (Cu 100 M), (Zn 100 M), (Zn 200 M), (Zn 400 M), (Cu+Zn 25+100 M), (Cu+Zn 50+200 M), (Cu+Zn 100+400 M) and two exposure periods (5th and 25th day). Molecular analyses indicated a significant induction of PCS gene expression on the 5th day, especially at the lower concentrations (Cu 50 M, Zn 100 M and Cu+Zn 25+100 M), followed by a strong reduction on the 25th day and complete suppression at the most toxic doses, suggesting a limitation of the chelation response under prolonged stress. Biochemical analyses revealed an initial increase in phenolic compounds, flavonoids, antioxidant capacity and lipid peroxidation, reflecting activation of antioxidant pathways. Chlorophyll a fluorescence analysis indicated progressive impairment of electron transport (decline in PIabs, PItotal and P0), accompanied by an increase in energy dissipation (DI0/RC), with photochemical collapse under the most severe treatments. The strong early induction of the PCS pathway demonstrates rapid activation of the chelation system to sequester Cu and Zn, supporting molecular defense during the initial phases of exposure. Biochemical responses follow the transcriptional dynamics, with an early rise in antioxidant compounds and subsequent depletion under intense stress. These results indicate that S. plumieri plants are capable of activating an integrated protection system, via phytochelatins, antioxidant pathways and photoprotective mechanisms, which confers potential for phytoremediation of trace elements in coastal environments.
