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 biodiversity and the functional stability of Restinga environments. In this context, Scaevola plumieri plants were evaluated regarding their molecular, biochemical, and
physiological responses under exposure to copper (Cu), zinc (Zn), and the combined treatment of Cu+Zn, aiming to understand their tolerance mechanisms and phytoremediation potential. The experiment was conducted in a completely randomized design with different trace-element concentrations: T1 (Control), T2 (Cu 25 M), T3 (Cu 50 M), T4 (Cu 100 M), T5 (Zn 100 M), T6 (Zn 200 M), T7 (Zn 400 M), T8 (Cu+Zn 25+100 M), T9 (Cu+Zn 50+200 M), and T10 (Cu+Zn 100+400 M), evaluated at two exposure periods (5th and 25th day). Molecular analyses indicated a significant induction of PCS gene expression on the 5th day, especially at lower treatment concentrations (T3, T5, and T8), followed by a marked reduction on the 25th day and complete suppression at the highest doses, indicating 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 defenses. Chlorophyll a fluorescence analysis showed a progressive impairment of electron transport (reduction of PIabs, PITotal, and P0), accompanied by an increase in energy dissipation (DI0/RC), culminating in photochemical collapse at higher concentrations. The strong early induction of the PCS pathway demonstrates rapid activation of metal chelation mechanisms to sequester Cu and Zn, sustaining molecular defense during the initial exposure phase. Biochemical responses followed this transcriptional pattern, with increased antioxidant activity at early stages and depletion under severe stress. These findings indicate that S. plumieri activates an integrated protection system involving phytochelatin synthesis, antioxidant pathways, and photoprotective mechanisms, supporting its potential for phytoremediation of trace elements in coastal environments.
