Phytodegradation of Organic Pollutants: Plant Metabolism, Enzymatic Transformation and Environmental Detoxification
Shweta Nag *
University Department of Botany, Ranchi University, Jharkhand, India.
*Author to whom correspondence should be addressed.
Abstract
Organic pollutants released through agriculture, industry, municipal wastewater and contaminated-site legacies can enter vegetation, but their disappearance from environmental compartments does not necessarily demonstrate their destruction by plants. This critical narrative review examines how exposure, uptake, enzymatic transformation, conjugation and sequestration determine the fate of organic contaminants within terrestrial and wetland plants. Literature published from 1992 to 1 September 2026 was assessed, with earlier foundational studies retained where necessary. Evidence from mechanistic plant experiments, isotopic tracing, transformation-product analysis, engineered systems and field studies was interpreted according to its capacity to distinguish direct plant metabolism from microbial degradation, physical retention and volatilisation. The established three-phase model of plant xenobiotic metabolism explains many reactions involving cytochrome P450 monooxygenases, hydrolases, glutathione transferases, glycosyltransferases and transport proteins, but it does not imply complete mineralisation or toxicological safety. Research on trichloroethylene, selected herbicides, pharmaceuticals and chlorinated aromatics demonstrates compound- and species-dependent transformation. Isotope-labelled studies reveal substantial non-extractable residues, whereas field comparisons show that enhanced enzymatic capacity may not translate into proportionate contaminant removal. In constructed wetlands and petroleum-contaminated soils, plant-associated microbiota frequently contribute substantially to treatment, complicating attribution to plant metabolism. Transformation products in edible tissues, remobilisation of bound residues and emissions of volatile contaminants remain under-assessed. The review proposes an evidence hierarchy linking molecular mechanism, contaminant mass balance and effect-based toxicity to field-scale outcomes. Future research should prioritise realistic exposure conditions, causal separation of plant and microbial pathways, long-term product tracking and transparent assessment of ecological trade-offs. Phytodegradation is consequently best regarded as a conditional component of remediation rather than a general synonym for pollutant elimination.
Keywords: Xenobiotic biotransformation, cytochrome P450, glutathione S-transferase, glycosylation, non-extractable residues, transformation products, constructed wetlands, contaminant mass balance