Pyrene distribution dynamics and its possible degradation pathways in proso millet tissues: an experimental approach

Area of Science:

• Environmental Science
• Plant Biology
• Bioremediation

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are hazardous environmental pollutants.
• Soil contamination by PAHs poses risks to fertility and ecosystems.
• Understanding plant interactions with PAHs is crucial for remediation strategies.

Purpose of the Study:

• To investigate the uptake, accumulation, and detoxification of pyrene (PYR) by proso millet (Panicum miliaceum).
• To examine the distribution dynamics and degradation pathways of PYR in plant tissues.
• To assess the impact of varying PYR concentrations on plant growth and physiology.

Main Methods:

• Hydroponic system utilized to expose proso millet to different PYR concentrations (0–2,000 ppm).
• Analysis of PYR distribution within root and shoot tissues over a 30-day period.
• Evaluation of bioconcentration and translocation factors.
• Proposed degradation pathways based on observed transformations.

Main Results:

• Higher PYR concentrations negatively affected plant growth.
• Plant-assisted dissipation removed 29–43% of PYR over 30 days.
• PYR accumulated in roots, while shoot concentrations decreased at higher levels, with roots showing higher PYR by day 30.
• Bioconcentration and translocation peaked at 500 ppm, with translocation to shoots limited by day 30.

Conclusions:

• Proso millet exhibits potential for phytoremediation of PYR-contaminated environments.
• Plant tissues, particularly roots, play a significant role in PYR sequestration and dissipation.
• A three-step degradation pathway involving oxidation, enzymatic transformation, and synthesis of new compounds is proposed for PYR in P. miliaceum.