Ascorbic Acid Enhances the Accumulation of Polycyclic Aromatic Hydrocarbons (PAHs) in Roots of Tall Fescue (Festuca arundinacea Schreb.)

Yanzheng Gao,Hui Li,Shuaishuai Gong,Aditya Bhushan Pant

doi:10.1371/journal.pone.0050467

Yanzheng Gao, Hui Li + Show 2 more

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https://doi.org/10.1371/journal.pone.0050467

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Abstract

Plant contamination by polycyclic aromatic hydrocarbons (PAHs) is crucial to food safety and human health. Enzyme inhibitors are commonly utilized in agriculture to control plant metabolism of organic components. This study revealed that the enzyme inhibitor ascorbic acid (AA) significantly reduced the activities of peroxidase (POD) and polyphenol oxidase (PPO), thus enhancing the potential risks of PAH contamination in tall fescue (Festuca arundinacea Schreb.). POD and PPO enzymes in vitro effectively decomposed naphthalene (NAP), phenanthrene (PHE) and anthracene (ANT). The presence of AA reduced POD and PPO activities in plants, and thus was likely responsible for enhanced PAH accumulation in tall fescue. This conclusion is supported by the significantly enhanced uptake of PHE in plants in the presence of AA, and the positive correlation between enzyme inhibition efficiencies and the rates of metabolism of PHE in tall fescue roots. This study provides a new perspective, that the common application of enzyme inhibitors in agricultural production could increase the accumulation of organic contaminants in plants, hence enhancing risks to food safety and quality.

Highlights

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs) that demonstrate carcinogenic and mutagenic toxicities [1,2]
Tall fescue was chosen as a test plant in this investigation. These findings suggest that the common use of enzyme inhibitors in agricultural production may promote the accumulation of organic contaminants in plants, increasing risk in terms of food safety and quality
Where CPAH-i and C PAH-o are the PAH concentrations in solution at time i and time 0. This in vitro experiment clearly demonstrated that the presence of POD and polyphenol oxidase (PPO) in the solution facilitated the decomposition of PAHs with varying degradation rates

Summary

Introduction

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs) that demonstrate carcinogenic and mutagenic toxicities [1,2]. These contaminants are frequently detected at relatively high concentrations (mg/kg) in soils worldwide [3,4]. PAH uptake by plants from the soil to roots is a major pathway; the subsequent transport to shoots via the transpiration stream flux favors compounds with greater aqueous solubility [6,14]. Kang et al (2010) reported that the lipid contents of intracellular components determined the accumulation of lipophilic compounds; e.g. PAHs, and that the corresponding diffusion rate was determined by the concentration gradient between the cell wall and intracellular organelles [7]

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