Metabolism Of Polycyclic Aromatic Hydrocarbons In Plant

Nowadays, polycyclic aromatic hydrocarbons (PAHs) pollution is a serious worldwide environmental problem. How to assess the risk of crop pollution and provide safe agricultural products in the contaminated area has become a hot topic in many countries. Understanding the uptake of PAHs by plant would be of much importance for food security and human health, and plant metabolisms involved are of great concerns.In this work, metabolism of PAHs, anthracene and phenanthrene as representatives, by ryegrass(Lolium multiflorum Lam.) and tall fescue(Festuca arundinacea Schreb.) were investigated using a greenhouse study, the correlations of PAH metabolisms with the enzymes in plants were discussed. The subcellular distribution of PAHs and its major metabolities in plants were elucidated. Main original findings are shown as follows.(1) Metabolism of anthracene as a representative PAHs by ryegrass(Lolium multiflorum Lam.) was studied using a greenhouse study. Anthraqinone and anthrone as the first-grade metabolities of anthracene was analyzed. It was observed that concentrations of anthracene in ryegrass decreased from0.760mg-kg-1to O.147mg·kg-1, and80.6%of anthracene was degrdaded in16d. Anthracene was proved to be metabolized by ryegrass, and roots were the main part where the metabolism performed. In0-16d, anthrone was found to accumulate, while anthraqinone was further metabolized in plant. The release of anthraqinone and anthrone from plant root to culture solution was detected and elucidated. Translocation of anthraqinone and anthrone from plant root to shoot was observed, and TF (translocation factor) values of anthrone and anthraqinone were0.796～1.285and0.239～0.653, indicating the more readable translocation of anthrone than anthraqinone in ryegrass.(2) The addition of enzyme inhibitors Vc and Na2SO3at high concentrations led to the inhibition of phenanthrene metabolism in tall fescue(Festuca arundinacea). By contrast, these two enzyme inhibitors at low concentrations can promote the metabolism of phenanthrene in tall fescue. The activities of enzyme in plant may be completely inhibited by the addition of enzyme inhibitor at a high concentration. However, enzyme inhibitor at a low concentration may regenerate the enzyme activity. Comparing with the control treatments with no addition of enzyme inhibitor, the plant’s enzyme activities were even higher for those treatment with enzyme inhibitor of a low concentration.(3) The subcellular distribution of anthracene and its first-grade metabolities including anthraqinone and anthrone in tall fescue (Festuca arundinacea Schreb.) was elucidated. Anthracene can initially be detected in cytosol, cell wall and organelles. About78.6%of anthracene was accumulated in root cell organelles, while81%was present in leaf cell wall. On the other hand, anthraqinone was proved to be subsequently metabolized in cytosol.90%and92%of anthraqinone was degrdaded after1-2d in root cytosol and leaf cytosol, respectively. Anthrone was found to accumulate mainly in cell cytosol and organelles.