Stress responses to polycyclic aromatic hydrocarbons in Arabidopsis include growth inhibition and hypersensitive response-like symptoms.
Polycyclic aromatic hydrocarbons (PAHs) are of global environmental concern because they cause many health problems including cancer and inflammation of tissue in humans. Plants are important in removing PAHs from the atmosphere; yet, information on the physiology, cell and molecular biology, and biochemistry of PAH stress responses in plants is lacking. The PAH stress response was studied in Arabidopsis (Arabidopsis thaliana) exposed to the three-ring aromatic compound, phenanthrene. Morphological symptoms of PAH stress were growth reduction of the root and shoot, deformed trichomes, reduced root hairs, chlorosis, late flowering, and the appearance of white spots, which later developed into necrotic lesions. At the tissue and cellular levels, plants experienced oxidative stress. This was indicated by localized H2O2 production and cell death, which were detected using 3, 3'-diaminobenzidine and trypan blue staining, respectively. Gas chromatography-mass spectrometry and fluorescence spectrometry analyses showed that phenanthrene is internalized by the plant. Gene expression of the cell wall-loosening protein expansin was repressed, whereas gene expression of the pathogenesis related protein PR1 was induced in response to PAH exposure. These findings show that (i) Arabidopsis takes up phenanthrene, suggesting possible degradation in plants, (ii) a PAH response in plants and animals may share similar stress mechanisms, since in animal cells detoxification of PAHs also results in oxidative stress, and (iii) plant specific defence mechanisms contribute to PAH stress response in Arabidopsis.
Alkio
Merianne
M
Department of Biology and Department of Environmental, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA 02125, USA.
Tabuchi
Tomoko M
TM
Wang
Xuchen
X
Colón-Carmona
Adán
A
D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics; D016923:Cell Death / Q000187:drug effects; D035264:Flowers / Q000187:drug effects / Q000254:growth & development; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D010616:Phenanthrenes / Q000378:metabolism / Q000633:toxicity*; D010935:Plant Diseases / Q000139:chemically induced*; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism / Q000633:toxicity*; D015398:Signal Transduction / Q000187:drug effects
D029681:Arabidopsis Proteins; D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons; C031181:phenanthrene