Stress response and phytoextraction potential of two Noccaea caerulescens populations in multicontaminated soil

Multicontamination of soils by various organic and inorganic pollutants is considered as an obstacle for the development of hyperaccumulator plants and phytoextraction of metals. The aim of this study was to investigate the effect of polycyclic aromatic hydrocarbons (PAHs) in combination with trace elements on the antioxidant response and phytoextraction efficiency of two populations of the hyperaccumulator Noccaea caerulescens from either a metalliferous (Ganges) or a nonmetalliferous (Chavignée) site. Plants were grown for 17 days in soil containing moderate concentrations of trace elements and under the effect of phenanthrene (PHE), a PAH stress model. In general, exposure to PHE resulted in a reduction of growth parameters, together with the upregulation of antioxidant enzymes and compounds and limitations in nutrient uptake and heavy metal extraction in N. caerulescens. Variations were observed in the extent of enzymatic activities and the amount of metals extracted between the two populations studied. Plants from Chavignée exhibited a slightly more tolerant response to PHE stress than those from Ganges. The presence of PHE in the soil proved highly toxic to N. caerulescens, resulting in low numbers of survivors. Nevertheless, the differences observed between the two populations with regard to growth, metal extraction, and antioxidant defense responses suggest that the difference in defense capacity may ensure different tolerance. This difference may be linked to adaptations acquired by each population according to the soil type from which it originates. However, these results need to be confirmed by further experiments.