Heavy Metal-induced Cuticular Alkane Changes of Tall Fescue (Festuca arundinacea) Plantlets

Heavy metal pollution of ecosystems is of great concern, due to the persistence of metals in ecosystem. In this regard, the mountainous pastures of Romanian Carpathians, especially those in the areas of abandoned mines, need particular attention. The aim of this work was to assess the effect of heavy metals and metalloids exposure on cuticular wax composition of tall fescue leaves (Festuca arundinacea). Therefore, we have particularly investigated the variations of long chain hydrocarbon fractions, which are acknowledged to act as a protection for plants especially in toxic environments. The exposure experiments were conducted in triplicates for arsenic and the following metal ions: Ba2+, Cu2+, Fe2+ and Pb2+. The 0.5 mM aqueous solutions of their corresponding salts were used as treatment solutions. Triplicate experiments were also performed for control samples using distilled water as exposure media. The plantlets were kept for growing in controlled environment for 15 days followed by n-hexane hydrocarbon fraction extraction from 0.5 g of sampled leaves. The obtained extracts were semi-quantitatively analyzed (identification followed by peak area measurement) through an optimized method based on gas-chromatography coupled with mass spectrometry. We focused on the measurement of several long chain n-alkanes with the following number of carbon atoms: C21-C31. Significant differences were obtained between results performed for Ba2+, Pb2+ and Fe2+, when compared to AsO43- and Cu2+, which may suggest multiple mechanisms through which the tested plants could develop and adapt when exposed to various chemicals characterized by different degrees of toxicity.