Copper uptake and copper-induced physiological changes in the epiphytic lichen Evernia prunastri

The lichen Evernia prunastri is very frequently employed in lichen biomonitoring studies and its sensitivity to air pollution has been confirmed at the community level many times. However, studies focused on the physiological responses of this lichen to pollutants are underrepresented. The degree of total as well as intracellular Cu uptake by the lichen after 4 and 24?h prolonged exposure was compared with selected physiological markers including levels of assimilation pigments, chlorophyll a fluorescence, ergosterol, soluble proteins, hydrogen peroxide, superoxide, amino acids, reducing sugars and total soluble phenols. Although the degree of total as well as intracellular Cu uptake by the lichen after 4 and 24?h prolonged exposure were comparable, metabolic responses after 4 and 24?h were very different. Carotenoids, ergosterol and soluble proteins decreased due to Cu exposure and these processes were followed with an increase of superoxide content. Excess of Cu in thalli of E. prunastri after 24?h was toxic and altered almost all tested parameters, including depletion of reducing sugars. We did not observe stimulation of free amino acid synthesis in Cu treated lichen, in fact the content of many particular amino acids decreased. Content of total soluble phenols was unaltered by Cu excess.