Physiological responses of Xanthoria parietina to longterm copper excess: role of the extracellular secondary metabolite parietin
2019
Ivana Biľová | Michal Goga | Martin Bačkor
Xanthoria parietina is a common lichen that is widespread around the world. Tolerance ofheavy metal pollution in this lichen is well known. Xanthoria parietina contains the secondarymetabolite parietin, which protects the photobiont from high UV- radiation. Secondary metabolitesof lichens have been found to form complexes with metal cations. In a long-term experiment(lasting 8 weeks), we tested the resistance of X. parietina with and without the secondarymetabolite parietin against two concentrations of Cu (50 μM and 500 μM). Removal of parietindid not affect the measured physiological parameters. However, it caused higher accumulationof intracellular Cu. De novo synthesis of parietin in the lichen thallus after removal of the metabolitewas not observed. Physiological parameters (chlorophyll a fluorescence, chlorophylla integrity, content of soluble proteins, ergosterol levels, TBARS production) were affected bythe higher dose of Cu during the long-term experiment. It seems that the secondary metaboliteparietin does not protect the lichen against Cu excess.
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