Seasonal changes in solar radiation drive acclimation of the sun-screening compound parietin in the lichen Xanthoria parietina

Population genetics of lichen-forming fungi – a review

“…Based on chemotypic variation, gene flow was found to be common in some lichenized fungi (Culberson et al 1988), whereas other mycobiont taxa appeared to be reproductively isolated (Culberson et al 1993). Secondary metabolites of lichen-forming fungi have been reported to function as a light screen protecting the algal populations in a thallus (Gauslaa & Solhaug 2001;Gauslaa & McEvoy 2005), or to operate as metal chelators, water repelling agents, and deterrents against parasites (Stocker-Wörgötter et al 2004). Chemotypic variation in lichens is therefore probably not to be considered as selectively neutral.…”

“…Unfortunately, the resolution of the studies of chemotypic variation in lichenized fungi is generally too low to allow for detailed population genetic analyses (Culberson & Culberson 1994), which is why they were later replaced by studies employing other tools. Recent studies suggest that the concentration of secondary metabolites in lichen thalli may vary seasonally (Bjerke et al 2005;Gauslaa & McEvoy 2005), and changes with light intensity (Armaleo et al 2008b).…”

Characterization of Gamma Irradiation Absorbing Compounds from Lichens for Biomedical Applications

“…Lichen fungi exposed to high light intensities are recognized to accumulate various pigments in the cortical layers overlying the algal cells. 17 Lichens are having capacities to biosynthesis of various radiation absorbing molecules in the cortical region of the thallus. The radiation absorbing molecules are secondary compounds which are the combination of phenolics, alkaloids and terpenoids.…”

Antiproliferative activity of lichen extracts on murine myeloma cells

“…high light influx, SO 2 pollution, paraquat treatment) in lichens can follow several routes, such as production of crystalline deposits of calcium oxalate (Modenesi 1993;Modenesi et al 1998), increased synthesis of ascorbic acid (Caviglia & Modenesi 1999), and usnic acid (Caviglia et al 2001). In X. parietina, the orange coloured cortical anthraquinone compound parietin synthesised by the mycobiont protects the lichen photobiont against oxidation by excessive solar radiation (Gauslaa & McEvoy 2005). However, parietin did not show any inhibitory activity on platelet-type 12(S)-lypoxygenase, which is involved in malignant cell growth (Bucar et al 2004).…”