Lichen Substances Prevent Lichens from Nutrient Deficiency

Abstract

The dibenzofuran usnic acid, a widespread cortical secondary metabolite produced by lichen-forming fungi, was shown to promote the intracellular uptake of Cu 2+ in two epiphytic lichens, Evernia mesomorpha and Ramalina menziesii, from acidic, nutrient-poor bark. Higher Cu 2+ uptake in the former, which produces the depside divaricatic acid in addition to usnic acid, suggests that this depside promotes Cu 2+ uptake. Since Cu 2+ is one of the rarest micronutrients, promotion of Cu 2+ uptake by lichen substances may be crucial for the studied lichens to survive in their nutrient-poor habitats. In contrast, study of the uptake of other metals in E. mesomorpha revealed that the intracellular uptake of Mn 2+ , which regularly exceeds potentially toxic concentrations in leachates of acidic tree bark, was partially inhibited by the lichen substances produced by this species. Inhibition of Mn 2+ uptake by lichen substances previously has been demonstrated in lichens. The uptake of Fe 2+ , Fe 3+ , Mg 2+ , and Zn 2+ , which fail to reach toxic concentrations in acidic bark at unpolluted sites, although they are more common than Cu 2+ , was not affected by lichen substances of E. mesomorpha.

Advanced methods for the study of the chemistry and the metabolism of lichens

“…The dibenzofuran compound usnic acid was reported to facilitate the uptake of cations such as Cu 2? (Hauck et al 2009). Some lichen compounds were shown to exhibit antibacterial (Motohashi et al 2010;Paudel et al 2010), cytostatic (Bogo et al 2010;Millot et al 2009;Tokiwano et al 2009), and antiviral activities (Esimone et al 2009).…”

Comparison of the Phytotoxic Effects of Usnic Acid on Cultures of Free-Living Alga Scenedesmus quadricauda and Aposymbiotically Grown Lichen Photobiont Trebouxia erici

“…These roles include antimicrobial activity, allelopathy, antiherbivory, chelating of heavy metals, light screening, and other proposed functions not yet sufficiently supported by experimental evidence under laboratory conditions (Lawrey 1986;Pöykkö et al 2005;Latkowska et al 2006;Hauck et al 2009;Solhaug et al 2009). Secondary metabolites may be responsible for the ecological success of lichenization, allowing lichens frequently to be the dominant organisms in environments characterized by extreme ecological conditions.…”

The Impact of Cadmium on Photosynthetic Performance and Secondary Metabolites in the Lichens Parmelia sulcata, Flavoparmelia caperata and Evernia prunastri

“…For example, physodalic acid from Hypogymnia physdodes, increase the Fe 2+ uptake and decrease the uptake of Cu 2+ , Mn 2+ and Na + (Hauck andHuneck 2007, Hauck 2008). Dibenzofurane usnic acid and divaricatic acid were both found to increase the intracellular uptake of Cu 2+ in Evernia mesomorpha and Ramalina menziesii (Hauck et al 2009), but reduce the Mn 2+ uptake. Recently, UV spectroscopic studies and X-ray diffraction analyses showed that the complexation of metal ions with lichen substances is widespread Fahselt 2004, Hauck et al 2009).…”