The Lichenologist

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UV-B induces usnic acid in reindeer lichens


Line  NYBAKKEN a1 and Riitta  JULKUNEN-TIITTO a2
a1 Department of Ecology and Natural Resource Management, Box 5003, Norwegian University of Life Sciences, N-1432 Ås, Norway
a2 Natural Products Research Laboratories, Department of Biology, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland

Article author query
nybakken l   [PubMed][Google Scholar] 
julkunen-tiitto r   [PubMed][Google Scholar] 

Abstract

Induction of secondary compounds in three reindeer lichens (Cladonia arbuscula, C. rangiferina and C. stellaris) was studied under controlled conditions in a growth chamber. Acetone rinsed (secondary compounds removed) lichen mats were subjected to three light regimes (PAR, PAR+UV-A and PAR+UV-A+UV-B), each combined with simulated herbivory (clipping). After 4 weeks, lichen extracts were analyzed by HPLC for any synthesized secondary compounds. UV-B induced the synthesis of usnic acid in C. arbuscula and C. stellaris and melanic pigments in C. rangiferina. Atranorin, fumarprotocetraric acid and perlatolic acid were not influenced by light quality. None of the identified compounds were significantly influenced by clipping. In conclusion, all three lichen species responded to UV-B radiation by developing cortical UV-B absorbing pigments that might function as protective screens. However, the experiment did not produce evidence for a herbivore-deterrent role of compounds studied.

(Accepted March 10 2006)


Key Words: atronorin; Cladonia spp.; fumarprotocetraric acid; herbivory; melanin; perlatolic acid.