Abstract
Lichens, representing mutualistic symbioses between photobionts and mycobionts, often accumulate high concentrations of secondary compounds synthesized by the fungal partner. Light screening is one function for cortical compounds being deposited as crystals outside fungal hyphae. These compounds can non-destructively be extracted by 100% acetone from air-dry living thalli. Extraction of atranorin from Physcia aipolia changed the lichen colour from pale grey to green in the hydrated state, whereas acetone-rinsed and control thalli were all pale grey when dry. Removal of parietin from Xanthoria parietina changed the colour of desiccated thalli from orange to grey. Colour changes were quantified by reflectance measurements. By a new chlorophyll fluorescence method, screening was assessed as the decrease in incident irradiance (PAR) necessary to reach identical effective quantum yields of PSII (ΦPSII) in acetone-rinsed and control thalli. Thereby, we estimated a screening efficiency due to cortical atranorin crystals at 61, 38, and 40% of blue, green and red light, respectively, whereas parietin screened 81, 27 and 1% of these wavelength ranges. Removal of atranorin caused similar levels of increased photoinhibition for P. aipolia in blue, green and red light, whereas parietin-deficient thalli of X. parietina exhibited increased photoinhibition with decreasing wavelengths. Atranorin possibly prevents water from entering the spaces between the hyphae in the cortex. The air-filled cavities with white atranorin crystals reflect excess light, whereas the yellow compound parietin absorbs excess light. Thereby, both atranorin and parietin play significant photoprotective roles for symbiotic green algae, but with compound-specific screening mechanisms.
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Abbreviations
- ETR:
-
Electron transport rate
- ETRapp :
-
Apparent electron transport rate
- ETRabs :
-
Absolute electron transport rate
- Fm :
-
Maximal fluorescence in dark-adapted samples
- F0 :
-
Minimum fluorescence in dark-adapted samples
- Fv :
-
Variable fluorescence (Fv = Fm − F0)
- Fv/Fm :
-
Maximal quantum yield of PSII
- Fm′:
-
Maximal fluorescence in illuminated samples
- Ft :
-
Minimum fluorescence in illuminated samples
- ΦPSII :
-
Quantum yield of PSII during exposure to light
- PAR:
-
Photosynthetically active radiation
- PSII:
-
Photosystem II
References
Armaleo D, Zhang Y, Cheung S (2008) Light might regulate divergently depside and depsidone accumulation in the lichen Parmotrema hypotropum by affecting thallus temperature and water potential. Mycologia 100:565–576
Bilger W, Veit M, Schreiber L, Schreiber U (1997) Measurement of leaf epidermal transmittance of UV radiation by chlorophyll fluorescence. Physiol Plant 101:754–763
Bilger W, Johnsen T, Schreiber U (2001) UV-excited chlorophyll fluorescence as a tool for the assessment of UV protection by the epidermis of plants. J Exp Bot 52:2007–2014
Björn LO (2002) The nature of light and its interaction with matter. In: Björn LO (ed) Photobiology. The science of light and life. Kluwer Academic Publishers, Dordrecht, pp 1–35
de Vera JP, Rettberg P, Ott S (2008) Life at the limits: capacities of isolated and cultured lichen symbionts to resist extreme environmental stresses. Orig Life Evol Biosph 38:457–468
Dietz S, Büdel B, Lange OL, Bilger W (2000) Transmittance of light through the cortex of lichens from contrasting habitats. Bibl Lichenol 75:171–182
Ertl L (1951) Über die Lichtverhältnisse in Laubflechten. Planta 39:245–270
Gauslaa Y (1984) Heat resistance and energy budget in different Scandinavian plants. Holarct Ecol 7:1–78
Gauslaa Y (2005) Lichen palatability depends on investments in herbivore defence. Oecologia 143:94–105
Gauslaa Y (2009) Ecological functions of lichen compounds. In: Bayerische Akademie der Wissenschaften (ed) Rundgespräche der Kommission für Ökologie, vol 36 Ökologische Rolle der Flechten. Verlag Dr. Friedrich Pfeil, München, pp 95–108
Gauslaa Y, Solhaug KA (1996) Differences in the susceptibility to light stress between epiphytic lichens of ancient and young boreal forest stands. Funct Ecol 10:344–354
Gauslaa Y, Solhaug KA (2001) Fungal melanins as a sun screen for symbiotic green algae in the lichen Lobaria pulmonaria. Oecologia 126:462–471
Gauslaa Y, Ustvedt EM (2003) Is parietin a UV-B or a blue-light screening pigment in the lichen Xanthoria parietina? Photochem Photobiol Sci 2:424–432
Genty B, Briantais JM, Baker NR (1989) The relationship between the quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence. Biochim Biophys Acta 990:87–92
Honegger R (2003) The impact of different long-term storage conditions on the viability of lichen-forming ascomycetes and their green algal photobiont, Trebouxia spp. Plant Biol 5:324–330
Huneck S (1999) The significance of lichens and their metabolites. Naturwissenschaften 86:559–570
Huneck S (2001) New results on the chemistry of lichen substances. In: Herz W, Falk H, Kirby GW, Moore RE (eds) Fortschritte der Chemie organischer Naturstoffe: progress in the chemistry of organic natural products, vol 81. Springer, Wien, pp 1–313
Ingolfsdottir K (2002) Usnic acid. Phytochemistry 61:729–736
Lange OL, Green TGA, Reichenberger H, Hesbacher S, Proksch P (1997) Do secondary substances in the thallus of a lichen promote CO2 diffusion and prevent depression of net photosynthesis at high water content? Oecologia 112:1–3
McEvoy M, Solhaug KA, Gauslaa Y (2007) Solar radiation screening in usnic acid-containing cortices of the lichen Nephroma arcticum. Symbiosis 43:143–150
Moberg R (2002) Physcia. Nordic Lichen Flora 2:33–38
Nimis PL, Skert N (2006) Lichen chemistry and selective grazing by the coleopteran Lasioderma serricorne. Environ Exp Bot 55:175–182
Nybakken L, Julkunen-Tiitto R (2006) UV-B induces usnic acid in reindeer lichens. Lichenologist 38:477–485
Ohnishi N, Allakhverdiev SI, Takahashi S, Higashi S, Watanabe M, Nishiyama Y, Murata N (2005) Two-step mechanism of photodamage to photosystem II: step 1 occurs at the oxygen-evolving complex and step 2 occurs at the photochemical reaction center. Biochemistry 44:8494–8499
Sancho LG, de la Torre R, Horneck G, Ascaso C, de los Rios A, Pintado A, Wierzchos J, Schuster M (2007) Lichens survive in space: results from the 2005 LICHENS experiment. Astrobiology 7:443–454
Sarvikas P, Hakala M, Patsikka E, Tyystjärvi T, Tyystjärvi E (2006) Action spectrum of photoinhibition in leaves of wild-type and npq1–2 and npq4–1 mutants of Arabidopsis thaliana. Plant Cell Physiol 47:391–400
Scherrer S, Haisch A, Honegger R (2002) Characterization and expression of XPH1, the hydrophobin gene of the lichen-forming ascomycete Xanthoria parietina. New Phytol 154:175–184
Solhaug KA, Gauslaa Y (1996) Parietin, a photoprotective secondary product of the lichen Xanthoria parietina. Oecologia 108:412–418
Solhaug KA, Gauslaa Y (2001) Acetone rinsing: a method for testing ecological and physiological roles of secondary compounds in living lichens. Symbiosis 30:301–315
Solhaug KA, Gauslaa Y, Nybakken L, Bilger W (2003) UV-induction of sun-screening pigments in lichens. New Phytol 158:91–100
Acknowledgments
The students, Guillermot Gonnet and Helen Hatch, are thanked for some of the measurements. Our thanks are also due to Dr. Line Nybakken for help with the HPLC analysis.
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Solhaug, K.A., Larsson, P. & Gauslaa, Y. Light screening in lichen cortices can be quantified by chlorophyll fluorescence techniques for both reflecting and absorbing pigments. Planta 231, 1003–1011 (2010). https://doi.org/10.1007/s00425-010-1103-3
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DOI: https://doi.org/10.1007/s00425-010-1103-3