EPIPHYTIC LICHENS AS ENVIRONMENTAL INDICATORS: PART I: Introduction to structure and biology

Transcription

1 EPIPHYTIC LICHENS AS ENVIRONMENTAL INDICATORS: PART I: Introduction to structure and biology

2 Historic overview ery few notes about lichens from antique and middle ages; in culture of Knosos_ dies for house painting Micheli, 1727 (Nova Plantarum Genera); 300 lichen species, first drawing of ascus; soralia treated as seeds Carl Lineus (1753, Species Plantarum, only 80 lichen species Scopoli (Flora carniolica, 1772, Vol. II; 54 taxa, 52 possible to indentify by todays nomenclature) Acharius (Ach.) ; 1803;» A father of lichenology«; Methodes Lichenum; 1810 Lichenographia universalis; 1814 Synopsis Methodica Lichenum; a concept of lichen species is founded; progress in lichen thallus anatomy: asci, ; a huge herbarium in Helsinki Fries, E. (FR.) Systema mycologicum;» a father of mycology«; 1831 Lichenographia europaea reformata; a concept of lichenized fungi - lichens as part of fungi! 1850 _De Notarius; Massalongo (Italy); Koerber (Germany), Fries, Th.M. (Upsalla) new contributions 1822 Nylander; cca taxa!; first reflexion on duble nature of lichens; excursions to tropics; 1866 first chemical kew for lichens;»spot test«(k +, Cl -,

3 11866 De Bary; 1867, Schwenderer: duble nature of lichens;»a symbiotic structure«

4 1877 Stahl - first success in cultivations of lichens, development from spores; even today difficult task 1890 Vainio, E. :» Lichens are fungi«; lichens are classified in the fungi system, but he was aware of their symbiotic nature Zahlbruckner; Catalogus lichenus universalis stil today one of the most important lichenological publications 1907 Zopf;» Die Flechtenstoffe«; introduces the importance of lichens substances; for biology of lichens and taxonomy; he described more than 100 substances, today over 600! 1954 Asahina & Shibata; Chemistry of the lichen substances; further development in the field of lichen substances

5 More recent and contemporary lichen literature and lichenologists 1969 Poelt, J. : Bestimungsschluessel europaischer Flechten 1973 Ahmadjian, V. & M.E. Hale : The lichens 1974 Henssen, A., & H-M. Jahns: Lichens. Eine Einfuehrung in die Flechtenkunde 1983 Hale, M.E. : The biology of Lichens 1984 Hawksworth, D.L. & Hill, D.L. : The lichen forming fungy Galun et al. : Handbook of Lichenology 1984 Honegger, R : lichen cytology, physiology 1995 Wirth, V (1980, 1987): Flechtenflora 1993 Santesson, R. : The lichen of Sweden and Norway

6 Lichen symbiosis semantic problems with definition ( De Bary 1866, Schwenderer 1867,., Ahmadjian Hawkworth et al. 1988, Hawksworth & Honeggger 1994, fungus : exobiont (= exhabitant); mykobiont; heterotrophic partner alga (cyanobacterium): endobiont (inhabitant); photobiont ; autotrophic partner stabile, selfsustaining association of fungus and alga (cyanobacterium); ecologicaly: obligatory mutualism; different types of symbiosis: mycobiont as inhabitant mycophycobiosis;»endophytes«of brown alga; mycobiont as exhabitant: the most common type of symbiosis in lichens; two biont symbiosis : the most common type; three- biont symbiosis: formation of cephalodia (N 2 fixation);

7 Special types of symbiosis morphotypes (phototypes) (in Slovenia Lobaria amplissima- green alga; Dendriscocaulon sp. cyanobacterium; similar in Scotland: Sticta canariensis Sticta dufourii; in New Zealand: Sticta filix Dendriscocaulon sp. 2 mycobiont 1 photobiont symbiosis: obligatory parasits of lichenised fungi, four stages of relations; 4 partner symbiosis: lichenicolous fungi ( 3 photobionts- 1 mycobiont; 3 photobionts 1 mycobiont, 3 mycobionts 1 photobiont

8 Morphotypes (phototypes) The sama fungus exibits different morfology, depenedent on photobiont

9 Photobionts cca 100 species of algae, some cyanobacteria, green algae: Chlorococcales: cocal green algae Trebouxia ; in 70-80% of all lichens Coccomyxa, Myrmecia Chlorella; Trentepohliales Trentepohlia, Phycopeltis cyanobionts: Chroococcales: Gleocapsa Stigonematales: Stigonema Nostocales: Nostoc

10 MYCOBIONTS

11 Ascomycets are the most spread mycobionts Lichenisation occurreed several times in the evolution of ascomycets Several groups of free living ascomycets are descendants of delichenised taxa

12 Taxon total number of species lichenised % Ascomycota ,25 Basidiomycota ,31 Deuteromycota ,18 Mastigiomycota ,09 Myxomycota ,32 Zygomycota Total

13 Thallus structure There are three basic thallus types:crustose, foliose and fruticose Fungus makes major part of biomas, except at certain cyanolichens Thallus morfology depends on fungus structures

14 Vegetative thallus structures Fastening structures are well developed on foliose thalli Rhizine- projections of fungal lower cortex Fibrile fungal projections of thalli edges

15 Main types of thallus structure Heteromerous:photobi onts in gonidial layer (green algae); dorsiventral or radial Homeomerous: cianobionts evenly distributed btween the two cortex layer

16 Vegetative propagules:soredia Soralia, in which soredia are formed are widespread structures Position, shape, colour and size are important for taxonomy

17 Vegetative propagules: isidia Isidia are miniature thallus like structures Shape, size, colour and site of appearance are important for taxonomy

18 Sexual reproduction: only fungus:ascomata, basidiomata Apothecium, the most spred type of ascomata Dick shaped, sunk in warts, elongated (lirella) or petiolated Lecanorine, lecideine, coniocarpous

19 Sexual reproduction: ascomata, basidiomata Perithecium, in the thallus sunk ascomata of diverse structure Basidiomata are mostly perennial, basidiomata are ephemeral

20 Ascospors and vegetative parts of ascomata Ascospors are developed in asks Number, size, colour and cell wall structure Are important for taxonomy Vegetative part of ascomata are also relevant

21 BIOLOGY: as a system lichens are autotrophic Fungus creates microenvironment for photobionts (water, nutrient uptake; light intensity control, defence against herbivores and pathogens) Photobiont makes food for fungus (carbohydrates, amino acids) Fungus synthetises secondary metabolites

22 Comunication with environment: H 2 O, CO 2, nutrient uptake Poikilohydrous and poikilothermic organisms There is structural regulation of water and nutrient uptake by specialised hyphae Pseudocyphelae or cyphelae act as stomata Cephalodia with cianobionts bind atmospheric N 2

23 Internal structure of thallus In heteromeric thallus fungal hyphae are differentiated in two cortex layers and medulla, of very different cell wall structures Photobionts are in gonial layer below upper cortex Medular hyphae are highly hydrophobic, what enables gass transport

24 Communcations between partners Several types of haustoria have been developed for nutrient exchange between partners, depending on type of simbionts Cell wall structure of both partners is again crucial

25 Which currency is used by photobionts? Green algae export mostly sugar alcohols Cianobionts export sugars

26 Mutual contact causes production of secondary metabolites- lichen substances Lichen substances have several important tasks: regulate conductivity of cell walls and thallus defence thallus against patogens and herbivors, modify thallus light properties

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29 ECOLOGY Lichens are probably first atempt to settle harsh terrestrial environment by autotrophs; symbiosis was necessary Mycologist treat them sometimes just as one of the possible life style of fungi All their structural and physiological adaptation enable them to settle axtrem biotopes; in more favurable enviroments they are outcompeted by mosses and higher plants

30 Where lichens prevail? Extreme, harsh environments: 1-very cold and dry: polar and mountain tundras 2- very hot and dry: deserts, semideserts Favurable environments: microsites where they are not outcompeted by other plants (rocks, barren soil, man made substrates) Epiphytic life-style

31 Major ecological groups Epiphytic: corticolous:on bark; lignicolous:on wood; folicolous: on leaves) Terricolous: on ground (soil); muscicolous: on moss; saxicolous: on rocks

32 Ecosystem function Primari producers (taiga, tundra, deserts, clifs, rocks, steppes) Soil formation (rocks, clifs) Water and nutrient retention (epiphytes in forests) Formation of microhabitats (avertebrates) and row material (material for nests)

33 Importance for mankind Food (rare old-fashion practices; Lecanora esculenta (Bible); Cetraria islandica periods of hunger in past in polaric regions Fodder: raindeer breeders Dyes for textil walls (Antique, Middle ages) Row material for perfums and phytopharmaceutical products Bioindication of environment (air pollution, forest continuity)

34 Biodiversity Lichen diversity number of species: Total cca Austria F.R Germany 1674 Italy 2145 Norway&Sweden 2271 Slovenia cca 900 ( )