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Photobiont diversity in lichen thallus Psora decipiens
Jadrná, Iva ; Škaloud, Pavel (advisor) ; Peksa, Ondřej (referee)
Psora decipiens is a characteristic species of the terricolous lichen community Toninio-Psoretum decipientis distributed mostly on calcareous or basic substrates. The community consists in various modifications of lichens Placidium squamulosum, Toninia sedifolia, T. opuntioides, Fulgensia fulgens, F. bracteata and others. Photobionts of the lichen Psora decipiens were determined. Psora decipiens shared with Placidium sp. the single photobiont species, a common terrestrial alga Myrmecia israeliensis. Cloning of ITS rDNA revealed high intrathalline variability in M. israeliensis within a single lichen thallus. Several genotypes were often found in a thallus, uncovering either a high mutation rate of the algae or constant relichenization processes. Saxicolous Psora species (P. testacea, P. himalayana, P. valesiaca and P. rubiformis) had M. biatorellae as a photobiont, indicating a possible photobiont influence on substrate specifity of Psora lichens. Finally, the proper methodology used for identification of lichen photobionts is discussed. For a correct photobiont identification, morphological investigations of intrathaline diversity combined with coherent molecular techniques are needed. Such procedure was not applied in the former studies of Psora decipiens, resulting in a poor characterization of...
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Diversity of green algae identified as lichen photobionts
Vaiglová, Zuzana ; Škaloud, Pavel (advisor) ; Štifterová, Anna (referee)
This thesis is focused on green algae, which have been recorded as lichen photobionts. The thesis consists of description of genera from the green algal from classes Ulvophyceae, Trebouxiophyceae and Chlorophyceae. I focused on phylogenetics position of genera, I define their morphology and I summarize their participation in lichen symbiotic relationships. I compare evidences based on the traditional morphological methods and modern molecular data. The following genera can be stated to uncertainly represent lichen photobionts: Trentepohlia, Cephaleuros, Phycopeltis and Dilabifilum from the class Ulvophyceae, and Dictyochloropsis, Chloroidium, Elliptochloris, Coccomyxa, Diplosphaera, Auxenochlorella, Myrmecia, Asterochloris, Trebouxia, Coccobotrys and Leptosira from the class Trebouxiophyceae. The genera Chlorella and Stichococcus are morphologically poorly defined, but they are commonly reported as lichen photobionts. Prasiola associates with the mycobiont, but the identity of their partnership is not certainly defined. The lichen symbiosis of genera Parachloroidium, Pseudochlorella and Gloeocystis has not been confirmed by molecular methods, so far. Key words photobiont, lichen, green algae, Chlorophyta, diversity, phylogeny, Trebouxiophyceae
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The efect of environmental variables on diversity of lichen photobionts
Červenková, Tereza ; Škaloud, Pavel (advisor) ; Peksa, Ondřej (referee)
Lichens represent a synergistic combination of at least two organisms, a heterotrophic fungus and a photosynthetic alga or a cyanobacterium. This association has resulted in a symbiotic organism, which is well tolerant to environmental influences. In fact, symbiotic relationship provides mutual benefit for both organisms. It is generally well known that the fungal partners of lichens are far less sensitive to environmental conditions, such as the temperature, altitude, rainfall or the type and composition of the substrate, in comparison to their algal partners. Therefore, lichen forming fungi have much wider ecological valences than the photobionts interacting with them. Indeed, most of the photosyntetic genera and species are adapted only to certain environmental conditions. For this reason, the symbiotic algae and cyanobacteria probably play a major role during the initial lichen formation on the site. This thesis focuses on the adaptability of photoautotrophic symbionts of lichens, coccoid green algae and cyanobacteria, to environmental conditions. Ecological diversification of photobionts has a direct impact on their genetic differentiation and thus to differentiate lichen species themselves. Unfortunately, in many studies the authors mostly dealt with the diversity of macroscopic symbiotic...
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Biogeography and specificity of Asterochloris photobionts
Řídká, Tereza ; Škaloud, Pavel (advisor) ; Vondrák, Jan (referee)
This diploma thesis has focused on the diversity and biogeography of Asterochloris photobionts. Since no study so far has been published on the biogeography of symbiotic microorganisms, the presented thesis is the first attemp to trace the biogeographic distribution and endemism of symbionts. By gathering 121 Asterochloris sequences obtained from lichen thalli sampled outside Europe and America, the diversity within the genus increased dramatically. The phylogenetic analysis based on the concatenated alignment of ITS rDNA and actin sequences obtained from Cladonia and Stereocaulon photobionts revealed 28 differently supported clades. Of them, eight lineages were newly discovered. Three environmental factors explaining the best the distribution pattern of Asterochloris photobionts were selected according to the statistical tests of the phylogenetic signal: two different types of biogeographical ecoregions and the substrate type. In general, the genus Asterochloris is distributed cosmopolitally, with a very low rate of endemism. Newly obtained data indicate that the restricted distribution of any photobiont clade is not caused by either historic or biological factors, but more likely by specific climatic or habitat preferences.
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Photobiont diversity in the lichen genus Stereocaulon (Lecanoromycetes, Ascomycota)
Vančurová, Lucie ; Škaloud, Pavel (advisor) ; Peksa, Ondřej (referee)
This thesis is focused on the diversity of lichen photobionts and its relation to the mycobionts and environmental factors. The key objective is to map the diversity of lichen photobionts of the genus Stereocaulon, which has been insufficiently examined in comparison with related lichens Cladonia and Lepraria. In total, 92 samples belonging to 12 species of genus Stereocaulon were examined, being found in four continents, at the altitude of 50 to 2 900 metres a. s. l., and variety of natural and artificial substrata. Phylogenetic analyses were inferred on the basis of ITS rDNA, actin type I, 18S rDNA and rbcL sequences. Photobionts belonging to two unrelated genera within Trebouxiophyceae, Asterochloris and Chloroidium, were found in thalli of Stereocaulon lichens. While Asterochloris represents one of the most frequent photobionts of various lichens, Chloroidium has been until now recorded as a lichen photobiont very rarely. The content of heavy metals in substratum can be considered as a determinative factor for its occurrence. A new lineage affiliated to genus Asterochloris was discovered on the island La Palma (the Canary Islands). Interestingly, none of common, widespread Asterochloris lineages has been found in this locality. The lichen photobionts of the genus Stereocaulon were discovered in 12 of...
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