Journal articles: 'Lichen symbiosis'

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Bates, Scott T., Garrett W. G. Cropsey, J. Gregory Caporaso, Rob Knight, and Noah Fierer. "Bacterial Communities Associated with the Lichen Symbiosis." Applied and Environmental Microbiology 77, no. 4 (December 17, 2010): 1309–14. http://dx.doi.org/10.1128/aem.02257-10.

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ABSTRACTLichens are commonly described as a mutualistic symbiosis between fungi and “algae” (ChlorophytaorCyanobacteria); however, they also have internal bacterial communities. Recent research suggests that lichen-associated microbes are an integral component of lichen thalli and that the classical view of this symbiotic relationship should be expanded to include bacteria. However, we still have a limited understanding of the phylogenetic structure of these communities and their variability across lichen species. To address these knowledge gaps, we used bar-coded pyrosequencing to survey the bacterial communities associated with lichens. Bacterial sequences obtained from four lichen species at multiple locations on rock outcrops suggested that each lichen species harbored a distinct community and that all communities were dominated byAlphaproteobacteria. Across all samples, we recovered numerous bacterial phylotypes that were closely related to sequences isolated from lichens in prior investigations, including those from a lichen-associatedRhizobialeslineage (LAR1; putative N2fixers). LAR1-related phylotypes were relatively abundant and were found in all four lichen species, and many sequences closely related to other known N2fixers (e.g.,Azospirillum,Bradyrhizobium, andFrankia) were recovered. Our findings confirm the presence of highly structured bacterial communities within lichens and provide additional evidence that these bacteria may serve distinct functional roles within lichen symbioses.

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Nelsen, Matthew P., Robert Lücking, C. Kevin Boyce, H. Thorsten Lumbsch, and Richard H. Ree. "The macroevolutionary dynamics of symbiotic and phenotypic diversification in lichens." Proceedings of the National Academy of Sciences 117, no. 35 (August 13, 2020): 21495–503. http://dx.doi.org/10.1073/pnas.2001913117.

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Symbioses are evolutionarily pervasive and play fundamental roles in structuring ecosystems, yet our understanding of their macroevolutionary origins, persistence, and consequences is incomplete. We traced the macroevolutionary history of symbiotic and phenotypic diversification in an iconic symbiosis, lichens. By inferring the most comprehensive time-scaled phylogeny of lichen-forming fungi (LFF) to date (over 3,300 species), we identified shifts among symbiont classes that broadly coincided with the convergent evolution of phylogenetically or functionally similar associations in diverse lineages (plants, fungi, bacteria). While a relatively recent loss of lichenization in Lecanoromycetes was previously identified, our work instead suggests lichenization was abandoned far earlier, interrupting what had previously been considered a direct switch between trebouxiophycean and trentepohlialean algal symbionts. Consequently, some of the most diverse clades of LFF are instead derived from nonlichenized ancestors and re-evolved lichenization with Trentepohliales algae, a clade that also facilitated lichenization in unrelated lineages of LFF. Furthermore, while symbiont identity and symbiotic phenotype influence the ecology and physiology of lichens, they are not correlated with rates of lineage birth and death, suggesting more complex dynamics underly lichen diversification. Finally, diversification patterns of LFF differed from those of wood-rotting and ectomycorrhizal taxa, likely reflecting contrasts in their fundamental biological properties. Together, our work provides a timeline for the ecological contributions of lichens, and reshapes our understanding of symbiotic persistence in a classic model of symbiosis.

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Douglas, Angela E. "Sir David Cecil Smith. 21 May 1930—29 June 2018." Biographical Memoirs of Fellows of the Royal Society 67 (August 14, 2019): 401–19. http://dx.doi.org/10.1098/rsbm.2019.0011.

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David Smith was an international authority in the biological discipline of symbiosis and an influential leader in academic life. Through his work on photosynthetic symbioses in lichens and invertebrate animals, David transformed the field of symbiosis from a study of taxonomy and morphology into an experimental science. In particular, he applied novel radiotracer techniques to demonstrate that lichens are metabolically dynamic, with photosynthetically-fixed carbon transferred from symbionts to lichen host at high rates. His subsequent study of diverse symbioses led him to develop common principles underlying symbioses, including the regulated transfer of metabolites between partners and the role of ecological processes of colonization and community assembly in the establishment of symbioses. In his academic service, David had multiple leadership roles, including head of the Department of Botany at University of Bristol (1974–1980), head of the Department of Agricultural Science at University of Oxford (1980–1987), principal of University of Edinburgh (1987–1994) and president of Wolfson College, University of Oxford (1994–2000). David was biological secretary of the Royal Society (1983–1987) and he was knighted in 1986.

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Molnár, Katalin, and Edit Farkas. "Current Results on Biological Activities of Lichen Secondary Metabolites: a Review." Zeitschrift für Naturforschung C 65, no. 3-4 (April 1, 2010): 157–73. http://dx.doi.org/10.1515/znc-2010-3-401.

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Lichens are symbiotic organisms of fungi and algae or cyanobacteria. Lichen-forming fungi synthesize a great variety of secondary metabolites, many of which are unique. Developments in analytical techniques and experimental methods have resulted in the identification of about 1050 lichen substances (including those found in cultures). In addition to their role in lichen chemotaxonomy and systematics, lichen secondary compounds have several possible biological roles, including photoprotection against intense radiation, as well as allelochemical, antiviral, antitumor, antibacterial, antiherbivore, and antioxidant action. These compounds are also important factors in metal homeostasis and pollution tolerance of lichen thalli. Although our knowledge of the contribution of these extracellular products to the success of the lichen symbiosis has increased significantly in the last decades, their biotic and abiotic roles have not been entirely explored.

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Methuen, Andrew S., and Vernon Ahmadjian. "The Lichen Symbiosis." Mycologia 86, no. 5 (September 1994): 715. http://dx.doi.org/10.2307/3760549.

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III, Thomas H. Nash, and Vernon Ahmadjian. "The Lichen Symbiosis." Bryologist 98, no. 3 (1995): 432. http://dx.doi.org/10.2307/3243387.

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Brown, D. H. "The lichen symbiosis." Endeavour 18, no. 1 (January 1994): 45. http://dx.doi.org/10.1016/0160-9327(94)90129-5.

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ten Veldhuis, Marie-Claire, Gennady Ananyev, and G. Charles Dismukes. "Symbiosis extended: exchange of photosynthetic O2 and fungal-respired CO2 mutually power metabolism of lichen symbionts." Photosynthesis Research 143, no. 3 (December 31, 2019): 287–99. http://dx.doi.org/10.1007/s11120-019-00702-0.

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AbstractLichens are a symbiosis between a fungus and one or more photosynthetic microorganisms that enables the symbionts to thrive in places and conditions they could not compete independently. Exchanges of water and sugars between the symbionts are the established mechanisms that support lichen symbiosis. Herein, we present a new linkage between algal photosynthesis and fungal respiration in lichen Flavoparmelia caperata that extends the physiological nature of symbiotic co-dependent metabolisms, mutually boosting energy conversion rates in both symbionts. Measurements of electron transport by oximetry show that photosynthetic O2 is consumed internally by fungal respiration. At low light intensity, very low levels of O2 are released, while photosynthetic electron transport from water oxidation is normal as shown by intrinsic chlorophyll variable fluorescence yield (period-4 oscillations in flash-induced Fv/Fm). The rate of algal O2 production increases following consecutive series of illumination periods, at low and with limited saturation at high light intensities, in contrast to light saturation in free-living algae. We attribute this effect to arise from the availability of more CO2 produced by fungal respiration of photosynthetically generated sugars. We conclude that the lichen symbionts are metabolically coupled by energy conversion through exchange of terminal electron donors and acceptors used in both photosynthesis and fungal respiration. Algal sugars and O2 are consumed by the fungal symbiont, while fungal delivered CO2 is consumed by the alga.

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Ahmadjian, V., and J. B. Jacobs. "Artificial Re-Establishment of Lichens IV. Comparison between Natural and Synthetic Thalli of Usnea Strigosa." Lichenologist 17, no. 2 (June 1985): 149–65. http://dx.doi.org/10.1017/s0024282985000202.

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AbstractSynthetic thalli of Usnea strigosa produced the same fibril morphology and secondary compounds as natural thalli. The outer cortex of synthetic lichens was covered with crystals of usnic acid and compounds related to norstictic acids. The common presence on the fibrils of lichen acids suggests that these compounds have a functional role in the symbiosis. During alcohol dehydration, crystals of usnic acid dissolved and left impressions in the mucilage around the symbionts. The impressions were valuable indicators of the position of crystals in the lichen thallus. Crystal impressions of usnic acid were common on the cortical hyphae and were seen also on the surface of algal cells. The crystal impressions were larger in the synthetic lichen than in natural thalli. Impressions of norstictic acid and related compounds were not seen.

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Xu, Maonian, Hugo De Boer, Elin Soffia Olafsdottir, Sesselja Omarsdottir, and Starri Heidmarsson. "Phylogenetic diversity of the lichenized algal genus Trebouxia (Trebouxiophyceae, Chlorophyta): a new lineage and novel insights from fungal-algal association patterns of Icelandic cetrarioid lichens (Parmeliaceae, Ascomycota)." Botanical Journal of the Linnean Society 194, no. 4 (July 20, 2020): 460–68. http://dx.doi.org/10.1093/botlinnean/boaa050.

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Abstract Lichens have high tolerance to harsh environmental conditions, where lichen symbiont interactions (e.g. myco- and photobionts) may play a crucial role. The characterization of fungal-algal association patterns is essential to understand their symbiotic interactions. This study investigated fungal-algal association patterns in Icelandic cetrarioid lichens using a multi-locus phylogenetic framework, including fungal nrITS, MCM7, mtSSU, RPB1 and RPB2 and algal nrITS, nrLSU, rbcL and mtCOXII data. Most Icelandic cetrarioid lichenized fungi were found to be specifically associated to the known Trebouxia clade “S” (Trebouxia simplex/suecica group), whereas the lichen-forming fungus Cetrariella delisei forms a symbiosis with a previously unrecognized lineage of Trebouxia, provisionally named as the “D” clade. This new Trebouxia lineage is supported by maximum likelihood and Bayesian phylogenetic analyses using all four included algal loci.

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WA, Elkhateeb. "Lichentherapy: Highlights on the Pharmaceutical Potentials of Lichens." Open Access Journal of Microbiology & Biotechnology 6, no. 2 (2021): 1–10. http://dx.doi.org/10.23880/oajmb-16000190.

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Lichens exist in every continent and have a history of being used as food, medicine, a source of dyes and animal feed. Lichens are now being used as natural indicators of climate change and for air quality monitoring worldwide. Lichens play an important role in many ecosystems and exist as a symbiotic association between fungi and algae or cyanobacteria. This symbiosis results in the production of unique secondary metabolites known as lichen substances, which arise within the thalli and are typically in crystal form on the surface of the fungal hyphae. Recently, lichens and their secondary metabolites have been receiving increased attention due to their nutritional value and pharmaceutical potential. This review aims to highlight on the importance and variety of common lichen substances (secondary metabolites). Finally, the commercialization of lichens is growing but, in the future, metabolic and biotechnological approaches can be used as an alternative product to overcome the limited availability of biologically active, commercially valuable and medicinally important secondary metabolite components.

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Werth, Silke, and Christoph Scheidegger. "Congruent Genetic Structure in the Lichen-Forming Fungus Lobaria pulmonaria and Its Green-Algal Photobiont." Molecular Plant-Microbe Interactions® 25, no. 2 (February 2012): 220–30. http://dx.doi.org/10.1094/mpmi-03-11-0081.

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The extent of codispersal of symbionts is one of the key factors shaping genetic structures of symbiotic organisms. Concordant patterns of genetic structure are expected in vertically transmitted symbioses, whereas horizontal transmission generally uncouples genetic structures unless the partners are coadapted. Here, we compared the genetic structures of mutualists, the lichen-forming fungus Lobaria pulmonaria and its primary green-algal photobiont, Dictyochloropsis reticulata. We performed analysis of molecular variance and variogram analysis to compare genetic structures between symbiosis partners. We simulated the expected number of multilocus-genotype recurrences to reveal whether the distribution of multilocus genotypes of either species was concordant with panmixia. Simulations and tests of linkage disequilibrium provided compelling evidence for the codispersal of mutualists. To test whether genotype associations between symbionts were consistent with randomness, as expected under horizontal transmission, we simulated the recurrence of fungal-algal multilocus genotype associations expected by chance. Our data showed nonrandom associations of fungal and algal genotypes. Either vertical transmission or horizontal transmission coupled with coadaptation between symbiont genotypes may have created these nonrandom associations. This study is among the first to show codispersal and highly congruent genetic structures in the partners of a lichen mutualism.

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Fernández-Marín, Beatriz, Marina López-Pozo, Alicia V. Perera-Castro, Miren Irati Arzac, Ana Sáenz-Ceniceros, Claudia Colesie, Asunción de los Ríos, et al. "Symbiosis at its limits: ecophysiological consequences of lichenization in the genus Prasiola in Antarctica." Annals of Botany 124, no. 7 (September 24, 2019): 1211–26. http://dx.doi.org/10.1093/aob/mcz149.

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Abstract Background and Aims Lichens represent a symbiotic relationship between at least one fungal and one photosynthetic partner. The association between the lichen-forming fungus Mastodia tessellata (Verrucariaceae) and different species of Prasiola (Trebouxiophyceae) has an amphipolar distribution and represents a unique case study for the understanding of lichen symbiosis because of the macroalgal nature of the photobiont, the flexibility of the symbiotic interaction and the co-existence of free-living and lichenized forms in the same microenvironment. In this context, we aimed to (1) characterize the photosynthetic performance of co-occurring populations of free-living and lichenized Prasiola and (2) assess the effect of the symbiosis on water relations in Prasiola, including its tolerance of desiccation and its survival and performance under sub-zero temperatures. Methods Photochemical responses to irradiance, desiccation and freezing temperature and pressure–volume curves of co-existing free-living and lichenized Prasiola thalli were measured in situ in Livingston Island (Maritime Antarctica). Analyses of photosynthetic pigment, glass transition and ice nucleation temperatures, surface hydrophobicity extent and molecular analyses were conducted in the laboratory. Key Results Free-living and lichenized forms of Prasiola were identified as two different species: P. crispa and Prasiola sp., respectively. While lichenization appears to have no effect on the photochemical performance of the alga or its tolerance of desiccation (in the short term), the symbiotic lifestyle involves (1) changes in water relations, (2) a considerable decrease in the net carbon balance and (3) enhanced freezing tolerance. Conclusions Our results support improved tolerance of sub-zero temperature as the main benefit of lichenization for the photobiont, but highlight that lichenization represents a delicate equilibrium between a mutualistic and a less reciprocal relationship. In a warmer climate scenario, the spread of the free-living Prasiola to the detriment of the lichen form would be likely, with unknown consequences for Maritime Antarctic ecosystems.

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HAUCK, Markus. "Eutrophication threatens the biochemical diversity in lichens." Lichenologist 43, no. 2 (February 1, 2011): 147–54. http://dx.doi.org/10.1017/s0024282910000654.

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AbstractLichens respond sensitively to ambient nitrogen levels. Global change, which includes the increase of nitrogen-polluted environments, causes the decline of species sensitive to eutrophication, whereas some species tolerant of high nitrogen levels increase. Lichens produce hundreds of carbon-based secondary substances (so-called lichen substances), most of which are unique to the lichen symbiosis. In the present paper, correlative patterns between the eutrophication tolerance of lichen species and their secondary chemistry are analyzed using two data sets, one classifying the eutrophication tolerance of more than 500 Central European lichen species, and another of epiphytic lichens from more than 1200 plots from the Netherlands. Analyses show that, in general, the diversity of lichen secondary metabolites decreases along with increasing tolerance to eutrophication. Most notable is the reduced diversity of depsides and depsidones, the two largest groups of lichen substances, but dibenzofurans and fatty acids are also generally found in lichens sensitive to eutrophication. Conversely, anthraquinones and pulvinic acids are found most frequently in lichens from nitrogen-rich environments that can result from eutrophication. A family-wide analysis of the datasets indicates that loss of chemical diversity is not due to a single species-rich lichen family, but a characteristic of many lichen families.

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Dyer, Paul S. "Hydrophobins in the lichen symbiosis." New Phytologist 154, no. 1 (April 4, 2002): 1–4. http://dx.doi.org/10.1046/j.1469-8137.2002.00387.x.

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HAUCK, Markus, Gert HELMS, and Thomas FRIEDL. "Photobiont selectivity in the epiphytic lichens Hypogymnia physodes and Lecanora conizaeoides." Lichenologist 39, no. 2 (February 20, 2007): 195–204. http://dx.doi.org/10.1017/s0024282907006639.

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Abstract:In two lichen species, Hypogymnia physodes and Lecanora conizaeoides, often used as model organisms for pollution-sensitive and pollution-tolerant epiphytic lichens, respectively, the hypothesis was tested that the toxitolerance of the Trebouxia photobiont limits the tolerance of the entire lichen symbiosis. Being lecanoralean-trebouxioid associations, H. physodes and L. conizaeoides represent the most common type of lichens. Photobionts of both lichen species deriving from microhabitats with varying supply of S and heavy metals were identified using nuclear ITS nrDNA sequencing. The photobiont of L. conizaeoides was identified as T. simplex, whereas the photobiont of H. physodes belongs to an undescribed Trebouxia species, related to T. jamesii subsp. angustilobata and provisionally named as T. hypogymniae Hauck & Friedl ined. Since T. hypogymniae ined. is also known from Lecidea silacea, which is characteristic of rock and slag with high heavy metal content, a high sensitivity of this alga to pollutants is unlikely to be a key factor for the relatively low toxitolerance of H. physodes. Furthermore, the photobiont cannot be crucial for the extremely high toxitolerance of L. conizaeoides, as T. simplex is also known from pollution-sensitive lichens of the fruticose genus Pseudevernia. These findings suggest that the photobiont is not generally a key factor determining pollution sensitivity in the most common type of lichen symbiosis. The high specificity for T. simplex in L. conizaeoides in existing populations of L. conizaeoides suggest that already established thalli could be a source of photobiont cells for re-lichenization.

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Elkhateeb, Waill. "Fungi over fungi, endophytic fungi associated with mushroom fruiting bodies and lichens." Pharmaceutics and Pharmacology Research 4, no. 2 (March 2, 2021): 01–04. http://dx.doi.org/10.31579/2693-7247/028.

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Mushrooms are macrofungi that are famous for their nutritional and pharmaceutical values. On the other hand, lichens are the form of symbiosis representing the complex relation between fungi and algae. Understanding the ability of fungi to grow over anything, this review is focusing on endophytic fungi capable of growing in association with mushrooms and lichens, respectively. Although reports describing these association are rare, it is important to highlight such relation, and encourage for conducting more studies in order to understand the consequences of growth of endophytes on mushroom, status of lichen endophytes, and to investigate the diversity of endophytic fungi within lichen thalli.

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Honegger, R. "Functional Aspects of the Lichen Symbiosis." Annual Review of Plant Physiology and Plant Molecular Biology 42, no. 1 (June 1991): 553–78. http://dx.doi.org/10.1146/annurev.pp.42.060191.003005.

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Calcott, Mark J., David F. Ackerley, Allison Knight, Robert A. Keyzers, and Jeremy G. Owen. "Secondary metabolism in the lichen symbiosis." Chemical Society Reviews 47, no. 5 (2018): 1730–60. http://dx.doi.org/10.1039/c7cs00431a.

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Lichens, which are defined by a symbiosis between a mycobiont (fungal partner) and a photobiont (photoautotrophic partner), are in fact complex assemblages of microorganisms that constitute a largely untapped source of bioactive secondary metabolites.

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Almendras, Katerin, Jaime García, Margarita Carú, and Julieta Orlando. "Nitrogen-Fixing Bacteria Associated with Peltigera Cyanolichens and Cladonia Chlorolichens." Molecules 23, no. 12 (November 25, 2018): 3077. http://dx.doi.org/10.3390/molecules23123077.

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Lichens have been extensively studied and described; however, recent evidence suggests that members of the bacterial community associated with them could contribute new functions to the symbiotic interaction. In this work, we compare the nitrogen-fixing guild associated with bipartite terricolous lichens with different types of photobiont: Peltigera cyanolichens and Cladonia chlorolichens. Since cyanobacteria contribute nitrogen to the symbiosis, we propose that chlorolichens have more diverse bacteria with the ability to fix nitrogen compared to cyanolichens. In addition, since part of these bacteria could be recruited from the substrate where lichens grow, we propose that thalli and substrates share some bacteria in common. The structure of the nitrogen-fixing guild in the lichen and substrate bacterial communities of both lichens was determined by terminal restriction fragment length polymorphism (TRFLP) of the nifH gene. Multivariate analyses showed that the nitrogen-fixing bacteria associated with both types of lichen were distinguishable from those present in their substrates. Likewise, the structure of the nitrogen-fixing bacteria present in the cyanolichens was different from that of chlorolichens. Finally, the diversity of this bacterial guild calculated using the Shannon index confirms the hypothesis that chlorolichens have a higher diversity of nitrogen-fixing bacteria than cyanolichens.

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Greshake Tzovaras, Bastian, Francisca H. I. D. Segers, Anne Bicker, Francesco Dal Grande, Jürgen Otte, Seyed Yahya Anvar, Thomas Hankeln, Imke Schmitt, and Ingo Ebersberger. "What Is in Umbilicaria pustulata? A Metagenomic Approach to Reconstruct the Holo-Genome of a Lichen." Genome Biology and Evolution 12, no. 4 (March 12, 2020): 309–24. http://dx.doi.org/10.1093/gbe/evaa049.

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Abstract Lichens are valuable models in symbiosis research and promising sources of biosynthetic genes for biotechnological applications. Most lichenized fungi grow slowly, resist aposymbiotic cultivation, and are poor candidates for experimentation. Obtaining contiguous, high-quality genomes for such symbiotic communities is technically challenging. Here, we present the first assembly of a lichen holo-genome from metagenomic whole-genome shotgun data comprising both PacBio long reads and Illumina short reads. The nuclear genomes of the two primary components of the lichen symbiosis—the fungus Umbilicaria pustulata (33 Mb) and the green alga Trebouxia sp. (53 Mb)—were assembled at contiguities comparable to single-species assemblies. The analysis of the read coverage pattern revealed a relative abundance of fungal to algal nuclei of ∼20:1. Gap-free, circular sequences for all organellar genomes were obtained. The bacterial community is dominated by Acidobacteriaceae and encompasses strains closely related to bacteria isolated from other lichens. Gene set analyses showed no evidence of horizontal gene transfer from algae or bacteria into the fungal genome. Our data suggest a lineage-specific loss of a putative gibberellin-20-oxidase in the fungus, a gene fusion in the fungal mitochondrion, and a relocation of an algal chloroplast gene to the algal nucleus. Major technical obstacles during reconstruction of the holo-genome were coverage differences among individual genomes surpassing three orders of magnitude. Moreover, we show that GC-rich inverted repeats paired with nonrandom sequencing error in PacBio data can result in missing gene predictions. This likely poses a general problem for genome assemblies based on long reads.

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Paulsrud, Per, and Peter Lindblad. "Sequence Variation of the tRNALeuIntron as a Marker for Genetic Diversity and Specificity of Symbiotic Cyanobacteria in Some Lichens." Applied and Environmental Microbiology 64, no. 1 (January 1, 1998): 310–15. http://dx.doi.org/10.1128/aem.64.1.310-315.1998.

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ABSTRACT We examined the genetic diversity of Nostoc symbionts in some lichens by using the tRNALeu (UAA) intron as a genetic marker. The nucleotide sequence was analyzed in the context of the secondary structure of the transcribed intron. Cyanobacterial tRNALeu (UAA) introns were specifically amplified from freshly collected lichen samples without previous DNA extraction. The lichen species used in the present study were Nephroma arcticum, Peltigera aphthosa, P. membranacea, and P. canina. Introns with different sizes around 300 bp were consistently obtained. Multiple clones from single PCRs were screened by using their single-stranded conformational polymorphism pattern, and the nucleotide sequence was determined. No evidence for sample heterogenity was found. This implies that the symbiont in situ is not a diverse community of cyanobionts but, rather, one Nostoc strain. Furthermore, each lichen thallus contained only one intron type, indicating that each thallus is colonized only once or that there is a high degree of specificity. The same cyanobacterial intron sequence was also found in samples of one lichen species from different localities. In a phylogenetic analysis, the cyanobacterial lichen sequences grouped together with the sequences from two free-living Nostoc strains. The size differences in the intron were due to insertions and deletions in highly variable regions. The sequence data were used in discussions concerning specificity and biology of the lichen symbiosis. It is concluded that the tRNALeu (UAA) intron can be of great value when examining cyanobacterial diversity.

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Zarabska-Bożejewicz, Daria. "The Impact of Nitrogen Pollution in the Agricultural Landscape on Lichens: A Review of Their Responses at the Community, Species, Biont and Physiological Levels." Agronomy 10, no. 12 (November 25, 2020): 1852. http://dx.doi.org/10.3390/agronomy10121852.

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Lichenized fungi are widely used as bioindicators owing to their sensitivity to various anthropogenic impacts. Increased nitrogen deposition affects the occurrence, abundance and distribution of lichens. The main sources of nitrogen in the agricultural landscape are ammonia (NH3) and the ammonium cation (NH4+). Livestock farming and the use of organic and mineral fertilizers are primarily responsible for the emissions of these compounds. N in excess can negatively impact lichen biota and lead, for example, to species decline, impoverishment of lichen communities or unbalanced symbiosis. However, there is also evidence for certain opposite effects, in particular at medium N concentrations. Positive influences may be manifested, for example, by higher chlorophyll a concentrations, or by a greater lichen diversity being supported by the coexistence of lichens with different trophic requirements. Indicator values of lichens in relation to N input are exhibited, for example, by some biont markers (the contents of ergosterol and chlorophyll a), particular species, such as Xanthoriaparietina, or trophic functional groups (oligotrophilous and nitrophilous lichens). Gaps identified in the current knowledge are discussed.

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Murningsih, Murningsih, and Husna Mafazaa. "Jenis-Jenis Lichen Di Kampus Undip Semarang." Bioma : Berkala Ilmiah Biologi 18, no. 2 (August 10, 2016): 20. http://dx.doi.org/10.14710/bioma.18.2.20-29.

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Lichen is a symbion organism which own huge positive effect over environment. Lichen is formed by a symbiosis between fungi (mikobiont) from Ascomycetes and Basidiomycetes, and alga (fikobiont) from Cyanobacteria or Chlorophyceae. Corticolous lichens lives as an epiphyte in substrate of skin branches. It grows in Diponegoro University (Undip) campus area where a lot of shaded trees can be found as the substrate. The research aimed to define the names of lichen in Undip area by using purposive random sampling. The sampling was found in four locations: 1. Eastern of green boulevard, in front of Farm Faculty; 2. Western of green boulevard, in front of Medical Plants Biology building; 3. Northern of green boulevard, next to Economic and Business Faculty; 4. Green Boulevard as a main road, in front of Engineering Faculty. The research encountered 7 families of lichen which are Graphis scripta, Graphis sp. (Family of Graphidaceae), Lepraria sp. (Family of Leprariaceae), Dirinaria applanata, Dirinaria picta, Dirinaria sp., (Family of Physciaceae), Caloplaca sp. (Family of Caloplacaceae), Parmelia sp., Parmelia sulcata (Family of Parmeliaceae), Lecanora sp. (Family of Lecanoraceae), Arthonia sp. (Family of Arthoniaceae). The lichens are in groups of talus types: foliose and crustose. Keywords: names of lichen, talus types, Undip

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Лыскова (Lyskova), Надежда (Nadezhda) Сергеевна (Sergeevna), Юлия (Iuliia) Генриховна (Genrikhovna) Базарнова (Bazarnova), and Игорь (Igor') Вадимович (Vadimovic) Кручина-Богданов (Kruchina-Bogdanov ). "STUDY OF THE COMPOSITION AND PROPERTIES OF SECONDARY METABOLITES OF THE LICHEN USNEA BARBATA." chemistry of plant raw material, no. 1 (October 19, 2017): 121–27. http://dx.doi.org/10.14258/jcprm.2018011966.

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In the modern society value of many biological resources remains underestimated. Lichens are one of the unique poorly studied bioresources. These are amazing organisms, formed by symbiosis of algae and fungus. Due to this combination, lichens have a number of unique properties.In this article the results of study the composition of biologically active secondary lichen metabolites of the Usnea barbata lichen. Antioxidant activity and antimicrobial properties of dry lichen extract against bacteria Bac. Subtilis. The conditions for extraction of biologically active metabolites using solvent systems such as water, water-ethanol mixtures with ethanol content of 40 and 70%, 1,4-dioxane and a mixture of 1,4-dioxane and water (1: 1) were selected. With use of the modern analytical methods, the composition of secondary metabolites in the extracts was studied. By the method of spectroscopy in the UV and visible region of the spectrum to determine the content usnic acid, which is 16,2 (solvent - water) to 60,0 (1,4-dioxane) mg/100 ml of extract.It is shown that the dioxane extract has pronounced atioxidant properties. The active substances (in terms of usnic acid) of the dry extract of lichen Usnea barbata are able to inhibit the growth of bacteria Bac. Subtilis.

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Yuan, X. "Lichen-Like Symbiosis 600 Million Years Ago." Science 308, no. 5724 (May 13, 2005): 1017–20. http://dx.doi.org/10.1126/science.1111347.

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Insarova, I. D., and E. Yu Blagoveshchenskaya. "Lichen symbiosis: Search and recognition of partners." Biology Bulletin 43, no. 5 (September 2016): 408–18. http://dx.doi.org/10.1134/s1062359016040038.

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Pratama, Ari, and Manap Trianto. "Diversity of Lichen in Mangrove Forest of Tomoli Village Parigi Moutong Regency." BIO-EDU: Jurnal Pendidikan Biologi 5, no. 3 (December 13, 2020): 140–50. http://dx.doi.org/10.32938/jbe.v5i3.730.

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Lichen is an organism resulting from a symbiotic association between fungi and algae in mutualistic symbiosis and eroticism, forming a morphological unity that is different from other species from its constituent components. This study aims to determine the level of lichen species diversity that grows in mangrove forests in Tomoli Village, Parigi Moutong Regency. This research was conducted in July 2019. The method used in this study was a survey method, the sampling technique was purposive sampling, namely by using a 10 cm x 10 cm plot on the mangrove trees in each path at the research location. The research results found ten types of lichen consisting of six genera, five families, seven orders, and four classes divided into two groups based on the kind of thallus, namely lichen crustose and foliose. The crustose lichen group is Aspicilia calcarea, Aspicilia sp, Pyrenula sp, Pyrenula dermatodes, Pyrenula santensis, Cryptothecia striata, Phaeographis sp, Graphis script, Verrucaria sp. Meanwhile, the foliose lichen group is Flavoparmelia caperata. The lichen diversity index value obtained in the mangrove forest in Tomoli Village was 2,225, indicating that the level of diversity is moderate.

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HESTMARK, Geir, François LUTZONI, and Jolanta MIADLIKOWSKA. "Photobiont associations in co-occurring umbilicate lichens with contrasting modes of reproduction in coastal Norway." Lichenologist 48, no. 5 (September 2016): 545–57. http://dx.doi.org/10.1017/s0024282916000232.

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AbstractThe identity and phylogenetic placement of photobionts associated with two lichen-forming fungi, Umbilicaria spodochroa and Lasallia pustulata were examined. These lichens commonly grow together in high abundance on coastal cliffs in Norway, Sweden and Finland. The mycobiont of U. spodochroa reproduces sexually through ascospores, and must find a suitable algal partner in the environment to re-establish the lichen symbiosis. Lasallia pustulata reproduces mainly vegetatively using symbiotic propagules (isidia) containing both symbiotic partners (photobiont and mycobiont). Based on DNA sequences of the internal transcribed spacer region (ITS) we detected seven haplotypes of the green-algal genus Trebouxia in 19 pairs of adjacent thalli of U. spodochroa and L. pustulata from five coastal localities in Norway. As expected, U. spodochroa associated with a higher diversity of photobionts (seven haplotypes) than the mostly asexually reproducing L. pustulata (four haplotypes). The latter was associated with the same haplotype in 15 of the 19 thalli sampled. Nine of the lichen pairs examined share the same algal haplotype, supporting the hypothesis that the mycobiont of U. spodochroa might associate with the photobiont ‘pirated’ from the abundant isidia produced by L. pustulata that are often scattered on the cliff surfaces. Up to six haplotypes of Trebouxia were found within a single sampling site, indicating a low level of specificity of both mycobionts for their algal partner. Most photobiont strains associated with species of Umbilicaria and Lasallia, including samples from this study, represent phylogenetically closely related taxa of Trebouxia grouped within a small number of main clades (Trebouxia sp., T. simplex/T. jamesii, and T. incrustata+T. gigantea). Three of the photobiont haplotypes were found only in U. spodochroa thalli.

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Hamida, Reham Samir, Mohamed Abdelaal Ali, Nabila Elsayed Abdelmeguid, Mayasar Ibrahim Al-Zaban, Lina Baz, and Mashael Mohammed Bin-Meferij. "Lichens—A Potential Source for Nanoparticles Fabrication: A Review on Nanoparticles Biosynthesis and Their Prospective Applications." Journal of Fungi 7, no. 4 (April 12, 2021): 291. http://dx.doi.org/10.3390/jof7040291.

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Green synthesis of nanoparticles (NPs) is a safe, eco-friendly, and relatively inexpensive alternative to conventional routes of NPs production. These methods require natural resources such as cyanobacteria, algae, plants, fungi, lichens, and naturally extracted biomolecules such as pigments, vitamins, polysaccharides, proteins, and enzymes to reduce bulk materials (the target metal salts) into a nanoscale product. Synthesis of nanomaterials (NMs) using lichen extracts is a promising eco-friendly, simple, low-cost biological synthesis process. Lichens are groups of organisms including multiple types of fungi and algae that live in symbiosis. Until now, the fabrication of NPs using lichens has remained largely unexplored, although the role of lichens as natural factories for synthesizing NPs has been reported. Lichens have a potential reducible activity to fabricate different types of NMs, including metal and metal oxide NPs and bimetallic alloys and nanocomposites. These NPs exhibit promising catalytic and antidiabetic, antioxidant, and antimicrobial activities. To the best of our knowledge, this review provides, for the first time, an overview of the main published studies concerning the use of lichen for nanofabrication and the applications of these NMs in different sectors. Moreover, the possible mechanisms of biosynthesis are discussed, together with the various optimization factors influencing the biological synthesis and toxicity of NPs.

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Platt, Jamie L., and Joseph W. Spatafora. "A Re-Examination of Generic Concepts of Baeomycetoid Lichens Based on Phylogenetic Analyses of Nuclear ssu and Lsu Ribosomal Dna." Lichenologist 31, no. 5 (September 1999): 409–18. http://dx.doi.org/10.1006/lich.1999.0230.

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AbstractThe lichen symbiosis has evolved several times within the fungal kingdom, although the total number of lichenization events leading to extant taxa is still unclear. Two lichenized families, the Icmadophilaceae and Baeomycetaceae have been classified in the Helotiales. Because the Helotiales are predominantly nonlichenized, this suggests that these families represent independent evolutionary episodes of lichenization from the Lecanorales. As a first step towards understanding the evolution of the lichen symbiosis within this order, we tested recent hypotheses concerning the segregation of lichen genera between the two lichen families. Specifically, we used phylogenetic analyses of nucleotide sequence data from nuclear small-subunit and large-subunit ribosomal DNA to test the morphology-based hypotheses that Dibaeis is a distinct genus from Baeomyces and that Dibaeis is a member of the Icmadophilaceae rather than the Baeomycetaceae. Phylogenetic analyses of nuclear SSU rDNA and combined SSU and LSU rDNA data support the hypothesis that Dibaeis is more closely related to IcmadophUa than it is to Baeomyces. Therefore, these data support the resurrection of Dibaeis from its previous synonymy with Baeomyces based on the characters of ascocarp colour and ascus morphology. The recognition of two distinct genera is also consistent with character state distribution of unique lichen acids.

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Liu, Rundong, Wonyong Kim, Jaycee Augusto Paguirigan, Min-Hye Jeong, and Jae-Seoun Hur. "Establishment of Agrobacterium tumefaciens-Mediated Transformation of Cladonia macilenta, a Model Lichen-Forming Fungus." Journal of Fungi 7, no. 4 (March 26, 2021): 252. http://dx.doi.org/10.3390/jof7040252.

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Despite the fascinating biology of lichens, such as the symbiotic association of lichen-forming fungi (mycobiont) with their photosynthetic partners and their ability to grow in harsh habitats, lack of genetic tools manipulating mycobiont has hindered studies on genetic mechanisms underpinning lichen biology. Thus, we established an Agrobacterium tumefaciens-mediated transformation (ATMT) system for genetic transformation of a mycobiont isolated from Cladonia macilenta. A set of combinations of ATMT conditions, such as input biomass of mycobiont, co-cultivation period with Agrobacterium cells, and incubation temperature, were tested to identify an optimized ATMT condition for the C. macilenta mycobiont. As a result, more than 10 days of co-cultivation period and at least 2 mg of input biomass of the mycobiont were recommended for an efficient ATMT, owing to extremely slow growth rate of mycobionts in general. Moreover, we examined T-DNA copy number variation in a total of 180 transformants and found that 88% of the transformants had a single copy T-DNA insertion. To identify precise T-DNA insertion sites that interrupt gene function in C. macilenta, we performed TAIL-PCR analyses for selected transformants. A hypothetical gene encoding ankyrin repeats at its C-terminus was interrupted by T-DNA insertion in a transformant producing dark-brown colored pigment. Although the identification of the pigment awaits further investigation, this proof-of-concept study demonstrated the feasibility of use of ATMT in construction of a random T-DNA insertion mutant library in mycobionts for studying genetic mechanisms behind the lichen symbiosis, stress tolerance, and secondary metabolite biosynthesis.

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de Vera, J. P., G. Horneck, P. Rettberg, and S. Ott. "The potential of the lichen symbiosis to cope with extreme conditions of outer space – I. Influence of UV radiation and space vacuum on the vitality of lichen symbiosis and germination capacity." International Journal of Astrobiology 1, no. 4 (October 2002): 285–93. http://dx.doi.org/10.1017/s1473550403001216.

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The lichen symbiotic organisms Fulgensia bracteata and Xanthoria elegans as well as their isolated photobionts and mycobionts were exposed to conditions simulating the extreme parameters of outer space in order to assess their limits of survival, e.g. during a potential interplanetary transfer or on the surface of an extraterrestrial body. Using the space simulation facilities at DLR, the test parameters under investigation were vacuum (10−3 Pa) and ultraviolet (UV) radiation at wavelength ranges from vacuum-UV to UV-A, applied separately or in combination. An analysis of vitality was made using confocal laser scanning microscopy and LIVE/DEAD staining using FUN I or SYTOX green. Intact lichens were extremely resistant to vacuum exposure as well as to UV radiation up to doses of about 160 kJ m−2 (200<λ<400 nm). Removal of the upper-cortex structure significantly increased the sensitivity of the lichens to the space parameters: already a relatively short treatment of about 5 h and a UV dose of about 50 kJ m−2 reduced the vitality rate to nearly 50%; however, the dose effect curves levelled off and continued treatment did not reduce the vitality further. Similar survival curves levelling off at higher UV doses were observed for the isolated photobionts; however, in the latter cases, the saturation occurred at five times lower doses (full UV spectrum). Also spores of the mycobionts showed a remarkable UV (254 nm) resistance up to doses of about 3 kJ m−2. The data suggest that the symbiotic features peculiar to lichens allow them to cope with the extreme conditions of outer space or even with Martian surface conditions provided suitable niche habitats are available to serve as refuges and complementary endogenous or exogenous protection mechanisms are established.

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Grube, Martin, and Lucia Muggia. "Lichen symbiosis: Success by flexible management of algal partners." Biochemist 35, no. 4 (August 1, 2013): 10–13. http://dx.doi.org/10.1042/bio03504010.

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Lichens resemble light-exposed microscopic greenhouses, as the fungal symbiont produces a highly organized and compact mycelial structure for phototrophic partners. The symbiotic fungus shelters the internal, yet extracellularly located, photobionts. Only suitable combinations of fungi and algal species give rise to the typical symbiotic morphology, which is then long-lived and a prerequisite for developing sexual fungal spores. Recent evidence suggests that ecological and evolutionary success of lichens may be linked to their ability to fine-tune photobiont associations across a range of environmental conditions.

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Honegger, Rosmarie. "The Lichen Symbiosis—What is so Spectacular about it?" Lichenologist 30, no. 03 (May 1998): 193. http://dx.doi.org/10.1017/s002428299200015x.

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Singh, Ram S., and Amandeep K. Walia. "Characteristics of lichen lectins and their role in symbiosis." Symbiosis 62, no. 3 (March 2014): 123–34. http://dx.doi.org/10.1007/s13199-014-0278-y.

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Joneson, Suzanne, and Francois Lutzoni. "Compatibility and thigmotropism in the lichen symbiosis: A reappraisal." Symbiosis 47, no. 2 (January 2009): 109–15. http://dx.doi.org/10.1007/bf03182294.

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Honegger, Rosmarie. "The Lichen Symbiosis—What is so Spectacular about it?" Lichenologist 30, no. 3 (May 1998): 193–212. http://dx.doi.org/10.1006/lich.1998.0140.

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AbstractLichen mycobionts are typical representatives of their fungal classes but differ from non-lichenized taxa by their manifold adaptations to symbiosis with a population of minute photobiont cells. Most interesting are the morphologically complex macrolichens, the fungal partner of which competes for space above ground and contains photobiont cells optimally positioned for gas exchange and illumination. Such thalli are the product of an amazing hyphal polymorphism, with multiple switches between polar and apolar growth and hydrophilic or hydrophobic cell wall surfaces. Hydrophobic sealing of the apoplastic continuum between the partners by means of mycobiont-derived hydrophobic compounds canalizes the fluxes of solutes during the often quite dramatic de- and rehydration processes and keeps the algal layer gas-filled at any level of hydration. The impressive tolerance of drought, heat and cold stress of most lichen-forming fungi and their photobionts is due to a very interesting combination of protective and repair mechanisms at the cellular level, the molecular bases of which remain to be explored. Contemporary experimental lichenology is analysed and strategies are proposed aimed at better integration into mainstream biology.

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WERTH, Silke. "Population genetics of lichen-forming fungi – a review." Lichenologist 42, no. 5 (August 3, 2010): 499–519. http://dx.doi.org/10.1017/s0024282910000125.

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AbstractPopulation genetics investigates the distribution of genetic variation in natural populations and the genetic differentiation among populations. Lichen-forming fungi are exciting subjects for population genetic studies due to their obligate symbiosis with a green-algal and/or cyanobacterial photobiont, and because their different reproductive strategies could influence fungal genetic structures in various ways. In this review, first, I briefly summarize the results from studies of chemotype variation in populations of lichen-forming fungi. Second, I compare and evaluate the DNA-based molecular tools available for population genetics of lichen-forming fungi. Third, I review the literature available on the genetic structure of lichen fungi to show general trends. I discuss some fascinating examples, and point out directions for future research.

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Wang, Yanyan, Xinli Wei, Zhuyun Bian, Jiangchun Wei, and Jin-Rong Xu. "Coregulation of dimorphism and symbiosis by cyclic AMP signaling in the lichenized fungusUmbilicaria muhlenbergii." Proceedings of the National Academy of Sciences 117, no. 38 (September 1, 2020): 23847–58. http://dx.doi.org/10.1073/pnas.2005109117.

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Umbilicaria muhlenbergiiis the only known dimorphic lichenized fungus that grows in the hyphal form in lichen thalli but as yeast cells in axenic cultures. However, the regulation of yeast-to-hypha transition and its relationship to the establishment of symbiosis are not clear. In this study, we show that nutrient limitation and hyperosmotic stress trigger the dimorphic change inU. muhlenbergii. Contact with algal cells of its photobiontTrebouxia jamesiiinduced pseudohyphal growth. Treatments with the cAMP diphosphoesterase inhibitor IBMX (3-isobutyl-1-methylxanthine) induced pseudohyphal/hyphal growth and resulted in the differentiation of heavily melanized, lichen cortex-like structures in culture, indicating the role of cAMP signaling in regulating dimorphism. To confirm this observation, we identified and characterized two Gα subunitsUmGPA2andUmGPA3. Whereas deletion ofUmGPA2had only a minor effect on pseudohyphal growth, the ΔUmgpa3mutant was defective in yeast-to-pseudohypha transition induced by hyperosmotic stress orT. jamesiicells. IBMX treatment suppressed the defect of ΔUmgpa3in pseudohyphal growth. Transformants expressing theUmGPA3G45VorUmGPA3Q208Ldominant active allele were enhanced in the yeast-to-pseudohypha transition and developed pseudohyphae under conditions noninducible to the wild type. Interestingly,T. jamesiicells in close contact with pseudohyphae ofUmGPA3G45VandUmGPA3Q208Ltransformants often collapsed and died after coincubation for over 72 h, indicating that improperly regulated pseudohyphal growth due to dominant active mutations may disrupt the initial establishment of symbiotic interaction between the photobiont and mycobiont. Taken together, these results show that the cAMP-PKA pathway plays a critical role in regulating dimorphism and symbiosis inU. muhlenbergii.

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Kaasalainen, Ulla, David P. Fewer, Jouni Jokela, Matti Wahlsten, Kaarina Sivonen, and Jouko Rikkinen. "Lichen species identity and diversity of cyanobacterial toxins in symbiosis." New Phytologist 198, no. 3 (March 6, 2013): 647–51. http://dx.doi.org/10.1111/nph.12215.

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Singh, Garima, Francesco Dal Grande, Pradeep K. Divakar, Jürgen Otte, Ana Crespo, and Imke Schmitt. "Fungal-algal association patterns in lichen symbiosis linked to macroclimate." New Phytologist 214, no. 1 (December 5, 2016): 317–29. http://dx.doi.org/10.1111/nph.14366.

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Papazi, Aikaterini, Elizabeth Kastanaki, Stergios Pirintsos, and Kiriakos Kotzabasis. "Lichen Symbiosis: Nature's High Yielding Machines for Induced Hydrogen Production." PLOS ONE 10, no. 3 (March 31, 2015): e0121325. http://dx.doi.org/10.1371/journal.pone.0121325.

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Hyvarinen, Marko, Roger Hardling, and Juha Tuomi. "Cyanobacterial lichen symbiosis: the fungal partner as an optimal harvester." Oikos 98, no. 3 (September 2002): 498–504. http://dx.doi.org/10.1034/j.1600-0706.2002.980314.x.

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Tripp, Erin A., and James C. Lendemer. "Twenty-seven modes of reproduction in the obligate lichen symbiosis." Brittonia 70, no. 1 (December 12, 2017): 1–14. http://dx.doi.org/10.1007/s12228-017-9500-6.

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Resl, Philipp, Fernando Fernández-Mendoza, Helmut Mayrhofer, and Toby Spribille. "The evolution of fungal substrate specificity in a widespread group of crustose lichens." Proceedings of the Royal Society B: Biological Sciences 285, no. 1889 (October 17, 2018): 20180640. http://dx.doi.org/10.1098/rspb.2018.0640.

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Lichens exhibit varying degrees of specialization with regard to the surfaces they colonize, ranging from substrate generalists to strict substrate specialists. Though long recognized, the causes and consequences of substrate specialization are poorly known. Using a phylogeny of a 150–200 Mya clade of lichen fungi, we asked whether substrate niche is phylogenetically conserved, which substrates are ancestral, whether specialists arise from generalists or vice versa and how specialization affects speciation/extinction processes. We found strong phylogenetic signal for niche conservatism. Specialists evolved into generalists and back again, but transitions from generalism to specialism were more common than the reverse. Our models suggest that for this group of fungi, ‘escape’ from specialization for soil, rock and bark occurred, but specialization for wood foreclosed evolution away from that substrate type. In parallel, speciation models showed positive diversification rates for soil and rock dwellers but not other specialists. Patterns in the studied group suggest that fungal substrate specificity is a key determinant of evolutionary trajectory for the entire lichen symbiosis.

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Kaasalainen, Ulla, Jouni Jokela, David P. Fewer, Kaarina Sivonen, and Jouko Rikkinen. "Microcystin Production in the Tripartite Cyanolichen Peltigera leucophlebia." Molecular Plant-Microbe Interactions® 22, no. 6 (June 2009): 695–702. http://dx.doi.org/10.1094/mpmi-22-6-0695.

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We show that the cyanobacterial symbionts of a tripartite cyanolichen can produce hepatotoxic microcystins in situ. Microcystins were detected with high-performance liquid chromatography mass spectrometry both from cephalodia of the tripartite cyanolichen Peltigera leucophlebia and from a symbiotic Nostoc strain isolated from the same lichen specimen. Genetic identities of symbiotic Nostoc strains were studied by amplifying and sequencing the 16S rRNA gene. Also, the presence of the microcystin synthetase gene mcyE was confirmed by sequencing. Three highly toxic microcystins were detected from the lichen specimen. Several different Nostoc 16S rRNA haplotypes were present in the lichen sample but only one was found in the toxin-producing cultures. In culture, the toxin-producing Nostoc strain produced a total of 19 different microcystin variants. In phylogenetic analysis, this cyanobacterium and related strains from the lichen thallus grouped together with a previously known microcystin-producing Nostoc strain and other strains previously isolated from the symbiotic thalloid bryophyte Blasia pusilla. Our finding is the first direct evidence of in situ production of microcystins in lichens or plant–cyanobacterial symbioses. Microcystins may explain why cyanolichens and symbiotic bryophytes are not among the preferred food sources of most animal grazers.

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Cardós, J. L. H., M. Prieto, M. Jylhä, G. Aragón, M. C. Molina, I. Martínez, and J. Rikkinen. "A case study on the re-establishment of the cyanolichen symbiosis: where do the compatible photobionts come from?" Annals of Botany 124, no. 3 (April 25, 2019): 379–88. http://dx.doi.org/10.1093/aob/mcz052.

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AbstractBackground and AimsIn order to re-establish lichen symbiosis, fungal spores must first germinate and then associate with a compatible photobiont. To detect possible establishment limitations in a sexually reproducing cyanolichen species, we studied ascospore germination, photobiont growth and photobiont association patterns in Pectenia plumbea.MethodsGermination tests were made with ascospores from 500 apothecia under different treatments, and photobiont growth was analysed in 192 isolates obtained from 24 thalli. We determined the genotype identity [tRNALeu (UAA) intron] of the Nostoc cyanobionts from 30 P. plumbea thalli from one population. We also sequenced cyanobionts of 41 specimens of other cyanolichen species and 58 Nostoc free-living colonies cultured from the bark substrate.Key ResultsNot a single fungal ascospore germinated and none of the photobiont isolates produced motile hormogonia. Genetic analyses revealed that P. plumbea shares Nostoc genotypes with two other cyanolichen species of the same habitat, but these photobionts were hardly present in the bark substrate.ConclusionsDue to the inability of both symbionts to thrive independently, the establishment of P. plumbea seems to depend on Dendriscocaulon umhausense, the only cyanolichen species in the same habitat that reproduces asexually and acts as a source of appropriate cyanobionts. This provides support to the hypothesis about facilitation among lichens.

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Huỳnh, Thu. "ANTIOXIDANT, α-GLUCOSIDASE INHIBITORY AND ANTIFUNGAL ACTIVITIES OF EXTRACTS FROM LICHENS COLLECTED IN VIET NAM." Vietnam Journal of Science and Technology 54, no. 4A (March 21, 2018): 156. http://dx.doi.org/10.15625/2525-2518/54/4a/11989.

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Lichens are one of the earliest colonizers of terrestrial habitats on the earth. They are a unique life form of symbiosis between fungi (mycobionts) and algae and/or cyanobacteria (photobionts). Lichens have been used as a cure for diabetes, coughs, pulmonary tuberculosis, wound curing, and dermatological diseases. The aim of this study is to evaluate the antioxidant, α-glucosidase inhibitory and antifungal activities of methanol extracts of lichens from eleven lichen species isolated in Viet Nam including Usnea, Lobaria, and Parmotrema were evaluated. The antioxidant activity was determined by ABTS radical scavenging activities. The results indicated that eleven species of lichens extracts possessed relatively high antioxidant activity with IC50 values ranging from 21.59 to 570.85 µg/ml for 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assay. The extracts of U101 was more efficient for α- glucosidase inhibitory activity, with the IC50 value of 75.23 ppm. In addition, all extracts also exhibited inhibitory activity on the growth of Aspergillus fumigatus (17.5 – 32.7 %) and Penicillium sp. (16.7 – 33.4 %).

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DAL GRANDE, F., I. WIDMER, H. H. WAGNER, and C. SCHEIDEGGER. "Vertical and horizontal photobiont transmission within populations of a lichen symbiosis." Molecular Ecology 21, no. 13 (March 2, 2012): 3159–72. http://dx.doi.org/10.1111/j.1365-294x.2012.05482.x.

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Journal articles on the topic 'Lichen symbiosis'

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