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MicroCT as a Useful Tool for Analysing the 3D Structure of Lichens and Quantifying Internal Cephalodia in Lobaria pulmonaria. Appl Microbiol 2021. [DOI: 10.3390/applmicrobiol1020015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
High-resolution X-ray computer tomography (microCT) is a well-established technique to analyse three-dimensional microstructures in 3D non-destructive imaging. The non-destructive three-dimensional analysis of lichens is interesting for many reasons. The examination of hidden structural characteristics can, e.g., provide information on internal structural features (form and distribution of fungal-supporting tissue/hypha), gas-filled spaces within the thallus (important for gas exchange and, thus, physiological processes), or yield information on the symbiont composition within the lichen, e.g., the localisation and amount of additional cyanobacteria in cephalodia. Here, we present the possibilities and current limitations for applying conventional laboratory-based high-resolution X-ray computer tomography to analyse lichens. MicroCT allows the virtual 3D reconstruction of a sample from 2D X-ray projections and is helpful for the non-destructive analysis of structural characters or the symbiont composition of lichens. By means of a quantitative 3D image analysis, the volume of internal cephalodia is determined for Lobaria pulmonaria and the external cephalodia of Peltigera leucophlebia. Nevertheless, the need for higher-resolution tomography for more detailed studies is emphasised. Particular challenges are the large sizes of datasets to be analysed and the high variability of the lichen microstructures.
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Potkay A, Ten Veldhuis MC, Fan Y, Mattos CRC, Ananyev G, Dismukes GC. Water and vapor transport in algal-fungal lichen: Modeling constrained by laboratory experiments, an application for Flavoparmelia caperata. PLANT, CELL & ENVIRONMENT 2020; 43:945-964. [PMID: 31759337 DOI: 10.1111/pce.13690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 11/11/2019] [Accepted: 11/18/2019] [Indexed: 06/10/2023]
Abstract
Algal-fungal symbionts share water, nutrients, and gases via an architecture unique to lichens. Because lichen activity is controlled by moisture dynamics, understanding water transport is prerequisite to understand their fundamental biology. We propose a model of water distributions within foliose lichens governed by laws of fluid motion. Our model differentiates between water stored in symbionts, on extracellular surfaces, and in distinct morphological layers. We parameterize our model with hydraulic properties inverted from laboratory measurements of Flavoparmelia caperata and validate for wetting and drying. We ask: (1) Where is the bottleneck to water transport? (2) How do hydration and dehydration dynamics differ? and (3) What causes these differences? Resistance to vapor flow is concentrated at thallus surfaces and acts as the bottleneck for equilibrium, while internal resistances are small. The model captures hysteresis in hydration and desiccation, which are shown to be controlled by nonlinearities in hydraulic capacitance. Muting existing nonlinearities slowed drying and accelerated wetting, while exaggerating nonlinearities accelerated drying and slowed wetting. The hydraulic nonlinearity of F. caperata is considerable, which may reflect its preference for humid and stable environments. The model establishes the physical foundation for future investigations of transport of water, gas, and sugar between symbionts.
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Affiliation(s)
- Aaron Potkay
- Department of Earth and Planetary Sciences, Rutgers University
| | - Marie-Claire Ten Veldhuis
- Water Management Department, Delft University of Technology
- Waksman Institute of Microbiology, Rutgers University
| | - Ying Fan
- Department of Earth and Planetary Sciences, Rutgers University
| | - Caio R C Mattos
- Department of Earth and Planetary Sciences, Rutgers University
| | - Gennady Ananyev
- Waksman Institute of Microbiology, Rutgers University
- Department of Chemistry and Chemical Biology, Rutgers University
| | - G Charles Dismukes
- Waksman Institute of Microbiology, Rutgers University
- Department of Chemistry and Chemical Biology, Rutgers University
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Fernández-Marín B, López-Pozo M, Perera-Castro AV, Arzac MI, Sáenz-Ceniceros A, Colesie C, de los Ríos A, Sancho LG, Pintado A, Laza JM, Pérez-Ortega S, García-Plazaola JI. Symbiosis at its limits: ecophysiological consequences of lichenization in the genus Prasiola in Antarctica. ANNALS OF BOTANY 2020; 124:1211-1226. [PMID: 31549137 PMCID: PMC6943718 DOI: 10.1093/aob/mcz149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 09/13/2019] [Indexed: 05/06/2023]
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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Affiliation(s)
- Beatriz Fernández-Marín
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain
- Department of Botany, Ecology and Physiology, University of La Laguna (ULL), La Laguna, Canarias, Spain
| | - Marina López-Pozo
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Alicia V Perera-Castro
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears (UIB) - Instituto de Investigaciones Agroambientales y de Economía del Agua (INAGEA), Palma, Illes Balears, Spain
| | - Miren Irati Arzac
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Ana Sáenz-Ceniceros
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Claudia Colesie
- Global Change Institute, School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | | | - Leo G Sancho
- Botany Section, Fac. Farmacia, Universidad Complutense, Madrid, Spain
| | - Ana Pintado
- Botany Section, Fac. Farmacia, Universidad Complutense, Madrid, Spain
| | - José M Laza
- Laboratory of Macromolecular Chemistry (Labquimac), Department of Physical Chemistry, University of the Basque Country (UPV/EHU), Leioa, Spain
| | | | - José I García-Plazaola
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain
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Petruzzellis F, Savi T, Bertuzzi S, Montagner A, Tretiach M, Nardini A. Relationships between water status and photosystem functionality in a chlorolichen and its isolated photobiont. PLANTA 2018; 247:705-714. [PMID: 29170912 DOI: 10.1007/s00425-017-2814-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/14/2017] [Indexed: 05/15/2023]
Abstract
Drought tolerance was greater in the whole lichen than in its isolated photobiont. Cell turgor state has an influence on the functionality of photosynthetic process in lichens. Irreversible thermodynamics is widely used to describe the water relations of vascular plants. However, poikilohydrous organisms like lichens and aeroterrestrial microalgae have seldom been studied using this approach. Water relations of lichens are generally addressed without separate analysis of the mycobiont and photobiont, and only few studies have correlated changes in photosynthetic efficiency of dehydrating lichens to accurate measurements of their water potential components. We measured water potential isotherms and chlorophyll a fluorescence in the lichen Flavoparmelia caperata harvested in different seasons, as well as in its isolated photobiont, the green alga Trebouxia gelatinosa, either exposed to water stress cycles or fully hydrated. No significant seasonal trends were observed in lichen water relations parameters. Turgor loss point and osmotic potential of the whole thallus were significantly lower than those measured in the photobiont, while differences between the water stressed photobiont and controls were not significant. Dehydration-induced drop of F v/F m was correlated with turgor loss, revealing that the photosynthetic activity of lichens partly depends on their turgor level. We provided one of the first quantitative evidences of the influence that turgor status could exert on the functionality of photosynthetic processes in lichens.
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Affiliation(s)
- Francesco Petruzzellis
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy.
| | - Tadeja Savi
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy
| | - Stefano Bertuzzi
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy
| | - Alice Montagner
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy
| | - Mauro Tretiach
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy
| | - Andrea Nardini
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy
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Holzinger A, Herburger K, Blaas K, Lewis LA, Karsten U. The terrestrial green macroalga Prasiola calophylla (Trebouxiophyceae, Chlorophyta): ecophysiological performance under water-limiting conditions. PROTOPLASMA 2017; 254:1755-1767. [PMID: 28066876 PMCID: PMC5474099 DOI: 10.1007/s00709-016-1068-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 12/21/2016] [Indexed: 05/22/2023]
Abstract
The phylogenetic placement of Prasiola calophylla, from an anthropogenic habitat previously shown to contain a novel UV sunscreen compound, was confirmed by analysis of its rbcL gene. This alga has the capacity to tolerate strong water-limiting conditions. The photosynthetic performance and ultrastructural changes under desiccation and osmotic stress were investigated. Freshly harvested thalli showed an effective quantum yield of PSII [Y(II)] of 0.52 ± 0.06 that decreased to ∼60% of the initial value at 3000 mM sorbitol, and 4000 mM sorbitol led to a complete loss of Y(II). The Y(II) of thalli exposed to controlled desiccating conditions at 60% relative humidity (RH) ceased within 240 min, whereas zero values were reached after 120 min at 20% RH. All investigated samples completely recovered Y(II) within ∼100 min after rehydration. Relative electron transport rates (rETR) were temperature dependent, increasing from 5, 10, to 25 °C but strongly declining at 45 °C. Transmission electron microscopy of samples desiccated for 2.5 h showed an electron dense appearance of the entire cytoplasm when compared to control samples. Thylakoid membranes were still visible in desiccated cells, corroborating the ability to recover. Control and desiccated cells contained numerous storage lipids and starch grains, providing reserves. Overall, P. calophylla showed a high capacity to cope with water-limiting conditions on a physiological and structural basis. A lipophilic outer layer of the cell walls might contribute to reduce water evaporation in this poikilohydric organism.
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Affiliation(s)
- Andreas Holzinger
- Functional Plant Biology, Institute of Botany, University of Innsbruck, Sternwartestrasse 15, 6020, Innsbruck, Austria.
| | - Klaus Herburger
- Functional Plant Biology, Institute of Botany, University of Innsbruck, Sternwartestrasse 15, 6020, Innsbruck, Austria
| | - Kathrin Blaas
- Functional Plant Biology, Institute of Botany, University of Innsbruck, Sternwartestrasse 15, 6020, Innsbruck, Austria
| | - Louise A Lewis
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269-3043, USA
| | - Ulf Karsten
- Institute of Biological Sciences, Applied Ecology and Phycology, University of Rostock, Albert-Einstein-Straße 3, 18059, Rostock, Germany
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Centeno DC, Hell AF, Braga MR, Del Campo EM, Casano LM. Contrasting strategies used by lichen microalgae to cope with desiccation-rehydration stress revealed by metabolite profiling and cell wall analysis. Environ Microbiol 2016; 18:1546-60. [PMID: 26914009 DOI: 10.1111/1462-2920.13249] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 01/21/2016] [Accepted: 01/21/2016] [Indexed: 01/07/2023]
Abstract
Most lichens in general, and their phycobionts in particular, are desiccation tolerant, but their mechanisms of desiccation tolerance (DT) remain obscure. The physiological responses and cell wall features of two putatively contrasting lichen-forming microalgae, Trebouxia sp. TR9 (TR9), isolated from Ramalina farinacea (adapted to frequent desiccation-rehydration cycles), and Coccomyxa solorina-saccatae (Csol), obtained from Solorina saccata (growing in usually humid limestone crevices, subjected to seasonal dry periods) was characterized. Microalgal cultures were desiccated under 25%-30% RH and then rehydrated. Under these conditions, RWC and ψw decreased faster and simultaneously during dehydration in Csol, whereas TR9 maintained its ψw until 70% RWC. The metabolic profile indicated that polyols played a key role in DT of both microalgae. However, TR9 constitutively accumulated higher amounts of polyols, whereas Csol induced the polyol synthesis under desiccation-rehydration. Csol also accumulated ascorbic acid, while TR9 synthesized protective raffinose-family oligosaccharides (RFOs) and increased its content of phenolics. Additionally, TR9 exhibited thicker and qualitatively different cell wall and extracellular polymeric layer compared with Csol, indicating higher water retention capability. The findings were consistent with the notion that lichen microalgae would have evolved distinct strategies to cope with desiccation-rehydration stress in correspondence with the water regime of their respective habitats.
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Affiliation(s)
- Danilo C Centeno
- Centre of Natural Sciences and Humanities, Federal University of ABC, 09606-070, São Bernardo do Campo, SP, Brazil.,Department of Plant Physiology and Biochemistry, Institute of Botany, 04301-912, São Paulo, SP, Brazil
| | - Aline F Hell
- Department of Plant Physiology and Biochemistry, Institute of Botany, 04301-912, São Paulo, SP, Brazil
| | - Marcia R Braga
- Department of Plant Physiology and Biochemistry, Institute of Botany, 04301-912, São Paulo, SP, Brazil
| | - Eva M Del Campo
- Department of Life Sciences, University of Alcalá, 28805-, Alcalá de Henares (Madrid), Spain
| | - Leonardo M Casano
- Department of Life Sciences, University of Alcalá, 28805-, Alcalá de Henares (Madrid), Spain
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Holzinger A, Herburger K, Kaplan F, Lewis LA. Desiccation tolerance in the chlorophyte green alga Ulva compressa: does cell wall architecture contribute to ecological success? PLANTA 2015; 242:477-92. [PMID: 25896374 PMCID: PMC4498240 DOI: 10.1007/s00425-015-2292-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 03/31/2015] [Indexed: 05/24/2023]
Abstract
MAIN CONCLUSION Desiccation leads to structural changes of the inner pectic cell wall layers in Ulva compressa. This contributes to protection against mechanical damage due to desiccation-rehydration cycles. Ulva compressa, characterized by rbcL phylogeny, is a common species in the Mediterranean Sea. Ulva as an intertidal species tolerates repeated desiccation-rehydration cycles in nature; the physiological and structural basis were investigated under experimental conditions here. Desiccation to 73% relative water content (RWC) led to a significant decrease of the maximum quantum yield of photosystem II (F v/F m) to about half of the initial value. A reduction to 48 or 27% RWC caused a more drastic effect and thalli were only able to recover fully from desiccation to 73% RWC. Relative electron transport rates were stimulated at 73% RWC, but decreased significantly at 48 and 27% RWC, respectively. Imaging-PAM analysis demonstrated a homogenous desiccation process within individual thallus discs. The different cell wall layers of U. compressa were characterized by standard staining procedures, i.e. calcofluor white and aniline blue for structural components (cellulose, callose), ruthenium red for pectins and toluidine blue for acidic polysaccharides. Already a reduction to 73% RWC caused severe changes of the cell walls. The inner pectin-rich layers followed the shrinkage process of the cytoplasm, while the outer denser fibrillar layers maintained their shape. In this way, the thalli were not plasmolyzed during water loss, and upon recovery not negatively influenced by any mechanical damage. Transmission electron microscopy corroborated the arrangement of the different layers clearly distinguishable by their texture and electron density. We suggest the flexibility of the pectin-rich cell wall layers as a major contribution to desiccation tolerance in Ulva.
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Affiliation(s)
- Andreas Holzinger
- Institute of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestrasse 15, 6020, Innsbruck, Austria,
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