Formally described species woefully underrepresent phylogenetic diversity in the common lichen photobiont genus Trebouxia (Trebouxiophyceae, Chlorophyta): An impetus for developing an integrated taxonomy.

Lichens provide valuable systems for studying symbiotic interactions. In lichens, these interactions are frequently described in terms of availability, selectivity and specificity of the mycobionts and photobionts towards one another. The lichen-forming, green algal genus Trebouxia Puymaly is among the most widespread photobiont, associating with a broad range of lichen-forming fungi. To date, 29 species have been described, but studies consistently indicate that the vast majority of species-level lineages still lack formal description, and new, previously unrecognized lineages are frequently reported. To reappraise the diversity and the evolutionary relationships of species-level lineages …

The genetic structure of the cosmopolitan three-partner lichenRamalina farinaceaevidences the concerted diversification of symbionts

The epiphytic lichen Ramalina farinacea is distributed throughout the northern hemisphere in which the same two algal Trebouxia species (provisionally named TR1 and TR9) coexist in every thallus. Ramalina farinacea symbionts were characterized based on the two fungal nuclear loci (nrITS and rpb2 ) along with the primary and secondary structures of nrITS from each Trebouxia species in the Iberian Peninsula and Canary Islands. The results indicated a noticeable genetic differentiation between mycobionts from these two geographic areas and also suggested concerted changes in the three partners of a lichen symbiosis toward two clearly distinguishable ‘holobiont’ lineages. Modeling of ITS2 RNA s…

Responses of citrus plants to ozone: leaf biochemistry, antioxidant mechanisms and lipid peroxidation.

The effects of ozone upon 3-year-old trees of Clementina mandarin (Citrus clementina Hort. ex Tan.) cv. Marisol exposed for 12 months to ambient (10 nl l(-1)) and high (30 and 65 nl l(-1)) concentrations in open top chambers (OTCs) were investigated. The data showed that in leaves, ozone reduced total chlorophylls, carotenoid and carbohydrate concentration. and increased 1-aminocyclopropane-1-carboxylic acid (ACC) content and ethylene production. In treated plants, the ascorbate leaf pool was decreased, while lipid peroxidation and Solute leakaGe were significantly higher than in ozone-free controls. The data indicated that ozone triggered protective mechanisms against oxidative stress in c…

Evolutionary implications of intron-exon distribution and the properties and sequences of the RPL10A gene in eukaryotes.

The RPL10A gene encodes the RPL10 protein, required for joining 40S and 60S subunits into a functional 80S ribosome. This highly conserved gene, ubiquitous across all eukaryotic super-groups, is characterized by a variable number of spliceosomal introns, present in most organisms. These properties facilitate the recognition of orthologs among distant taxa and thus comparative studies of sequences as well as the distribution and properties of introns in taxonomically distant groups of eukaryotes. The present study examined the multiple ways in which RPL10A conservation vs. sequence changes in the gene over the course of evolution, including in exons, introns, and the encoded proteins, can be…

A rapid and cost-efficient DMSO-based method for isolating DNA from cultured lichen photobionts

We have developed a simple and fast procedure for the purification of PCR-quality DNA from cultured lichen photobionts. This new one-step method uses the solvent dimethyl sulfoxide (DMSO) combined with heat treatment to chemically breakdown algal and plant tissues. The DMSO-DNA extracts may be directly precipitated and purified by standard techniques in a total time of approximately 30 min. Compared to other DNA extraction protocols, the DMSO-based method suppresses the need for liquid nitrogen, any extraction buffer, grinding, phenol, and long incubation or centrifugation steps, thereby considerably reducing the possibility of contamination. In addition, minimal amounts of starting materia…

Effects of 2-month ozone exposure in spinach leaves on photosynthesis, antioxidant systems and lipid peroxidation

The photosynthesis response, antioxidant systems and lipid peroxidation were studied in leaves from spinach plants (Spinacia oleracea L.) in response to ozone fumigation, ambient air and charcoal filtered air treatments. The photosynthetic activity was tested through gas exchange and chlorophyll a fluorescence measurements. Ambient air and ozone fumigation caused a decrease in the photosynthetic rate (25% and 63%, respectively) mainly due to a reduced mesophyll activity, as evidenced by the increased intercellular CO, concentration. These data agree with a large reduction in the non-cyclic electron flow (7% and 16%), a lower capacity to reduce the quinone pool and a higher development of no…

Photosynthesis in Lichen: Light Reactions and Protective Mechanisms

Lichens are symbiotic associations (holobionts) established between fungi (mycobionts) and certain groups of cyanobacteria or unicellular green algae (photobionts). This symbiotic association has been essential in establishing the colonization of terrestrial and consequently dry habitats. About 44 genera of algae and cyanobacteria have been reported as lichen photobionts. Due to the uncertain taxonomy of many of these photobionts, these numbers were considered as approximations only. Ahmadjian (1993) estimates that only 25 genera were typical lichen photobionts. The most common cyanobionts are Nostoc, Scytonema, Stigonema, Gloeocapsa, and Calothrix, in order of frequency (Budel, 1992). Gree…

Innovative Approaches Using Lichen Enriched Media to Improve Isolation and Culturability of Lichen Associated Bacteria

Lichens, self-supporting mutualistic associations between a fungal partner and one or more photosynthetic partners, also harbor non-photosynthetic bacteria. The diversity and contribution of these bacteria to the functioning of lichen symbiosis have recently begun to be studied, often by culture-independent techniques due to difficulties in their isolation and culture. However, culturing as yet unculturable lichenic bacteria is critical to unravel their potential functional roles in lichen symbiogenesis, to explore and exploit their biotechnological potential and for the description of new taxa. Our objective was to improve the recovery of lichen associated bacteria by developing novel isol…

Diversidad liquénica asociada a fenómenos post-incendio en los alcornocales valenciano-castellonenses.

FOS, S., CALATAYUD, A. & BARRENO, E. 2001. Lichen diversity associated with post-fire colonization in the Valenciano-castellonense cork-oak forests. Bot. Complutensis 25: 103113. 103 Simón Fos et al. Diversidad liquénica asociada a fenómenos post-incendio... The post-fire colonization of the burned barks of cork-oaks (Quercus suber L.) by epiphytic lichens affected by fire episodes has been studied in different areas of the Valenciano-castellonense cork-oak forests (Asplenio onopteridis-Querco suberis sigmetum). These forests, which have been affected by fires of different intensity, are located in Espadán and Calderona mountains and in the Desierto de Las Palmas and differ with respect…

Oxidative stress induces distinct physiological responses in the two Trebouxia phycobionts of the lichen Ramalina farinacea

† Background and Aims Most lichens form associations with Trebouxia phycobionts and some of them simultaneously include genetically different algal lineages. In other symbiotic systems involving algae (e.g. reef corals), the relative abundances of different endosymbiotic algal clades may change over time. This process seems to provide a mechanism allowing the organism to respond to environmental stress. A similar mechanism may operate in lichens with more than one algal lineage, likewise protecting them against environmental stresses. Here, the physiological responses to oxidative stress of two distinct Trebouxia phycobionts (provisionally named TR1 and TR9) that coexist within the lichen R…

How did terricolous fungi originate in the Mediterranean region? A case study with a gypsicolous lichenized species

Aim: The historical causes responsible for the wide distribution of terricolous, crustose lichenized fungi across the Mediterranean Basin and the Canary Islands have never been explored. Here, we used the terricolous, circum-Mediterranean/Macaronesian species Buellia zoharyi (Caliciaceae, Ascomycota) to infer the time frame, and the climatic, geological and ecological factors influencing the origin and current spatial distribution of this species. Location: Mediterranean Basin and Canary Islands. Methods: Data from two nuclear markers (nrITS and tef1) obtained from 226 specimens of 23 populations covering the entire distribution range of B. zoharyi were used to calculate genetic diversity i…

Differences in the cell walls and extracellular polymers of the two Trebouxia microalgae coexisting in the lichen Ramalina farinacea are consistent with their distinct capacity to immobilize extracellular Pb

Trebouxia TR1 and T. TR9 are the two microalgae that coexist within Ramalina farinacea thalli. In the presence of Pb, TR9 formed extracellular aggregates, while TR1 showed a lower wall lead retention capability. Herein, we studied the cell walls and extracellular polymers (EPS) of TR1 and TR9, and their possible implication in the different Pb retention capacity of these microalgae. The proportion of cell walls on the overall cell biomass was 2.6 times higher in TR9 than in TR1. Glycosyl linkage analysis indicated the presence of hot-water soluble β-galactofuranan(s) in both cell walls, distinct from that previously described in Asterochloris, with increased rhamnose content in TR9 and a hi…

Biodiversity Patterns and Ecological Preferences of the Photobionts Associated With the Lichen-Forming Genus Parmelia

The worldwide, ecologically relevant lichen-forming genusParmeliacurrently includes 41 accepted species, of which theParmelia sulcatagroup (PSULgp) and theParmelia saxatilisgroup (PSAXgp) have received considerable attention over recent decades; however, phycobiont diversity is poorly known inParmelias. lat. Here, we studied the diversity ofTrebouxiamicroalgae associated with 159 thalli collected from 30 locations, including nineParmeliaspp.:P. barrenoae, P. encryptata, P. ernstiae, P. mayi, P. omphalodes, P. saxatilis, P. serrana, P. submontana, andP. sulcata. The mycobionts were studied by carrying out phylogenetic analyses of the nrITS. Microalgae genetic diversity was examined by using …

Inhibition of NO Biosynthetic Activities during Rehydration of Ramalina farinacea Lichen Thalli Provokes Increases in Lipid Peroxidation

Lichens are poikilohydrous symbiotic associations between a fungus, photosynthetic partners, and bacteria. They are tolerant to repeated desiccation/rehydration cycles and adapted to anhydrobiosis. Nitric oxide (NO) is a keystone for stress tolerance of lichens

Lichen microalgae are sensitive to environmental concentrations of atrazine

The identification of new organisms for environmental toxicology bioassays is currently a priority, since these tools are strongly limited by the ecological relevance of taxa used to study global change. Lichens are sensitive bioindicators of air quality and their microalgae are an untapped source for new low-cost miniaturized bioassays with ecological importance. In order to increase the availability of a wider range of taxa for bioassays, the sensitivity of two symbiotic lichen microalgae, Asterochloris erici and Trebouxia sp. TR9, to atrazine was evaluated. To achieve this goal, axenic cultures of these phycobionts in suspension were exposed to a range of environmental concentrations of …

Response to ozone in two lettuce varieties on chlorophyll a fluorescence, photosynthetic pigments and lipid peroxidation.

The effect of different O3 concentrations on two lettuce (Lactuca sativa L.) varieties (Valladolid and Morella) was investigated through chlorophyll (Chl) a fluorescence parameters, photosynthetic pigments (Chl a, b and total carotenoid), lipid peroxidation and crop yield. Ozone fumigation caused: a decrease in maximum quantum yield of photosystem II (PSII) photochemistry (Fv/Fm) in mature leaves, a reduction in the non-cyclic electron flow (phiPSII) and a lower capacity to reoxidize the QA pool (qP). These reductions were significant in the Valladolid var. but not in the Morella var. A significant decrease in Chl a, b and in the total carotenoids was observed in the Valladolid var. but not…

The hidden diversity of lichenized Trebouxiophyceae (Chlorophyta).

The class Trebouxiophyceae is comprised of coccoid to ellipsoid unicells, filaments, blades and colony-forming species of green algae occurring in diverse terrestrial and aquatic environments. Some representatives have evolved parasitic heterotrophic lifestyles, others have been investigated for their biotechnological potential and others have evolved as integral components of lichen symbioses. In this review, we provide an overview of the current understanding of diversity, taxonomy and evolutionary context for the important lichen-forming algal class Trebouxiophyceae (Chlorophyta). In particular, we focus on members of the family Trebouxiaceae (Trebouxiales), the best-known, most widespre…

Dehydration rate determines the degree of membrane damage and desiccation tolerance in bryophytes.

Desiccation tolerant (DT) organisms are able to withstand an extended loss of body water and rapidly resume metabolism upon rehydration. This ability, however, is strongly dependent on a slow dehydration rate. Fast dehydration affects membrane integrity leading to intracellular solute leakage upon rehydration and thereby impairs metabolism recovery. We test the hypothesis that the increased cell membrane damage and membrane permeability observed under fast dehydration, compared with slow dehydration, is related to an increase in lipid peroxidation. Our results reject this hypothesis because following rehydration lipid peroxidation remains unaltered, a fact that could be due to the high incr…

Changes in chlorophyll a fluorescence, photosynthetic CO 2 assimilation and xanthophyll cycle interconversions during dehydration in desiccation-tolerant and intolerant liverworts

The interactions among water content, chlorophyll a fluorescence emission, xanthophyll interconversions and net photosynthesis were analyzed during dehydration in desiccation-tolerant Frullania dilatata (L.) Dum. and desiccation-intolerant Pellia endiviifolia (Dicks) Dum. Water loss led to a progressive suppression of photosynthetic carbon assimilation in both species. Their chlorophyll fluorescence characteristics at low water content were: low photosynthetic quantum conversion efficiency, high excitation pressure on photosystem II and strong non-photochemical quenching. However, dissipation activity was lower in P. endiviifolia and was not accompanied by a rise in the concentration of de-…

Watanabea green microalgae (Trebouxiophyceae) inhabiting lichen holobiomes: Watanabea lichenicola sp. nova

Effects of ozone on photosynthetic CO2 exchange, chlorophyll a fluorescence and antioxidant systems in lettuce leaves

The effects of ozone exposure on lettuce leaves were investigated by means of gas exchange, modulated chlorophyll a fluorescence and antioxidants systems. High ozone concentration decreased the rate of photosynthesis at light saturation level and changes in stomatal conductance and transpiration rate. However, an increase in intercellular CO 2 concentration indicated a decrease in the carboxylation efficiency. These data agreed with a reduction of non-cyclic electron flow and lower capacity to reduce the quinone pool. Ozone affected the ascorbate pool and decreased ascorbate peroxidase activity, increased lipid peroxidation, altered membrane properties and reduced the development of non-pho…

Inactivation of a plastid evolutionary conserved gene affects PSII electron transport, life span and fitness of tobacco plants

Chloroplasts contain a plastoquinone-NADH-oxidoreductase (Ndh) complex involved in protection against stress and the maintenance of cyclic electron flow. Inactivation of the Ndh complex delays the development of leaf senescence symptoms. Chlorophyll a fluorescence measurements, blue native gel electrophoresis, immunodetection and other techniques were employed to study tobacco (Nicotiana tabacum) Ndh-defective mutants (DeltandhF). The DeltandhF mutants compared with wild-type plants presented: (i) higher photosystem II : photosystem I (PSII : PSI) ratios; (ii) similar or higher levels of ascorbate, carotenoids, thylakoid peroxidase and superoxide dismutase, yield (Phi(PSII)) and maximal pho…

The response ofAsterochloris erici(Ahmadjian) Skaloud et Peksa to desiccation: a proteomic approach

The study of desiccation tolerance of lichens, and of their chlorobionts in particular, has frequently focused on the anti- oxidant system that protects the cell against photo-oxidative stress during dehydration/rehydration cycles. In this study, we used proteomic and transcript analyses to assess the changes associated with desiccation in the isolated phycobiont Aste- rochloris erici. Algae were dried either slowly (5-6 h) or rapidly (<60 min), and rehydrated after 24 h in the desiccated state. To identify proteins that accumulated during the drying or rehydration processes, we employed two-dimensional (2D) difference gel electrophoresis (DIGE) coupled with individual protein identificatio…

Dynamic evolution of mitochondrial genomes in Trebouxiophyceae, including the first completely assembled mtDNA from a lichen-symbiont microalga (Trebouxia sp. TR9)

AbstractTrebouxiophyceae (Chlorophyta) is a species-rich class of green algae with a remarkable morphological and ecological diversity. Currently, there are a few completely sequenced mitochondrial genomes (mtDNA) from diverse Trebouxiophyceae but none from lichen symbionts. Here, we report the mitochondrial genome sequence of Trebouxia sp. TR9 as the first complete mtDNA sequence available for a lichen-symbiont microalga. A comparative study of the mitochondrial genome of Trebouxia sp. TR9 with other chlorophytes showed important organizational changes, even between closely related taxa. The most remarkable change is the enlargement of the genome in certain Trebouxiophyceae, which is princ…

Lecanora Herteliana (Lecanoraceae, Ascomycetes), a New Lichen Species from Spain

AbstractLecanora herteliana is described from several collections from hard siliceous sandstone, in typically Mediterranean habitats in eastern Spain. The new species has a whitish thallus containing atranorin and norstictic acid. Its apothecia are mostly black, with a thalline exciple, which is finally excluded, and with a well developed true exciple.Lecanora herteliana is most closely related to L. subcoarctata, and it is discussed in relation to this species and other members of the L. marginata group.

Foliar Spraying with Zineb Increases Fruit Productivity and Alleviates Oxidative Stress in Two Tomato Cultivars

The effects of foliar spraying of the dithiocarbamate zineb on two cultivars of tomato grown in the field in a site with high ozone concentrations were studied by means of biomass assessment, antioxidant enzyme assays, lipid peroxidation, and chlorophyll fluorescence measurements. Zineb prevented the peroxidation of membrane lipids and decreased the activity of scavenging enzymes, which suggests that plants sprayed with zineb are subjected to lower oxidative stress than controls. The beneficial effects of zineb protection is the utilization of a larger fraction of absorbed radiant energy in photosynthesis and a larger fruit yield in plants of both cultivars.

Molecular phylogeny and ultrastructure of the lichen microalga Asterochloris mediterranea sp. nov. from Mediterranean and Canary Islands ecosystems

The microalgae of the genus Asterochloris are the preferential phycobionts in Cladonia, Lepraria and Stereocaulon lichens. Recent studies have highlighted the hidden diversity of the genus, even though phycobionts hosting Cladonia spp. in Mediterranean and Canarian ecosystems have been poorly explored. Phylogenetic analyses were made by concatenation of the sequences obtained with a plastid -LSU rDNA- and two nuclear -ITS rDNA and actin- molecular markers of the phycobionts living in several populations of Cladonia convoluta-C. foliacea complex, C. rangiformis and C. cervicornis species widely distributed in these areas in a great variety of substrata and habitats. A new strongly supported …

Two Trebouxia algae with different physiological performances are ever-present in lichen thalli of Ramalina farinacea. Coexistence versus Competition?

This study was funded by the Spanish Ministry of Education and Science (CGL2006-12917-C02-01/02), the Spanish Ministry of Science and Innovation (CGL2009-13429-C02-01/02), the AECID (PCI_A/024755/09) and the Generalitat Valenciana (PROMETEO 174/2008 GVA). We are grateful to Dr J. Gimeno-Romeu (University of California, Davis, USA) and to Dr P. J. G. de Nova (IREC, Ciudad Real, Spain), who were the first to isolate DNA from Ramalina farinacea thalli in our group. Wendy Ran revised the manuscript in English.

Similar Effects of Ozone on Four Cultivars of Lettuce in Open Top Chambers During Winter

Ozone is the major phytotoxic air pollutant that reduces the yield of several agricultural crops in the Spanish Mediterranean area. We studied four lettuce cultivars (Lactuca sativa L.) for the effects of different O3 concentrations during the winter on chlorophyll (Chl) a fluorescence, lipid peroxidation, and root length in outdoor open-top chambers. Under O3 the photosynthetic quantum conversion declined while heat emissions increased in all cultivars; these results provide more evidence of non-filtered air with additional ozone (NFA+O3) treatment compared with non-filtered air (NFA) and charcoal filtered ozone-free air (CFA). Changes in the Chl a fluorescence may be associated with an in…

Unexpected associated microalgal diversity in the lichen Ramalina farinacea is uncovered by pyrosequencing analyses

The current literature reveals that the intrathalline coexistence of multiple microalgal taxa in lichens is more common than previously thought, and additional complexity is supported by the coexistence of bacteria and basidiomycete yeasts in lichen thalli. This replaces the old paradigm that lichen symbiosis occurs between a fungus and a single photobiont. The lichen Ramalina farinacea has proven to be a suitable model to study the multiplicity of microalgae in lichen thalli due to the constant coexistence of Trebouxia sp. TR9 and T. jamesii in long-distance populations. To date, studies involving phycobiont diversity within entire thalli are based on Sanger sequencing, but this method see…

Differences in ozone sensitivity in three varieties of cabbage (Brassica oleracea L.) in the rural Mediterranean area

Summary The effects of air quality with three levels of ozone (O 3 ) were studied on three cabbage varieties during a one month exposure period in the Valencia area by means of modulated chlorophyll (Chl) a fluorescence, lipid peroxidation and solute leakage. Increasing O 3 exposure reduced the maximum quantum yield of PSII photochemistry (F v /F m ) in line with a reduction in non-cyclic electron flow (ϕ PSII ), lower capacity to reduce the quinone pool (q P ) and a decrease in the potential phothosynthetic quantum conversion, Rfd ratio. These reductions were more evident in Caramba and Sentinel varieties but lower in Othelo. Ozone and its oxidative derivates weakened the plasmalemma, whic…

The Role of Phospholipase D and MAPK Signaling Cascades in the Adaption of Lichen Microalgae to Desiccation: Changes in Membrane Lipids and Phosphoproteome.

Classically, lichen phycobionts are described as poikilohydric organisms able to undergo desiccation due to the constitutive presence of molecular protection mechanisms. However, little is known about the induction of cellular responses in lichen phycobionts during drying. The analysis of the lipid composition of the desiccated lichen microalga Asterochloris erici revealed the unusual accumulation of highly polar lipids (oligogalactolipids and phosphatidylinositol), which prevents the fusion of membranes during stress, but also the active degradation of cone-shaped lipids (monogalactosyldiacylglycerol and phosphatidylethanolamine) to stabilize membranes in desiccated cells. The level of pho…

Nitric oxide: a multitask player in plant–microorganism symbioses

Symbiosis is a close and often long-term interaction between two different biological organisms, i.e. plants or fungi and microorganisms. Two main types of plant–microorganism interactions, mutualistic and cooperative, have been categorized. Mutualistic interactions, including nitrogen-fixing and mycorrhizal symbioses, refer to mostly obligate relationships between a host plant and a symbiont microorganism. Cooperative interactions correspond to less obligate and specific relationships. They involve microorganisms, referred to as plant growth-promoting rhizobia (PGPR), able to colonize root surface or inner tissues. Lichens are symbiotic associations of host fungi and photosynthetic partner…

Chloroplast morphology and pyrenoid ultrastructural analyses reappraise the diversity of the lichen phycobiont genus Trebouxia (Chlorophyta)

Abstract Trebouxiophyceae is a wide class of green algae comprising coccoid and elliptic unicells, filaments, blades and colony-forming species that occur in diverse terrestrial and aquatic environments. Within this class, the genus Trebouxia Puymaly is among the most widespread lichen phycobionts worldwide. However, the 29 formally described species based on the combination of morphological traits and genetic diversity woefully underrepresented the overall species-level diversity recognized in the genus. In Trebouxia, reliable differentiation and characterization of the species-level lineages can be achieved by studying the diversity of key diagnostic features of pyrenoid ultrastructure an…

Different strategies to achieve Pb-tolerance by the two Trebouxia algae coexisting in the lichen Ramalina farinacea.

Lichen thalli are permeable to airborne substances, including heavy metals, which are harmful to cell metabolism. Ramalina farinacea shows a moderate tolerance to Pb. This lichen comprises two Trebouxia phycobionts, provisionally referred to as TR1 and TR9, with distinct physiological responses to acute oxidative stress. Thus, there is a more severe decay in photosynthesis and photosynthetic pigments in TR1 than in TR9. Similarly, under oxidative stress, antioxidant enzymes and HSP70 protein decrease in TR1 but increase in TR9. Since Pb toxicity is associated with increased ROS formation, we hypothesized greater Pb tolerance in this phycobiont. Accordingly, the aim of the present study was …

The chloroplast genome of the lichen‐symbiont microalga Trebouxia sp. Tr9 (Trebouxiophyceae, Chlorophyta) shows short inverted repeats with a single gene and loss of the rps4 gene, which is encoded by the nucleus

The Trebouxiophyceae is the class of Chlorophyta algae from which the highest number of chloroplast genome (cpDNA) sequences has been obtained. Several species in this class participate in symbioses with fungi to form lichens. However, no cpDNA has been obtained from any Trebouxia lichen-symbiont microalgae, which are present in approximately half of all lichens. Here, we report the sequence of the completely assembled cpDNA from Trebouxia sp. TR9 and a comparative study with other Trebouxio-phyceae. The organization of the chloroplast genome of Trebouxia sp. TR9 has certain features that are unusual in the Trebouxiophyceae and other green algae. The most remarkable characteristics are the …

Thallus Growth Stage and Geographic Origin Shape Microalgal Diversity in Ramalina farinacea Lichen Holobionts

Lichen symbioses are microecosystems hosting many other living organisms besides the two major lichen symbionts (i.e., lichenized fungi [the mycobiont] and green microalgae or cyanobacteria [the photobiont]). Recent investigations evidenced that other fungi, non-photosynthetic bacteria, and microalgae co-inhabit within the lichen thalli, but their diversity and their roles are still underinvestigated. Here we present an ad hoc stratified sampling design and in-depth Illumina paired-end metabarcoding approach to explore microalgal diversity in lichen thalli of the model species Ramalina farinacea from different ecologies. Lichen thalli were surveyed according to three different sizes, and di…

Chlorophyll a fluorescence in transplants of Parmelia sulcata Taylor near a power station (La Robla, León, Spain)

Healthy thalli of Parmelia sulcata Taylor were transplanted to 8 localities in the surroundings of a power station (La Robla, León, Spain), the sole pollution source in the region. Changes in chlorophyll a fluorescence were monitored in the transplants 12 months, 18 months and 24 months after transplantation. Statistically significant differences were observed in the ratio of variable to maximal fluorescence, non-photochemical fluorescence quenching and vitality index. The decrease in fluorescence parameters was higher in the localities of Cuadros and Rabanal de Fenar, which are situated a few kilometres away from the power station and in the same direction as the prevailing winds.

A new Lichenostigma on vagrant Aspicilia species

AbstractLichenostigma radicans Calat. &amp; Barreno, a lichenicolous fungus growing on vagrant Aspicilia species, is described as new to science from Spain. It is superficially similar to L. maureri, with cushion-like ascomata, but differing mainly by its ascomata connected at their base to immersed, brown, vegetative hyphae. Comments on the variability of iodine reactions of asci and ascospore walls, and on an associated conidial fungus with small bacilliform conidia, are given for L. maureri.

Biological Strategies of Lichen Symbionts to the Toxicity of Lead (Pb)

Lichens are symbiotic organisms, originated by mutualistic associations of heterotrophic fungi (mycobiont), photosynthetic partners (photobionts) which can be either cyanobacteria (cyanobionts) or green microalgae (phycobionts), and bacterial consortia. They are poikilohydric organisms without cuticles or nutrient absorption organs adapted to anhydrobiosis. They present a large range of tolerance to abiotic stress (UV radiation, extreme temperatures, high salinity, mineral excess, etc.) and prosper all around the Earth, especially in harsh habitats, including Antarctica and warm deserts. Their biodiversity is widely used as a bioindicator of environmental quality due to this diversity of to…

Chlorophyll a fluorescence, antioxidant enzymes and lipid peroxidation in tomato in response to ozone and benomyl

Ozone is a widely distributed phytotoxic air pollutant and is known to reduce the yield of several important agricultural crops in Spain. However, benomyl has been found to lessen the adverse impact of ozone on plants. We studied the effects of ozone and benomyl on chlorophyll a fluorescence, antioxidant enzymes, and lipid peroxidation in tomato (Lycopersicon esculentum Mill. cv. Tiny Tim) grown in open-top chambers in the field. Our results indicate that benomyl prevented the peroxidation of membrane lipids and increased protection of PSII from ozone. There was also a significant reduction in the activity of the antioxidant enzyme superoxide dismutase in ozone-exposed plants that had not b…

Phylogenetic generic classification of parmelioid lichens (Parmeliaceae, Ascomycota) based on molecular, morphological and chemical evidence

WOS: 000285566000008

Fungal-associated NO is involved in the regulation of oxidative stress during rehydration in lichen symbiosis

[EN] Background Reactive oxygen species (ROS) are normally produced in respiratory and photosynthetic electron chains and their production is enhanced during desiccation/rehydration. Nitric oxide (NO) is a ubiquitous and multifaceted molecule involved in cell signaling and abiotic stress. Lichens are poikilohydrous organisms that can survive continuous cycles of desiccation and rehydration. Although the production of ROS and NO was recently demonstrated during lichen rehydration, the functions of these compounds are unknown. The aim of this study was to analyze the role of NO during rehydration of the lichen Ramalina farinacea (L.) Ach., its isolated photobiont partner Trebouxia sp. and Ast…