Survey of Lichenized Fungi DNA Barcodes on King George Island (Antarctica): An Aid to Species Discovery

DNA barcoding is a powerful method for the identification of lichenized fungi groups for which the diversity is already well-represented in nucleotide databases, and an accurate, robust taxonomy has been established. However, the effectiveness of DNA barcoding for identification is expected to be limited for understudied taxa or regions. One such region is Antarctica, where, despite the importance of lichens and lichenized fungi identification, their genetic diversity is far from characterized. The aim of this exploratory study was to survey the lichenized fungi diversity of King George Island using a fungal barcode marker as an initial identification tool. Samples were collected unrestricted to specific taxa in coastal areas near Admiralty Bay. Most samples were identified using the barcode marker and verified up to the species or genus level with a high degree of similarity. A posterior morphological evaluation focused on samples with novel barcodes allowed for the identification of unknown Austrolecia, Buellia, and Lecidea s.l. species. These results contribute to better represent the lichenized fungi diversity in understudied regions such as Antarctica by increasing the richness of the nucleotide databases. Furthermore, the approach used in this study is valuable for exploratory surveys in understudied regions to guide taxonomic efforts towards species recognition and discovery.

Towards understanding the effect of heavy metals on mycobiont physiological condition in a widespread metal-tolerant lichen Cladonia rei

Heavy metals present in the environment can cause a variety of injury symptoms in various organisms including lichens. Most studies examined metal-induced stress under controlled laboratory conditions, and little is known about actual response of lichens in their natural habitat. This study aims to recognize the effect of heavy metal accumulation (total and intracellular) on lichen physiological and biochemical parameters specifically related to the functioning of fungal component. Cladonia rei was used as a model species due to its common occurrence both in unpolluted and extremely polluted sites. We observed a decline in the fungal metabolism which was expressed by a decrease in ergosterol content and an increase in cell membrane damage as a result of increased Zn, Cd, Cu and Ni accumulation. Additionally, the results indicated that increased accumulation of xenobiotics (Pb and As) caused reduction of glutathione (GSH) concentrations and increased membrane lipid peroxidation. Therefore, we conclude that GSH does not provide high oxidative stress protection in C. rei which is somewhat against its insensitivity to pollution. The reduced pool of GSH could be explained by its oxidation to glutathione disulphide induced by heavy metal stress or its use for phytochelatin (PC) synthesis. The content of secondary metabolites was not related to heavy metal accumulation and remained at a relatively stable level. This indicates that the decline in the physiological condition did not weaken the mycobiont of C. rei enough to inhibit the synthesis of secondary metabolites and their precursors were supplied at a sufficient level. Thus, the potential function of main secondary metabolites as extracellular metal immobilizers and antioxidants is still possible even in individuals growing at extremely polluted sites. Despite the evident heavy metal stress, C. rei copes well and spreads easily through extremely polluted environments, which underlines its unique pioneering abilities in highly disturbed sites.

Metabolic processes involved with sugar alcohol and secondary metabolite production in the hyperaccumulator lichen Diploschistes muscorum reveal its complex adaptation strategy against heavy-metal stress

The synthesis of various unique secondary metabolites by lichens is the result of mutualistic symbiotic association between the mycobiont and autotrophic photobiont. The function of these compounds and causal factors for their production are not fully understood. This paper examines the effect of heavy-metal bioaccumulation and physiological parameters related to photosynthesis and carbon metabolism on the production of lichen substances in hyperaccumulator Diploschistes muscorum. The obtained model of secondary metabolite concentrations in the thalli demonstrates that the carbon source provided by the photobiont and associated polyols produced by the mycobiont have positive impact on the production; on the contrary, the increased intracellular load of heavy metals and excessive loss of cell membrane integrity adversely affected secondary metabolite contents. Additionally, the production of secondary metabolites appears to be more dependent on intracellular metal concentrations than on soil pollution level. To compensate for metal stress, both efficient functioning of algal component and sufficient production of secondary metabolites are required. The balanced physiological functioning of mycobiont and photobiont constitutes the complex protective mechanism to alleviate the harmful effects of heavy metal stress on primary and secondary metabolism of lichens.

Neogene speciation and Pleistocene expansion of the genus Pseudephebe (Parmeliaceae, lichenized fungi) involving multiple colonizations of Antarctica

Widespread geographic distributions in lichens have been usually explained by the high dispersal capacity of their tiny diaspores. However, recent phylogenetic surveys have challenged this assumption and provided compelling evidence for cryptic speciation and more restricted distribution ranges in diverse lineages of lichen-forming fungi. To evaluate these scenarios, we focus on the fungal genus Pseudephebe (Parmeliaceae) which includes amphitropical species, a distribution pattern whose origin has been a matter of debate since first recognized in the nineteenth century. In our study, a six-locus dataset and a broad specimen sampling covering almost all Earth's continents is used to investigate species delimitation in Pseudephebe. Population structure, gene flow and dating analyses, as well as genealogical reconstruction methods, are employed to disentangle the most plausible transcontinental migration routes, and estimate the timing of the origin of the amphitropical distribution and the Antarctic populations. Our results demonstrate the existence of three partly admixed phylogenetic species that diverged between the Miocene and Pliocene, and whose Quaternary distribution has been strongly driven by glacial cycles. Pseudephebe minuscula is the only species showing an amphitropical distribution, with populations in Antarctica, whereas the restricted distribution of P. pubescens and an undescribed Alaskan species might reflect the survival of these species in European and North American refugia. Our microevolutionary analyses suggest a Northern Hemisphere origin for P. minuscula, which could have dispersed into the Southern Hemisphere directly and/or through "mountain-hopping" during the Pleistocene. The Antarctic populations of this species are sorted into two genetic clusters: populations of the Antarctic Peninsula were grouped together with South American ones, and the Antarctic Continental populations formed a second cluster with Bolivian and Svalbard populations. Therefore, our data strongly suggest that the current distribution of P. minuscula in Antarctica is the outcome of multiple, recent colonizations. In conclusion, our results stress the need for integrating species delimitation and population analyses to properly approach historical biogeography in lichen-forming fungi.

Determination of the effect of RBBR on laccase activity and gene expression level of fungi in lichen structure

This study provides information about the differential transcription regulation of laccase genes in response to RBBR dye. To this purpose, we determined the laccase gene expression, laccase activity, and protein profile of lichen-forming fungi supported to RBBR dye. For those obtained from optimal laccase genes expression profiles, we modified different RNA extraction protocols to obtain high quality and quantity RNA to be used in downstream applications in lichen-forming fungus. We also determined the expression of ten laccase genes in response to RBBR dye by qRT-PCR and validated protein profile. As a result of our study, a high laccase activity of 522 U mL^-1 was obtained after submerged fermentation for 17 days. The maximal laccase activity to RBBR dye was obtained at 408 h. The expression profiles of laccase gene expression on ten laccase genes showed up- or down-regulation in course of eight fermentation times. The most up-regulated gene during the process was lac8. However, poxa1b gene expression was lowest in lichen-forming fungi biomass supplemented with RBBR dye. This study has revealed the influence of RBBR dye on laccase activity levels and the determination of gene expression levels in lichen-forming fungi.

The conservation of polyol transporter proteins and their involvement in lichenized Ascomycota

In lichen symbiosis, polyol transfer from green algae is important for acquiring the fungal carbon source. However, the existence of polyol transporter genes and their correlation with lichenization remain unclear. Here, we report candidate polyol transporter genes selected from the genome of the lichen-forming fungus (LFF) Ramalina conduplicans. A phylogenetic analysis using characterized polyol and monosaccharide transporter proteins and hypothetical polyol transporter proteins of R. conduplicans and various ascomycetous fungi suggested that the characterized yeast' polyol transporters form multiple clades with the polyol transporter-like proteins selected from the diverse ascomycetous taxa. Thus, polyol transporter genes are widely conserved among Ascomycota, regardless of lichen-forming status. In addition, the phylogenetic clusters suggested that LFFs belonging to Lecanoromycetes have duplicated proteins in each cluster. Consequently, the number of sequences similar to characterized yeast' polyol transporters were evaluated using the genomes of 472 species or strains of Ascomycota. Among these, LFFs belonging to Lecanoromycetes had greater numbers of deduced polyol transporter proteins. Thus, various polyol transporters are conserved in Ascomycota and polyol transporter genes appear to have expanded during the evolution of Lecanoromycetes.

Plant hormones promote growth in lichen-forming fungi

The effect of plant hormones on the growth of lichen-forming fungi (LFF) was evaluated. The use of 2,3,5-triiodobenzoic acid and indole-3-butyric acid resulted in a 99% and 57% increase in dry weight of the lichen-forming fungus Nephromopsis ornata. The results suggest that some plant hormones can be used as inducers or stimulators of LFF growth for large-scale culture.

Notes on Lichen Genus Buellia De Not. (lichenized Ascomycetes) from South Korea

Based on a literature survey and assessment of the important features of lichen genus Buellia (spore shape and size, anatomy of the exciple as well as analysis of the lichen substances), the present paper describes four new records of B. maritima, B. polyspora, B. spuria and B. stellulata from South Korea. Among them, B. maritima and B. polyspora are firstly reported in East Asia including in China, the Korean Peninsula and Japan. Brief description of all the new records along with earlier described species placed under genus Amandinea and Hafellia are provided with their distribution and chemistry. A key to all the Buellia species reported so far from South Korea is also provided.

Effect of Ribitol and Plant Hormones on Aposymbiotical Growth of the Lichen-forming Fungi of Ramalina farinacea and Ramalina fastigiata

This study was aimed at evaluating the growth promoting effect of symbiotic algal polyol (ribitol) and plant hormones on the lichen-forming fungi (LFF), Ramalina farinacea (CH050010 and 40403) and Ramalina fastigiata. The addition of ribitol to basal (malt-yeast extract) medium enhanced the relative growth rates of all three LFF. R. farinacea (CH050010), R. farinacea (40403) and R. fastigiata (H06127) showed 35.3%, 29.0% and 29.3% higher growth rates, respectively, compared to the control. IBA (indole-3-butyric acid) and TIBA (2,3,5-tridobenzoic acid) also increased growth rates of the LFF by 34 to 64% and 7 to 28%, respectively, compared to the control. The combination of ribitol with IBA or TIBA synergistically increased the growth of all LFF. For example, ribitol and IBA treatments increased growth rates of R. farinacea (CH050010), R. farinacea (40403) and R. fastigiata (H06127) by 79.4%, 40.3% and 72.8% in, respectively, compared to those grown on the basal medium. The stimulating effect of ribitol and IBA on the LFF growth induced vertical development of the fungal mass in culture. We suggest that lichen-forming fungal growth of Ramalina lichens can be stimulated aposymbiotically by supplementing polyols and plant hormones to the basal medium in the mass production of lichen secondary metabolites under large scale culture conditions.

New Record of Lecanora muralis (Lichenized Fungus) in South Korea

Lecanora muralis was found on the rock along coastal line during the field trip in Jeju island in 2006. Thallus crustose, placodioid, closely adnate, forming orbicular patches; upper surface grayish green, glossy; central lobes areolate, marginal parts plane, edges thin pruinose; lower surface ecorticate; apothecia sessile, lecanorine type, exciple dense and intact when young, and disc plane, but when mature, exciple laciniate, disc protrudent, yellowish brown to orange, 0.5~1.5 mm in diameter; ascospores ellipsoid, simple, colorless, 12.5~15.0 × 5.0~7.5 µm. Usnic acid and zeorin contained in thallus. This is the first record of this species in South Korea.

New Record of Karoowia saxeti (Stizenb.) Hale in South Korea

Karoowia saxeti was recorded during the lichen field expedition in southern part of Korea in 2006. The lichen was found on the rock surface along coastal line. This species was easily recognized by chemistry (K+ yellow) and the presence of isidia. Thallus was saxicolous, subcrustose, more or less lobate at the center with clearly lobed margins, 2~6 cm broad and pale yellowish green. Thalli lobes were irregular, variable, up to 1.0mm wide, not branched, flat to more or less convex and contiguous to subimbricate. Upper surface of the thalli was continuous, emaculate, moderately isidiate. The isidia was subglobose to cynlindrical, darkening at the tips and unbranched. Low surface of the thalii was black with a spongy rhizoidal and lamellar layer. HPLC analysis proved the presence of stictic acid (K+ yellow), norstictic acid and usnic acid. This is the first record of the species in South Korea.