Accurate estimation of cryptogam biomass, encompassing bryophytes and lichens, is crucial for understanding their ecological significance. This estimation is conducted based on the strong correlations between mass and volume of cryptogams. However, mass-volume correlations vary among cryptogams because of their morphological differences. This problem can be solved using models that consider life forms that classify cryptogams based on morphological similarities. In this study, we investigated whether life form models improve cryptogam biomass estimation accuracy. The cryptogam mass-volume correlation of each life form was estimated using Bayesian linear models. The coefficients and intercepts of linear models differed between life forms, which was attributed to the morphological characteristics of each life form. Therefore, life form models can improve the accuracy of estimation models by incorporating morphological differences. However, taxonomic models that consider only the taxonomic difference (bryophytes vs lichens) demonstrated better overall estimation than the life form models, probably because of the ability of taxonomic models to capture systematic differences between bryophytes and lichens. Furthermore, these models may mitigate estimation errors related to morphological variations that cannot be adequately represented by life form types. Based on these results, we propose the appropriate use of estimation models.

Sterols play important structural and regulatory roles in numerous intracellular processes. Unlike animals, plants contain a distinctive and diverse variety of sterols. Recently, information has emerged showing that stigmasterol is a \"stress sterol\". Stigmasterol is synthesized via the mevalonate biosynthesis pathway and has structural similarity to β-sitosterol but differs in the presence of a trans-oriented double bond in the side chain. In plants, the accumulation of stigmasterol has been observed in response to various stresses. However, the precise ways that stigmasterol is involved in the stress responses of plants remain unclear. This comprehensive review provides an update on the biology of stigmasterol, particularly the physicochemical properties of this ethylsterol, its biosynthesis, and its occurrence in higher plants and extremophilic organisms, e.g., mosses and lichens. Special emphasis is given to the evolutionary aspects of stigmasterol biosynthesis, particularly the variations in the gene structure of C22-sterol desaturase, which catalyzes the formation of stigmasterol from β-sitosterol, in a diversity of evolutionarily distant organisms. The roles of stigmasterol in the tolerance of plants to hostile environments and the prospects for its biomedical applications are also discussed. Taken together, the available data suggest that stigmasterol plays important roles in plant metabolism, although in some aspects, it remains an enigmatic compound.

Biocrusts represent associations of lichens, green algae, cyanobacteria, fungi and other microorganisms, colonizing soils in varying proportions of principally arid biomes. The so-called grit crust represents a recently discovered type of biocrust situated in the Coastal Range of the Atacama Desert (Chile) made of microorganisms growing on and in granitoid pebbles, resulting in a checkerboard pattern visible to the naked eye on the landscape scale. This specific microbiome fulfills a broad range of ecosystem services, all probably driven by fog and dew-induced photosynthetic activity of mainly micro-lichens. To understand its biodiversity and impact, we applied a polyphasic approach on the phototrophic microbiome of this biocrust, combining isolation and characterization of the lichen photobionts, multi-gene phylogeny of the photobionts and mycobionts based on a direct sequencing and microphotography approach, metabarcoding and determination of chlorophylla+b contents. Metabarcoding showed that yet undescribed lichens within the Caliciaceae dominated the biocrust together with Trebouxia as the most abundant eukaryote in all plots. Together with high mean chlorophylla+b contents exceeding 410 mg m-2, this distinguished the symbiotic algae Trebouxia as the main driver of the grit crust ecosystem. The trebouxioid photobionts could be assigned to the I (T. impressa/gelatinosa) and A (T. arboricola) clades and represented several lineages containing five potential species candidates, which were identified based on the unique phylogenetic position, morphological features, and developmental cycles of the corresponding isolates. These results designate the grit crust as the only known coherent soil layer with significant landscape covering impact of at least 440 km2, predominantly ruled by a single symbiotic algal genus.

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A lichen is a symbiotic association composed of a primary mycobionts and one or more photobionts living mutualistically together, forming a distinct morphological entity beneficial to their partnership and to other associated fungi, photobionts, and bacteria that collectively make up the lichen biome. The taxonomic identification of a lichen species often requires determination of the primary mycobiont\'s secondary metabolites, the key morphological characteristics of the thallus, and how it relates to other lichen species as seen in DNA phylogeny. This chapter covers lichens and their bionts, taxonomic identification, and their chemical constituents as exemplified by what is found in lichen biomes, especially those endemic to North America. Extraction and isolation, as well as updates on dereplication methods using mass spectrometric GNPS and NMR spectroscopic spin network fingerprint procedures, and marker-based techniques to identify lichens are discussed. The isolation and structure elucidation of secondary metabolites of an endolichenic Penicillium species that produces bioactive compounds will be described in detail.

This paper documents the occurrence of the genus Umbilicaria in the Argentine Islands-Kyiv Peninsula region of the Graham Coast in the maritime Antarctic. The presence of seven Umbilicaria species (U. africana, U. antarctica, U. aprina, U. decussata, U. kappenii, U. nylanderiana and U. umbilicarioides) in the ice-free areas of the Argentine Islands-Kyiv Peninsula region were confirmed. The species of U. africana and U. aprina are documented from the studied region for the first time. This study moves the southern distribution limit of U. africana about 300 km to the south: to the Argentine Islands-Kyiv Peninsula region. The distribution maps of Umbilicaria species for the studied region and maritime Antarctica are prepared.

The presence or absence of lichens serves as an indicator of the condition of an ecosystem and the degree to which it is contaminated by various agents, such as agrochemicals and metals. Evaluating the use of lichens as bioindicators of agrochemical contamination could provide a more comprehensive perspective of current contamination levels. Monitoring was conducted over a 4-month period in two study areas: one was a well-conserved area contaminated by metals, and the other was an area surrounded by agricultural crops contaminated by agrochemicals. Data on the presence and abundance of lichens in each study area were recorded at 10 monitoring points, a procedure that was repeated 16 times (every 15 days), and concentrations of heavy metals and \"organophosphate\" agrochemicals in the lichens collected were measured by means of Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-OES) and Gas Chromatography (GC), respectively. Generalized linear mixed models were used to assess abundance and richness, while general linear mixed models were used to attain Shannon diversity and Simpson dominance indices. Moreover, a multivariate analysis was performed in order to compare the lichen communities in both areas. The results indicated differences between the area contaminated by metals and that contaminated by agrochemicals in terms of abundance and Simpson\'s dominance index, while no differences were found in the case of the richness and diversity models. The PERMANOVA analysis additionally showed differences between the lichen communities in the two areas. The results also demonstrated that Canoparmelia caroliniana bioaccumulated metals in both areas. The levels of barium, cadmium, and sodium were higher in the area contaminated by metals, while concentrations of chromium and copper were higher in the area contaminated by agrochemicals. Finally, the concentrations of agrochemicals were higher in the area contaminated by agrochemicals and included toxic substances such as Methylparathion and Parathion, which are prohibited in Ecuador. In conclusion, this research underscores the importance of lichens as precise indicators of environmental health and contamination by agrochemicals and metals.

Ore mineralizations in bedrock and their exploitation may have a negative impact on air quality of surrounding urban areas and, subsequently, on human health. This study uses lichens as bioindicators of atmospheric pollution to evaluate the spatial distribution of potentially toxic elements (PTEs) in the towns close to the massive sulfide deposits of the Iberian Pyrite Belt (IPB) in SW Spain. Altogether 89 native lichen samples of Xanthoria parietina were collected from the mining towns, control towns out of the reach of the mining activity, as well as from distal sampling sites. The samples were analyzed for 29 elements after acid digestion. The concentrations for Co, Ni, Cu, Zn, As, Rb, Mo, Cd, Sn, Sb, Cs, Ba, W, Tl, Pb, S, and Fe are significantly higher in the mining towns in comparison to the control towns. The ore mineral-associated PTEs, including Cu, Zn, As, Ba, and Pb, exhibit extreme concentrations in the urban areas close to the mining activity, and particularly in the small settlement of La Dehesa next to the mineral processing plant and the tailings pond. The distal samples confirm the decrease in the concentrations of all PTEs, and these samples present similar values as in the control areas. The results, point at increased bioaccumulation of PTEs in the lichen thalli of the adjacent urban areas, suggesting that the air quality of the adjacent urban areas is locally impacted by the massive polymetallic sulfide deposits which is enhanced by the mining activity. Therefore, monitoring the urban air quality is recommended.

The selection of the appropriate biomonitor species is a crucial criterion for biomonitoring on a broad spatial scale. Mosses Hypnum cupressiforme and Brachythecium spp. and lichen Evernia prunastri were sampled at 22 remote sites over Serbia aiming interspecies comparison of their bioconcentration capacities. The concentration of 16 potentially toxic elements (PTEs), Al, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, P, Pb, S, Sr, V, and Zn, was measured in the samples. Between the co-located mosses, linear regression analysis (type II) showed significant determination coefficients only for a couple of the elements (Cd and S), while for H. cupressiforme vs. lichen, significant regression lines were obtained for a broader set of elements (Ba, Cd, Fe, Hg, Mn, Ni, Sr). The ratio of the PTEs in the mosses discovered higher concentrations in H. cupressiforme than in another moss at some sites and vice versa at other sites. According to the PTE ratios, H. cupressiforme accumulated much more element content than the lichen, but followed a similar spatial pattern. In addition, principal component analysis (PCA) pointed out a different grouping of the PTEs depending on the species tested. The poor correlation of the moss-moss data is perhaps because several species of the genus Brachythecium were sampled, which possibly influenced the average genus accumulation capacity. In addition, morphological features of the mosses (concave vs. flat leaflets, creeping vs. cushiony life form) presumably delegate differences in PTE accumulation. To conclude, it should be careful with using more biomonitor species, even of the same genus, within the same study.

The present study evaluated an integrated biomonitoring approach based on three different bioindicators: tree rings, lichens, and beetles in a complex environment (urban-industrial-forest). In Central Italy, four sampling sites were selected to assess the anthropogenic impact of cement plants taking into account (1) long-term exposure (1988-2020) through the analysis of trace elements in tree rings of Quercus pubescens; (2) medium-term exposure (2020-2021) through the analysis of trace elements in thalli (outermost portions) of the lichen Xanthoria parietina; (3) short-term exposure in spring 2021 through the bioaccumulation and evaluation of sample vitality in transplants of the lichen Evernia prunastri and a periodic survey of entomological biodiversity carried out during spring and summer 2021. Trace elements of industrial origin were found in tree rings, with different levels of accumulation between 1988 and 2020 and a maximum in 2012. Native thalli of the lichen X. parietina showed an overall low bioaccumulation of trace elements except for Cr, probably reflecting the influence of national lockdown measures. The transplants of E. prunastri showed a weak stress response in the industrial and urban sites, but not in the forest, and identified Tl and V as the main elements contributing to atmospheric contamination, with peaks at the industrial sites. Concerning the beetles, a significantly lower number of species was found at the Semonte industrial site.