A new mushroom hyperaccumulator: Cadmium and arsenic in the ectomycorrhizal basidiomycete Thelephora penicillata

Stable isotopic signature of cadmium in tracing the source, fate, and translocation of cadmium in soil: A review

Cadmium (Cd), one of the most severe environmental pollutants in soil, poses a great threat to food safety and human health. Understanding the potential sources, fate, and translocation of Cd in soil-plant systems can provide valuable information on Cd contamination and its environmental impacts. Stable Cd isotopic ratios (δ114/110Cd) can provide "fingerprint" information on the sources and fate of Cd in the soil environment. Here, we review the application of Cd isotopes in soil, including (i) the Cd isotopic signature of soil and anthropogenic sources, (ii) the interactions of Cd with soil constituents and associated Cd isotopic fractionation, and (iii) the translocation of Cd at soil-plant interfaces and inside plant bodies, which aims to provide an in-depth understanding of Cd transport and migration in soil and soil-plant systems. This review would help to improve the understanding and application of Cd isotopic techniques for tracing the potential sources and (bio-)geochemical cycling of Cd in soil environment.

Accumulation and within-mushroom distribution of elements in red cracking bolete (Xerocomellus chrysenteron) collected over the extended period from compositionally contrasting substrates

We conducted a study of elemental compositions of Xerocomellus chrysenteron samples accompanied by samples of related substrate soils. All samples were collected during the harvesting seasons 2021 and 2022 from three forested sites almost unpolluted by recent human activities and underlain by contrasting bedrock (granite, amphibolite, and serpentinite). Elements such as Ag, Cd, K, P, Rb, S, Se, and Zn were the main elements enriched in the mushroom's fruiting bodies relative to the substrate. Concentrations of most elements in mushrooms were not site-dependent, with only Ag, As, Rb, and Se concentrations significantly depending on the bedrock composition. Some elements analyzed in mushrooms displayed temporal features, but such features were not systematic and varied for each element. Most analyzed elements were distributed unevenly within the mushroom's fruiting bodies, with apical parts generally enriched in mobile elements. Mushrooms influenced concentrations of Ag, Cd, K, and Rb and a few other elements in the substrate via uptake, but such influence was very limited and can be responsible for only 2.5-11.5% of total depletion of the affected substrate in the named elements.

Molecular phylogeny and morphology reveal four new species of Thelephora (Thelephorales, Basidiomycota) from subtropical China, closely related to T. ganbajun

The genus of Thelephora is a group of cosmopolitan ectomycorrhizal fungi with basidiocarps of morphological diversity that has an extremely scarce species reported from the forest ecosystem in China. In this study, phylogenetic analyses of Thelephora species from subtropical China were carried out based on multiple loci including the internal transcribed spacer (ITS) regions, the large subunit of nuclear ribosomal RNA gene (nLSU), and the small subunit of mitochondrial rRNA gene (mtSSU). Maximum likelihood and Bayesian analyses were used to construct the phylogenetic tree. The phylogenetic positions of four new species, Th. aquila, Th. glaucoflora, Th. nebula, and Th. pseudoganbajun, were revealed based on morphological and molecular evidence. Molecular analyses demonstrated that the four new species were closely related to Th. ganbajun and formed a clade with robust support in the phylogenetic tree. Regarding morphology, they share some common morphological characteristics, including flabelliform to imbricate pilei, generative hyphae more or less covered by crystals, and subglobose to irregularly lobed basidiospores (5–8 × 4–7 μm) with tuberculate ornamentation. These new species are described and illustrated and are compared to similar morphological or phylogenetically related species. A key to the new and allied species from China is provided.

Cadmium in the hyperaccumulating mushroom Thelephora penicillata: Intracellular speciation and isotopic composition

Thelephora penicillata is an ectomycorrhizal mushroom that can accumulate extraordinarily high concentrations of Cd, As, Cu, and Zn in its fruit-bodies. To better understand its element accumulation ability, we compared the element concentrations in T. penicillata with 10 distinct ectomycorrhizal mushroom species growing at the same site (Karlina Pila, Czech Republic). On average, T. penicillata accumulated 330, 2130, 26, and 4 times more Cd, As, Cu, and Zn, respectively, than other mushrooms. Size-exclusion chromatography and an electrophoretic analysis of T. penicillata cell extracts indicate that intracellular Cd may be present mainly in >1 kDa, presumably compartmentalized, Cd species, and partially binding with 6-kDa cysteinyl-containing peptide(s) resembling metallothioneins. The cadmium isotopic composition of mushroom fruit-bodies, soil digests, and soil extracts was investigated by thermal ionization mass spectrometry (TIMS) with double spike correction. The isotopic composition (δ^114/110Cd) of ectomycorrhizal mushrooms from Karlina Pila varied in a wide range of -0.37 to +0.14 ‰. However, remarkably low δ^114/110Cd values were observed in the majority of the investigated mushrooms when compared to the relatively homogeneous Cd isotopic composition of bulk soil (δ^114/110Cd = +0.09 ‰) and the comparatively heavy isotopic composition of soil extracts (mean δ^114/110Cd values of +0.11 ± 0.01 ‰ and +0.22 ± 0.01 ‰, depending on the extraction method). The isotopic composition of Cd hyperaccumulated in T. penicillata essentially matched the mycoavailable soil Cd fraction. However, most isotopic data indicates isotopic fractionation at the soil/fruit-body interface, which could be of environmental significance.

Extensive Collection of Psychotropic Mushrooms with Determination of Their Tryptamine Alkaloids

Since not only psilocybin (PSB) but also PSB-containing mushrooms are used for psychedelic therapy and microdosing, it is necessary to know their concentration variability in wild-grown mushrooms. This article aimed to determine the PSB, psilocin (PS), baeocystin (BA), norbaeocystin (NB), and aeruginascin (AE) concentrations in a large sample set of mushrooms belonging to genera previously reported to contain psychotropic tryptamines. Ultra-high performance liquid chromatography coupled with tandem mass spectrometry was used to quantify tryptamine alkaloids in the mushroom samples. Most mushroom collections were documented by fungarium specimens and/or ITS rDNA/LSU/EF1-α sequencing. Concentrations of five tryptamine alkaloids were determined in a large sample set of 226 fruiting bodies of 82 individual collections from seven mushroom genera. For many mushroom species, concentrations of BA, NB, and AE are reported for the first time. The highest PSB/PS concentrations were found in Psilocybe species, but no tryptamines were detected in the P. fuscofulva and P. fimetaria collections. The tryptamine concentrations in mushrooms are extremely variable, representing a problem for mushroom consumers due to the apparent risk of overdose. The varied cocktail of tryptamines in wild mushrooms could influence the medicinal effect compared to therapy with chemically pure PSB, posing a serious problem for data interpretation.

Fungus–Fungus Association of Boletus griseus and Hypomyces chrysospermus and Cadmium Resistance Characteristics of Symbiotic Fungus Hypomyces chrysospermus

Fungi bioaccumulation of heavy metals is a promising approach to remediate polluted soil and water. Boletus griseus could accumulate high amounts of Cd, even in a natural habitat with low Cd contents. This study found a symbiotic association of B. griseus with a fungus. The symbiotic fungus was isolated and identified as Hypomyces chrysospermus. The isolated strain had a strong ability to tolerate Cd. The minimum inhibitory concentration of Cd of fungal growth was 200 mg·L−1. The Cd bioaccumulation capacity of the fungus reached 10.03 mg·g−1. The biomass production of the fungus was promoted by 20 mg·L−1 Cd. However, high concentrations of Cd suppressed fungal growth and significantly altered the morphology and fine texture of fungal hyphae and chlamydospores. The immobilization effects of the cell wall and acid compounds and antioxidant enzymes were employed by the fungus to alleviate the toxic effects of Cd. The results not only demonstrate a new insight into the Cd bioconcentration mechanisms of B. griseus but also provide a potential bioremediation fungus for Cd contamination.