The complete mitochondrial genome of enigmatic mycoparasitic fungus Squamanita imbachii.

The complete mitochondrial genome of Squamanita imbachii I. Saar, is unveiled in this research for the first time. It covers 76,643 base pairs (bp) and exhibits a guanine-cytosine (GC) content of 23%. The genome includes 14 conserved protein-coding genes, 1 DNA polymerase gene, 2 ribosomal RNA gene (RNS and RNL), 25 transfer RNA (tRNA) genes and 18 open reading frames (ORFs). Phylogenetic analysis, utilizing a mitochondrial gene dataset from 15 taxa across seven families within the Agaricales order, was conducted employing the maximum-likelihood (ML) approach. This analysis identified a close phylogenetic relationship between S. imbachii and Floccularia luteovirens (Alb. & Schwein.) Pouzar 1957, positioning both within the Squamanitaceae family.

Transcriptome and metabolome analysis reveals stage-specific metabolite accumulation during maturity of Chinese black truffle Tuber indicum.

Tuber indicum is the most economically important member of Tuber, with the highest production and widest distribution in China. However, the overexploitation of immature ascocarps not only has driven wild resources of the species toward extinction, but also has caused enconomic losses and a decline in the reputation of T.indicum quality. In this study, stage-specific metabolites of T. indicum in relation to nutritional quality and the mechanism of their accumulations were explored by transcriptome and metabolome analysis at five harvest times, representing four maturation stages. A total of 663 compounds were identified in T. indicum ascocarps by a widely targeted metabolomic approach. Lipid compounds are the most prominent metabolites (18%) in our samples and also are higher accumulation at the immature stage than at mature stage, representing 30.16% differential accumulated metabolites in this stage. Levels of some of the amino acids, such as S-(methyl) glutathione, S-adenosylmethionine, which are known truffle aroma precursors, were increased at the mature stage. The gene expression level related to the biosynthesis of volatile organic compounds were verified by qPCR. This study contributes to the preliminary understanding of metabolites variations in T. indicum ascocarps during maturity for quality evaluation and truffle biology.

A new amide from the fruiting bodies of Tricholoma bakamatsutake.

A new amide tricholomine C was isolated from the dried fruiting bodies of Tricholoma bakamatsutake. Its structure was identified by a combination of nuclear magnetic resonance spectroscopic analysis and electronic circular dichroism (ECD) calculations. The ethyl alcohol crude extract and tricholomines A-C from T. bakamatsutake were evaluated for neuroprotective activities. Of these substances, the crude extract showed weak neurite outgrowth-promoting activity in rat pheochromocytoma (PC12) cells, as well as weak inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE).

Phylogenetic Analyses of Hydnobolites and New Species from China.

Hydnobolites is an ectomycorrhizal fungal genus with hypogeous ascomata in the family Pezizaceae (Pezizales). Molecular analyses of Hydnobolites using both single (ITS) and concatenated gene datasets (ITS-nLSU) showed a total of 223 sequences, including 92 newly gained sequences from Chinese specimens. Phylogenetic results based on these two datasets revealed seven distinct phylogenetic clades. Among them, the ITS phylogenetic tree confirmed the presence of at least 42 phylogenetic species in Hydnobolites. Combined the morphological observations with molecular analyses, five new species of Hydnobolites translucidus sp. nov., H. subrufus sp. nov., H. lini sp. nov., H. sichuanensis sp. nov. and H. tenuiperidius sp. nov., and one new record species of H. cerebriformis Tul., were illustrated from Southwest China. Macro- and micro-morphological analyses of ascomata revealed a few, but diagnostic differences between the H. cerebriformis complex, while the similarities of the ITS sequences ranged from 94.4 to 97.2% resulting in well-supported clades.

Ethnobiological notes and volatile profiles of two rare Chinese desert truffles.

The production of a distinct profile of volatile organic compounds plays a crucial role in the ecology of hypogeous Ascomycetes, and is also key to their gastronomic relevance. In this study, we explored the aroma components of two rarely investigated Chinese desert truffles, namely Mattirolomyces terfezioides and Choiromyces cerebriformis, using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Our investigation revealed the significant presence of sulphur-containing volatiles in the aroma of M. terfezioides but not in C. cerebriformis. We discussed available information on the distribution of these interesting truffles in China and their use as choice food by local people.

The complete mitochondrial genome of Polyozellus multiplex (Thelephorales).

The complete mitogenome of Polyozellus multiplex (Underw.) Murrill 1910, was first sequenced, assembled, and annotated in the present study. The mitogenome length was 47,054 bp with a GC content of 23.35%, including 14 conserved protein-coding genes, one ribosomal protein (RPS3), two DNA polymerases (DPO), two rRNA genes (RNS and RNL), and 24 transfer RNA (tRNA) genes. Phylogenetic analysis, based on a combined mitochondrial gene dataset from 17 taxa of four orders within the class Agaricomycetes, was conducted using maximum-likelihood (ML) and Bayesian inference (BI) methods. It is revealed that P. multiplex is closely related to Thelephora aurantiotincta Corner 1968, both of them have been clustered into Thelephorales.

Ectomycorrhizal synthesis between two Tuber species and six tree species: are different host-fungus combinations having dissimilar impacts on host plant growth?

Truffle cultivation has drawn more and more attention for its high economic and ecological values in the world. To select symbionts suitable for cultivation purposes, we conducted greenhouse-based mycorrhization trials of two Tuber species (T. formosanum and T. pseudohimalayense) with five broad-leaved tree species (Corylus yunnanensis, Quercus aliena var. acutiserrata, Q. acutissima, Q. robur, Q. variabilis) and one conifer species (Pinus armandii). Axenically germinated seedlings of all tree species were either inoculated, or not, with spore suspensions of these two truffles in the greenhouse. Eight months after inoculation, T. formosanum or T. pseudohimalayense ectomycorrhizae were successfully formed on these six tree species, as evidenced by both morphological and molecular analyses. All selected trees showed good receptivity to mycorrhization by both fungi, with average colonization rates visually estimated at 40-50%. Plant growth, photosynthesis, and nutrient uptake were assessed 2 years after inoculation and were mainly affected by host species. Mycorrhization by both fungi significantly improved P uptake of the hosts, and the interaction between truffle species and host plant species had significant effects on leaf water and leaf K concentrations. In addition, a significantly negative correlation between leaf Ca and leaf C concentration was found across all the seedlings. In addition, mycorrhization had slightly increased plant stem and canopy, but had no significant effects on plant photosynthesis. Overall, these results suggest that the effects of these two Tuber ECMF on plant growth and nutrient acquisition depend on the identity of the host species. Moreover, all selected plant species could be symbiotic partners with either T. pseudohimalayense or T. formosanum for field cultivation purposes.

The ectomycorrhizal association of Tricholoma matsutake and two allied species, T. bakamatsutake and T. fulvocastaneum, with native hosts in subtropical China.

Accurate identification of edible ectomycorrhizal (ECM) mushrooms and their host trees in nature is key to commercial production for consumption. For the first time we describe the ectomycorrhizal association of the three most common species of edible matsutake mushrooms with their native host trees in Yunnan Province in China. We collected ECM samples from three different localities in subtropical forests known to be highly productive areas of Tricholoma. Additionally, we collected basidiomata of Tricholoma from the field and markets in Yunnan. ECM samples were analyzed using morphological and molecular methods. We conducted phylogenetic analyses of nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and analyzed the intergenic spacer of cpDNA psbA-trnH to identify basidiomata and plant hosts, respectively. Three species of Tricholoma were identified: T. bakamatsutake, T. fulvocastaneum, and T. matsutake. Four ECM associations in the study area were detected: Tricholoma bakamatsutake + Castanopsis tibetana, T. fulvocastaneum + C. tibetana, T. fulvocastaneum + Pinus yunnanensis, and T. matsutake + P. yunnanensis. Detailed descriptions and illustrations of the ECM associations are presented.

A new edible species of Gomphus (Gomphaceae) from southwestern China.

Gomphus matijun, a new edible species, is described from southwestern China based on phylogenetic and morphological evidence. Phylogenetic analyses of the nrLSU and ITS datasets indicated that G. matijun is related to G. crassipes and G. ludovicianus with weak statistical support in maximum likelihood but strong statistical support in Bayesian analyses. Gomphus matijun is characterized by its gray-blue to blue or blue-purple pileus with a round or irregular outline, relatively smaller basidiospores [9-11(-13) × 6-7(-8) µm], mostly 2-spored basidia, and occurs in subtropical fagaceous forests. A key to the known species of Gomphus is provided.

A new p-terphenyl derivative from the fruiting bodies of Sarcodon imbricatus (L.) P. Karst.

A new p-terphenyl, 2',3'-diacetoxy-4,5,5',6',4'',5''-hexahydroxy-p-terphenyl (1), along with 12 known compounds were isolated from the fruiting bodies of Sarcodon imbricatus (Bankeraceae). Their structures were confirmed on the basis of extensive spectroscopic analysis and comparison with the spectral data in the literature. Compound 1 exhibited weak cytotoxicity against colon cancer SW480 and leukemia HL-60 cell lines, with IC50 values of 55.02 ± 1.79 µM and 44.71 ± 2.15 µM, respectively.

Tricholomines A and B, two new amides from the fruiting bodies of Tricholoma bakamatsutake.

Two new amides tricholomines A (1) and B (2), along with nine known compounds, were isolated from the dried fruiting bodies of Tricholoma bakamatsutake. Their structures were determined on the basis of extensive spectroscopic analysis or comparison with the data in the literatures. The absolute configuration of 1 was confirmed by single crystal X-ray diffraction analysis.

Mycorrhizal synthesis of Tuber pseudohimalayense with seven broad-leaved trees and Pinus armandii.

Truffle cultivation is successfully applied throughout the world for several truffles of European origin. However, just two Chinese black truffles (Tuber indicum and T. himalayense) have been cultivated with a favorable outcome so far. Tuber pseudohimalayense is a black truffle of significant economic relevance in China, but little is known about its mycorrhizal ecology and it is not cultivated in orchards yet. Here, we selected seven broad-leaved tree species (Quercus fabrei, Q. aliena, Castanea mollissima, Carya illinoinensis, Q. glauca, Castanopsis orthacantha, Betula costata), and one coniferous tree (Pinus armandii), and inoculated them with T. pseudohimalayense spore suspension using axenically germinated seedlings under greenhouse conditions. The obtained mycorrhizae, well-developed, were analyzed from the morpho-anatomical and molecular points of view, and their main characteristics described. Synthesized T. pseudohimalayense mycorrhizae showed similar characters on all tree species, with a typical interlocking pseudoparenchymatous mantle and Hartig net, swollen appearance, yellow-brownish color, and long hyaline emanating hyphae with right-angle ramifications. These features are similar to those reported for mycorrhizae formed by related black truffle species. The successful mycorrhizal synthesis of T. pseudohimalayense on multiple trees species indicates that it has potential for cultivation in China.

A new edible Rhizopogon species from Southwest China, and its mycorrhizal synthesis with two native pines.

A new Rhizopogon species associated with Pinus was discovered at local wild mushroom markets and Pinus armandii forests from March to July in Southwest China where it is considered a delicacy. Based on morphological and molecular phylogenetic analyses, the collections were described as Rhizopogon songmaodan sp. nov. belonging to the subgenus Versicolores. The new species described here increases the current number of Rhizopogon species known in China to ten. R. songmaodan establishes ectomycorrhizal associations with P. armandii which was confirmed by comparing rDNA ITS sequences from basidiomata and ectomycorrhizal root tips. Mycorrhizal synthesis via spore inoculation between R. songmaodan and two native pine species, Pinus armandii and P. yunnanensis was successfully carried out in a greenhouse study. The ease of R. songmaodan inoculation onto pine species, and the high market demand of its sporocarps, could make R. songmaodan a good candidate for cultivation in Southwest China.

The European delicacy Tuber melanosporum forms mycorrhizae with some indigenous Chinese Quercus species and promotes growth of the oak seedlings.

We aimed to test whether Tuber melanosporum and native Chinese oak species could form stable mycorrhizal symbioses. Six oak species were all either inoculated or not, with spores of the Périgord black truffle in the greenhouse. Ectomycorrhizal development was monitored for up to 32 months. Seedling growth was assessed 2 years after inoculation. From 6 months after inoculation, Tuber melanosporum ectomycorrhizae were successfully produced on five Quercus species endemic to China, as shown by morphological, anatomical, and molecular analyses. Quercus mongolica and Q. longispica showed high receptivity to mycorrhization by T. melanosporum. The symbioses obtained with these two species and with Quercus senescens were stable for at least 32 months. Averaged over all three oak species, mycorrhization by T. melanosporum significantly enhanced canopy diameter, number of leaves, and mean leaf dimension. In spring 2019, mycorrhization by T. melanosporum accelerated budbreak in Q. mongolica. Quercus fabrei and Q. variabilis formed ectomycorrhizae up to 9 months after inoculation but seedlings died 3 months later, probably because of damage by grazing insects. Quercus pseudosemecarpifolia failed to form ectomycorrhizae. Results suggest that T. melanosporum-mycorrhized Q. mongolica and Q. longispica seedlings could be tested for ascocarp production and increased performance in the field.

Ectomycorrhizae of Tuber huidongense and T. liyuanum with Castanea mollissima and Pinus armandii.

Tuber huidongense and T. liyuanum are common commercial white truffles in China that belong to the Rufum and Puberulum groups of the genus Tuber, respectively. Their mycorrhizae were successfully synthesized with two native trees--Castanea mollissima and Pinus armandii--under greenhouse conditions. The identities of the mycorrhizae were confirmed through internal transcribed spacer (ITS) sequence analyses, and their morphological characteristics were described. All of the obtained mycorrhizae have an interlocking pseudoparenchymatous mantle, which is a typical feature of truffle mycorrhizae. The mycorrhizae of T. huidongense on the two trees have hyaline branched emanating hyphae, similar to the documented mycorrhizae of the Rufum group. The unramified, spiky, and hyaline cystidia on the mycorrhizae of T. liyuanum with both C. mollissima and P. armandii further confirmed that this characteristic is constant for the mycorrhizae of the Puberulum group. The successful mycorrhizal syntheses on the two nut-producing trees will be of economic importance in the cultivation of the two truffles.

Mycorrhizal synthesis of Tuber indicum with two indigenous hosts, Castanea mollissima and Pinus armandii.

Tuber indicum is one of the most renowned commercialized fungi in China. Mycorrhizal investigations, however, have been carried out mainly with exotic trees. Up to now there is no detailed description of morphology of the mycorrhizae formed with the indigenous hosts of T. indicum. Containerized seedlings of two indigenous hosts of the fungus in southwestern China, Pinus armandii and Castanea mollissima, were inoculated with aqueous spore suspension of T. indicum in two kinds of substrates. Mycorrhizae began to form 4 months after inoculation and were harvested at 9 months. The contributing fungus of the mycorrhizae was confirmed to be T. indicum by morphological and ITS-rDNA sequence analyses. The morphology of emanating hyphae and epidermoid-like mantle appearance was similar to the mycorrhizae obtained with some European trees. The high morphological variation and the similarity to that of Tuber melanosporum makes it difficult to distinguish the mycorrhizae of the two species by morphology alone. The synthesis of mycorrhizae of T. indicum with its indigenous hosts will be of great significance for planned cultivation of the Asian black truffles.