Hypochnicium sensu lato (Polyporales, Basidiomycota) from Japan, with descriptions of a new genus and three new species.

Species of Hypochnicium (Polyporales, Basidiomycota) collected from Japan were studied on their taxonomy by morphological and phylogenetic approaches. Phylogenetic analyses based on a nrDNA LSU and ITS dataset including the Japanese specimens and other publicly available ones show that Hypochnicium is polyphyletic. Since the clade containing the type species H. bombycinum was well-supported, we defined this clade as Hypochnicium s. str., and emended Hypochnicium to include restricted taxa with only smooth basidiospores. The new genus Neohypochnicium is proposed to accommodate the remaining taxa excluded from the genus Hypochnicium s. str., which includes both species with smooth basidiospores and ornamented ones. Three new species, Gyrophanopsis japonica, N. asiaticum and N. perlongicystidiosum are described and illustrated based on morphological and phylogenetic analyses using an ITS region dataset. In addition, the following 15 new combinations are proposed: N. albostramineum, N. aotearoae, N. capitulateum, N. cremicolor, N. cystidiatum, N. geogenium, N. guineense, N. huinayense, N. michelii, N. microsporum, N. patagonicum, N. pini, N. punctulatum, N. subrigescens and N. wakefieldiae. An identification key to Japanese species of Bulbillomyces, Gyrophanopsis, Hypochnicium and Neohypochnicium is provided.

A global phylogenomic analysis of the shiitake genus Lentinula.

Lentinula is a broadly distributed group of fungi that contains the cultivated shiitake mushroom, L. edodes. We sequenced 24 genomes representing eight described species and several unnamed lineages of Lentinula from 15 countries on four continents. Lentinula comprises four major clades that arose in the Oligocene, three in the Americas and one in Asia-Australasia. To expand sampling of shiitake mushrooms, we assembled 60 genomes of L. edodes from China that were previously published as raw Illumina reads and added them to our dataset. Lentinula edodes sensu lato (s. lat.) contains three lineages that may warrant recognition as species, one including a single isolate from Nepal that is the sister group to the rest of L. edodes s. lat., a second with 20 cultivars and 12 wild isolates from China, Japan, Korea, and the Russian Far East, and a third with 28 wild isolates from China, Thailand, and Vietnam. Two additional lineages in China have arisen by hybridization among the second and third groups. Genes encoding cysteine sulfoxide lyase (lecsl) and γ-glutamyl transpeptidase (leggt), which are implicated in biosynthesis of the organosulfur flavor compound lenthionine, have diversified in Lentinula. Paralogs of both genes that are unique to Lentinula (lecsl 3 and leggt 5b) are coordinately up-regulated in fruiting bodies of L. edodes. The pangenome of L. edodes s. lat. contains 20,308 groups of orthologous genes, but only 6,438 orthogroups (32%) are shared among all strains, whereas 3,444 orthogroups (17%) are found only in wild populations, which should be targeted for conservation.

Two new species of Sistotrema s.l. (Cantharellales) from Japan with descriptions of their ectomycorrhizae.

We describe two new species of resupinate Sistotrema sensu lato (Cantharellales) collected in Japan: S. flavorhizomorphae and S. chloroporum. Both species have urniform basidia with more than four sterigmata and monomitic hyphal system, oil-rich hyphae in subiculum, which is typical for this genus. Sistotrema chloroporum is characterized by poroid hymenophore partly yellowish-green, basidia 4-6-spored, medium-sized basidiospores (4.5-6.5 × 3.5-6 µm), and broadleaf forest habitat. Sistotrema flavorhizomorphae is characterized by hydnoid-irpicoid hymenophore, bright yellowish rhizomorphs, basidia 6-8-spored, small basidiospores (3-3.5 × 2.5-3 µm), and pine forest habitat. Phylogenetic trees inferred from the fungal nrDNA ITS and LSU and the rpb2 sequences supported that both species were distinct and grouped with other ectomycorrhizal Sistotrema and Hydnum species, but their generic boundary was unclear. Mycorrhizae underneath basidiomes of both species were identified and described via molecular techniques. Mycorrhizae of S. chloroporum have similar characteristics to those of other Sistotrema s.l. and Hydnum species, i.e., S. confluens and H. repandum, whereas S. flavorhizomorphae has a distinct morpho-anatomy, for example, a distinct pseudoparenchymatous mantle. Comprehensive characterizations of basidiomes and mycorrhizae improve the taxonomic analysis of mycorrhizal species of Sistotrema s.l.

Suppression of Alternaria brassicicola infection by volatile compounds from spent mushroom substrates.

Most commercially circulating mushrooms are produced via cultivation using artificially produced mushroom substrates. However, after mushroom harvesting, the disposal of spent mushroom substrates (SMSs) is a serious problem for the mushroom industry owing to the need for a disposal site and the cost involved. Thus, in view of the possibility of recycling SMSs as a soil modifier, we examined the effect of soil mixed with SMSs on the infection of Arabidopsis leaves by Alternaria brassicicola, the causal agent of cabbage leaf spot. The mixing of SMSs used for Hypsizygus marmoreus, Pholiota microspora, Lyophyllum decastes, and Auricularia polytricha into culture soil suppressed the lesion formation caused by A. brassicicola. The defense responses of Arabidopsis were not induced by the culturing of these seedlings in soils containing SMSs. Suppressed lesion formation was observed after the seedlings were treated with volatiles emitted from SMSs that were incubated with soil for 7 days and used for H. marmoreus, P. microspora, L. decastes, A. polytricha, Lentinula edodes, and Cyclocybe cylindracea. The volatiles from the SMSs reduced the elongation of A. brassicicola hyphae. GC-MS analyses of extracts from the SMS containing soils led to the detection of various volatile compounds; among these, skatole, 2,4-di-tert-butylphenol, γ-dodecalactone, butyric acid, guaiacol, 6-amyl-2-pyrone, and 1-octen-3-ol were examined for inhibitory activity on A. brassicicola and found to suppress hyphae elongation. These findings indicate that the antifungal volatile compounds emitted by the SMSs suppress A. brassicicola infection.

Taxonomic revision of the Japanese Tricholoma ustale and closely related species based on molecular phylogenetic and morphological data.

"Kakishimeji" identified as Tricholoma ustale and belonging to Tricholoma sect. Genuina is a common poisonous mushroom in Japan. Kakishimeji contains the toxic compound ustalic acid and causes digestive trouble. However, this fungus is consumed in some regions of Japan without any digestive issues. We clarified the probable species complex of Kakishimeji based on a phylogenetic analysis. We collected 89 basidioma specimens of Kakishimeji and related species from various forest sites in Japan and conducted phylogenetic analyses using 7 nuclear and mitochondrial gene sequences. Kakishimeji was found to consist of four distinct phylogenetic clades based on all DNA regions tested. Of these, two clades included European T. stans and T. albobrunneum type specimens. Another two clades consisted of sister clades to T. pessundatum and T. ustaloides. In addition, all four phylogenetic clades of Kakishimeji had different spore and basidium sizes. Therefore, we regarded the latter two clades as two new Tricholoma species: T. kakishimeji and T. kakishimejioides.

Tricholoma olivaceonigrum, a new species of the section Tricholoma (Agaricales) from Japan.

A novel species of Tricholoma section Tricholoma, namely, T. olivaceonigrum, is described and illustrated based on samples found in an oak woods dominated by Quercus myrsinifolia, an evergreen oak, in Tottori Prefecture, western Japan. It is characterized by a conic-umbonate, dark-greenish olivaceous pileus with blackish innate fibrils; a whitish silky-fibrillose stipe, often faintly tinted pale yellow and with a narrowed subpointed base; subglobose to broadly elliptic spores; and fruiting in early winter. Phylogenetic analysis targeting the internal transcribed spacer region of the ribosomal RNA gene revealed that T. olivaceonigrum forms a well-supported clade sister to T. portentosum. Other morphologically and phylogenetically closely related species of the section Tricholoma are discussed.

Identification of antifungal compounds in the spent mushroom substrate of Lentinula edodes.

In view of the possibility that spent mushroom substrates (SMSs) may be used as agricultural materials to prevent crop diseases, we examined the effect of treatment with a hot water extract from the SMS of Lentinula edodes on plant resistance to pathogenic infection. The extract of Le. edodes SMS was sprayed onto the leaves of rice plants, followed by inoculation of the leaves with the conidia of rice blast fungus. The development of lesions was suppressed by treatment with the SMS extract. The extract markedly inhibited the germination of Pyricularia oryzae conidia. We purified compounds 1, 2, and 3, which showed inhibitory effects on conidial germination, from the Le. edodes SMS extract of by successive solvent extraction, column chromatography, and preparative HPLC. Spectroscopic analyses revealed that 1, 2, and 3 were phenolic acids with two carboxyl groups in common.

Discovery or Extinction of New Scleroderma Species in Amazonia?

The Amazon Forest is a hotspot of biodiversity harboring an unknown number of undescribed taxa. Inventory studies are urgent, mainly in the areas most endangered by human activities such as extensive dam construction, where species could be in risk of extinction before being described and named. In 2015, intensive studies performed in a few locations in the Brazilian Amazon rainforest revealed three new species of the genus Scleroderma: S. anomalosporum, S. camassuense and S. duckei. The two first species were located in one of the many areas flooded by construction of hydroelectric dams throughout the Amazon; and the third in the Reserva Florestal Adolpho Ducke, a protected reverse by the INPA. The species were identified through morphology and molecular analyses of barcoding sequences (Internal Transcribed Spacer nrDNA). Scleroderma anomalosporum is characterized mainly by the smooth spores under LM in mature basidiomata (under SEM with small, unevenly distributed granules, a characteristic not observed in other species of the genus), the large size of the basidiomata, up to 120 mm diameter, and the stelliform dehiscence; S. camassuense mainly by the irregular to stellate dehiscence, the subreticulated spores and the bright sulfur-yellow colour, and Scleroderma duckei mainly by the verrucose exoperidium, stelliform dehiscence, and verrucose spores. Description, illustration and affinities with other species of the genus are provided.