Isolation of tef1 encoding translation elongation factor EF1α from the homobasidiomycete Schizophyllum commune

A new and threatened species of Bondarzewia from the Brazilian cloud forests

A new and threatened polypore species, Bondarzewia loguerciae, is described from the cloud forests of southern Brazil. It is characterized by single-pileate basidiomata that grow on dead branches and along living stems of standing trunks and present a context with dark lines and resinous tubes. When growing in axenic culture, this species also develops chlamydospores. We provide an illustrated morphological description and molecular analysis. Our specimens from Brazil form a monophyletic group among other species of the Southern Hemisphere. The conservation status of B. loguerciae is assessed and published as "Critically Endangered" based on the International Union for Conservation of Nature  (IUCN) criteria. Additionally, a key to the species is provided.

Morphological characteristics and phylogenetic analyses revealed four new species of Agaricales from China

Four new species of Agaricales from China viz. Hohenbuehelia tomentosa, Rhodophana qinghaiensis, Rhodophana aershanensis, and Spodocybe tomentosum are described based on their unique morphological features and molecular evidence. Hohenbuehelia tomentosa is mainly characterized by its dark brown pileus with finely dense pure white tomentum, dirty white, decurrent lamellae, eccentric stipe, smooth spores, and fusiform metuloid cystidia. The characteristics of Rhodophana qinghaiensis are glabrous, smooth, reddish-brown pileus, gray-orange lamellae, and initially light orange becoming reddish brown stipe. The unique morphological characteristics of Rhodophana aershanensis are reddish brown pileus with age, brown-orange toward the margin, light orange lamellae and stipe dark brown at first, and reddish-brown with age. Spodocybe tomentosum is characterized by subclitocyboid and small basidiomes, finely dense pure white tomentum on the pileus surface, and broadly ellipsoid to ellipsoid and smaller basidiospores. Phylogenetic analysis showed that Hohenbuehelia tomentosa, Rhodophana qinghaiensis, Rhodophana aershanensis, and Spodocybe tomentosum formed an independent lineage. Full descriptions, illustrations, and phylogenetic trees of the four new species are provided in this study.

New genera, species, and combinations of Boletaceae from Brazil and Guyana

Brasilioporus olivaceoflavidus, gen. et sp. nov., Brasilioporus simoniarum, sp. nov., Neotropicomus australis, gen. et sp. nov., and Nevesoporus nigrostipitatus, gen. et sp. nov. (Boletaceae, Boletales, Basidiomycota), are described from the endangered Atlantic Forest biome of eastern Brazil. New combinations into these new genera are proposed for the Guyanese taxa Xerocomus parvogracilis, Tylopilus rufonigricans, and Tylopilus exiguus. Boletaceae subfamily Chalciporoideae was recircumscribed to include the new genus Nevesoporus. Molecular phylogenetic analyses using a multilocus data set (ITS+28S+TEF1+RPB1+RPB2) from a large taxon set across the Boletaceae justify recognition of the new genera. Morphological, ecological, and DNA sequence data are provided for the new species. A key to known native and introduced bolete species from the Brazilian Atlantic Forest is provided.

Neotropical Studies on Hymenochaetaceae: Unveiling the Diversity and Endemicity of Phellinotus

Phellinotus, a neotropical genus of wood-decay fungi commonly found on living members of the Fabaceae family, was initially described as containing two species, P. neoaridus and P. piptadeniae. The members of this genus, along with six other well-established genera and some unresolved lineages, are the current representatives of the ‘phellinotus clade’. On the other hand, based on a two-loci phylogenetic analysis, some entities/lineages of the ‘phellinotus clade’ have been found in Fomitiporella s.l. In this work, we performed four-loci phylogenetic analyses and based on our results the genera of the ‘phellinotus clade’ are shown to be monophyletic groups. In addition to the natural groups confirmed as different genera, morphological revisions, phylogenetic relationships, and host distribution of different specimens resembling P. neoaridus and P. piptadeniae revealed three new species in the Phellinotus genus, referred to here as P. magnoporatus, P. teixeirae and P. xerophyticus. Furthermore, for P. piptadeniae a narrower species concept was adopted with redefined morphological characters and a more limited distribution range. Both P. neoaridus and P. teixeirae have a distribution range restricted to seasonally dry tropical forests in South America. Additionally, based on detailed morphological revisions Phellinus badius, Phellinus resinaceus, and Phellinus scaber are transferred to the Phellinotus genus. The geographic distribution and host range of the genus are then discussed.

First Report of Southern Blight on Polygonatum sibiricum Caused by Sclerotium delphinii in China

Polygonatum sibiricum Delar. ex Redoute is a plant species used for medicine and food. On one hand, its rhizomes have potential medicinal values such as enhancing immunity, anti-aging, anti-tumor and antibacterial as well as the effects of improving memory and reducing blood lipid and sugar. On the other hand, the rhizomes can also be used as raw materials for drinks, preserves, and health products (Su et al. 2018). The annual demand of P. sibiricum is about 3500-4000 tons in China, and the market demands and the price continue to rise in recent years (Su et al. 2018). In August 2019, there was an outbreak of southern blight in the P. sibiricum planting fields (N30°04'06″, E115°39'47″) of Luotian County in Hubei province of China. Approximately 30% of plants were affected in many fields (333.33 ha). We observed that the surface of the infected rhizome and the surrounding soils were covered with white hyphae and sclerotia. The hyphae gradually extended downward to the rhizomes, causing rhizome rot and leaf yellowing and wilting. Mycelial fragments and sclerotia from ten symptomatic rhizomes were collected in the fields and incubated directly on potato dextrose agar (PDA containing 50 µg/ml kanamycin) at 27℃. The fungal colonies were transferred to PDA after two days of cultivation. The white colonies were formed with fluffy aerial mycelia, which grew radially with an average growth rate of 20.54±0.52 mm/d (n=10). The color of the sclerotia was milky white at first, and then gradually turned to beige and yellow-brown. After two-week-incubation, the sclerotia became dark brown. Most of the sclerotia were spherical or nearly spherical, with round-bulges on the surface. The number of mature sclerotia produced per plate ranged from 8-23 (n=10), and the size ranged from 2.5×3.0 mm to 7.5×13.0 mm (5.95 ± 2.34×7.51 ± 2.88 mm; n=50). In addition, clamp connections were observed under the microscope. For molecular identification, genomic DNA was extracted from isolate HJ-1 using the CTAB method (Mahadevakumar et al. 2018). The internal transcribed spacer (ITS) regions of rDNA were amplified with the primers ITS1/ITS4 (White et al. 1990). The resulting showed ITS sequence (Accession number: MW049362) was 99.66% homology with Sclerotium delphinii according to the GenBank database. In addition, the second largest subunit of RNA polymerase II gene (RBP2) and part of the elongation factor 1-alpha (EF1-α) gene were amplified by using the primers RPB26F/RPB2-7CR (Liu et al. 1999) and EF595F/EF1160R, respectively (Wendland and Kothe 1997). RPB2 gene sequence was deposited in GenBank (Accession number: MW415935), and was 99.53% similarity identity to Athelia rolfsii isolate MSB5-1. TEF-1α sequence was deposited in GenBank (Accession number: MW415934), and was 91.35% similarity to S. delphinii strain Sd_405. Because there are very few reference sequences of RPB2 genes from S. delphinii in GenBank to compare, we choose the ITS and TEF-1α gene sequences to construct the concatenated phylogenetic tree by the neighbor-joining method (Tamura et al. 2013). The results showed that HJ-1 was clustered with S. delphinii isolates selected from NCBI database. Based on morphological and molecular characteristics, the fungus was identified as S. delphinii Welch (teleomorph Athelia rolfsii (Curzi) C.C. Tu & Kimbr). Pathogenicity tests were performed on the healthy leaves, roots, stems and plants (n=3) of P. sibiricum. Each sample was inoculated with one sclerotia produced from a fifteen-day-old colony and there was on wound treatment. These inoculated and control samples (treated with sterile water) were incubated in a moist chamber (25 ± 2 °C, RH 85%) (Mahadevakumar et al. 2018). Typical disease symptoms were apparent on leaves, stems, rhizomes and plants at 4, 6, 5 and 15 days post inoculation, respectively. Fulfilling Koch's postulates, the fungal pathogens were isolated and purified from the inoculated site and were reconfirmed as S. delphinii based on the morphological features. To the best of our knowledge, this is the first report of S. delphinii causing southern blight on P. sibiricum in China. S. delphinii has a wide host range worldwide and often causes crop yield reduction. This study will be helpful for the prevention and control of P. sibiricum southern blight in the future.

Multigene phylogeny and taxonomic revision of Atheliales s.l.: Reinstatement of three families and one new family, Lobuliciaceae fam. nov

Atheliales (Agaricomycetes, Basidiomycota) is an order mostly composed of corticioid fungi, containing roughly 100 described species in 20 genera. Members exhibit remarkable ecological diversity, including saprotrophs, ectomycorrhizal symbionts, facultative parasites of plants or lichens, and symbionts of termites. Ectomycorrhizal members are well known because they often form a major part of boreal and temperate fungal communities. However, Atheliales is generally understudied, and molecular data are scarce. Furthermore, the order is riddled with many taxonomic problems; some genera are non-monophyletic and several species have been shown to be more closely related to other orders. We investigated the phylogenetic position of genera that are currently listed in Atheliales sensu lato by employing an Agaricomycetes-wide dataset with emphasis on Atheliales including the type species of genera therein. A phylogenetic analysis based on 5.8S, LSU, rpb2, and tef1 (excluding third codon) retrieved Atheliales in subclass Agaricomycetidae, as sister to Lepidostromatales. In addition, a number of Atheliales genera were retrieved in other orders with strong support: Byssoporia in Russulales, Digitatispora in Agaricales, Hypochnella in Polyporales, Lyoathelia in Hymenochaetales, and Pteridomyces in Trechisporales. Based on this result, we assembled another dataset focusing on the clade with Atheliales sensu stricto and representatives from Lepidostromatales and Boletales as outgroups, based on ITS (ITS1-5.8S-ITS2), LSU, rpb2, and tef1. The reconstructed phylogeny of Atheliales returned five distinct lineages, which we propose here as families. Lobulicium, a monotypic genus with a distinct morphology of seven-lobed basidiospores, was placed as sister to the rest of Atheliales. A new family is proposed to accommodate this genus, Lobuliciaceae fam. nov. The remaining four lineages can be named following the family-level classification by Jülich (1982), and thus we opted to use the names Atheliaceae, Byssocorticiaceae, Pilodermataceae, and Tylosporaceae, albeit with amended circumscriptions.

First Report of Green Mold Disease Caused by Trichoderma hengshanicum on Ganoderma lingzhi

Ganoderma lingzhi is a well-known source of natural fungal medicines which has been given for the treatment of several diseases. China is one of the major commercial producers of Ganoderma mushroom worldwide. However, with the expansion of the commercial cultivation, the occurrence of the fungal diseases on G. lingzhi has also been increased. The green mold disease symptoms were observed in the cultivation base of G. lingzhi in Zuojia Town, Jilin City, Jilin Province, China, causing the basidiomes to be rotten and withered, and the green mycelium layer generated gradually. The pathogenicity tests showed the same symptoms as appeared naturally in Zuojia mushroom base. Morphology characters revealed conidia green, ellipsoid, globose, 2.56-4.83 × 2.09-4.22 μm, length-width ratio was 1.1-1.2 (n = 10). Conidiophores trichoderma-like, often asymmetry, branches solitary, paired or in whorls of 3 phialides formed solitary, paired or in whorl, variable in shape, lageniform, sometimes ampulliform or subulate. While using molecular methodology, comparing with the sequences of Trichoderma hengshanicum from GenBank, the analyzed sequence showed 97.32% homology with the RPB2 sequences, 100% with the TEF1-α sequences. A fungus isolated from the diseased tissues was identified based on morphology and molecular studies as T. hengshanicum. This is the first report of T. hengshanicum causing the green mold disease of G. lingzhi in China.

Bambusicolous Fomitiporia revisited: multilocus phylogeny reveals a clade of host-exclusive species

FOMITIPORIA

is a genus of wood-inhabiting Hymenochaetaceae (Agaricomycetes) that includes pathogens and decomposers occurring on a wide array of plant substrates. Some species decay culms of woody bamboos, a poorly known biotic interaction. Four bambusicolous species of Fomitiporia are currently known. However, no studies concerning their phylogenetic relationships have been performed. In order to assess species boundaries and their relationships to each other, we conducted molecular phylogenetic analyses of nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and portions of nuc 28S rDNA (28S), RNA polymerase II second largest subunit (RPB2), and translation elongation factor 1-α (TEF1), as well as morphological analyses. Four species that occur on culms of woody bamboos, F. bambusarum, F. spinescens, F. uncinata, and the new species F. bambusipileata, grouped together in an exclusive clade within a primarily Neotropical lineage. The new species differs from all other species in the group by the pileate basidiomata. Hypotheses regarding host-exclusivity are discussed.

Metal release and sequestration from black slate mediated by a laccase of Schizophyllum commune

Schizophyllum commune is a filamentous basidiomycete which can degrade complex organic macromolecules like lignin by the secretion of a large repertoire of enzymes. One of these white rot enzymes, laccase, exhibits a broad substrate specificity and is able to oxidize a variety of substances including carbonaceous rocks. To investigate the role of laccase in bioweathering, laccase gene lcc2 was overexpressed, and the influence on weathering of black slate, originating from a former alum mine in Schmiedefeld, Germany, was examined. The metal release from the rock material was enhanced, associated with a partial metal accumulation into the mycelium. A sequestration of metals could be shown with fluorescent staining methods, and an accumulation of Zn, Cd, and Pb was visualized in different cell organelles. Additionally, we could show an increased metal resistance of the laccase overexpressing strain.

Phylogenetic constrains on Polyporus umbellatus-Armillaria associations

It has been well established that some Armillaria species are symbionts of Polyporus umbellatus, However, little is known about the evolutionary history of P. umbellatus-Armillaria associations. In this research, we used an analysis based on the strength of the phylogenetic signal to investigate P. umbellatus-Armillaria associations in 57 sclerotial samples across 11 provinces of China. We isolated Armillaria strains from the invasion cavity inside the sclerotia of P. umbellatus and then phylogenetically analyzed these Armillaria isolates. We also tested the effect of P. umbellatus and Armillaria phylogenies on the P. umbellatus-Armillaria associations. We isolated forty-seven Armillaria strains from 26 P. umbellatus sclerotial samples. All Armillaria isolates were classified into the 5 phylogenetic lineages found in China except for one singleton. Among the 5 phylogenetic lineages, one lineage (lineage 8) was recognized by delimitation of an uncertain phylogenetic lineage in previous study. Results of simple Mantel test implied that phylogenetically related P. umbellatus populations tend to interact with phylogenetically related Armillaria species. Phylogenetic network analyses revealed that the interaction between P. umbellatus and Armillaria is significantly influenced by the phylogenetic relationships between the Armillaria species.

Phylogenetic Analyses of Armillaria Reveal at Least 15 Phylogenetic Lineages in China, Seven of Which Are Associated with Cultivated Gastrodia elata

Fungal species of Armillaria, which can act as plant pathogens and/or symbionts of the Chinese traditional medicinal herb Gastrodia elata ("Tianma"), are ecologically and economically important and have consequently attracted the attention of mycologists. However, their taxonomy has been highly dependent on morphological characterization and mating tests. In this study, we phylogenetically analyzed Chinese Armillaria samples using the sequences of the internal transcribed spacer region, translation elongation factor-1 alpha gene and beta-tubulin gene. Our data revealed at least 15 phylogenetic lineages of Armillaria from China, of which seven were newly discovered and two were recorded from China for the first time. Fourteen Chinese biological species of Armillaria, which were previously defined based on mating tests, could be assigned to the 15 phylogenetic lineages identified herein. Seven of the 15 phylogenetic lineages were found to be disjunctively distributed in different continents of the Northern Hemisphere, while eight were revealed to be endemic to certain continents. In addition, we found that seven phylogenetic lineages of Armillaria were used for the cultivation of Tianma, only two of which had been recorded to be associated with Tianma previously. We also illustrated that G. elata f. glauca ("Brown Tianma") and G. elata f. elata ("Red Tianma"), two cultivars of Tianma grown in different regions of China, form symbiotic relationships with different phylogenetic lineages of Armillaria. These findings should aid the development of Tianma cultivation in China.

Phylogenetic relationship of two popular edible Pleurotus in China, Bailinggu (P. eryngii var. tuoliensis) and Xingbaogu (P. eryngii), determined by ITS, RPB2 and EF1α sequences

The aims of this study are to assess the utility of the internal transcribed spacer (ITS) region, and partial translation elongation factor (EF1α) and RNA polymerase II (RPB2) genes, for differentiation of Bailinggu, P. eryngii, and P. nebrodensis; to reconstruct phylogenetic relationships between the three species; and to confirm the taxonomic status of Bailinggu based on ribosomal and protein-coding genes. Pairwise genetic distances between Bailinggu, P. eryngii, and related Pleurotus strains were calculated by using the p-distance model, and molecular phylogeny of these isolates was estimated based on ITS, RPB2, and EF1α using maximum parsimony and Bayesian methods. Differences in ITS, RPB2, and EF1α sequences show that Bailinggu, P. eryngii, and P. nebrodensis are distinct at the species level. Phylogenetic analyses reveal that P. eryngii is closer to P. nebrodensis than to Bailinggu. Sequence analyses of ribosomal and protein-coding genes confirm that P. eryngii var. tuoliensis is identical to Bailinggu. P. eryngii var. tuoliensis should be raised to species level or a new name should be introduced for Bailinggu after a thorough investigation into Pleurotus isolates from Ferula in Xinjiang Province. This study helps to resolve uncertainty regarding Bailinggu, P. eryngii and P. nebrodensis, improving the resource management of these strains. ITS, EF1α, and RPB2 sequences can be used to distinguish Bailinggu, P. eryngii and P. nebrodensis as three different species, and P. eryngii var. tuoliensis should be the scientific name for Bailinggu at present.

Biosynthesis and Secretion of Indole-3-Acetic Acid and Its Morphological Effects on Tricholoma vaccinum-Spruce Ectomycorrhiza

Fungus-derived indole-3-acetic acid (IAA), which is involved in development of ectomycorrhiza, affects both partners, i.e., the tree and the fungus. The biosynthesis pathway, excretion from fungal hyphae, the induction of branching in fungal cultures, and enhanced Hartig net formation in mycorrhiza were shown. Gene expression studies, incorporation of labeled compounds into IAA, heterologous expression of a transporter, and bioinformatics were applied to study the effect of IAA on fungal morphogenesis and on ectomycorrhiza. Tricholoma vaccinum produces IAA from tryptophan via indole-3-pyruvate, with the last step of this biosynthetic pathway being catalyzed by an aldehyde dehydrogenase. The gene ald1 was found to be highly expressed in ectomycorrhiza and induced by indole-3-acetaldehyde. The export of IAA from fungal cells is supported by the multidrug and toxic extrusion (MATE) transporter Mte1 found in T. vaccinum. The addition of IAA and its precursors induced elongated cells and hyphal ramification of mycorrhizal fungi; in contrast, in saprobic fungi such as Schizophyllum commune, IAA did not induce morphogenetic changes. Mycorrhiza responded by increasing its Hartig net formation. The IAA of fungal origin acts as a diffusible signal, influencing root colonization and increasing Hartig net formation in ectomycorrhiza.

Sequence variation in two protein-coding genes correlates with mycelial compatibility groupings in Sclerotium rolfsii

Populations of Sclerotium rolfsii, the causal organism of Sclerotium root-rot on a wide range of hosts, can be placed into mycelial compatibility groups (MCGs). In this study, we evaluated three different molecular approaches to unequivocally identify each of 12 previously identified MCGs. These included restriction fragment length polymorphism (RFLP) patterns of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (rDNA) and sequence analysis of two protein-coding genes: translation elongation factor 1α (EF1α) and RNA polymerase II subunit two (RPB2). A collection of 238 single-sclerotial isolates representing 12 MCGs of S. rolfsii were obtained from diseased sugar beet plants from Chile, Italy, Portugal, and Spain. ITS-RFLP analysis using four restriction enzymes (AluI, HpaII, RsaI, and MboI) displayed a low degree of variability among MCGs. Only three different restriction profiles were identified among S. rolfsii isolates, with no correlation to MCG or to geographic origin. Based on nucleotide polymorphisms, the RPB2 gene was more variable among MCGs compared with the EF1α gene. Thus, 10 of 12 MCGs could be characterized utilizing the RPB2 region only, while the EF1α region resolved 7 MCGs. However, the analysis of combined partial sequences of EF1α and RPB2 genes allowed discrimination among each of the 12 MCGs. All isolates belonging to the same MCG showed identical nucleotide sequences that differed by at least in one nucleotide from a different MCG. The consistency of our results to identify the MCG of a given S. rolfsii isolate using the combined sequences of EF1α and RPB2 genes was confirmed using blind trials. Our study demonstrates that sequence variation in the protein-coding genes EF1α and RPB2 may be exploited as a diagnostic tool for MCG typing in S. rolfsii as well as to identify previously undescribed MCGs.

Impact of endochitinase-transformed white spruce on soil fungal biomass and ectendomycorrhizal symbiosis

The impact of transgenic white spruce [Picea glauca (Moench) Voss] containing the endochitinase gene (ech42) on soil fungal biomass and on the ectendomycorrhizal fungi Wilcoxina spp. was tested using a greenhouse trial. The measured level of endochitinase in roots of transgenic white spruce was up to 10 times higher than that in roots of nontransformed white spruce. The level of endochitinase in root exudates of three of four ech42-transformed lines was significantly greater than that in controls. Analysis soil ergosterol showed that the amount of fungal biomass in soil samples from control white spruce was slightly larger than that in soil samples from ech42-transformed white spruce. Nevertheless, the difference was not statistically significant. The rates of mycorrhizal colonization of transformed lines and controls were similar. Sequencing the internal transcribed spacer rRNA region revealed that the root tips were colonized by the ectendomycorrhizal fungi Wilcoxina spp. and the dark septate endophyte Phialocephala fortinii. Colonization of root tips by Wilcoxina spp. was monitored by real-time PCR to quantify the fungus present during the development of ectendomycorrhizal symbiosis in ech42-transformed and control lines. The numbers of Wilcoxina molecules in the transformed lines and the controls were not significantly different (P > 0.05, as determined by analysis of covariance), indicating that in spite of higher levels of endochitinase expression, mycorrhization was not inhibited. Our results indicate that the higher levels of chitinolytic activity in root exudates and root tissues from ech42-transformed lines did not alter the soil fungal biomass or the development of ectendomycorrhizal symbiosis involving Wilcoxina spp.

Pleurotus eryngii species complex: sequence analysis and phylogeny based on partial EF1α and RPB2 genes

The Pleurotus eryngii species complex comprises at least six varieties (var. eryngii (DC.: Fr) Quel., ferulae Lanzi, elaeoselini Venturella et al., nebrodensis (Inzenga) Sacc., tingitanus Lewinsohn et al. and tuoliensis C.J. Mou). This species is unique among the genus Pleurotus because in nature it is found in association with certain species of the Apiaceae (Umbelliferae) and Asteraceae (Compositae) families. Sequences of partial regions of the translation elongation factor (EF1α) and RNA polymerase II (RPB2) genes were analyzed in order to detect nucleotide polymorphisms that might unequivocally distinguish varieties eryngii, ferulae, elaeoselini and nebrodensis. A phylogenetic analysis was also performed with an aim to establish phylogenetic relationships among those. Sequence analysis of the partial EF1α and RPB2 genes contained nucleotide polymorphisms able to unequivocally distinguish variety nebrodensis from the rest. However, distinction among eryngii, elaeoselini and ferulae was achieved only through the RPB2 gene. The phylogenetic analyses from the combined data sets (EF1α and RPB2) indicated that P. eryngii is a monophyletic group and that varieties eryngii, elaeoselini and ferulae are closely related. P. eryngii var. nebrodensis was placed in a distinct clade clearly differentiated from the other varieties but still monophyletic with the P. eryngii complex. The limited nucleotide variation in partial EF1α and RPB2 among varieties eryngii, ferulae and elaeoselini supports the placement of these groups as varieties and not species within the complex.

Resolving the phylogenetic position of the Wallemiomycetes: an enigmatic major lineage of Basidiomycota

The Wallemiomycetes includes three species of molds from the genus Wallemia . These fungi are adapted to environments of high osmotic stress, contaminate various foods, cause respiratory disease, and have an unusual mode of asexual reproduction. Wallemia was recently proposed as a new class based on 18S ribosomal RNA gene sequences to accommodate the isolated position of the clade in the Basidiomycota. We analyzed the phylogenetic position of the Wallemiomycetes using 3451 nucleotide characters of the 18S, 25S, and 5.8S ribosomal RNA genes and 1282 amino acid positions of rpb1, rpb2, and tef1 nuclear protein-coding genes across 91 taxa. Different gene regions and methods of phylogenetic inference produce mildly conflicting placements of the Wallemiomycetes. Parsimony analyses of nrDNA data suggest that the Wallemiomycetes is an early diverging lineage of Basidiomycota, occupying a basal position near the Entorrhizomycetidae. Ultrastructural data, some Bayesian analyses, and amino acid sequences suggest the Wallemiomycetes may be the sister group of the Agaricomycotina or Ustilaginomycotina. The combined gene tree supports the Wallemiomycetes as a lineage basal to a core clade of Pucciniomycotina, Ustilaginomycotina, and Agaricomycotina with robust measures of branch support. This study reinforces the isolated position of Wallemia in the Basidiomycota using molecular data from six nuclear genes. In total, five major lineages of Basidiomycota are recognized: the Agaricomycotina, Ustilaginomycotina, Pucciniomycotina, Entorrhizomycetidae, and the Wallemiomycetes.

Ras GTPase-activating protein gap1 of the homobasidiomycete Schizophyllum commune regulates hyphal growth orientation and sexual development

The white rot fungus Schizophyllum commune is used for the analysis of mating and sexual development in homobasidiomycete fungi. In this study, we isolated the gene gap1 encoding a GTPase-activating protein for Ras. Disruption of gap1 should therefore lead to strains accumulating Ras in its activated, GTP-bound state and to constitutive Ras signaling. Haploid Deltagap1 monokaryons of different mating types did not show alterations in mating behavior in the four different mating interactions possible in fungi expressing a tetrapolar mating type system. Instead, the growth rate in Deltagap1 monokaryons was reduced by ca. 25% and ca. 50% in homozygous Deltagap1/Deltagap1 dikaryons. Monokaryons, as well as homozygous dikaryons, carrying the disrupted gap1 alleles exhibited a disorientated growth pattern. Dikaryons showed a strong phenotype during clamp formation since hook cells failed to fuse with the peg beside them. Instead, the dikaryotic character of the hyphae was rescued by fusion of the hooks with nearby developing branches. Deltagap1/Deltagap1 dikaryons formed increased numbers of fruitbody primordia, whereas the amount of fruitbodies was not raised. Mature fruitbodies formed no or abnormal gills. No production of spores could be observed. The results suggest Ras involvement in growth, clamp formation, and fruitbody development.

Phylogenetic analysis of EF-1 alpha gene sequences from isolates of Microdochium nivale leads to elevation of varieties majus and nivale to species status

Degenerate PCR primers were designed based on EF-1 alpha (EF-1alpha) gene sequences of several filamentous fungi retrieved from sequence databases. These primers were used to isolate a partial sequence, approximately 830 bp in length of the EF-1alpha from isolates of Microdochium nivale obtained from various geographic locations across the world. Two distinct groups of isolates were evident among those isolates examined. Sequence homology for comparisons within group was 99.7% for group A and 99.8% for group B. Primers specific to either group A or group B sequences were designed and tested on isolates from around the world. Comparisons were made with primers previously reported for the two varieties of M. nivale and revealed that Group A type isolates correlated with M. nivale var. majus and group B isolates with M. nivale var. nivale. The primers from this study and those previously reported were in agreement for all isolates with the exception of one isolate (NRRL 3289) which failed to amplify with previously published M. nivale primers. Sequence analysis of NRRL 3289 suggested that it was an isolate of M. nivale var. nivale as indicated by the EF-1alpha based primers developed in this study. This study provides sequence based phylogenetic evidence of two species and when taken together with biological differences reported, leads to the recognition of M. majus comb. nov. (syn. Fusarium nivale var. majus). Descriptions of the two species are provided.