The genome of the xerotolerant mold Wallemia sebi reveals adaptations to osmotic stress and suggests cryptic sexual reproduction

Wallemia (Wallemiales, Wallemiomycetes) is a genus of xerophilic Fungi of uncertain phylogenetic position within Basidiomycota. Most commonly found as food contaminants, species of Wallemia have also been isolated from hypersaline environments. The ability to tolerate environments with reduced water activity is rare in Basidiomycota. We sequenced the genome of W. sebi in order to understand its adaptations for surviving in osmotically challenging environments, and we performed phylogenomic and ultrastructural analyses to address its systematic placement and reproductive biology. W. sebi has a compact genome (9.8 Mb), with few repeats and the largest fraction of genes with functional domains compared with other Basidiomycota. We applied several approaches to searching for osmotic stress-related proteins. In silico analyses identified 93 putative osmotic stress proteins; homology searches showed the HOG (High Osmolarity Glycerol) pathway to be mostly conserved. Despite the seemingly reduced genome, several gene family expansions and a high number of transporters (549) were found that also provide clues to the ability of W. sebi to colonize harsh environments. Phylogenetic analyses of a 71-protein dataset support the position of Wallemia as the earliest diverging lineage of Agaricomycotina, which is confirmed by septal pore ultrastructure that shows the septal pore apparatus as a variant of the Tremella-type. Mating type gene homologs were identified although we found no evidence of meiosis during conidiogenesis, suggesting there may be aspects of the life cycle of W. sebi that remain cryptic.Keywords: Ion homeostasis, Aqua(glycero)porins, Solute accumulation, Electron microscopy, Xerophile, Halophil

Discovering New Fungal Species to Kick-Start a Passion for Science

Our recent project supported through Unlocking Curious Minds funding from New Zealand's Ministry of Business Innovation and Employment enabled us to introduce school students to the fascinating, yet frequently forgotten, fungal kingdom. In this project, we demystified the science of species discovery. We collaborated with students at three schools and initially introduced the fungal kingdom to students that ranged in age from 8–17. We then set out to find, discriminate, and describe a species new to science with each school. We communicated with the students through social media and traditional means at each step of the discovery process, which culminated with the students visiting us at Manaaki Whenua-Landcare Research in Auckland. The students were given a tour of our two nationally significant collections, the New Zealand Fungarium and the International Collection of Microorganisms from Plants. During this visit we revealed the genus of the fungus that the students had discovered and the students chose the species epithets for each new fungal species. These new species were published in scientific papers in which the names of the students, and their main teachers, from each school were included. Our project enabled us not only to educate students about Fungi, which are often overlooked in school curricula, but also to introduce students to the importance of species discovery, taxonomy, and the role of collections

Fungi species description rates confirm high global diversity and suggest half remain unnamed

Global estimates of the number of species of Fungi have ranged from 1.5 to 13.2 million, but have been based more on opinion and simple ratios than quantitative assessment. We analysed trends in the rate of description of fungal species over four centuries, noted the use of molecular methods in species delimitation, and used a statistical model designed for such data to predict future trends. A total of 144,035 fungal species were analysed, along with smaller species groups extracted from the core dataset that approximated biological and ecological traits. The groups explored included fungi of medical significance (728 spp), those associated with the marine environment (972 spp), rust and smut fungi (9,125 spp), arthropod ectoparasites of class Laboulbeniomycetes (2,376 spp), mushroom-forming fungi of class Agaricomycetes (37,717 spp), the budding yeasts of subphylum Saccharomycotina (1,165 spp), the class Dothideomycetes (30,912 spp), and lichenized fungi of classes Lecanoromycetes and Arthoniomycetes (12,154 spp). There was an acceleration in overall fungal description rates within the last two decades accompanied by the increased use of genetic data in new species descriptions. Mushroom-forming, lichenized, and plant-associated fungi were predicted to experience the greatest increase in new species. Increased description rates are supported by an increase in the number of authors describing species. However, the number of species described per author in a year has been declining since 1875. Because less than 10% of currently accepted fungal species have molecular data associated with corresponding type specimens, genetic data should not be used to discriminate new species without associated phenotypic information. An additional 68,750 species (48%) were predicted to be described this century, making Fungi the least well-described Kingdom assessed to date

Addressing the diversity of Xylodon raduloides complex through integrative taxonomy

In this study, the taxonomic diversity of the Xylodon raduloides species complex (Hymenochaetales, Basidiomycota) is examined. Specimens were studied using an integrative taxonomic approach that includes molecular phylogenetic and morphological analyses, and environmental niche comparisons. Four different species were found inside the Xylodon raduloides complex, with a biogeographic distribution pattern bound by geographic regions: Europe, North America, Patagonia, and Australia–New Zealand. Molecular, morphological, and environmental evidences delimit two lineages within this complex: a Northern Hemisphere clade with longer basidiospores and wider ranges in temperature and precipitation tolerance, and a Southern Hemisphere clade with smaller and more spherical basidiospores, and an isothermal and more humid climate preference. The integrative taxonomic approach used in this study demonstrates congruence between data sets and shows how morphological and environmental characteristics contribute to the differentiation of fungal species complexes. By combining various sources of taxonomic information, three new species are described: Xylodon laurentianus, X. novozelandicus, and X. patagonicus.This work was supported by the Plan Nacional I + D + i projects n° CGL2012– 35559, CGL2015–67459-P and by the CSIC/Fundación Endesa/Fundación San Ignacio de Huinay project (2011HUIN10; 2013CL0012). JFL was supported by Fernández-López et al. IMA Fungus (2019) 10:2 Page 17 of 20 a Predoctoral Grant from the Ministerio de Economía y Competitividad (Spain) (BES-2013-066429).We acknowledge support of the publication fee by the CSIC Open Access Support Initiative through its Unit of Information Resources for Research (URICI

Competing sexual and asexual generic names in Pucciniomycotina and Ustilaginomycotina (Basidiomycota) and recommendations for use

With the change to one scientific name for pleomorphic fungi, generic names typified by sexual and asexual morphs have been evaluated to recommend which name to use when two names represent the same genus and thus compete for use. In this paper, generic names in Pucciniomycotina and Ustilaginomycotina are evaluated based on their type species to determine which names are synonyms. Twenty-one sets of sexually and asexually typified names in Pucciniomycotina and eight sets in Ustilaginomycotina were determined to be congeneric and compete for use. Recommendations are made as to which generic name to use. In most cases the principle of priority is followed. However, eight generic names in the Pucciniomycotina, and none in Ustilaginomycotina, are recommended for protection: Classicula over Naiadella, Gymnosporangium over Roestelia, Helicobasidium over Thanatophytum and Tuberculina, Melampsorella over Peridermium, Milesina over Milesia, Phragmidium over Aregma, Sporobolomyces over Blastoderma and Rhodomyces, and Uromyces over Uredo. In addition, eight new combinations are made: Blastospora juruensis, B. subneurophyla, Cronartium bethelii, C. kurilense, C. sahoanum, C. yamabense, Milesina polypodii, and Prospodium crusculum combs. nov.ISSN:2210-6340ISSN:2210-635

Competing sexual and asexual generic names in Pucciniomycotina and Ustilaginomycotina (Basidiomycota) and recommendations for use

With the change to one scientific name for pleomorphic fungi, generic names typified by sexual and asexual morphs have been evaluated to recommend which name to use when two names represent the same genus and thus compete for use. In this paper, generic names in Pucciniomycotina and Ustilaginomycotina are evaluated based on their type species to determine which names are synonyms. Twenty-one sets of sexually and asexually typified names in Pucciniomycotina and eight sets in Ustilaginomycotina were determined to be congeneric and compete for use. Recommendations are made as to which generic name to use. In most cases the principle of priority is followed. However, eight generic names in the Pucciniomycotina, and none in Ustilaginomycotina, are recommended for protection: Classicula over Naiadella, Gymnosporangium over Roestelia, Helicobasidium over Thanatophytum and Tuberculina, Melampsorella over Peridermium, Milesina over Milesia, Phragmidium over Aregma, Sporobolomyces over Blastoderma and Rhodomyces, and Uromyces over Uredo. In addition, eight new combinations are made: Blastospora juruensis, B. subneurophyla, Cronartium bethelii, C. kurilense, C. sahoanum, C. yamabense, Milesina polypodii, and Prospodium crusculum combs. nov

The genome of the xerotolerant mold Wallemia sebi reveals adaptations to osmotic stress and suggests cryptic sexual reproduction

Wallemia (Wallemiales, Wallemiomycetes) is a genus of xerophilic Fungi of uncertain phylogenetic position within Basidiomycota. Most commonly found as food contaminants, species of Wallemia have also been isolated from hypersaline environments. The ability to tolerate environments with reduced water activity is rare in Basidiomycota. We sequenced the genome of W. sebi in order to understand its adaptations for surviving in osmotically challenging environments, and we performed phylogenomic and ultrastructural analyses to address its systematic placement and reproductive biology. W. sebi has a compact genome (9.8Mb), with few repeats and the largest fraction of genes with functional domains compared with other Basidiomycota. We applied several approaches to searching for osmotic stress-related proteins. In silico analyses identified 93 putative osmotic stress proteins; homology searches showed the HOG (High Osmolarity Glycerol) pathway to be mostly conserved. Despite the seemingly reduced genome, several gene family expansions and a high number of transporters (549) were found that also provide clues to the ability of W. sebi to colonize harsh environments. Phylogenetic analyses of a 71-protein dataset support the position of Wallemia as the earliest diverging lineage of Agaricomycotina, which is confirmed by septal pore ultrastructure that shows the septal pore apparatus as a variant of the Tremella-type. Mating type gene homologs were identified although we found no evidence of meiosis during conidiogenesis, suggesting there may be aspects of the life cycle of W. sebi that remain cryptic