Sex does not sell: the argument for using the terms “anamorph” and “teleomorph” for fungi

Grazing practices affect soil microbial networks but not diversity and composition in alpine meadows of northeastern Qinghai-Tibetan plateau

Livestock grazing is the primary practice in alpine meadows and can alter soil microbiomes, which is critical for ecosystem functions and services. Seasonal grazing (SG) and continuous grazing (CG) are two kinds of different grazing practices that dominate alpine meadows on the Qinghai-Tibetan Plateau (QTP), and how they affect soil microbial communities remains in-depth exploration. The present study was conducted to investigate the effects of different grazing practices (i.e., SG and CG) on the diversity, composition, and co-occurrence networks of soil bacteria and fungi in QTP alpine meadows. Soil microbial α- and β-diversity showed no obvious difference between SG and CG grasslands. Grazing practices had little impact on soil microbial composition, except that the relative abundance of Proteobacteria and Ascomycota showed significant difference between SG and CG grasslands. Soil microbial networks were more complex and less stable in SG grasslands than that in CG grasslands, and the bacterial networks were more complex than fungal networks. Soil fungal diversity was more strongly correlated with environmental factors than bacteria, whereas both fungal and bacterial structures were mainly influenced by soil pH, total nitrogen, and ammonium nitrogen. These findings indicate that microbial associations are more sensitive to grazing practices than microbial diversity and composition, and that SG may be a better grazing practice for ecological benefits in alpine meadows.

Ultrastructure and Physiological Characterization of Morchella Mitospores and Their Relevance in the Understanding of the Morel Life Cycle

Morels, which belong to the Ascomycete genus Morchella, are highly valued edible fungi treasured by gourmet chefs worldwide. Some species are saprotrophic and others are able to form facultative mycorrhizal-like associations with plant roots without establishing true ectomycorrhizal symbioses. In general, it is considered that the formation of asexual spores, or mitospores, is an important step in the life cycle of morels. However, ultrastructure characterization and physiological attributes of morel mitospores have received little attention. In this contribution, the mitospores of M. sextelata were successfully induced under laboratory conditions and their ultrastructure, occurrence, germination, physiological characteristics and mating type gene structure were studied. Mitospore production was closely related to aeration, nutrition and humidity conditions. The average germination rate of mitospores on different media and under various induction stimuli was very low, with an average of 1/100,000. Based on the ultrastructure characterization, low germination rate, growth rate decline, rapid aging and mating genotyping, it was concluded that the mitospores of M. sextelata had lost their conventional function as conidia and might act more as mate sperm-like (gamete) structures. Thus, this study contributed to a deeper understanding of the life cycle of the economically and ecologically important morel fungal group.

Species Diversity in the Fusarium solani (Neocosmospora) Complex and Their Pathogenicity for Plants and Humans

The Fusarium solani species complex is a large group of soil saprotrophs with a broad adaptive potential, which allows the fungi to exist under various conditions and to parasitize on different hosts. The review analyzes the modern data concerning the genetic peculiarities of species from this complex by the example of F. solani f. sp. pisi and generalizes the data on the most widespread species pathogenic for both plants and humans. The enhanced resistance of the F. solani species complex to the most of modern antifungal agents and the need for novel therapeutic agents against fusariosis has been considered.

Apothecial Ancestry, Evolution, and Re-Evolution in Thelebolales (Leotiomycetes, Fungi)

Simple Summary

Leotiomycetes is one of the most speciose classes of the phylum Ascomycota (Fungi). Its species are mainly apothecioid, paraphysate, and possess active ascospore discharge. Thelebolales are a distinctive order of the Leotiomycetes class whose members have mostly closed ascomata, evanescent asci, and thus passively dispersed ascospores. Within the order, a great diversity of peridia have evolved as adaptations to different dispersal strategies. The genus Thelebolus is an exceptional case of ascomatal evolution within the order. Its species are the most diverse in functional traits, encompassing species with closed ascomata and evanescent asci, and species with open ascomata, active ascospore discharge, and paraphyses. Open ascomata were previously suggested as the ancestral state in the genus, these ascomata depend on mammals and birds as dispersal agents. In our work, we used morphological and phylogenetic methods, as well as the reconstruction of ancestral traits for ascomatal type, asci dehiscence, the presence or absence of paraphyses, and ascospore features to explore evolution within Thelebolales. We demonstrate the apothecial ancestry in Thelebolales and propose a new hypothesis about the evolution of the open ascomata in Thelebolus involving a process of re-evolution where the active dispersal of ascospores appears independently twice within the order. A new family, Holwayaceae, is proposed within Thelebolales, comprising three genera: Holwaya, Patinella, and Ramgea.

Abstract

Closed cleistothecia-like ascomata have repeatedly evolved in non-related perithecioid and apothecioid lineages of lichenized and non-lichenized Ascomycota. The evolution of a closed, darkly pigmented ascoma that protects asci and ascospores is conceived as either an adaptation to harsh environmental conditions or a specialized dispersal strategy. Species with closed ascomata have mostly lost sterile hymenial elements (paraphyses) and the capacity to actively discharge ascospores. The class Leotiomycetes, one of the most speciose classes of Ascomycota, is mainly apothecioid, paraphysate, and possesses active ascospore discharge. Lineages with closed ascomata, and their morphological variants, have evolved independently in several families, such as Erysiphaceae, Myxotrichaceae, Rutstroemiaceae, etc. Thelebolales is a distinctive order in the Leotiomycetes class. It has two widespread families (Thelebolaceae, Pseudeurotiaceae) with mostly closed ascomata, evanescent asci, and thus passively dispersed ascospores. Within the order, closed ascomata dominate and a great diversity of peridia have evolved as adaptations to different dispersal strategies. The type genus, Thelebolus, is an exceptional case of ascomatal evolution within the order. Its species are the most diverse in functional traits, encompassing species with closed ascomata and evanescent asci, and species with open ascomata, active ascospore discharge, and paraphyses. Open ascomata were previously suggested as the ancestral state in the genus, these ascomata depend on mammals and birds as dispersal agents. In this scheme, species with closed ascomata, a lack of paraphyses, and passive ascospore discharge exhibit derived traits that evolved in adaptation to cold ecosystems. Here, we used morphological and phylogenetic methods, as well as the reconstruction of ancestral traits for ascomatal type, asci dehiscence, the presence or absence of paraphyses, and ascospore features to explore evolution within Thelebolales. We demonstrate the apothecial ancestry in Thelebolales and propose a new hypothesis about the evolution of the open ascomata in Thelebolus, involving a process of re-evolution where the active dispersal of ascospores appears independently twice within the order. We propose a new family, Holwayaceae, within Thelebolales, that retains the phenotypic features exhibited by species of Thelebolus, i.e., pigmented capitate paraphyses and active asci discharge with an opening limitation ring.

Predicting global numbers of teleomorphic ascomycetes

Sexual reproduction is the basic way to form high genetic diversity and it is beneficial in evolution and speciation of fungi. The global diversity of teleomorphic species in Ascomycota has not been estimated. This paper estimates the species number for sexual ascomycetes based on five different estimation approaches, viz. by numbers of described fungi, by fungus:substrate ratio, by ecological distribution, by meta-DNA barcoding or culture-independent studies and by previous estimates of species in Ascomycota. The assumptions were made with the currently most accepted, “2.2–3.8 million” species estimate and results of previous studies concluding that 90% of the described ascomycetes reproduce sexually. The Catalogue of Life, Species Fungorum and published research were used for data procurement. The average value of teleomorphic species in Ascomycota from all methods is 1.86 million, ranging from 1.37 to 2.56 million. However, only around 83,000 teleomorphic species have been described in Ascomycota and deposited in data repositories. The ratio between described teleomorphic ascomycetes to predicted teleomorphic ascomycetes is 1:22. Therefore, where are the undiscovered teleomorphic ascomycetes? The undescribed species are no doubt to be found in biodiversity hot spots, poorly-studied areas and species complexes. Other poorly studied niches include extremophiles, lichenicolous fungi, human pathogens, marine fungi, and fungicolous fungi. Undescribed species are present in unexamined collections in specimen repositories or incompletely described earlier species. Nomenclatural issues, such as the use of separate names for teleomorph and anamorphs, synonyms, conspecific names, illegitimate and invalid names also affect the number of described species. Interspecies introgression results in new species, while species numbers are reduced by extinctions.

Mating Systems in True Morels (Morchella)

True morels (Morchella spp., Morchellaceae, Ascomycota) are widely regarded as a highly prized delicacy and are of great economic and scientific value. Recently, the rapid development of cultivation technology and expansion of areas for artificial morel cultivation have propelled morel research into a hot topic. Many studies have been conducted in various aspects of morel biology, but despite this, cultivation sites still frequently report failure to fruit or only low production of fruiting bodies. Key problems include the gap between cultivation practices and basic knowledge of morel biology. In this review, in an effort to highlight the mating systems, evolution, and life cycle of morels, we summarize the current state of knowledge of morel sexual reproduction, the structure and evolution of mating-type genes, the sexual process itself, and the influence of mating-type genes on the asexual stages and conidium production. Understanding of these processes is critical for improving technology for the cultivation of morels and for scaling up their commercial production. Morel species may well be good candidates as model species for improving sexual development research in ascomycetes in the future.

Freshwater Fungi as a Source of Chemical Diversity: A Review

As their name indicates, freshwater fungi occur on submerged substrates in fresh water habitats. This review brings together the chemical diversity and biological activity of 199 of the 280 known freshwater fungal metabolites published from 1992 to 2020, representing at least seven structural classes, including polyketides, phenylpropanoids, terpenoids, meroterpenoids, alkaloids, polypeptides, and monosaccharides. In addition to describing what they are, where they are found, and what they do, we also discuss strategies for the collection, isolation, and identification of fungi from freshwater habitats, with the goal of enhancing chemists' knowledge of several mycological principles. We anticipate that this review will provide a springboard for future natural products studies from this fascinating but underexplored group of Ascomycota.