Fungal Genetics and Biology最新文献

Hyphae are viscoelastic tubes whose internal pressure pushes the cell membrane against the inner surface of the cell wall. Catalytic yielding of the wall allows this turgor to force its polymers apart as new materials are added to the surface of the growing tip. Turgor drops slightly as the wall expands, creating a pressure gradient that causes the cytoplasm to flow toward the tip. These physiological processes affect the rate of extension of the hypha and determine the magnitude of the force that it uses for invasive growth. This paper provides an overview of the experimental basis for this description of hyphal mechanics and explains the wider significance of biophysical studies on fungi and water molds.

Wheat stripe rust caused by the fungus Puccinia striiformis f. sp. tritici (Pst) is currently the most destructive disease of wheat. The major control methods which include the deployment of resistant wheat cultivars and application of chemical fungicides are losing efficiency as the fungus evolves. Natural antagonists of Pst may be an avenue for alternative and environmentally sustainable control of the disease in the field. Here we describe a novel fungus found growing on Pst pustules. We identified the fungus as a novel isolate of the plant endophyte Penicillium coffeae. We present a high-quality reference genome and a comparative transcriptomic analysis used to investigate how the fungus deploys its genes during growth amongst Pst spores. The gene content of the P. coffeae ANU01 genome is suggestive of a generalist that makes use of diverse substrates. An abundance of genes related to lipid, amino acid and carbohydrate metabolism indicate that P. coffeae ANU01 has evolved the ability to exploit nutrient stores in Pst urediniospores. P. coffeae ANU01 deploys a number of biosynthetic gene clusters during growth on Pst spores, potentially to inhibit urediniospores germination and halt defence responses. A number of genes encoding carbohydrate active enzymes are also highly upregulated, suggesting targeting and degradation of Pst urediniospores structures. Alongside carbohydrates, P. coffeae ANU01 appears to target spore lipids as a nutrient source, secreting several highly upregulated lipases. Our findings broaden the understanding of growth associated with rust spores as an evolutionary strategy and provide insight into the genes potentially required for this process.

The vascular wilt fungus Verticillium dahliae is a destructive soil-borne pathogen that causes yield loss on various economically important crops. Membrane-spanning sensor protein SLN1 have been demonstrated to contribute to virulence in varying degrees among numerous devastating fungal pathogens. However, the biological function of SLN1 in V. dahliae remains unclear. In this study, we identified the membrane-spanning sensor protein encoding gene VdSLN1 and it interacts physically with Vst50 and regulates the expression of MAPK module Vst50-Vst11-Vst7. The expression of VdSLN1 was also positively regulated by the MAPK signaling pathways transmembrane-associated members VdSho1 and VdMsb2, suggesting that the expression of VdSLN1 is associated with VdSho1 and VdMsb2. In addition, we found that VdSLN1, similar to VdSho1 and VdMsb2, is not required for V. dahliae vegetative growth and response to various abiotic stresses. While, ΔVdSLN1 mutant exhibited slightly reduced ability to penetrate a cellophane membrane and melanin synthesis compared with the wild type strain. Further experiments indicate that VdSLN1, VdSho1 and VdMsb2 has an additive effect on the virulence, cellophane penetration and melanin biosynthesis and of V. dahliae. In short, VdSLN1, though not essential, plays a role in cellophane penetration, melanin biosynthesis, also contributes to the virulence, as the downstream factor of VdSho1 and VdMsb2.

Zymocin-like killer toxins are anticodon nucleases secreted by some budding yeast species, which kill competitor yeasts by cleaving tRNA molecules. They are encoded by virus-like elements (VLEs), cytosolic linear DNA molecules that are also called killer plasmids. To date, toxins of this type have been found only in budding yeast species (Saccharomycotina). Here, we show that the nuclear genomes of many filamentous fungi (Pezizomycotina) contain small clusters of genes coding for a zymocin-like ribonuclease (γ-toxin), a chitinase (toxin α/β-subunit), and in some cases an immunity protein. The γ-toxins from Fusarium oxysporum and Colletotrichum siamense abolished growth when expressed intracellularly in S. cerevisiae. Phylogenetic analysis of glycoside hydrolase 18 (GH18) domains shows that the chitinase genes in the gene clusters are members of the previously described C-II subgroup of Pezizomycotina chitinases. We propose that the Pezizomycotina gene clusters originated by integration of a yeast-like VLE into the nuclear genome, but this event must have been ancient because (1) phylogenetically, the Pezizomycotina C-II chitinases and the Saccharomycotina VLE-encoded toxin α/β subunit chitinases are sister clades with neither of them nested inside the other, and (2) many of the Pezizomycotina toxin cluster genes contain introns, whereas VLEs do not. One of the toxin gene clusters in Fusarium graminearum is a locus that has previously been shown to be under diversifying selection in North American populations of this plant pathogen. We also show that two genera of agaric mushrooms (Basidiomycota) have acquired toxin gene clusters by horizontal transfers from different Pezizomycotina donors.

Anaerobic gut fungi of the phylum Neocallimastigomycota are microbes proficient in valorizing low-cost but difficult-to-breakdown lignocellulosic plant biomass. Characterization of different fungal life stages and how they contribute to biomass breakdown are critical for biotechnological applications, yet we lack foundational knowledge about the transcriptional, metabolic, and enzyme secretion behavior of different life stages of anaerobic gut fungi: zoospores, germlings, immature thalli, and mature zoosporangia. A Miracloth-based technique was developed to enrich cell pellets with zoospores - the free-swimming, flagellated, young life stage of anaerobic gut fungi. By contrast, fungal mats contained relatively more vegetative, encysted, mature sporangia that form films. Global gene expression profiles were compared from two sample types (zoospore-enriched cell pellets vs. mature mats) harvested from the anaerobic gut fungal strain Neocallimastix californiae G1. Despite cultures being grown on glucose, the fungal zoospore-enriched samples were transcriptionally primed to encounter plant matter substrate, as evidenced by upregulation of catabolic carbohydrate-active enzymes and putative carbohydrate transporters. Furthermore, we report significant differential gene expression for gene annotation groups, including putative secondary metabolites and transcription factors. Understanding global gene expression differences between the fungal zoospore-enriched cells and mature fungi aid in characterizing fungal development, unmasking gene function, and guiding cultivation conditions and engineering targets to promote enzyme secretion.

The rapid decline of significant plant species due to deforestation and slow regrowth has endangered many trees that are crucial for producing life-saving medications. This dual crisis of conserving plant biodiversity while meeting pharmaceutical demands necessitates innovative solutions. Endophytic fungi, naturally occurring symbionts within plants, present an eco-friendly and economically viable alternative. These fungi can produce a wide range of bioactive compounds, offering a sustainable source of pharmaceuticals. This study investigated endophytic fungi isolated from the inflorescence, leaf, and culm of Cynodon dactylon, a perennial medicinal grass. The research involved the isolation of endophytic fungi on potato dextrose agar (PDA) and water agar (WA), extracting secondary metabolites, and performing antimicrobial and antioxidant assays and gas chromatography-mass spectroscopy (GC-MS) profiling. A total of 21 endophytic fungi were isolated, with species of Alternaria, Aspergillus, and Cladosporium being predominant. These fungi were identified through morphological and molecular (internal transcribed sequences-ITS) characterization. Based on factors such as fungal dominance and specificity, five fungi (Aspergillus chevalieri, Aspergillus stellatus, Hypoxylon sp., and Xylaria apiculate) were selected and they exhibited significant activity against plant pathogens (Sclerotium rolfsii and Aspergillus niger) and radical scavenging properties in DPPH assays. GC-MS analysis revealed over twenty bioactive compounds in each fungal extract. These findings underscore the potential of endophytic fungi as sustainable sources of novel pharmaceuticals and effective biocontrol agents, offering a promising approach to address the current ecological and medicinal challenges.

Candida albicans (C. albicans), a common fungal pathogen, is responsible for infections such as oral candidiasis. Given the widespread misuse of antifungal medications and the increasing resistance, it is critical to explore new strategies to eradicate C. albicans. This study investigates ferroptosis, a form of cell death previously underexplored in fungi, focusing on the role of the fungus-specific protein phosphatase Z1 (PPZ1) in regulating the target of rapamycin complex 1 (TORC1) pathway during tert-butyl hydroperoxide (t-BuOOH)-induced ferroptosis. We demonstrated that ferroptosis induced by t-BuOOH promoted the accumulation of iron-dependent lipid peroxides, leading to the death of C. albicans. Furthermore, PPZ1 deletion impairs TORC1 signaling, activates autophagy, increases sensitivity to ferroptosis following t-BuOOH exposure, and reduces resistance to various antifungal drugs. These findings reveal the role of the PPZ1-TORC1 pathway in ferroptosis and provide a theoretical basis for developing ferroptosis as a novel antifungal strategy to eradicate C. albicans. The potential combined application of ferroptosis and antifungal drugs is expected to improve the efficacy of treating fungal infections.

The intensity of fungal virulence is likely to increase in northern forests as climate change alters environmental conditions, favoring pathogen proliferation in existing ecosystems while also facilitating their expansion into new geographic areas. In Finland, Diplodia sapinea, the causal agent of disease called "Diplodia tip blight", has emerged as a new pathogen within the past few years. To reveal the current distribution of the novel fungal pathogen, and the effect of temperature and rainfall on its distribution, we utilized citizen science for the detection and collection of symptomatic Scots pine (Pinus sylvestris) shoots. The Finnish culture collection of D. sapinea was initiated using in vitro cultured symptomatic samples, and selected strains were studied for their virulence and disease cycle. Furthermore, the mycobiome of selected symptomatic and asymptomatic Scots pine shoots was studied using amplicon sequencing and the presence of D. sapinea was confirmed with culturing, qPCR, and species-specific PCR. Based on over 500 Scots pine shoots testing positive for D. sapinea, the distribution of this fungal pathogen is concentrated along the coastal areas of Finland, extending up to 200 km inland from the coastline. The observed presence of D. sapinea followed the period of highest average temperatures recorded in Finland in 2023 and was also found to be related to less precipitation. The amplicon sequencing showed that abundance of D. sapinea was higher in the healthy tissues of symptomatic shoots compared to visually healthy shoots. Similarly, the abundance was higher in samples collected from coastal areas in Southwestern Finland, which are the most heavily impacted by this disease. Here, we show that the presence of D. sapinea is more extensive than previously assumed, and lastly illustrate the hypothesized disease cycle of the fungal pathogen in Finland based on observations made in the field from 2021 to 2024 and in vivo and in vitro studies.

Germination is the fundamental process whereby fungi transition from the dormant and stress resistant spores into actively replicating cells such as hyphae. Germination is essential for fungal colonization of new environments and pathogenesis, yet this differentiation process remains relatively poorly understood. For filamentous fungi, the study of germination has been limited by the lack of high-throughput, temporal, low cost, and easy-to-use methods of quantifying germination. To this end we have developed an image analysis pipeline to automate the quantification of germination from microscopy images. We have optimized this tool for the fungal pathogen Aspergillus fumigatus and demonstrated its potential applications by evaluating different strains, germination inhibitors, and auxotrophic and antifungal resistant mutants. Finally, we have expanded this tool to a variety of filamentous fungi and developed an easy-to-use web app for the fungal research community.