Hyphal morphology and substrate porosity -rather than melanization- drive penetration of black fungi into carbonate substrates

Cyclophilin (Cyp) and Ca2+/calcineurin proteins are cellular components related to fungal morphogenesis and virulence; however, their roles in mediating the pathogenesis of Botrytis cinerea, the causative agent of gray mold on over 1000 plant species, remain largely unexplored. Here, we show that disruption of cyclophilin gene BcCYP2 did not impair the pathogen mycelial growth, osmotic and oxidative stress adaptation as well as cell wall integrity, but delayed conidial germination and germling development, altered conidial and sclerotial morphology, reduced infection cushion (IC) formation, sclerotial production and virulence. Exogenous cyclic adenosine monophosphate (cAMP) rescued the deficiency of IC formation of the ∆Bccyp2 mutants, and exogenous cyclosporine A (CsA), an inhibitor targeting cyclophilins, altered hyphal morphology and prevented host-cell penetration in the BcCYP2 harboring strains. Moreover, calcineurin-dependent (CND) genes are differentially expressed in strains losing BcCYP2 in the presence of CsA, suggesting that BcCyp2 functions in the upstream of cAMP- and Ca2+/calcineurin-dependent signaling pathways. Interestingly, during IC formation, expression of BcCYP2 is downregulated in a mutant losing BcJAR1, a gene encoding histone 3 lysine 4 (H3K4) demethylase that regulates fungal development and pathogenesis, in B. cinerea, implying that BcCyp2 functions under the control of BcJar1. Collectively, our findings provide new insights into cyclophilins mediating the pathogenesis of B. cinerea and potential targets for drug intervention for fungal diseases.

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Transcription Profiling ofCandida albicansCells Undergoing the Yeast-to-Hyphal Transition

Molecular Biology of the Cell ◽

10.1091/mbc.e02-05-0272 ◽

2002 ◽

Vol 13 (10) ◽

pp. 3452-3465 ◽

Cited By ~ 271

Author(s):

André Nantel ◽

Daniel Dignard ◽

Catherine Bachewich ◽

Doreen Harcus ◽

Anne Marcil ◽

...

Keyword(s):

Time Course ◽

Dna Microarrays ◽

Culture Medium ◽

Developmental Process ◽

Pathogenic Fungus ◽

Hyphal Growth ◽

Transcription Profiles ◽

Hyphal Morphology ◽

External Signals ◽

Temperature Time

The ability of the pathogenic fungus Candida albicans to switch from a yeast to a hyphal morphology in response to external signals is implicated in its pathogenicity. We used glass DNA microarrays to investigate the transcription profiles of 6333 predicted ORFs in cells undergoing this transition and their responses to changes in temperature and culture medium. We have identified several genes whose transcriptional profiles are similar to those of known virulence factors that are modulated by the switch to hyphal growth caused by addition of serum and a 37°C growth temperature. Time course analysis of this transition identified transcripts that are induced before germ tube initiation and shut off later in the developmental process. A strain deleted for the Efg1p and Cph1p transcription factors is defective in hyphae formation, and its response to serum and increased temperature is almost identical to the response of a wild-type strain grown at 37°C in the absence of serum. Thus Efg1p and Cph1p are needed for the activation of the transcriptional program that is induced by the presence of serum.

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Calcineurin Controls Growth, Morphology, and Pathogenicity in Aspergillus fumigatus

Eukaryotic Cell ◽

10.1128/ec.00139-06 ◽

2006 ◽

Vol 5 (7) ◽

pp. 1091-1103 ◽

Cited By ~ 199

Author(s):

William J. Steinbach ◽

Robert A. Cramer ◽

B. Zachary Perfect ◽

Yohannes G. Asfaw ◽

Theodor C. Sauer ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Clinical Observation ◽

Immunocompromised Patient ◽

Fungal Growth ◽

Pathogenic Fungi ◽

Wild Type ◽

Therapeutic Approaches ◽

Growth Morphology ◽

Different Types ◽

Hyphal Morphology

ABSTRACT Calcineurin is implicated in a myriad of human diseases as well as homeostasis and virulence in several major human pathogenic microorganisms. The fungus Aspergillus fumigatus is a leading cause of infectious death in the rapidly expanding immunocompromised patient population. Current antifungal treatments for invasive aspergillosis are often ineffective, and novel therapeutic approaches are urgently needed. We demonstrate that a mutant of A. fumigatus lacking the calcineurin A (cnaA) catalytic subunit exhibited defective hyphal morphology related to apical extension and polarized growth, which resulted in drastically decreased filamentation. The ΔcnaA mutant lacked the extensive lattice of invading hyphae seen with the wild-type and complemented strains. Sporulation was also affected in the ΔcnaA mutant, including morphological conidial defects with the absence of surface rodlets and the added presence of disjunctors creating long conidial chains. Infection with the ΔcnaA mutant in several distinct animal models with different types of immunosuppression and inoculum delivery led to a profound attenuation of pathogenicity compared to infection with the wild-type and complemented strains. Lung tissue from animals infected with the ΔcnaA mutant showed a complete absence of hyphae, in contrast to tissue from animals infected with the wild-type and complemented strains. Quantitative fungal burden and pulmonary infarct scoring confirmed these findings. Our results support the clinical observation that substantially decreasing fungal growth can prevent disease establishment and decrease mortality. Our findings reveal that calcineurin appears to play a globally conserved role in the virulence of several pathogenic fungi and yet plays specialized roles in each and can be an excellent target for therapeutic intervention.

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Farnesol restores wild-type colony morphology to 96% of Candida albicans colony morphology variants recovered following treatment with mutagens

Genome ◽

10.1139/g05-117 ◽

2006 ◽

Vol 49 (4) ◽

pp. 346-353 ◽

Cited By ~ 9

Author(s):

Ellen C Jensen ◽

Jacob M Hornby ◽

Nicole E Pagliaccetti ◽

Chuleeon M Wolter ◽

Kenneth W Nickerson ◽

...

Keyword(s):

Candida Albicans ◽

Quorum Sensing ◽

Environmental Conditions ◽

Budding Yeast ◽

Colony Morphology ◽

Morphological Transition ◽

Strongly Correlated ◽

Wild Type ◽

Hyphal Morphology

Candida albicans is a diploid fungus that undergoes a morphological transition between budding yeast, hyphal, and pseudohyphal forms. The morphological transition is strongly correlated with virulence and is regulated in part by quorum sensing. Candida albicans produces and secretes farnesol that regulates the yeast to mycelia morphological transition. Mutants that fail to synthesize or respond to farnesol could be locked in the filamentous mode. To test this hypothesis, a collection of C. albicans mutants were isolated that have altered colony morphologies indicative of the presence of hyphal cells under environmental conditions where C. albicans normally grows only as yeasts. All mutants were characterized for their ability to respond to farnesol. Of these, 95.9% fully or partially reverted to wild-type morphology on yeast malt (YM) agar plates supplemented with farnesol. All mutants that respond to farnesol regained their hyphal morphology when restreaked on YM plates without farnesol. The observation that farnesol remedial mutants are so common (95.9%) relative to mutants that fail to respond to farnesol (4.1%) suggests that farnesol activates and (or) induces a pathway that can override many of the morphogenesis defects in these mutants. Additionally, 9 mutants chosen at random were screened for farnesol production. Two mutants failed to produce detectable levels of farnesol.Key words: farnesol-remedial mutants, farnesol-sensing mutants, farnesol-synthesis mutants, quorum sensing, Candida albicans, morphological transition.

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Muellerella, a lichenicolous fungal genus recovered as polyphyletic within Chaetothyriomycetidae (Eurotiomycetes, Ascomycota)

Plant and Fungal Systematics ◽

10.2478/pfs-2019-0024 ◽

2019 ◽

Vol 64 (2) ◽

pp. 367-381

Author(s):

Lucia Muggia ◽

Sergio Pérez-Ortega ◽

Damien Ertz

Keyword(s):

Environmental Samples ◽

Strong Support ◽

Morphological Diversity ◽

Molecular Data ◽

Taxon Sampling ◽

Phylogenetic Placement ◽

Monophyletic Lineage ◽

Black Fungi ◽

Culture Dependent ◽

Multilocus Phylogeny

AbstractMolecular data and culture-dependent methods have helped to uncover the phylogenetic relationships of numerous species of lichenicolous fungi, a specialized group of taxa that inhabit lichens and have developed diverse degrees of specificity and parasitic behaviors. The majority of lichenicolous fungal taxa are known in either their anamorphic or teleomorphic states, although their anamorph-teleomorph relationships have been resolved in only a few cases. The pycnidium-forming Lichenodiplis lecanorae and the perithecioid taxa Muellerella atricola and M. lichenicola were recently recovered as monophyletic in Chaetothyriales (Eurotiomycetes). Both genera are lichenicolous on multiple lichen hosts, upon which they show a subtle morphological diversity reflected in the description of 14 species in Muellerella (of which 12 are lichenicolous) and 12 in Lichenodiplis. Here we focus on the teleomorphic genus Muellerella and investigate its monophyly by expanding the taxon sampling to other species occurring on diverse lichen hosts. We generated molecular data for two nuclear and one mitochondrial loci (28S, 18S and 16S) from environmental samples. The present multilocus phylogeny confirms the monophyletic lineage of the teleomorphic M. atricola and M. lichenicola with their L. lecanorae-like anamorphs, but places the rest of the Muellerella species studied in two different monophyletic lineages with strong support. The first, Muellerella spp. 1, is nested within some new lineages of black fungi isolated from different epilithic lichen thalli, while the second, Muellerella spp. 2, is closely related to the Verrucariales. Based on these results, we reappraise the phylogenetic placement of Muellerella and suggest its polyphyly within Chaetothyriomycetidae.

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2.1 Black fungi inhabiting rock surfaces

Life at Rock Surfaces ◽

10.1515/9783110646467-003 ◽

2021 ◽

pp. 57-86

Author(s):

Claudia Coleine ◽

Laura Selbmann

Keyword(s):

Black Fungi

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The effects of external Mn2+ concentration on hyphal morphology and citric acid production are mediated primarily by the NRAMP-family transporter DmtA in Aspergillus niger

Microbial Cell Factories ◽

10.1186/s12934-020-1286-7 ◽

2020 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Balázs Fejes ◽

Jean-Paul Ouedraogo ◽

Erzsébet Fekete ◽

Erzsébet Sándor ◽

Michel Flipphi ◽

...

Keyword(s):

Citric Acid ◽

Aspergillus Niger ◽

Acid Production ◽

Parent Strain ◽

Transmembrane Protein ◽

Citric Acid Production ◽

High Yield ◽

Industrial Biotechnology ◽

High Sequence Identity ◽

Hyphal Morphology

Abstract Background Citric acid, a commodity product of industrial biotechnology, is produced by fermentation of the filamentous fungus Aspergillus niger. A requirement for high-yield citric acid production is keeping the concentration of Mn2+ ions in the medium at or below 5 µg L−1. Understanding manganese metabolism in A. niger is therefore of critical importance to citric acid production. To this end, we investigated transport of Mn2+ ions in A. niger NRRL2270. Results we identified an A. niger gene (dmtA; NRRL3_07789), predicted to encode a transmembrane protein, with high sequence identity to the yeast manganese transporters Smf1p and Smf2p. Deletion of dmtA in A. niger eliminated the intake of Mn2+ at low (5 µg L−1) external Mn2+ concentration, and reduced the intake of Mn2+ at high (> 100 µg L−1) external Mn2+ concentration. Compared to the parent strain, overexpression of dmtA increased Mn2+ intake at both low and high external Mn2+ concentrations. Cultivation of the parent strain under Mn2+ ions limitation conditions (5 µg L−1) reduced germination and led to the formation of stubby, swollen hyphae that formed compact pellets. Deletion of dmtA caused defects in germination and hyphal morphology even in the presence of 100 µg L−1 Mn2+, while overexpression of dmtA led to enhanced germination and normal hyphal morphology at limiting Mn2+ concentration. Growth of both the parent and the deletion strains under citric acid producing conditions resulted in molar yields (Yp/s) of citric acid of > 0.8, although the deletion strain produced ~ 30% less biomass. This yield was reduced only by 20% in the presence of 100 µg L−1 Mn2+, whereas production by the parent strain was reduced by 60%. The Yp/s of the overexpressing strain was 17% of that of the parent strain, irrespective of the concentrations of external Mn2+. Conclusions Our results demonstrate that dmtA is physiologically important in the transport of Mn2+ ions in A. niger, and manipulation of its expression modulates citric acid overflow.

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