Investigating the Role of BLADE-ON-PETIOLE Genes and Hydrophobic Cell-Wall Polymer Suberin in Arabidopsis thaliana Defense Against Bacterial and Fungal Pathogens

ABSTRACTThe fungusCryptococcuscontributes a large global burden of infectious death in both HIV-infected and healthy individuals. AsCryptococcusis an opportunistic pathogen, much of the evolutionary pressure shaping virulence occurs in environments in contact with plants and soil. The present studies investigated inoculation of intact seeds of the common weedArabidopsis thalianawith fungal cells over a 21-day period.C. gattiiwas the more virulent plant pathogen, resulting in disrupted germination as well as increased stem lodging, fungal burden, and plant tissue colocalization.C. neoformanswas a less virulent plant pathogen but exhibited prolonged tissue residence within the cuticle and vascular spaces. Arabidopsis mutants of thePRN1gene, which is involved in abiotic and biotic signaling affecting phenylalanine-derived flavonoids, showed altered susceptibility to cryptoccocal infections, suggesting roles for this pathway in cryptococcal defense. The fungal virulence factor laccase was also implicated in plant pathogenesis, as a cryptococcallac1Δ strain was less virulent than wild-type fungi and was unable to colonize seedlings. In conclusion, these studies expand knowledge concerning the ecological niche ofCryptococcusby demonstrating the pathogenic capacity of the anamorphic form of cryptococcal cells against healthy seedlings under physiologically relevant conditions. In addition, an important role of laccase in plant as well as human virulence may suggest mechanisms for laccase retention and optimization during evolution of this fungal pathogen.

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The Glycosylphosphatidylinositol-Anchored Superoxide Dismutase of Scedosporium apiospermum Protects the Conidia from Oxidative Stress

Journal of Fungi ◽

10.3390/jof7070575 ◽

2021 ◽

Vol 7 (7) ◽

pp. 575

Author(s):

Cindy Staerck ◽

Hajar Yaakoub ◽

Patrick Vandeputte ◽

Julie Tabiasco ◽

Charlotte Godon ◽

...

Keyword(s):

Oxidative Stress ◽

Cell Wall ◽

Superoxide Dismutase ◽

Fungal Pathogens ◽

Microscopic Analysis ◽

Antioxidant Systems ◽

Blood Monocytes ◽

Phagocytic Cells ◽

Electron Microscopic

Scedosporium species are common fungal pathogens in patients with cystic fibrosis (CF). To colonize the CF lungs, fungi must cope with the host immune response, especially the reactive oxygen species (ROS) released by phagocytic cells. To this aim, pathogens have developed various antioxidant systems, including superoxide dismutases (SODs) which constitute the first-line protection against oxidative stress. Interestingly, one of the S. apiospermum SOD-encoding genes (SODD gene) exhibits a glycosylphosphatidylinositol (GPI) anchor-binding site and encodes a conidial-specific surface SOD. In this study, a SODDΔ mutant was engineered from a non-homologous end joining-deficient strain (KU70Δ) of S. apiospermum. Compared to its parent strain, the double mutant KU70Δ/SODDΔ exhibited increased susceptibility to various oxidizing agents and triazole antifungals. In addition, the loss of SodD resulted in an increased intracellular killing of the conidia by M1 macrophages derived from human blood monocytes, suggesting the involvement of this superoxide dismutase in the evasion to the host defenses. Nevertheless, one cannot disregard an indirect role of the enzyme in the synthesis or assembly of the cell wall components since transmission electron microscopic analysis revealed a thickening of the inner cell wall layer of the conidia. Further studies are needed to confirm the role of this enzyme in the pathogenesis of Scedosporium infections, including the production of a recombinant protein and study of its protective effect against the infection in a mouse model of scedosporiosis.

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The cell wall is crucial for cellular sensitivity to low pH: the role of class III peroxidases and ethylene in cell death in Arabidopsis thaliana roots

10.11606/t.11.2018.tde-25072018-164614 ◽

2018 ◽

Cited By ~ 2

Author(s):

Jonathas Pereira das Graças

Keyword(s):

Arabidopsis Thaliana ◽

Cell Death ◽

Cell Wall ◽

Low Ph ◽

Class Iii ◽

Cellular Sensitivity ◽

Class Iii Peroxidases

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Characterization of Extracellular Vesicles Produced by Aspergillus fumigatus Protoplasts

mSphere ◽

10.1128/msphere.00476-20 ◽

2020 ◽

Vol 5 (4) ◽

Cited By ~ 1

Author(s):

Juliana Rizzo ◽

Thibault Chaze ◽

Kildare Miranda ◽

Robert W. Roberson ◽

Olivier Gorgette ◽

...

Keyword(s):

Electron Microscopy ◽

Cell Wall ◽

Aspergillus Fumigatus ◽

Extracellular Vesicles ◽

Fungal Pathogen ◽

Fungal Pathogens ◽

Biologically Active ◽

Content Type ◽

Cell Wall Biogenesis

ABSTRACT Extracellular vesicles (EVs) are membranous compartments produced by yeast and mycelial forms of several fungal species. One of the difficulties in perceiving the role of EVs during the fungal life, and particularly in cell wall biogenesis, is caused by the presence of a thick cell wall. One alternative to have better access to these vesicles is to use protoplasts. This approach has been investigated here with Aspergillus fumigatus, one of the most common opportunistic fungal pathogens worldwide. Analysis of regenerating protoplasts by scanning electron microscopy and fluorescence microscopy indicated the occurrence of outer membrane projections in association with surface components and the release of particles with properties resembling those of fungal EVs. EVs in culture supernatants were characterized by transmission electron microscopy and nanoparticle tracking analysis. Proteomic and glycome analysis of EVs revealed the presence of a complex array of enzymes related to lipid/sugar metabolism, pathogenic processes, and cell wall biosynthesis. Our data indicate that (i) EV production is a common feature of different morphological stages of this major fungal pathogen and (ii) protoplastic EVs are promising tools for undertaking studies of vesicle functions in fungal cells. IMPORTANCE Fungal cells use extracellular vesicles (EVs) to export biologically active molecules to the extracellular space. In this study, we used protoplasts of Aspergillus fumigatus, a major fungal pathogen, as a model to evaluate the role of EV production in cell wall biogenesis. Our results demonstrated that wall-less A. fumigatus exports plasma membrane-derived EVs containing a complex combination of proteins and glycans. Our report is the first to characterize fungal EVs in the absence of a cell wall. Our results suggest that protoplasts represent a promising model for functional studies of fungal vesicles.

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