scholarly journals Molecular Mechanisms of Chitosan Interactions with Fungi and Plants

2019 ◽  
Vol 20 (2) ◽  
pp. 332 ◽  
Author(s):  
Federico Lopez-Moya ◽  
Marta Suarez-Fernandez ◽  
Luis Lopez-Llorca
Keyword(s):  
Cell Walls ◽  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Plant Immunity ◽  
Fungal Colonization ◽  
Fungal Cell ◽  
Physiological Basis ◽  
Mammalian Cell Lines ◽  
Root Interactions ◽  
Plant Chitinases

Chitosan is a versatile compound with multiple biotechnological applications. This polymer inhibits clinically important human fungal pathogens under the same carbon and nitrogen status as in blood. Chitosan permeabilises their high-fluidity plasma membrane and increases production of intracellular oxygen species (ROS). Conversely, chitosan is compatible with mammalian cell lines as well as with biocontrol fungi (BCF). BCF resistant to chitosan have low-fluidity membranes and high glucan/chitin ratios in their cell walls. Recent studies illustrate molecular and physiological basis of chitosan-root interactions. Chitosan induces auxin accumulation in Arabidopsis roots. This polymer causes overexpression of tryptophan-dependent auxin biosynthesis pathway. It also blocks auxin translocation in roots. Chitosan is a plant defense modulator. Endophytes and fungal pathogens evade plant immunity converting chitin into chitosan. LysM effectors shield chitin and protect fungal cell walls from plant chitinases. These enzymes together with fungal chitin deacetylases, chitosanases and effectors play determinant roles during fungal colonization of plants. This review describes chitosan mode of action (cell and gene targets) in fungi and plants. This knowledge will help to develop chitosan for agrobiotechnological and medical applications.

scholarly journals The Chitin-Binding Cladosporium fulvum Effector Protein Avr4 Is a Virulence Factor

2007 ◽  
Vol 20 (9) ◽  
pp. 1092-1101 ◽  
Author(s):  
H. Peter van Esse ◽  
Melvin D. Bolton ◽  
Ioannis Stergiopoulos ◽  
Pierre J. G. M. de Wit ◽  
Bart P. H. J. Thomma
Keyword(s):  
Cell Walls ◽  
Fungal Pathogens ◽  
Cladosporium Fulvum ◽  
Fungal Cell ◽  
Pathogen Virulence ◽  
Passalora Fulva ◽  
Tomato Leaf Mold ◽  
Defensive Activity ◽  
Plant Chitinases ◽  
Intrinsic Function

The biotrophic fungal pathogen Cladosporium fulvum (syn. Passalora fulva) is the causal agent of tomato leaf mold. The Avr4 protein belongs to a set of effectors that is secreted by C. fulvum during infection and is thought to play a role in pathogen virulence. Previous studies have shown that Avr4 binds to chitin present in fungal cell walls and that, through this binding, Avr4 can protect these cell walls against hydrolysis by plant chitinases. In this study, we demonstrate that Avr4 expression in Arabidopsis results in increased virulence of several fungal pathogens with exposed chitin in their cell walls, whereas the virulence of a bacterium and an oomycete remained unaltered. Heterologous expression of Avr4 in tomato increased the virulence of Fusarium oxysporum f. sp. lycopersici. Through tomato GeneChip analyses, we demonstrate that Avr4 expression in tomato results in the induced expression of only a few genes. Finally, we demonstrate that silencing of the Avr4 gene in C. fulvum decreases its virulence on tomato. This is the first report on the intrinsic function of a fungal avirulence protein that has a counter-defensive activity required for full virulence of the pathogen.

scholarly journals Bdelloid rotifers use hundreds of horizontally acquired genes against fungal pathogens

2021 ◽  
Author(s):  
Reuben W Nowell ◽  
Timothy G Barraclough ◽  
Christopher G Wilson
Keyword(s):  
Fungal Pathogen ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Fungal Cell ◽  
Bdelloid Rotifers ◽  
Fungal Toxins ◽  
Foreign Genes ◽  
Fungal Cell Walls

Obligately asexual lineages are typically rare and short-lived. According to one hypothesis, they adapt too slowly to withstand relentlessly coevolving pathogens. Bdelloid rotifers seem to have avoided this fate, by enduring millions of years without males or sex. We investigated whether bdelloids' unusual capacity to acquire non-metazoan genes horizontally has enhanced their resistance to pathogens. We found that horizontally transferred genes are three times more likely than native genes to be upregulated in response to a natural fungal pathogen. This enrichment was twofold stronger than that elicited by a physical stressor (desiccation), and the genes showed little overlap. Among hundreds of upregulated non-metazoan genes were RNA ligases putatively involved in resisting fungal toxins and glucanases predicted to bind to fungal cell walls, acquired from bacteria. Our results provide evidence that bdelloids mitigate a predicted challenge of long-term asexuality in part through their ability to acquire and deploy so many foreign genes.

Transgenic Potato Plants Expressing Soybean ß-1,3-Endoglucanase Gene Exhibit an Increased Resistance to Phytophthora infestans

1998 ◽  
Vol 53 (11-12) ◽  
pp. 1012-1016 ◽  
Author(s):  
Maria Borkowska ◽  
Magdalena Krzymowska ◽  
Andrzej Talarczyk ◽  
Malik F. M. Awan ◽  
Ludmila Yakovleva ◽  
...  
Keyword(s):  
Transgenic Plants ◽  
Phytophthora Infestans ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Pcr Amplification ◽  
Transgenic Potato ◽  
Fungal Cell ◽  
Potato Genome ◽  
Potato Plants ◽  
Transgenic Potato Plants

Abstract Soybean β-1,3-endoglucanase represents a model system for studies on early plant re­sponses to infection by fungal pathogens, and it has been implicated in the release of elicitors from fungal cell walls. In the present study, potato plants were transformed with the soybean β-1,3-endoglucanase cDNA via Agrobacterium delivery system. The transfer of the gene into potato genome was confirmed by (i) PCR amplification, (ii) Northern blot analyses, and (Hi) an increase in the activity of β-1,3-endoglucanase in transgenic plants. The transformation resulted in an increased resistance of selected transgenic plants to infection by Phytophthora infestans, an important pathogen.

scholarly journals Fungal gene expression during ectomycorrhiza formation

1995 ◽  
Vol 73 (S1) ◽  
pp. 541-547 ◽  
Author(s):  
F. Martin ◽  
P. Laurent ◽  
D. de Carvalho ◽  
T. Burgess ◽  
P. Murphy ◽  
...  
Keyword(s):  
Cell Walls ◽  
Molecular Mechanisms ◽  
Sequence Similarity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Pisolithus Tinctorius ◽  
Amino Acid Sequence Similarity ◽  
Cell Fractionation ◽  
Fungal Cell ◽  
Temporal Expressions ◽  
Fungal Genes

Ectomycorrhiza development involves the differentiation of structurally specialized fungal tissues (e.g., mantle and Hartig net) and an interface between symbionts. Polypeptides presenting a preferential, up-, or down-regulated synthesis have been characterized in several developing ectomycorrhizal associations. Their spatial and temporal expressions have been characterized by cell fractionation, two-dimensional polyacrylamide gel electrophoresis, and immunochemical assays in the Eucalyptus spp. – Pisolithus tinctorius mycorrhizas. These studies have emphasized the importance of fungal cell wall polypeptides during the early stages of the ectomycorrhizal interaction. The increased synthesis of 30- to 32-kDa acidic polypeptides, together with the decreased accumulation of a prominent 95-kDa mannoprotein provided evidence for major alterations of Pisolithus tinctorius cell walls during mycorrhiza formation. Differential cDNA library screening and shotgun cDNA sequencing were used to clone symbiosis-regulated fungal genes. Several abundant transcripts showed a significant amino acid sequence similarity to a family of secreted morphogenetic fungal proteins, the so-called hydrophobic. In P. tinctorius, the content of hydrophobin transcripts is high in aerial hyphae and during the ectomycorrhizal sheath formation. Alteration of cell walls and the extracellular matrix is therefore a key event in the ectomycorrhiza development. An understanding of the molecular mechanisms that underlies the temporal and spatial control of genes and proteins involved in the development of the symbiotic interface is now within reach, as more sophisticated techniques of molecular and genetic analysis are applied to the mycorrhizal interactions. Key words: cell walls, ectomycorrhiza, ectomycorrhizins, fungal development, hydrophobins, symbiosis-regulated polypeptides.

scholarly journals A secreted LysM effector protects fungal hyphae through chitin-dependent homodimer polymerization

2019 ◽  
Author(s):  
Andrea Sánchez-Vallet ◽  
Hui Tian ◽  
Luis Rodriguez-Moreno ◽  
Dirk-Jan Valkenburg ◽  
Raspudin Saleem-Batcha ◽  
...  
Keyword(s):  
Immune Responses ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Cladosporium Fulvum ◽  
Zymoseptoria Tritici ◽  
Fungal Cell ◽  
Lysm Domain ◽  
Fungal Hyphae ◽  
Binding Groove ◽  
Fungal Cell Walls

ABSTRACTPlants trigger immune responses upon recognition of fungal cell wall chitin, followed by the release of various antimicrobials, including chitinase enzymes that hydrolyze chitin. In turn, many fungal pathogens secrete LysM effectors that prevent chitin recognition by the host through scavenging of chitin oligomers. We previously showed that intrachain LysM dimerization of the Cladosporium fulvum effector Ecp6 confers an ultrahigh-affinity binding groove that competitively sequesters chitin oligomers from host immune receptors. Additionally, particular LysM effectors are found to protect fungal hyphae against chitinase hydrolysis during host colonization. However, the molecular basis for the protection of fungal cell walls against hydrolysis remained unclear. Here, we determined a crystal structure of the single LysM domain-containing effector Mg1LysM of the wheat pathogen Zymoseptoria tritici and reveal that Mg1LysM is involved in the formation of two kinds of dimers; a chitin-dependent dimer as well as a chitin-independent homodimer. In this manner, Mg1LysM gains the capacity to form a supramolecular structure by chitin-induced oligomerization of chitin-independent Mg1LysM homodimers, a property that confers protection to fungal cell walls against host chitinases.

scholarly journals Cell Wall Chitosaccharides Are Essential Components and Exposed Patterns of the Phytopathogenic Oomycete Aphanomyces euteiches

2008 ◽  
Vol 7 (11) ◽  
pp. 1980-1993 ◽  
Author(s):  
Ilham Badreddine ◽  
Claude Lafitte ◽  
Laurent Heux ◽  
Nicholas Skandalis ◽  
Zacharoula Spanou ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Molecular Mechanisms ◽  
Expressed Sequence Tag ◽  
Pathogenic Fungi ◽  
Aphanomyces Euteiches ◽  
Fungal Cell ◽  
Cdna Sequences ◽  
Essential Components ◽  
Biochemical Analyses

ABSTRACT Chitin is an essential component of fungal cell walls, where it forms a crystalline scaffold, and chitooligosaccharides derived from it are signaling molecules recognized by the hosts of pathogenic fungi. Oomycetes are cellulosic fungus-like microorganisms which most often lack chitin in their cell walls. Here we present the first study of the cell wall of the oomycete Aphanomyces euteiches, a major parasite of legume plants. Biochemical analyses demonstrated the presence of ca. 10% N-acetyl-d-glucosamine (GlcNAc) in the cell wall. Further characterization of the GlcNAc-containing material revealed that it corresponds to noncrystalline chitosaccharides associated with glucans, rather than to chitin per se. Two putative chitin synthase (CHS) genes were identified by data mining of an A. euteiches expressed sequence tag collection and Southern blot analysis, and full-length cDNA sequences of both genes were obtained. Phylogeny analysis indicated that oomycete CHS diversification occurred before the divergence of the major oomycete lineages. Remarkably, lectin labeling showed that the Aphanomyces euteiches chitosaccharides are exposed at the cell wall surface, and study of the effect of the CHS inhibitor nikkomycin Z demonstrated that they are involved in cell wall function. These data open new perspectives for the development of antioomycete drugs and further studies of the molecular mechanisms involved in the recognition of pathogenic oomycetes by the host plants.

scholarly journals Fungal LysM effectors that comprise two LysM domains bind chitin through intermolecular dimerization

2020 ◽  
Author(s):  
Hui Tian ◽  
Gabriel L. Fiorin ◽  
Anja Kombrink ◽  
Jeroen R. Mesters ◽  
Bart P.H.J. Thomma
Keyword(s):  
Fungal Pathogens ◽  
Plant Immunity ◽  
Effector Proteins ◽  
Broad Host Range ◽  
Fungal Cell ◽  
Mould Fungus ◽  
Colletotrichum Higginsianum ◽  
Molecular Pattern ◽  
Wide Range ◽  
Binding Groove

SUMMARYChitin is a polymer of β-(1,4)-linked N-acetyl-D-glucosamine (GlcNAc) and a major structural component of fungal cell walls that acts as a microbe-associated molecular pattern (MAMP) that can be recognized by plant cell surface-localized pattern recognition receptors (PRRs) to activate a wide range of immune responses. In order to deregulate chitin-induced plant immunity and successfully establish their infection, many fungal pathogens secrete effector proteins with LysM domains. We previously determined that two of the three LysM domains of the LysM effector Ecp6 from the tomato leaf mould fungus Cladosporium fulvum cooperate to form a chitin-binding groove that binds chitin with ultra-high affinity, allowing to outcompete host PRRs for chitin binding. In this study, we describe functional and structural analyses aimed to investigate whether LysM effectors that contain two LysM domains bind chitin through intramolecular or intermolecular LysM dimerization. To this end, we focus on MoSlp1 from the rice blast fungus Magnaporthe oryzae, Vd2LysM from the broad host range vascular wilt fungus Verticillium dahliae, and ChElp1 and ChElp2 from the Brassicaceae anthracnose fungus Colletotrichum higginsianum. We show that these LysM effectors bind chitin through intermolecular LysM dimerization, allowing the formation of polymeric complexes that may precipitate in order to eliminate the presence of chitin oligomers at infection sites to suppress activation of chitin-induced plant immunity. In this manner, many fungal pathogens are able to subvert chitin-triggered immunity in their plant hosts.

scholarly journals Mannan detecting C-type lectin receptor probes recognise immune epitopes with diverse chemical, spatial and phylogenetic heterogeneity in fungal cell walls

2019 ◽  
Author(s):  
Ingrida Vendele ◽  
Janet A. Willment ◽  
Lisete M. Silva ◽  
Angelina S. Palma ◽  
Wengang Chai ◽  
...  
Keyword(s):  
Cell Wall ◽  
Immune Responses ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Fungal Species ◽  
Fungal Cell Wall ◽  
Immune Recognition ◽  
Cell Surfaces ◽  
Fungal Cell ◽  
Wall Components

AbstractDuring the course of fungal infection, pathogen recognition by the innate immune system is critical to initiate efficient protective immune responses. The primary event that triggers immune responses is the binding of Pattern Recognition Receptors (PRRs), which are expressed at the surface of host immune cells, to Pathogen-Associated Molecular Patterns (PAMPs) located predominantly in the fungal cell wall. Most fungi have mannosylated PAMPs in their cell walls and these are recognized by a range of C-type lectin receptors (CTLs). However, the precise spatial distribution of the ligands that induce immune responses within the cell walls of fungi are not well defined. We used recombinant IgG Fc-CTLs fusions of three murine mannan detecting CTLs, including dectin-2, the mannose receptor (MR) carbohydrate recognition domains (CRDs) 4-7 (CRD4-7), and human DC-SIGN (hDC-SIGN) and the β-1,3 glucan-binding lectin dectin-1 to map PRR ligands in the fungal cell wall. We show that epitopes of mannan-specific CTL receptors can be clustered or diffuse, superficial or buried in the inner cell wall. We demonstrate that PRR ligands do not correlate well with phylogenetic relationships between fungi, and that Fc-lectin binding discriminated between mannosides expressed on different cell morphologies of the same fungus. We also demonstrate CTL epitope differentiation during different phases of the growth cycle ofCandida albicansand that MR and DC-SIGN labelled outer chainN-mannans whilst dectin-2 labelled coreN-mannans displayed deeper in the cell wall. These immune receptor maps of fungal walls therefore reveal remarkable spatial, temporal and chemical diversity, indicating that the triggering of immune recognition events originates from multiple physical origins at the fungal cell surface.Author SummaryInvasive fungal infections remain an important health problem in immunocompromised patients. Immune recognition of fungal pathogens involves binding of specific cell wall components by pathogen recognition receptors (PRRs) and subsequent activation of immune defences. Some cell wall components are conserved among fungal species while other components are species-specific and phenotypically diverse. The fungal cell wall is dynamic and capable of changing its composition and organization when adapting to different growth niches and environmental stresses. Differences in the composition of the cell wall lead to differential immune recognition by the host. Understanding how changes in the cell wall composition affect recognition by PRRs is likely to be of major diagnostic and clinical relevance. Here we address this fundamental question using four soluble immune receptor-probes which recognize mannans and β-glucan in the cell wall. We use this novel methodology to demonstrate that mannan epitopes are differentially distributed in the inner and outer layers of fungal cell wall in a clustered or diffuse manner. Immune reactivity of fungal cell surfaces did not correlate with relatedness of different fungal species, and mannan-detecting receptor-probes discriminated between cell surface mannans generated by the same fungus growing under different conditions. These studies demonstrate that mannan-epitopes on fungal cell surfaces are differentially distributed within and between the cell walls of fungal pathogens.

scholarly journals Dectin-1-Targeted Antifungal Liposomes Exhibit Enhanced Efficacy

mSphere ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Suresh Ambati ◽  
Aileen R. Ferarro ◽  
S. Earl Kang ◽  
Jianfeng Lin ◽  
Xiaorong Lin ◽  
...  
Keyword(s):  
Invasive Aspergillosis ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Antifungal Drugs ◽  
Beta Glucan ◽  
Fungal Cell ◽  
Content Type ◽  
Current Therapies ◽  
Mammalian Protein ◽  
Fungal Cell Walls

The fungus Aspergillus fumigatus causes pulmonary invasive aspergillosis resulting in nearly 100,000 deaths each year. Patients are often treated with antifungal drugs such as amphotericin B (AmB) loaded into liposomes (AmB-LLs), but all antifungal drugs, including AmB-LLs, have serious limitations due to human toxicity and insufficient fungal cell killing. Even with the best current therapies, 1-year survival among patients with invasive aspergillosis is only 25 to 60%. Hence, there is a critical need for improved antifungal therapeutics. Dectin-1 is a mammalian protein that binds to beta-glucan polysaccharides found in nearly all fungal cell walls. We coated AmB-LLs with Dectin-1 to make DEC-AmB-LLs. DEC-AmB-LLs bound strongly to fungal cells, while AmB-LLs had little affinity. DEC-AmB-LLs killed or inhibited A. fumigatus 10 times more efficiently than untargeted liposomes, decreasing the effective dose of AmB. Dectin-1-coated drug-loaded liposomes targeting fungal pathogens have the potential to greatly enhance antifungal therapeutics.

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