A Ras protein from a phytopathogenic fungus causes defects in hyphal growth polarity, and induces tumors in mice

1999 ◽  
Vol 262 (1) ◽  
pp. 46-54 ◽  
Author(s):  
G. M. Truesdell ◽  
C. Jones ◽  
T. Holt ◽  
G. Henderson ◽  
M. B. Dickman
Keyword(s):  
Hyphal Growth ◽  
Phytopathogenic Fungus ◽  
Ras Protein ◽  
Growth Polarity

scholarly journals Biosynthesis of Fusapyrone Depends on the H3K9 Methyltransferase, FmKmt1, in Fusarium mangiferae

2021 ◽  
Vol 2 ◽  
Author(s):  
Anna K. Atanasoff-Kardjalieff ◽  
Friederike Lünne ◽  
Svetlana Kalinina ◽  
Joseph Strauss ◽  
Hans-Ulrich Humpf ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Polyketide Synthase ◽  
Wide Spectrum ◽  
Hyphal Growth ◽  
Phytopathogenic Fungus ◽  
Fusarium Fujikuroi ◽  
Plant Infection ◽  
Expression Studies ◽  
Fusarium Semitectum ◽  
Fusarium Mangiferae

The phytopathogenic fungus Fusarium mangiferae belongs to the Fusarium fujikuroi species complex (FFSC). Members of this group cause a wide spectrum of devastating diseases on diverse agricultural crops. F. mangiferae is the causal agent of the mango malformation disease (MMD) and as such detrimental for agriculture in the southern hemisphere. During plant infection, the fungus produces a plethora of bioactive secondary metabolites (SMs), which most often lead to severe adverse defects on plants health. Changes in chromatin structure achieved by posttranslational modifications (PTM) of histones play a key role in regulation of fungal SM biosynthesis. Posttranslational tri-methylation of histone 3 lysine 9 (H3K9me3) is considered a hallmark of heterochromatin and established by the SET-domain protein Kmt1. Here, we show that FmKmt1 is involved in H3K9me3 in F. mangiferae. Loss of FmKmt1 only slightly though significantly affected fungal hyphal growth and stress response and is required for wild type-like conidiation. While FmKmt1 is largely dispensable for the biosynthesis of most known SMs, removal of FmKMT1 resulted in an almost complete loss of fusapyrone and deoxyfusapyrone, γ-pyrones previously only known from Fusarium semitectum. Here, we identified the polyketide synthase (PKS) FmPKS40 to be involved in fusapyrone biosynthesis, delineate putative cluster borders by co-expression studies and provide insights into its regulation.

scholarly journals An Ash1-Like Protein MoKMT2H Null Mutant Is Delayed for Conidium Germination and Pathogenesis inMagnaporthe oryzae

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Zhaojun Cao ◽  
Yue Yin ◽  
Xuan Sun ◽  
Jun Han ◽  
Qing peng Sun ◽  
...  
Keyword(s):  
Target Gene ◽  
Hyphal Growth ◽  
Gene Replacement ◽  
Phytopathogenic Fungus ◽  
Null Mutant ◽  
Lesion Formation ◽  
Target Gene Replacement ◽  
Conidium Germination ◽  
Rice Leaves ◽  
And Function

Ash1 is a known H3K36-specific histone demethylase that is required for normal Hox gene expression and fertility inDrosophilaand mammals. However, little is known about the expression and function of the fungal ortholog of Ash1 in phytopathogenic fungusMagnaporthe oryzae. Here we report that MoKMT2H, an Ash1-like protein, is required for conidium germination and virulence in rice. We obtainedMoKMT2Hnull mutant (ΔMoKMT2H) using a target gene replacement strategy. In theΔMoKMT2Hnull mutants, global histone methyltransferase modifications (H3K4me3, H3K9me3, H3K27me3, and H3K36me2/3) of the genome were unaffected. TheΔMoKMT2Hmutants showed no defect in vegetative hyphal growth, conidium morphology, conidiation, or disease lesion formation on rice leaves. However, theMoKMT2Hdeletion mutants were delayed for conidium germination and consequently had decreased virulence. Taken together, our results indicated that MoKMT2H plays an important role in conidium germination during appressorium formation in the rice blast fungus and perhaps other pathogenic plant fungi.

scholarly journals A Fungus-Specific Protein Domain Is Essential for RasA-Mediated Morphogenetic Signaling in Aspergillus fumigatus

mSphere ◽  
2016 ◽  
Vol 1 (6) ◽  
Author(s):  
Qusai Al Abdallah ◽  
Tiffany S. Norton ◽  
Amy M. Hill ◽  
Lawrence L. LeClaire ◽  
Jarrod R. Fortwendel
Keyword(s):  
Aspergillus Fumigatus ◽  
Fungal Pathogen ◽  
Hyphal Growth ◽  
Invasive Disease ◽  
Ras Signaling ◽  
Specific Domain ◽  
Content Type ◽  
Ras Protein ◽  
Crucial Difference ◽  
Higher Eukaryotes

ABSTRACT Aspergillus fumigatus is an important fungal pathogen against which limited treatments exist. During invasive disease, A. fumigatus hyphae grow in a highly polarized fashion, forming filaments that invade blood vessels and disseminate to distant sites. Once invasion and dissemination occur, mortality rates are high. We have previously shown that the Ras signaling pathway is an important regulator of the hyphal growth machinery supporting virulence in A. fumigatus. Here, we show that functional Ras signaling in A. fumigatus requires a novel, fungus-specific domain within the Ras protein. This domain is highly conserved among fungi, yet absent in higher eukaryotes, suggesting a potentially crucial difference in the regulation of Ras pathway activity between the human host and the fungal pathogen. Exploration of the mechanisms through which this domain regulates signaling could lead to novel antifungal therapies specifically targeting fungal Ras pathways. Ras proteins function as conserved regulators of eukaryotic growth and differentiation and are essential signaling proteins orchestrating virulence in pathogenic fungi. Here, we report the identification of a novel N-terminal domain of the RasA protein in the filamentous fungus Aspergillus fumigatus. Whereas this domain is absent in Ras homologs of higher eukaryotes, the N-terminal extension is conserved among fungi and is characterized by a short string of two to eight amino acids terminating in an invariant arginine. For this reason, we have termed the RasA N-terminal domain the invariant arginine domain (IRD). Through mutational analyses, the IRD was found to be essential for polarized morphogenesis and asexual development, with the invariant arginine residue being most essential. Although IRD truncation resulted in a nonfunctional Ras phenotype, IRD mutation was not associated with mislocalization of the RasA protein or significant changes in steady-state RasA activity levels. Mutation of the RasA IRD diminished protein kinase A (PKA) activation and resulted in decreased interaction with the Rho-type GTPase, Cdc42. Taken together, our findings reveal novel, fungus-specific mechanisms for Ras protein function and signal transduction. IMPORTANCE Aspergillus fumigatus is an important fungal pathogen against which limited treatments exist. During invasive disease, A. fumigatus hyphae grow in a highly polarized fashion, forming filaments that invade blood vessels and disseminate to distant sites. Once invasion and dissemination occur, mortality rates are high. We have previously shown that the Ras signaling pathway is an important regulator of the hyphal growth machinery supporting virulence in A. fumigatus. Here, we show that functional Ras signaling in A. fumigatus requires a novel, fungus-specific domain within the Ras protein. This domain is highly conserved among fungi, yet absent in higher eukaryotes, suggesting a potentially crucial difference in the regulation of Ras pathway activity between the human host and the fungal pathogen. Exploration of the mechanisms through which this domain regulates signaling could lead to novel antifungal therapies specifically targeting fungal Ras pathways.

scholarly journals Differential Effects of Inhibiting Chitin and 1,3-β-d-Glucan Synthesis in Ras and Calcineurin Mutants of Aspergillus fumigatus

2008 ◽  
Vol 53 (2) ◽  
pp. 476-482 ◽  
Author(s):  
Jarrod R. Fortwendel ◽  
Praveen Rao Juvvadi ◽  
Nadthanan Pinchai ◽  
B. Zachary Perfect ◽  
J. Andrew Alspaugh ◽  
...  
Keyword(s):  
Cell Wall ◽  
Aspergillus Fumigatus ◽  
Hyphal Growth ◽  
Invasive Disease ◽  
Growth Defect ◽  
Compensatory Response ◽  
Ras Protein ◽  
Genes Encoding ◽  
Glucan Synthesis ◽  
Calcineurin Pathway

ABSTRACT Aspergillus fumigatus must be able to properly form hyphae and maintain cell wall integrity in order to establish invasive disease. Ras proteins and calcineurin each have been implicated as having roles in these processes. Here, we further delineate the roles of calcineurin and Ras activity in cell wall biosynthesis and hyphal morphology using genetic and pharmacologic tools. Strains deleted for three genes encoding proteins of these pathways, rasA (the Ras protein), cnaA (calcineurin), or crzA (the zinc finger transcription factor downstream of calcineurin), all displayed decreased cell wall 1,3-β-d-glucan content. Echinocandin treatment further decreased the levels of 1,3-β-d-glucan for all strains tested yet also partially corrected the hyphal growth defect of the ΔrasA strain. The inhibition of glucan synthesis caused an increase in chitin content for wild-type, dominant-active rasA, and ΔrasA strains. However, this important compensatory response was diminished in the calcineurin pathway mutants (ΔcnaA and ΔcrzA). Taken together, our data suggest that the Ras and calcineurin pathways act in parallel to regulate cell wall formation and hyphal growth. Additionally, the calcineurin pathway elements cnaA and crzA play a major role in proper chitin and glucan incorporation into the A. fumigatus cell wall.

scholarly journals Ethylene Production by Botrytis cinerea In Vitro and in Tomatoes

2002 ◽  
Vol 68 (11) ◽  
pp. 5342-5350 ◽  
Author(s):  
Simona M. Cristescu ◽  
Domenico De Martinis ◽  
Sacco te Lintel Hekkert ◽  
David H. Parker ◽  
Frans J. M. Harren
Keyword(s):  
Botrytis Cinerea ◽  
Ethylene Production ◽  
Tomato Fruit ◽  
Hyphal Growth ◽  
Phytopathogenic Fungus ◽  
Aminooxyacetic Acid ◽  
Emission Rates ◽  
Ethylene Emission ◽  
Acid Pathway

ABSTRACT A laser-based ethylene detector was used for on-line monitoring of ethylene released by the phytopathogenic fungus Botrytis cinerea in vitro and in tomato fruit. Ethylene data were combined with the results of a cytological analysis of germination of B. cinerea conidia and hyphal growth. We found that aminoethoxyvinylglycine and aminooxyacetic acid, which are competitive inhibitors of the 1-aminocyclopropane-1-carboxylic acid pathway, did not inhibit the ethylene emission by B. cinerea and that the fungus most likely produces ethylene via the 2-keto-4-methylthiobutyric acid pathway. B. cinerea is able to produce ethylene in vitro, and the emission of ethylene follows the pattern that is associated with hyphal growth rather than the germination of conidia. Ethylene production in vitro depended on the l-methionine concentration added to the plating medium. Higher values and higher emission rates were observed when the concentration of conidia was increased. Compared with the ethylene released by the fungus, the infection-related ethylene produced by two tomato cultivars (cultivars Money Maker and Daniela) followed a similar pattern, but the levels of emission were 100-fold higher. The time evolution of enhanced ethylene production by the infected tomatoes and the cytological observations indicate that ethylene emission by the tomato-fungus system is not triggered by the ethylene produced by B. cinerea, although it is strongly synchronized with the growth rate of the fungus inside the tomato.

The relationship between rhythmic hyphal growth and circadian formation of sclerotia in Sclerotium rolfsii Sacc.

1977 ◽  
Vol 23 (8) ◽  
pp. 959-963
Author(s):  
G. Kritzman ◽  
I. Chet ◽  
Y. Henis
Keyword(s):  
Growth Rate ◽  
Solid Medium ◽  
Sclerotium Rolfsii ◽  
Rhythmic Activity ◽  
Hyphal Growth ◽  
Malate Synthase ◽  
Phytopathogenic Fungus ◽  
Rhythmic Growth ◽  
The Relationship

The mycelium of the phytopathogenic fungus Sclerotium rolfsii type R (ATCC 26326) grown on a solid medium supplemented with 10 mML-threonine exhibits a synchronous formation of sclerotia in circles whereas both leading and lateral hyphae enter into a rhythmic growth rate. A rhythmic activity of malate synthetase (malate synthase, EC 4.1.3.2) which accompanied the hyphal rhythm and preceded the formation of sclerotial circles was demonstrated. Both translocation of L-[14C]threonine and incorporation of L-[14C]leucine were significantly related to the circadian formation of sclerotia.

scholarly journals Molecular and comparative genomic analyses reveal evolutionarily conserved and unique features of the Schizosaccharomyces japonicus mycelial growth and the underlying genomic changes

2021 ◽  
Author(s):  
László Attila Papp ◽  
Lajos Ács-Szabó ◽  
Gyula Batta ◽  
Ida Miklós
Keyword(s):  
Mycelial Growth ◽  
Fungal Pathogens ◽  
Hyphal Growth ◽  
Phytopathogenic Fungus ◽  
Comparative Genomic ◽  
Human Pathogens ◽  
Sequence Alignments ◽  
Genomic Changes ◽  
Expression Of Genes ◽  
Genomic Analyses

AbstractFungal pathogens, from phytopathogenic fungus to human pathogens, are able to alternate between the yeast-like form and filamentous forms. This morphological transition (dimorphism) is in close connection with their pathogenic lifestyles and with their responses to changing environmental conditions. The mechanisms governing these morphogenetic conversions are still not fully understood. Therefore, we studied the filamentous growth of the less-known, non-pathogenic dimorphic fission yeast, S. japonicus, which belongs to an ancient and early evolved branch of the Ascomycota. Its RNA sequencing revealed that several hundred genes were up- or down-regulated in the hyphae compared to the yeast-phase cells. These genes belonged to different GO categories, confirming that mycelial growth is a rather complex process. The genes of transport- and metabolic processes appeared especially in high numbers among them. High expression of genes involved in glycolysis and ethanol production was found in the hyphae, while other results pointed to the regulatory role of the protein kinase A (PKA) pathway. The homologues of 49 S. japonicus filament-associated genes were found by sequence alignments also in seven distantly related dimorphic and filamentous species. The comparative genomic analyses between S. japonicus and the closely related but non-dimorphic S. pombe shed some light on the differences in their genomes. All these data can contribute to a better understanding of hyphal growth and those genomic rearrangements that underlie it.

scholarly journals Interactions in the Tomato Rhizosphere of Two Pseudomonas Biocontrol Strains with the Phytopathogenic Fungus Fusarium oxysporum f. sp. radicis-lycopersici

2003 ◽  
Vol 16 (11) ◽  
pp. 983-993 ◽  
Author(s):  
Annouschka Bolwerk ◽  
Anastasia L. Lagopodi ◽  
André H. M. Wijfjes ◽  
Gerda E. M. Lamers ◽  
Thomas F. C. Chin-A-Woeng ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Laser Scanning ◽  
Hyphal Growth ◽  
Confocal Laser Scanning Microscope ◽  
Systemic Resistance ◽  
Phytopathogenic Fungus ◽  
Confocal Laser ◽  
Bacterial Strains ◽  
Tomato Root ◽  
Biocontrol Bacteria

The fungus Fusarium oxysporum f. sp. radicis-lycopersici causes foot and root rot of tomato plants, which can be controlled by the bacteria Pseudomonas fluorescens WCS365 and P. chlororaphis PCL1391. Induced systemic resistance is thought to be involved in biocontrol by P. fluorescens WCS365. The antifungal metabolite phenazine-1-carbox-amide (PCN), as well as efficient root colonization, are essential in the mechanism of biocontrol by P. chlororaphis PCL1391. To understand the effects of bacterial strains WCS365 and PCL1391 on the fungus in the tomato rhizosphere, microscopic analyses were performed using different autofluorescent proteins as markers. Tomato seedlings were inoculated with biocontrol bacteria and planted in an F. oxysporum f. sp. radicis-lycopersici-infested gnotobiotic sand system. Confocal laser scanning microscope analyses of the interactions in the tomato rhizosphere revealed that i) the microbes effectively compete for the same niche, and presumably also for root exudate nutrients; ii) the presence of either of the two bacteria negatively affects infection of the tomato root by the fungus; iii) both biocontrol bacteria colonize the hyphae extensively, which may represent a new mechanism in biocontrol by these pseudomonads; and iv) the production of PCN by P. chlororaphis PCL1391 negatively affects hyphal growth and branching, which presumably affects the colonization and infecting ability of the fungus.

Microscopy studies of powdery mildew on summer squash

1991 ◽  
Vol 49 ◽  
pp. 520-521
Author(s):  
John S. Gardner ◽  
W. M. Hess
Keyword(s):  
Powdery Mildew ◽  
Tip Growth ◽  
Hyphal Growth ◽  
Plant Tissues ◽  
Vegetative Hypha ◽  
Powdery Mildews ◽  
Summer Squash ◽  
Conidial Formation ◽  
Polar Tip Growth ◽  
Short Conidiophore

Powdery mildews are characterized by the appearance of spots or patches of a white to grayish, powdery, mildewy growth on plant tissues, entire leaves or other organs. Ervsiphe cichoracearum, the powdery mildew of cucurbits is among the most serious parasites, and the most common. The conidia are formed similar to the process described for Ervsiphe graminis by Cole and Samson. Theconidial chains mature basipetally from a short, conidiophore mother-cell at the base of the fertile hypha which arises holoblastically from the conidiophore. During early development it probably elongates by polar-tip growth like a vegetative hypha. A septum forms just above the conidiophore apex. Additional septa develop in acropetal succession. However, the conidia of E. cichoracearum are more doliform than condia from E. graminis. The purpose of these investigations was to use scanning electron microscopy (SEM) to demonstrate the nature of hyphal growth and conidial formation of E. cichoracearum on field-grown squash leaves.

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