scholarly journals The cAMP Signaling Pathway in Fusarium verticillioides Is Important for Conidiation, Plant Infection, and Stress Responses but Not Fumonisin Production

2010 ◽  
Vol 23 (4) ◽  
pp. 522-533 ◽  
Author(s):  
Yoon-E Choi ◽  
Jin-Rong Xu
Keyword(s):  
Stress Responses ◽  
Fungal Pathogens ◽  
Fusarium Verticillioides ◽  
Animal Health ◽  
Toxin Production ◽  
Catalytic Subunit ◽  
Camp Signaling ◽  
Deletion Mutants ◽  
Plant Infection ◽  
Pka Pathway

Fusarium verticillioides is one of the most important fungal pathogens of maize. Mycotoxin, fumonisins produced by this pathogen pose a threat to human and animal health. Because cAMP signaling has been implicated in regulating diverse developmental and infection processes in fungal pathogens, in this study, we aimed to elucidate the function of the cAMP–protein kinase A (PKA) pathway in toxin production and plant infection in F. verticillioides. Targeted deletion mutants were generated for the CPK1 and FAC1 genes that encode a catalytic subunit of PKA and the adenylate cyclase, respectively. Defects in radial growth and macroconidiation were observed in both the cpk1 and fac1 deletion mutants. The fac1 mutant also was significantly reduced in virulence and microconidiation but increased in tolerance to heat and oxidative stresses. These phenotypes were not observed in the cpk1 mutant, indicating that additional catalytic subunit of PKA must exist and function downstream from FAC1. The fac1 mutant formed microconidia mainly in false heads. The expression levels of the hydrophobin genes HYD1 and HYD2, which are known to be associated with change in formation of microconidia, were significantly reduced in the fac1 mutant. Expression of F. verticillioides GSY2 and HSP26 genes, two other putative downstream targets of FAC1, was increased in the fac1 mutant and may be associated with its enhanced stress tolerance. Although fumonisin production was normal, biosynthesis of bikaverin was increased in the fac1 mutant, suggesting that FAC1 and cAMP signaling may have pathway-or metabolite-specific regulatory roles in secondary metabolism. Overall, the pleiotropic defects of the fac1 deletion mutant indicate that the cAMP-PKA pathway is involved in growth, conidiation, bikaverin production, and plant infection in F. verticillioides.

scholarly journals Fusarium verticillioides: Advancements in Understanding the Toxicity, Virulence, and Niche Adaptations of a Model Mycotoxigenic Pathogen of Maize

2018 ◽  
Vol 108 (3) ◽  
pp. 312-326 ◽  
Author(s):  
Alex A. Blacutt ◽  
Scott E. Gold ◽  
Kenneth A. Voss ◽  
Minglu Gao ◽  
Anthony E. Glenn
Keyword(s):  
Secondary Metabolites ◽  
Current Knowledge ◽  
Fusarium Verticillioides ◽  
Animal Health ◽  
Disease Outbreaks ◽  
Toxin Production ◽  
Economic Returns ◽  
Plant Host ◽  
Host Interactions ◽  
Basic And Applied Research

The importance of understanding the biology of the mycotoxigenic fungus Fusarium verticillioides and its various microbial and plant host interactions is critical given its threat to maize, one of the world’s most valuable food crops. Disease outbreaks and mycotoxin contamination of grain threaten economic returns and have grave implications for human and animal health and food security. Furthermore, F. verticillioides is a member of a genus of significant phytopathogens and, thus, data regarding its host association, biosynthesis of secondary metabolites, and other metabolic (degradative) capabilities are consequential to both basic and applied research efforts across multiple pathosystems. Notorious among its secondary metabolites are the fumonisin mycotoxins, which cause severe animal diseases and are implicated in human disease. Additionally, studies of these mycotoxins have led to new understandings of F. verticillioides plant pathogenicity and provide tools for research into cellular processes and host–pathogen interaction strategies. This review presents current knowledge regarding several significant lines of F. verticillioides research, including facets of toxin production, virulence, and novel fitness strategies exhibited by this fungus across rhizosphere and plant environments.

scholarly journals Regulation of biotic interactions and responses to abiotic stresses by MAP kinase pathways in plant pathogenic fungi

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Xue Zhang ◽  
Zeyi Wang ◽  
Cong Jiang ◽  
Jin-Rong Xu
Keyword(s):  
Cell Wall ◽  
Map Kinase ◽  
Stress Responses ◽  
Abiotic Stresses ◽  
Fungal Pathogens ◽  
Pathogenic Fungi ◽  
Hog Pathway ◽  
Mapk Pathways ◽  
Plant Infection ◽  
Map Kinase Pathways

AbstractLike other eukaryotes, fungi use MAP kinase (MAPK) pathways to mediate cellular changes responding to external stimuli. In the past two decades, three well-conserved MAP kinase pathways have been characterized in various plant pathogenic fungi for regulating responses and adaptations to a variety of biotic and abiotic stresses encountered during plant infection or survival in nature. The invasive growth (IG) pathway is homologous to the yeast pheromone response and filamentation pathways. In plant pathogens, the IG pathway often is essential for pathogenesis by regulating infection-related morphogenesis, such as appressorium formation, penetration, and invasive growth. The cell wall integrity (CWI) pathway also is important for plant infection although the infection processes it regulates vary among fungal pathogens. Besides its universal function in cell wall integrity, it often plays a minor role in responses to oxidative and cell wall stresses. Both the IG and CWI pathways are involved in regulating known virulence factors as well as effector genes during plant infection and mediating defenses against mycoviruses, bacteria, and other fungi. In contrast, the high osmolarity growth (HOG) pathway is dispensable for virulence in some fungi although it is essential for plant infection in others. It regulates osmoregulation in hyphae and is dispensable for appressorium turgor generation. The HOG pathway also plays a major role for responding to oxidative, heat, and other environmental stresses and is overstimulated by phenylpyrrole fungicides. Moreover, these three MAPK pathways crosstalk and coordinately regulate responses to various biotic and abiotic stresses. The IG and CWI pathways, particularly the latter, also are involved in responding to abiotic stresses to various degrees in different fungal pathogens, and the HOG pathway also plays a role in interactions with other microbes or fungi. Furthermore, some infection processes or stress responses are co-regulated by MAPK pathways with cAMP or Ca2+/CaM signaling. Overall, functions of individual MAP kinase pathways in pathogenesis and stress responses have been well characterized in a number of fungal pathogens, showing the conserved genetic elements with diverged functions, likely by rewiring transcriptional regulatory networks. In the near future, applications of genomics and proteomics approaches will likely lead to better understanding of crosstalk among the MAPKs and with other signaling pathways as well as roles of MAPKs in defense against other microbes (biotic interactions).

scholarly journals FvSTUA is a Key Regulator of Sporulation, Toxin Synthesis, and Virulence in Fusarium verticillioides

2020 ◽  
Vol 33 (7) ◽  
pp. 958-971
Author(s):  
M. Rath ◽  
N. J. Crenshaw ◽  
L. W. Lofton ◽  
A. E. Glenn ◽  
S. E. Gold
Keyword(s):  
Transcription Factor ◽  
Birth Defects ◽  
Fusarium Verticillioides ◽  
Transcriptional Regulator ◽  
Toxin Production ◽  
Deletion Mutants ◽  
Expression Of Genes ◽  
Aerial Hyphae ◽  
Differential Expression Of Genes

Fusarium verticillioides is one of the most important pathogens of maize, causing rot and producing fumonisin mycotoxins during infection. Ingestion of fumonisin-contaminated corn causes underperformance and even fatal toxicity in livestock and is associated with neural tube birth defects, growth stunting in children, and some cancers. StuA, an APSES-class transcription factor, is a major developmental transcriptional regulator in fungi. It has been shown to regulate crucial developmental processes, such as sporulation, virulence, and mycotoxin synthesis among others. In this study, the role of FvSTUA in F. verticillioides was examined by characterizing ∆FvstuA deletion mutants functionally and transcriptomally. The deletion mutants exhibited reduced vegetative growth, stunted aerial hyphae, and significant reductions in microconidiation. Macroconidiation and hydrophobicity of the deletion strains were reduced as well. Additionally, fumonisin production and virulence of the deletion mutants were greatly reduced. Transcriptomic analysis revealed downregulation of expression of several genes in the fumonisin and fusarin C biosynthetic clusters and differential expression of genes involved in conidiation and virulence. Nuclear localization of FvSTUA supported its likely function as a transcription factor. Together, our results indicate that FvSTUA plays a global role in transcriptional regulation in F. verticillioides influencing morphogenesis, toxin production, and virulence.

scholarly journals Virus Infection of Aspergillus fumigatus Compromises the Fungus in Intermicrobial Competition

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 686
Author(s):  
Hasan Nazik ◽  
Ioly Kotta-Loizou ◽  
Gabriele Sass ◽  
Robert H. A. Coutts ◽  
David A. Stevens
Keyword(s):  
Virus Infection ◽  
Aspergillus Fumigatus ◽  
Stress Responses ◽  
Fungal Pathogens ◽  
Clinical Settings ◽  
Virus Infections ◽  
Fungal Strains ◽  
Common Reference ◽  
Strain Virus ◽  
Free Strain

Aspergillus and Pseudomonas compete in nature, and are the commonest bacterial and fungal pathogens in some clinical settings, such as the cystic fibrosis lung. Virus infections of fungi occur naturally. Effects on fungal physiology need delineation. A common reference Aspergillus fumigatus strain, long studied in two (of many) laboratories, was found infected with the AfuPmV-1 virus. One isolate was cured of virus, producing a virus-free strain. Virus from the infected strain was purified and used to re-infect three subcultures of the virus-free fungus, producing six fungal strains, otherwise isogenic. They were studied in intermicrobial competition with Pseudomonasaeruginosa. Pseudomonas culture filtrates inhibited forming or preformed Aspergillus biofilm from infected strains to a greater extent, also seen when Pseudomonas volatiles were assayed on Aspergillus. Purified iron-chelating Pseudomonas molecules, known inhibitors of Aspergillus biofilm, reproduced these differences. Iron, a stimulus of Aspergillus, enhanced the virus-free fungus, compared to infected. All infected fungal strains behaved similarly in assays. We show an important consequence of virus infection, a weakening in intermicrobial competition. Viral infection may affect the outcome of bacterial–fungal competition in nature and patients. We suggest that this occurs via alteration in fungal stress responses, the mechanism best delineated here is a result of virus-induced altered Aspergillus iron metabolism.

scholarly journals The cAMP-PKA Pathway Regulates Growth, Sexual and Asexual Differentiation, and Pathogenesis in Fusarium graminearum

2014 ◽  
Vol 27 (6) ◽  
pp. 557-566 ◽  
Author(s):  
Shuai Hu ◽  
Xiaoying Zhou ◽  
Xiaoying Gu ◽  
Shulin Cao ◽  
Chengfang Wang ◽  
...  
Keyword(s):  
Fusarium Graminearum ◽  
Vegetative Growth ◽  
Double Mutant ◽  
Elevated Temperatures ◽  
Hyphal Growth ◽  
Growth Defects ◽  
Plant Infection ◽  
Dependent Protein ◽  
Pka Pathway

Like many other filamentous ascomycetes, Fusarium graminearum contains two genes named CPK1 and CPK2 that encode the catalytic subunits of cyclic AMP (cAMP)-dependent protein kinase A (PKA). To determine the role of cAMP signaling in pathogenesis and development in F. graminearum, we functionally characterized these two genes. In addition, we generated and characterized the cpk1 cpk2 double and fac1 adenylate cyclase gene deletion mutants. The cpk1 mutant was significantly reduced in vegetative growth, conidiation, and deoxynivalenol production but it had increased tolerance to elevated temperatures. It was defective in the production of penetration branches on plant surfaces, colonization of wheat rachises, and spreading in flowering wheat heads. Deletion of CPK1 had no effect on perithecium development but the cpk1 mutant was defective in ascospore maturation and releasing. In contrast, the cpk2 mutant had no detectable phenotypes, suggesting that CPK2 contributes minimally to PKA activities in F. graminearum. Nevertheless, the cpk1 cpk2 double mutant had more severe defects in vegetative growth and rarely produced morphologically abnormal conidia. The double mutant, unlike the cpk1 or cpk2 mutant, was nonpathogenic and failed to form perithecia on self-mating plates. Therefore, CPK1 and CPK2 must have overlapping functions in vegetative growth, differentiation, and plant infection in F. graminearum. The fac1 mutant was also nonpathogenic and had growth defects similar to those of the cpk1 cpk2 mutant. However, deletion of FAC1 had no effect on conidium morphology. These results indicated that CPK1 is the major PKA catalytic subunit gene and that the cAMP-PKA pathway plays critical roles in hyphal growth, conidiation, ascosporogenesis, and plant infection in F. graminearum.

scholarly journals Antifungal activities of thiosemicarbazones and semicarbazones against mycotoxigenic fungi

2014 ◽  
Vol 38 (6) ◽  
pp. 531-537 ◽  
Author(s):  
Rojane de Oliveira Paiva ◽  
Lucimar Ferreira Kneipp ◽  
Carla Marins Goular ◽  
Mariana Almeida Albuquerque ◽  
Aurea Echevarria
Keyword(s):  
Antifungal Activity ◽  
Aspergillus Flavus ◽  
Fungicidal Activity ◽  
Fusarium Verticillioides ◽  
Animal Health ◽  
Fungistatic Activity ◽  
Mycotoxigenic Fungi ◽  
Quality Of Food ◽  
Chelating Effect

Mycotoxigenic fungi can compromise the quality of food, exposing human and animal health at risk. The antifungal activity of eight thiosemicarbazones (1-8) and nine semicarbazones (9-17) was evaluated against Aspergillus flavus, A. nomius, A. ochraceus, A. parasiticus and Fusarium verticillioides. Thiosemicarbazones had MIC values of 125-500 µg/ml. The thiosemicarbazones 1 and 2 exerted fungistatic activity against Aspergillus spp., and thiosemicarbazone 2 exerted fungicidal activity against F. verticillioides. Compound 2 showed an iron chelating effect of 63%. The ergosterol content of A. parasiticus had a decrease of 28 and 71% for the 31.2 and 62.5 µg/ml concentrations of thiosemicarbazone 2 compared to the control. The obtained results of antifungal activity revealed that thiosemicarbazone class was more active when compared to semicarbazone class and, the thiosemicarbazone 2 was the most active compound, specially, against Aspergillus spp.

scholarly journals Structural and Evolutionary Analyses of PR-4 SUGARWINs Points to a Different Pattern of Protein Function

2021 ◽  
Vol 12 ◽  
Author(s):  
Lorhenn Bryanda Lemes Maia ◽  
Humberto D’Muniz Pereira ◽  
Richard Charles Garratt ◽  
José Brandão-Neto ◽  
Flavio Henrique-Silva ◽  
...  
Keyword(s):  
Protein Function ◽  
Fungal Pathogens ◽  
Fusarium Verticillioides ◽  
Homology Model ◽  
Rnase Activity ◽  
Structural Determinants ◽  
Diverse Range ◽  
Chitin Binding Domain ◽  
Pathogenesis Related Protein ◽  
Dynamics Simulations

SUGARWINs are PR-4 proteins associated with sugarcane defense against phytopathogens. Their expression is induced in response to damage by Diatraea saccharalis larvae. These proteins play an important role in plant defense, in particular against fungal pathogens, such as Colletothricum falcatum (Went) and Fusarium verticillioides. The pathogenesis-related protein-4 (PR-4) family is a group of proteins equipped with a BARWIN domain, which may be associated with a chitin-binding domain also known as the hevein-like domain. Several PR-4 proteins exhibit both chitinase and RNase activity, with the latter being associated with the presence of two histidine residues H11 and H113 (BARWIN) [H44 and H146, SUGARWINs] in the BARWIN-like domain. In sugarcane, similar to other PR-4 proteins, SUGARWIN1 exhibits ribonuclease, chitosanase and chitinase activities, whereas SUGARWIN2 only exhibits chitosanase activity. In order to decipher the structural determinants involved in this diverse range of enzyme specificities, we determined the 3-D structure of SUGARWIN2, at 1.55Å by X-ray diffraction. This is the first structure of a PR-4 protein where the first histidine has been replaced by asparagine and was subsequently used to build a homology model for SUGARWIN1. Molecular dynamics simulations of both proteins revealed the presence of a flexible loop only in SUGARWIN1 and we postulate that this, together with the presence of the catalytic histidine at position 42, renders it competent as a ribonuclease. The more electropositive surface potential of SUGARWIN1 would also be expected to favor complex formation with RNA. A phylogenetic analysis of PR-4 proteins obtained from 106 Embryophyta genomes showed that both catalytic histidines are widespread among them with few replacements in these amino acid positions during the gene family evolutionary history. We observe that the H11 replacement by N11 is also present in two other sugarcane PR-4 proteins: SUGARWIN3 and SUGARWIN4. We propose that RNase activity was present in the first Embryophyta PR-4 proteins but was recently lost in members of this family during the course of evolution.

scholarly journals Fusarium verticillioides FvPex8 is a key component of peroxisomal docking/translocation module that serves important roles in fumonisin biosynthesis but not in virulence

2020 ◽  
Author(s):  
Wenying Yu ◽  
Mei Lin ◽  
Minghui Peng ◽  
Huijuan Yan ◽  
Jie Zhou ◽  
...  
Keyword(s):  
Expression Profiles ◽  
Fusarium Verticillioides ◽  
Fumonisin B1 ◽  
Gene Expression Profiles ◽  
Deletion Mutants ◽  
Altered Expression ◽  
The Core ◽  
Metabolic Functions ◽  
Peroxisome Membrane

AbstractPeroxisomes are ubiquitous organelles in eukaryotic cells that fulfill various important metabolic functions. In this study, we investigated the role of Docking/Translocation Module (DTM) peroxins, mainly FvPex8, FvPex13, FvPex14, and FvPex33, in Fusarium verticillioides virulence and fumonisin B1 (FB1) biosynthesis. Protein interaction experiments suggested that FvPex13 serves as the core subunit of F. verticillioides DTM. When we generated gene deletion mutants (ΔFvpex8, ΔFvpex13, ΔFvpex14, ΔFvpex33, ΔFvpex33/14) and examined whether the expression of other peroxin genes were affected in the DTM mutants, ΔFvpex8 strain showed most drastic changes to PEX gene expression profiles. Deletion mutants exhibited disparity in carbon source utilization and defect in cell wall integrity when stress agents were applied. Under nutrient starvation, mutants also showed higher levels of lipid droplet accumulation. Notably, ΔFvpex8 mutant showed significant FB1 reduction and altered expression of FUM1 and FUM19 genes. However, FvPex13 was primarily responsible for virulence, while ΔFvpex33/14 double mutant also showed virulence defect. In summary, our study suggests that FvPex13 is the core component of DTM, regulating peroxisome membrane biogenesis as well as PTS1- and PTS2-mediated transmembrane cargo transportation. Importantly, we predict FvPex8 as a key component in DTM that affects peroxisome function in FB1 biosynthesis in F. verticillioides.

scholarly journals Pleiotropic Roles of the Msi1-Like Protein Msl1 in Cryptococcus neoformans

2012 ◽  
Vol 11 (12) ◽  
pp. 1482-1495 ◽  
Author(s):  
Dong-Hoon Yang ◽  
Shinae Maeng ◽  
Anna K. Strain ◽  
Anna Floyd ◽  
Kirsten Nielsen ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Stress Responses ◽  
Fungal Pathogens ◽  
Independent Manner ◽  
Content Type ◽  
Antifungal Drug Resistance ◽  
Human Fungal Pathogen ◽  
Assembly Factor ◽  
Life Threatening ◽  
Stress Related Genes

ABSTRACT Msi1-like (MSIL) proteins contain WD40 motifs and have a pleiotropic cellular function as negative regulators of the Ras/cyclic AMP (cAMP) pathway and components of chromatin assembly factor 1 (CAF-1), yet they have not been studied in fungal pathogens. Here we identified and characterized an MSIL protein, Msl1, in Cryptococcus neoformans , which causes life-threatening meningoencephalitis in humans. Notably, Msl1 plays pleiotropic roles in C. neoformans in both cAMP-dependent and -independent manners largely independent of Ras. Msl1 negatively controls antioxidant melanin production and sexual differentiation, and this was repressed by the inhibition of the cAMP-signaling pathway. In contrast, Msl1 controls thermotolerance, diverse stress responses, and antifungal drug resistance in a Ras/cAMP-independent manner. Cac2, which is the second CAF-1 component, appears to play both redundant and distinct functions compared to the functions of Msl1. Msl1 is required for the full virulence of C. neoformans . Transcriptome analysis identified a group of Msl1-regulated genes, which include stress-related genes such as HSP12 and HSP78 . In conclusion, this study demonstrates pleiotropic roles of Msl1 in the human fungal pathogen C. neoformans , providing insight into a potential novel antifungal therapeutic target.

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