scholarly journals Proteinaceous necrotrophic effectors in fungal virulence

2010 ◽  
Vol 37 (10) ◽  
pp. 907 ◽  
Author(s):  
Kar-Chun Tan ◽  
Richard P. Oliver ◽  
Peter S. Solomon ◽  
Caroline S. Moffat
Keyword(s):  
Fungal Pathogens ◽  
Host Plants ◽  
Triticum Aestivum L ◽  
Effector Proteins ◽  
Fungal Virulence ◽  
Pyrenophora Tritici Repentis ◽  
Necrotrophic Fungi ◽  
Necrotrophic Effectors ◽  
Inside Out ◽  
Shed Light

The host–pathogen interface can be considered as a biological battlefront. Molecules produced by both the pathogen and the host are critical factors determining the outcome of the interaction. Recent studies have revealed that an increasing number of necrotrophic fungal pathogens produce small proteinaceous effectors that are able to function as virulence factors. These molecules can cause tissue death in host plants that possess dominant sensitivity genes, leading to subsequent pathogen colonisation. Such effectors are only found in necrotrophic fungi, yet their roles in virulence are poorly understood. However, several recent key studies of necrotrophic effectors from two wheat (Triticum aestivum L.) pathogens, Pyrenophora tritici-repentis (Died.) Drechs. and Stagonospora nodorum (Berk.) Castell. & Germano, have shed light upon how these effector proteins serve to disable the host from the inside out.

scholarly journals The Ustilago hordei–Barley Interaction is a Versatile System for Characterization of Fungal Effectors

2021 ◽  
Vol 7 (2) ◽  
pp. 86
Author(s):  
Bilal Ökmen ◽  
Daniela Schwammbach ◽  
Guus Bakkeren ◽  
Ulla Neumann ◽  
Gunther Doehlemann
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Expression System ◽  
Pathogenic Fungi ◽  
Effector Proteins ◽  
Mating Partner ◽  
Fungal Virulence ◽  
Functional Studies ◽  
Infection Structures ◽  
Ustilago Hordei

Obligate biotrophic fungal pathogens, such as Blumeria graminis and Puccinia graminis, are amongst the most devastating plant pathogens, causing dramatic yield losses in many economically important crops worldwide. However, a lack of reliable tools for the efficient genetic transformation has hampered studies into the molecular basis of their virulence or pathogenicity. In this study, we present the Ustilago hordei–barley pathosystem as a model to characterize effectors from different plant pathogenic fungi. We generate U. hordei solopathogenic strains, which form infectious filaments without the presence of a compatible mating partner. Solopathogenic strains are suitable for heterologous expression system for fungal virulence factors. A highly efficient Crispr/Cas9 gene editing system is made available for U. hordei. In addition, U. hordei infection structures during barley colonization are analyzed using transmission electron microscopy, showing that U. hordei forms intracellular infection structures sharing high similarity to haustoria formed by obligate rust and powdery mildew fungi. Thus, U. hordei has high potential as a fungal expression platform for functional studies of heterologous effector proteins in barley.

scholarly journals Characterizing Virulence of the Pyrenophora tritici-repentis Isolates Lacking Both ToxA and ToxB Genes

Pathogens ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 74 ◽  
Author(s):  
Jingwei Guo ◽  
Gongjun Shi ◽  
Zhaohui Liu
Keyword(s):  
Triticum Aestivum L ◽  
Tan Spot ◽  
Pyrenophora Tritici Repentis ◽  
Tan Spot Disease ◽  
Hard Red Winter Wheat ◽  
Winter Wheat Cultivars ◽  
Race 2 ◽  
Genomic Regions ◽  
Race 4 ◽  
Necrotrophic Effectors

The fungus Pyrenophora tritici-repentis (Ptr) causes tan spot of wheat crops, which is an important disease worldwide. Based on the production of the three known necrotrophic effectors (NEs), the fungal isolates are classified into eight races with race 4 producing no known NEs. From a laboratory cross between 86–124 (race 2 carrying the ToxA gene for the production of Ptr ToxA) and DW5 (race 5 carrying the ToxB gene for the production of Ptr ToxB), we have obtained some Ptr isolates lacking both the ToxA and ToxB genes, which, by definition, should be classified as race 4. In this work, we characterized virulence of two of these isolates called B16 and B17 by inoculating them onto various common wheat (Triticum aestivum L.) and durum (T. turgidum L.) genotypes. It was found that the two isolates still caused disease on some genotypes of both common and durum wheat. Disease evaluations were also conducted in recombinant inbred line populations derived from two hard red winter wheat cultivars: Harry and Wesley. QTL mapping in this population revealed that three genomic regions were significantly associated with disease, which are different from the three known NE sensitivity loci. This result further indicates the existence of other NE-host sensitivity gene interactions in the wheat tan spot disease system.

scholarly journals Synergistic Action of a Metalloprotease and a Serine Protease from Fusarium oxysporum f. sp. lycopersici Cleaves Chitin-Binding Tomato Chitinases, Reduces Their Antifungal Activity, and Enhances Fungal Virulence

2015 ◽  
Vol 28 (9) ◽  
pp. 996-1008 ◽  
Author(s):  
Mansoor Karimi Jashni ◽  
Ivo H. M. Dols ◽  
Yuichiro Iida ◽  
Sjef Boeren ◽  
Henriek G. Beenen ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fusarium Oxysporum ◽  
Serine Protease ◽  
Fungal Pathogens ◽  
Effector Proteins ◽  
Fungal Cell ◽  
Fungal Virulence ◽  
Chitin Binding Domain ◽  
Double Deletion ◽  
Major Structural Component

As part of their defense strategy against fungal pathogens, plants secrete chitinases that degrade chitin, the major structural component of fungal cell walls. Some fungi are not sensitive to plant chitinases because they secrete chitin-binding effector proteins that protect their cell wall against these enzymes. However, it is not known how fungal pathogens that lack chitin-binding effectors overcome this plant defense barrier. Here, we investigated the ability of fungal tomato pathogens to cleave chitin-binding domain (CBD)-containing chitinases and its effect on fungal virulence. Four tomato CBD chitinases were produced in Pichia pastoris and were incubated with secreted proteins isolated from seven fungal tomato pathogens. Of these, Fusarium oxysporum f. sp. lycopersici, Verticillium dahliae, and Botrytis cinerea were able to cleave the extracellular tomato chitinases SlChi1 and SlChi13. Cleavage by F. oxysporum removed the CBD from the N-terminus, shown by mass spectrometry, and significantly reduced the chitinase and antifungal activity of both chitinases. Both secreted metalloprotease FoMep1 and serine protease FoSep1 were responsible for this cleavage. Double deletion mutants of FoMep1 and FoSep1 of F. oxysporum lacked chitinase cleavage activity on SlChi1 and SlChi13 and showed reduced virulence on tomato. These results demonstrate the importance of plant chitinase cleavage in fungal virulence.

scholarly journals Effectors of Plant Necrotrophic Fungi

2021 ◽  
Vol 12 ◽  
Author(s):  
Dandan Shao ◽  
Damon L. Smith ◽  
Mehdi Kabbage ◽  
Mitchell G. Roth
Keyword(s):  
Fungal Pathogens ◽  
Crop Production ◽  
Plant Diseases ◽  
Economic Losses ◽  
Plant Colonization ◽  
Genetic Intervention ◽  
Necrotrophic Fungi ◽  
Plant Pathogen Interaction ◽  
Functional Context ◽  
Necrotrophic Effectors

Plant diseases caused by necrotrophic fungal pathogens result in large economic losses in field crop production worldwide. Effectors are important players of plant-pathogen interaction and deployed by pathogens to facilitate plant colonization and nutrient acquisition. Compared to biotrophic and hemibiotrophic fungal pathogens, effector biology is poorly understood for necrotrophic fungal pathogens. Recent bioinformatics advances have accelerated the prediction and discovery of effectors from necrotrophic fungi, and their functional context is currently being clarified. In this review we examine effectors utilized by necrotrophic fungi and hemibiotrophic fungi in the latter stages of disease development, including plant cell death manipulation. We define “effectors” as secreted proteins and other molecules that affect plant physiology in ways that contribute to disease establishment and progression. Studying and understanding the mechanisms of necrotrophic effectors is critical for identifying avenues of genetic intervention that could lead to improved resistance to these pathogens in plants.

scholarly journals The barley powdery mildew effectors CSEP0139 and CSEP0182 suppress cell death and promote B. graminis fungal virulence in plants

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Xue Li ◽  
Cong Jin ◽  
Hongbo Yuan ◽  
Wanting Huang ◽  
Fang Liu ◽  
...  
Keyword(s):  
Cell Death ◽  
Powdery Mildew ◽  
Host Plants ◽  
Host Immunity ◽  
Effector Proteins ◽  
Fungal Virulence ◽  
Cell Death Pathways ◽  
Barley Powdery Mildew ◽  
Powdery Mildew Fungi ◽  
Transient Overexpression

AbstractThe powdery mildew fungi secrete numerous Candidate Secreted Effector Proteins (CSEPs) to manipulate host immunity during infection of host plants. However, the function of most of these CSEPs in cell death suppression has not yet been established. Here, we identified several CSEPs from Blumeria graminis f. sp. hordei (Bgh) that have the potential to suppress BAX- and NtMEK2DD-triggered cell death in Nicotiana benthamiana. We further characterized two effector candidates, CSEP0139 and CSEP0182, from family six and thirty-two, respectively. CSEP0139 and CSEP0182 contain a functional signal peptide and are likely secreted effectors. Expression of either CSEP0139 or CSEP0182 suppressed cell death triggered by BAX and NtMEK2DD but not by the AVRa13/MLA13 pair in N. benthamiana. Transient overexpression of CSEP0139 or CSEP0182 also inhibited BAX-induced cell death and collapse of cytoplasm in barley cells. Furthermore, overexpression of either CSEPs significantly increased Bgh haustorial formation in barley, whereas host-induced gene silencing (HIGS) of the CSEP genes reduced haustorial formation, suggesting both CSEPs promote Bgh virulence in barley. In addition, expression of CSEP0139 and CSEP0182 reduced size of the lesions caused by the necrotrophic Botrytis cinerea in N. benthamiana. Our findings suggest that CSEP0139 and CSEP0182 may target cell death components in plants to promote fungal virulence, which extends the current understanding of the functions of Bgh CSEPs and provides an opportunity for further investigation of fungal virulence in relation to cell death pathways in host plants.

scholarly journals The Ustilago hordei-barley interaction is a versatile system to characterize fungal effectors

2020 ◽  
Author(s):  
Bilal Ökmen ◽  
Daniela Schwammbach ◽  
Guus Bakkeren ◽  
Ulla Neumann ◽  
Gunther Doehlemann
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Expression System ◽  
Pathogenic Fungi ◽  
Effector Proteins ◽  
Mating Partner ◽  
Fungal Virulence ◽  
Functional Studies ◽  
Infection Structures ◽  
Expression Platform

AbstractObligate biotrophic fungal pathogens, such as Blumeria graminis and Puccinia graminis, are amongst the most devastating plant pathogens, causing dramatic yield losses in many economically important crops worldwide. However, a lack of reliable tools for the efficient genetic transformation has hampered studies into the molecular basis of their virulence/pathogenicity. In this study, we present the U. hordei-barley pathosystem as a model to characterize effectors from different plant pathogenic fungi. We have generated U. hordei solopathogenic strains, which form infectious filaments without presence of compatible mating partner. Solopathogenic strains are suitable as heterologous expression system for fungal virulence factors. A highly efficient Crispr/Cas9 gene editing system is made available for U. hordei. In addition, U. hordei infection structures during barley colonization were analyzed by transmission electron microscopy, which shows that U. hordei forms intracellular infection structures sharing high similarity to haustoria formed by obligate rust and powdery mildew fungi. Thus, U. hordei has high potential as a fungal expression platform for functional studies of heterologous effector proteins in barley.

scholarly journals Reactive Oxygen Species in Host Plant Are Required for an Early Defense Response against Attack of Stagonospora nodorum Berk. Necrotrophic Effectors SnTox

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1586
Author(s):  
Svetlana Veselova ◽  
Tatyana Nuzhnaya ◽  
Guzel Burkhanova ◽  
Sergey Rumyantsev ◽  
Igor Maksimov
Keyword(s):  
Reactive Oxygen Species ◽  
Early Stage ◽  
Reactive Oxygen ◽  
Triticum Aestivum L ◽  
Redox Status ◽  
Stagonospora Nodorum ◽  
Ros Generation ◽  
Ros Production ◽  
Oxygen Species ◽  
Necrotrophic Effectors

Reactive oxygen species (ROS) play a central role in plant immune responses. The most important virulence factors of the Stagonospora nodorum Berk. are multiple fungal necrotrophic effectors (NEs) (SnTox) that affect the redox-status and cause necrosis and/or chlorosis in wheat lines possessing dominant susceptibility genes (Snn). However, the effect of NEs on ROS generation at the early stages of infection has not been studied. We studied the early stage of infection of various wheat genotypes with S nodorum isolates -Sn4VD, SnB, and Sn9MN, carrying a different set of NE genes. Our results indicate that all three NEs of SnToxA, SnTox1, SnTox3 significantly contributed to cause disease, and the virulence of the isolates depended on their differential expression in plants (Triticum aestivum L.). The Tsn1–SnToxA, Snn1–SnTox1and Snn3–SnTox3 interactions played an important role in inhibition ROS production at the initial stage of infection. The Snn3–SnTox3 inhibited ROS production in wheat by affecting NADPH-oxidases, peroxidases, superoxide dismutase and catalase. The Tsn1–SnToxA inhibited ROS production in wheat by affecting peroxidases and catalase. The Snn1–SnTox1 inhibited the production of ROS in wheat by mainly affecting a peroxidase. Collectively, these results show that the inverse gene-for gene interactions between effector of pathogen and product of host sensitivity gene suppress the host’s own PAMP-triggered immunity pathway, resulting in NE-triggered susceptibility (NETS). These results are fundamentally changing our understanding of the development of this economical important wheat disease.

scholarly journals Camphor and Eucalyptol—Anticandidal Spectrum, Antivirulence Effect, Efflux Pumps Interference and Cytotoxicity

2021 ◽  
Vol 22 (2) ◽  
pp. 483
Author(s):  
Marija Ivanov ◽  
Abhilash Kannan ◽  
Dejan S. Stojković ◽  
Jasmina Glamočlija ◽  
Ricardo C. Calhelha ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Liver Cells ◽  
Ergosterol Biosynthesis ◽  
Antifungal Compound ◽  
Porcine Liver ◽  
Fungal Virulence ◽  
Genes Encoding ◽  
Plant Constituents

Candidaalbicans represents one of the most common fungal pathogens. Due to its increasing incidence and the poor efficacy of available antifungals, finding novel antifungal molecules is of great importance. Camphor and eucalyptol are bioactive terpenoid plant constituents and their antifungal properties have been explored previously. In this study, we examined their ability to inhibit the growth of different Candida species in suspension and biofilm, to block hyphal transition along with their impact on genes encoding for efflux pumps (CDR1 and CDR2), ergosterol biosynthesis (ERG11), and cytotoxicity to primary liver cells. Camphor showed excellent antifungal activity with a minimal inhibitory concentration of 0.125–0.35 mg/mL while eucalyptol was active in the range of 2–23 mg/mL. The results showed camphor’s potential to reduce fungal virulence traits, that is, biofilm establishment and hyphae formation. On the other hand, camphor and eucalyptol treatments upregulated CDR1;CDR2 was positively regulated after eucalyptol application while camphor downregulated it. Neither had an impact on ERG11 expression. The beneficial antifungal activities of camphor were achieved with an amount that was non-toxic to porcine liver cells, making it a promising antifungal compound for future development. The antifungal concentration of eucalyptol caused cytotoxic effects and increased expression of efflux pump genes, which suggests that it is an unsuitable antifungal candidate.

Red smudge infection modifies sprouting response in four wheat lines

2003 ◽  
Vol 83 (1) ◽  
pp. 163-169 ◽  
Author(s):  
S. L. Fox ◽  
M. R. Fernandez ◽  
R. M. DePauw
Keyword(s):  
Crude Extract ◽  
Triticum Aestivum L ◽  
Preharvest Sprouting ◽  
Conidial Suspension ◽  
Percentage Germination ◽  
Germination Time ◽  
Pyrenophora Tritici Repentis ◽  
Mean Germination Time ◽  
Sprouting Resistance ◽  
Lower Temperature

Infection of wheat (Triticum aestivum L.) spikes by Pyrenophora tritici-repentis (Died.) Drechs. (Ptr) causes kernel discolouration, reducing the commercial value of the grain. Preharvest sprouting in wheat causes loss of grain yield, grain functionality and value as seed. The objective of this research was to determine the effects of Ptr infection on the expression of preharvest sprouting response. Four genotypes representing a range of preharvest sprouting response were studied: RL4137 has very good sprouting resistance; SC8021V2, good; AC Karma, fair; and Genesis, poor. These genotypes were grown in a growth cabinet and their spikes were artificially inoculated with a conidial suspension of Ptr or water. Spikes were collected at physiologic maturity, threshed by hand and germinated on wetted filter paper at 10 or 20°C to obtain a percentage germination and a mean germination time. Healthy seeds were also germinated in a solution containing a crude extract of the fungus. At 20°C, sprouting-resistant genotypes showed a significant delay in germination compared to susceptible genotypes; however, differences were not significant at the lower temperature. Genesis germinated quickly at both temperatures. All genotypes except Genesis had reductions in sprouting resistance when infected by Ptr, but these effects were significant only at 20°C. When inoculated with Ptr and germinated at 20°C, AC Karma germinated as quickly as the water controls and gave a preharvest sprouting response similar to Genesis. However, SC8021V2 and RL4137 inoculated with Ptr retained 40 and 78%, respectively, of their mean germination time compared to the water controls. Germination of healthy seeds in a solution containing a crude extract of Ptr increased the percentage germination and shortened the mean germination time of all genotypes, but did not result in significant changes for any individual line. Key words: Triticum, Pyrenophora tritici-repentis, preharvest sprouting, smudge

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