Plant pathogenic fungi
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Ladybug Fungi | Cornell Mushroom Blog

Ladybug Fungi | Cornell Mushroom Blog | Plant pathogenic fungi | Scoop.it
They may be taking over the world, but they have problems too: They have an itch they can't scratch. The dead wear fur coats. They nuke their competitors with poisonous blood. Multicolored Asian ladybugs are host to three different fungi.
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Cereal diseases caused by Fusarium graminearum: from biology of the pathogen to oxidative burst-related host defense responses

Cereal diseases caused by Fusarium graminearum: from biology of the pathogen to oxidative burst-related host defense responses | Plant pathogenic fungi | Scoop.it

Fusarium graminearum Schwabe (teleomorph: Gibberella zeae) is a destructive fungus, causing economically important diseases such as seedling blight, root and crown rot and head blight on small grain cereals, in particular wheat and barley. It is a devastating phytopathogen, not only due to causing significant yield losses, but also because of contaminating plant tissues with trichothecenes and other types of mycotoxins, which are harmful for human animal health. Several disease management strategies are used to decrease yield losses and mycotoxin production in cereals caused by this pathogenic fungus. Among various disease control methods, use of resistant cultivars could be the most effective way to combat diseases caused by F. graminearum in cereals. However, any plant cultivar with complete resistance against this pathogen was not reported worldwide and only some of the host cultivars with partial resistance against F. graminearum were identified, so far. Therefore, understanding biochemical and cytomolecular aspects of interaction in F. graminearum-cereals pathosystems would be valuable for designing novel management strategies against various diseases caused by this hemibiotrophic fungal pathogen on economically important cereals. This review is focused on biology, pathogenicity, and genetic structure of F. graminearum populations together with the role of reactive oxygen species (ROS) and antioxidant systems in association with plant cell wall in defense responses of cereals, as the main resistance mechanisms against this destructive fungus.

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Integration of danger peptide signals with herbivore‐associated molecular pattern signaling amplifies anti‐herbivore defense responses in rice - Shinya - - The Plant Journal - Wiley Online Library

Integration of danger peptide signals with herbivore‐associated molecular pattern signaling amplifies anti‐herbivore defense responses in rice - Shinya - - The Plant Journal - Wiley Online Library | Plant pathogenic fungi | Scoop.it
Plant defense against herbivores is modulated by herbivore‐associated molecular patterns (HAMPs) from oral secretions (OS) and/or saliva of insects. Furthermore, feeding wounds initiate plant self‐damage responses modulated by danger‐associated molecular patterns (DAMPs) such as immune defense‐promoting plant elicitor peptides (Peps). While temporal and spatial co‐existence of both patterns during herbivory implies a possibility of their close interaction, the molecular mechanisms remain undetermined. Here we report that exogenous application of rice (Oryza sativa) peptides (OsPeps) can elicit multiple defense responses in rice cell cultures. Specific activation of OsPROPEP3 gene transcripts in rice leaves by wounding and OS treatments further suggests a possible involvement of the OsPep3 peptide in rice–herbivore interactions. Correspondingly, we found that simultaneous application of OsPep3 and Mythimna loreyi OS significantly amplifies an array of defense responses in rice cells, including mitogen‐activated protein kinase activation, and generation of defense‐related hormones and metabolites. The induction of OsPROPEP3/4 by OsPep3 points to a positive auto‐feedback loop in OsPep signaling which may contribute to additional enhancement of defense signal(s). Finally, the overexpression of the OsPep receptor OsPEPR1 increases the sensitivity of rice plants not only to the cognate OsPeps but also to OS signals. Our findings collectively suggest that HAMP–DAMP signal integration provides a critical step in the amplification of defense signaling in plants.
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A fungal ribonuclease-like effector protein inhibits plant host ribosomal RNA degradation

A fungal ribonuclease-like effector protein inhibits plant host ribosomal RNA degradation | Plant pathogenic fungi | Scoop.it
The biotrophic fungal pathogen Blumeria graminis causes the powdery mildew disease of cereals and grasses. Proteins with a predicted ribonuclease (RNase)-like fold (termed RALPHs) comprise the largest set of secreted effector candidates within the B. graminis f. sp. hordei genome. Their exceptional abundance suggests they play crucial functions during pathogenesis. We show that transgenic expression of RALPH CSEP0064/BEC1054 increases susceptibility to infection in monocotyledenous and dicotyledonous plants. CSEP0064/BEC1054 interacts in planta with five host proteins: two translation elongation factors (eEF1α and eEF1γ), two pathogenesis-related proteins (PR5 and PR10) and a glutathione-S-transferase. We present the first crystal structure of a RALPH, CSEP0064/BEC1054, demonstrating it has an RNase-like fold. The protein interacts with total RNA and weakly with DNA. Methyl jasmonate levels modulate susceptibility to aniline-induced host RNA fragmentation. In planta expression of CSEP0064/BEC1054 reduces the formation of this RNA fragment. We propose that CSEP0064/BEC1054 is a pseudoenzyme that binds to host ribosomes, thereby inhibiting the action of plant ribosome-inactivating proteins that would otherwise lead to host cell death, an unviable interaction and demise of the fungus.

Via Philip Carella
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Evidence of non-tandemly repeated rDNAs and their intragenomic heterogeneity in Rhizophagus irregularis

Evidence of non-tandemly repeated rDNAs and their intragenomic heterogeneity in Rhizophagus irregularis | Plant pathogenic fungi | Scoop.it

Arbuscular mycorrhizal fungus (AMF) species are one of the most widespread symbionts of land plants. Our substantially improved reference genome assembly of a model AMF, Rhizophagus irregularis DAOM-181602 (total contigs = 210), facilitated discovery of repetitive elements with unusual characteristics. R. irregularis has only ten or eleven copies of complete 45S rDNAs, whereas the general eukaryotic genome has tens to thousands of rDNA copies. R. irregularis rDNAs are highly heterogeneous and lack a tandem repeat structure. These findings provide evidence for the hypothesis that rDNA heterogeneity depends on the lack of tandem repeat structures. RNA-Seq analysis confirmed that all rDNA variants are actively transcribed. Observed rDNA/rRNA polymorphisms may modulate translation by using different ribosomes depending on biotic and abiotic interactions. The non-tandem repeat structure and intragenomic heterogeneity of AMF rDNA/rRNA may facilitate adaptation to a various environmental condition including the broad host range.


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Taro Maeda umiushi's comment, July 13, 1:47 AM
This preprint about non-tandemly repeated rDNAs finally published on Communications Biology!
https://www.nature.com/articles/s42003-018-0094-7
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Frontiers | Modify the Histone to Win the Battle: Chromatin Dynamics in Plant–Pathogen Interactions | Plant Science

Frontiers | Modify the Histone to Win the Battle: Chromatin Dynamics in Plant–Pathogen Interactions | Plant Science | Plant pathogenic fungi | Scoop.it
Relying on an immune system comes with a high energetic cost for plants. Defense responses in these organisms are therefore highly regulated and fine-tuned, permitting them to respond pertinently to the attack of a microbial pathogen. In recent years, the importance of the physical modification of chromatin, a highly organized structure composed of genomic DNA and its interacting proteins, has become evident in the research field of plant–pathogen interactions. Several processes, including DNA methylation, changes in histone density and variants, and various histone modifications, have been described as regulators of various developmental and defense responses. Herein, we review the state of the art in the epigenomic aspects of plant immunity, focusing on chromatin modifications, chromatin modifiers, and their physiological consequences. In addition, we explore the exciting field of understanding how plant pathogens have adapted to manipulate the plant epigenomic regulation in order to weaken their immune system and thrive in their host, as well as how histone modifications in eukaryotic pathogens are involved in the regulation of their virulence.

Via Christophe Jacquet
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Distinct domains of the AVRPM3A2/F2 avirulence protein from wheat powdery mildew are involved in immune receptor recognition and putative effector function - McNally - 2018 - New Phytologist -

Distinct domains of the AVRPM3A2/F2 avirulence protein from wheat powdery mildew are involved in immune receptor recognition and putative effector function - McNally - 2018 - New Phytologist - | Plant pathogenic fungi | Scoop.it
Recognition of the AVRPM3A2/F2 avirulence protein from powdery mildew by the wheat PM3A/F immune receptor induces a hypersensitive response after co‐expression in Nicotiana benthamiana. The molecular determinants of this interaction and how they shape natural AvrPm3a2/f2 allelic diversity are unknown.
We sequenced the AvrPm3a2/f2 gene in a worldwide collection of 272 mildew isolates. Using the natural polymorphisms of AvrPm3a2/f2 as well as sequence information from related gene family members, we tested 85 single‐residue‐altered AVRPM3A2/F2 variants with PM3A, PM3F and PM3FL456P/Y458H (modified for improved signaling) in Nicotiana benthamiana for effects on recognition.
An intact AvrPm3a2/f2 gene was found in all analyzed isolates and the protein variant recognized by PM3A/F occurred globally at high frequencies. Single‐residue alterations in AVRPM3A2/F2 mostly disrupted, but occasionally enhanced, the recognition response by PM3A, PM3F and PM3FL456P/Y458H. Residues enhancing hypersensitive responses constituted a protein domain separate from both naturally occurring polymorphisms and positively selected residues of the gene family.
These results demonstrate the utility of using gene family sequence diversity to screen residues for their role in recognition. This approach identified a putative interaction surface in AVRPM3A2/F2 not polymorphic in natural alleles. We conclude that molecular mechanisms besides recognition drive AvrPm3a2/f2 diversification.

Via Christophe Jacquet
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Microbial effectors and the role of water and sugar in the infection battle ground

Microbial effectors and the role of water and sugar in the infection battle ground | Plant pathogenic fungi | Scoop.it
Phytopathogenic microbes multiply in the apoplast — a plant's intercellular spaces — of infected plants, and hence their success relies on the conditions in this habitat. Despite being extracellular parasites, most microbes translocate effectors into host cells that promote disease by acting inside cells. Initial studies suggested that effectors act predominantly as suppressors of plant immunity. These pioneering studies were trend-setting, causing a strong bias in the functional investigation of effectors. Yet, recent studies on bacterial model pathogens have identified effectors that promote disease by causing either increased sugar or water levels in the apoplast. These studies are likely to initiate a new era of effector research that will clarify the disease-promoting rather than defense-suppressing function of effectors, a molecular rather than genetic distinction.

Via Christophe Jacquet
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Molecular dialogues between Trichoderma and roots: Role of the fungal secretome

Molecular dialogues between Trichoderma and roots: Role of the fungal secretome | Plant pathogenic fungi | Scoop.it
Trichoderma species are opportunistic fungi residing primarily in soil, tree bark and on wild mushrooms. Trichoderma is capable of killing other fungi and penetrating plant roots, and is commonly used as both a biofungicide and inducer of plant defence against pathogens. These fungi also exert other beneficial effects on plants including growth promotion and tolerance to abiotic stresses, primarily mediated by their intimate interactions with roots. In root–microbe interactions (both beneficial and harmful), fungal secreted proteins play a crucial role in establishing contact with the roots, fungal attachment, root penetration and triggering of plant responses. In Trichoderma–root interactions, the sucrose present in root exudates has been demonstrated to be important in fungal attraction. Attachment to roots is mediated by hydrophobin-like proteins, and secreted swollenins and plant cell wall degrading enzymes facilitate internalization of the fungal hyphae. During the early stage of penetration, suppression of plant defence is vital to successful initial root colonisation; this is mediated by small soluble cysteine-rich secreted proteins (effector-like proteins). Up to this stage, Trichoderma's behaviour is similar to that of a plant pathogen invading root structures. However, subsequent events like oxidative bursts, the synthesis of salicylic acid by the plants, and secretion of elicitor-like proteins by Trichoderma spp. differentiate this fungus from pathogens. These processes induce immunity in plants that help counter subsequent invasion by plant pathogens and insects. In this review, we present an inventory of soluble secreted proteins from Trichoderma that might play an active role in beneficial Trichoderma–plant interactions, and review the function of such proteins where known.
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Fungal species and their boundaries matter – Definitions, mechanisms and practical implications

Fungal species and their boundaries matter – Definitions, mechanisms and practical implications | Plant pathogenic fungi | Scoop.it
Highlights 
• Under certain conditions fungal species boundaries are permeable.  • Speciation and barrier genes determine formation of species and their boundaries. 
• Permeability of species boundaries widely impacts the population biology of fungi. 
• The dynamic nature of fungal species influences their taxonomy and control. 
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Microbial interactions within the plant holobiont | Microbiome |

Microbial interactions within the plant holobiont | Microbiome | | Plant pathogenic fungi | Scoop.it
Since the colonization of land by ancestral plant lineages 450 million years ago, plants and their associated microbes have been interacting with each other, forming an assemblage of species that is often referred to as a “holobiont.” Selective pressure acting on holobiont components has likely shaped plant-associated microbial communities and selected for host-adapted microorganisms that impact plant fitness. However, the high microbial densities detected on plant tissues, together with the fast generation time of microbes and their more ancient origin compared to their host, suggest that microbe-microbe interactions are also important selective forces sculpting complex microbial assemblages in the phyllosphere, rhizosphere, and plant endosphere compartments. Reductionist approaches conducted under laboratory conditions have been critical to decipher the strategies used by specific microbes to cooperate and compete within or outside plant tissues. Nonetheless, our understanding of these microbial interactions in shaping more complex plant-associated microbial communities, along with their relevance for host health in a more natural context, remains sparse. Using examples obtained from reductionist and community-level approaches, we discuss the fundamental role of microbe-microbe interactions (prokaryotes and micro-eukaryotes) for microbial community structure and plant health. We provide a conceptual framework illustrating that interactions among microbiota members are critical for the establishment and the maintenance of host-microbial homeostasis.

Via Stéphane Hacquard, Matt Agler
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A multi-gene phylogeny of Chlorophyllum (Agaricaceae, Basidiomycota): new species, new combination and infrageneric classification

A multi-gene phylogeny of Chlorophyllum (Agaricaceae, Basidiomycota): new species, new combination and infrageneric classification | Plant pathogenic fungi | Scoop.it
Taxonomic and phylogenetic studies of Chlorophyllum were carried out on the basis of morphological differences and molecular phylogenetic analyses. Based on the phylogeny inferred from the internal transcribed spacer (ITS), the partial large subunit nuclear ribosomal DNA (nrLSU), the second largest subunit of RNA polymerase II (rpb2) and translation elongation factor 1-α (tef1) sequences, six well-supported clades and 17 phylogenetic species are recognised. Within this phylogenetic framework and considering the diagnostic morphological characters, two new species, C. africanum and C. palaeotropicum, are described. In addition, a new infrageneric classification of Chlorophyllum is proposed, in which the genus is divided into six sections. One new combination is also made. This study provides a robust basis for a more detailed investigation of diversity and biogeography of Chlorophyllum.
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Clarification of species of one of the most common summer mushrooms
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Host‐ and stage‐dependent secretome of the arbuscular mycorrhizal fungus Rhizophagus irregularis 

Host‐ and stage‐dependent secretome of the arbuscular mycorrhizal fungus Rhizophagus irregularis  | Plant pathogenic fungi | Scoop.it
Figure 5. Laser microdissection combined with RNAseq to study stage-dependent expression. (a) Arbuscules (ARB) and intraradical mycelium (IRM) were collected by laser microdissection. Scales 100 µm. 14 µM-thick section of a mycorrhized Medicago root before and after laser dissection are shown. Regions selected for microdissection are indicated. (b) Stage-dependent secretome of Rhizophagus irregularis. 310 expressed SPs were grouped into arbuscule (ARB), intraradical mycelium (IRM) or extraradical mycelium (ERM) using the following criteria: FDR p<0.05 and fold change>4. (c) 12 out of 66 SPs showing ERMenriched expression shown in (a) are significantly higher expressed (FDR p value<0.05, fold change>4) in ERM compared to germinating spores (GS); 2 ERM-enriched SPs show higher expression in germinating spores.

Arbuscular mycorrhizal fungi form the most wide-spread endosymbiosis with plants. There is very little host-specificity in this interaction, however host preferences as well as varying symbiotic efficiencies have been observed. We hypothesize that secreted proteins (SPs) may act as fungal effectors to control symbiotic efficiency in a host-dependent manner. Therefore, we studied whether AM fungi adjust their secretome in a host- and stage-dependent manner to contribute to their extremely wide host-range. We investigated the expression of SP-encoding genes of Rhizophagus irregularis in three evolutionary distantly-related plant species, Medicago truncatula, Nicotiana benthamiana and Allium schoenoprasum. In addition we used laser microdissection in combination with RNAseq to study SP expression at different stages of the interaction in Medicago. Our data indicate that most expressed SPs show roughly equal expression levels in the interaction with all three host plants. In addition, a subset shows significant differential expression depending on the host plant. Furthermore, SP expression is controlled locally in the hyphal network in response to host dependent cues. Overall, this study presents a comprehensive analysis of the R. irregularis secretome, which now offers a solid basis to direct functional studies on the role of fungal SPs in AM symbiosis.

Via Pierre-Marc Delaux
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N-hydroxy-pipecolic acid is a mobile signal that induces systemic disease resistance in Arabidopsis

N-hydroxy-pipecolic acid is a mobile signal that induces systemic disease resistance in Arabidopsis | Plant pathogenic fungi | Scoop.it
Systemic acquired resistance (SAR) is a global response in plants induced at the site of infection that leads to long-lasting and broad-spectrum disease resistance at distal, uninfected tissues. Despite the importance of this priming mechanism, the identity of the mobile defense signal that moves systemically throughout plants to initiate SAR has remained elusive. In this paper, we describe a new metabolite, N-hydroxy-pipecolic acid (N-OH-Pip), and provide evidence that this molecule is a mobile signal that plays a central role in initiating SAR signal transduction in Arabidopsis thaliana. We demonstrate that FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1), a key regulator of SAR-associated defense priming, can synthesize N-OH-Pip from pipecolic acid in planta, and exogenously applied N-OH-PIP moves systemically in Arabidopsis and can rescue the SAR-deficiency of fmo1 mutants. We also demonstrate that N-OH-Pip treatment causes systemic changes in the expression of pathogenesis-related genes and metabolic pathways throughout the plant, and enhances resistance to a bacterial pathogen. This work provides new insight into the chemical nature of a mobile signal for SAR and also suggests that the N-OH-Pip pathway is a promising target for metabolic engineering to enhance disease resistance.

Via Philip Carella
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Rapid detection of Fusarium oxysporum f. sp. lactucae on soil, lettuce seeds and plants using loop‐mediated isothermal amplification - Franco Ortega - - Plant Pathology - Wiley Online Library

Rapid detection of Fusarium oxysporum f. sp. lactucae on soil, lettuce seeds and plants using loop‐mediated isothermal amplification - Franco Ortega - - Plant Pathology - Wiley Online Library | Plant pathogenic fungi | Scoop.it
Fusarium oxysporum f. sp. lactucae (FOL) is a soil‐ and seedborne pathogen and the causal agent of fusarium wilt on lettuce. Four races have been identified within FOL, with different worldwide distribution. Several molecular techniques have been used to detect and identify this pathogen; however, not all of them have the optimal characteristics in terms of sensitivity to perform FOL detection in plant and seed material. A loop‐mediated isothermal amplification (LAMP) assay was developed based on the sequence‐characterized amplified region (SCAR) obtained in a previous rapid amplification of polymorphic DNA (RAPD) study. The LAMP assay has been validated according to the EPPO standard PM7/98. The LAMP assay was tested with lettuce seeds, soil and plant material, and can be used successfully to amplify DNA from each of these matrices. In seed lots artificially inoculated with FOL, the detection limit of the LAMP test was 0.004% infected seed.
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The origin and evolution of mycorrhizal symbioses: from palaeomycology to phylogenomics - Strullu‐Derrien - - New Phytologist - Wiley Online Library

The origin and evolution of mycorrhizal symbioses: from palaeomycology to phylogenomics - Strullu‐Derrien - - New Phytologist - Wiley Online Library | Plant pathogenic fungi | Scoop.it
The ability of fungi to form mycorrhizas with plants is one of the most remarkable and enduring adaptations to life on land. The occurrence of mycorrhizas is now well established in c. 85% of extant plants, yet the geological record of these associations is sparse. Fossils preserved under exceptional conditions provide tantalizing glimpses into the evolutionary history of mycorrhizas, showing the extent of their occurrence and aspects of their evolution in extinct plants. The fossil record has important roles to play in establishing a chronology of when key fungal associations evolved and in understanding their importance in ecosystems through time. Together with calibrated phylogenetic trees, these approaches extend our understanding of when and how groups evolved in the context of major environmental change on a global scale. Phylogenomics furthers this understanding into the evolution of different types of mycorrhizal associations, and genomic studies of both plants and fungi are shedding light on how the complex set of symbiotic traits evolved. Here we present a review of the main phases of the evolution of mycorrhizal interactions from palaeontological, phylogenetic and genomic perspectives, with the aim of highlighting the potential of fossil material and a geological perspective in a cross‐disciplinary approach.

Via Jonathan Plett
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Not in your usual Top 10: protists that infect plants and algae - Schwelm - 2018 - Molecular Plant Pathology -

Not in your usual Top 10: protists that infect plants and algae - Schwelm - 2018 - Molecular Plant Pathology - | Plant pathogenic fungi | Scoop.it
Fungi, nematodes and oomycetes belong to the most prominent eukaryotic plant pathogenic organisms. Unicellular organisms from other eukaryotic lineages, commonly addressed as protists, also infect plants. This review provides an introduction to plant pathogenic protists, including algae infecting oomycetes, and their current state of research.

Via Christophe Jacquet
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Sniffing bacterial volatile compounds for healthier plants

Sniffing bacterial volatile compounds for healthier plants | Plant pathogenic fungi | Scoop.it
Highlights

•Intra-kingdom volatile signals modulate BVCs emission.
•Plant respond to BVCs in a spatiotemporal manner.
•BVCs-mediate plant–bacteria interaction have evolutionary history.
•BVCs may act as microbe-associated molecular patterns (MAMPs).
•BVCs target key points in plant physiology.

Bacterial volatile compounds (BVCs) are not waste or by-products of primary metabolism but rather have critical roles in the biology and ecological competence of bacteria. BVCs are exploited as a source of nutrients and information in plant–bacteria interactions. They target key points in plant physiology, activating downstream metabolic pathways by a domino effect. BVCs are an ancient signal and are involved in plant–bacteria communication, which was shaped during evolutionary history and established before the development of higher plants. This type of communication is not exclusive to mutualistic interactions, because pathogens also use volatiles to alter plant physiology. Here, fragmented information is drawn together to provide a clearer view of how BVCs affect such interactions.


Via Christophe Jacquet
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Modulation of plant autophagy during pathogen attack | Journal of Experimental Botany | Oxford Academic

Modulation of plant autophagy during pathogen attack | Journal of Experimental Botany | Oxford Academic | Plant pathogenic fungi | Scoop.it
In plants, the highly conserved catabolic process of autophagy has long been known as a means of maintaining cellular homeostasis and coping with abiotic stress conditions. Accumulating evidence has linked autophagy to immunity against invading pathogens, regulating plant cell death, and antimicrobial defences. In turn, it appears that phytopathogens have evolved ways not only to evade autophagic clearance but also to modulate and co-opt autophagy for their own benefit. In this review, we summarize and discuss the emerging discoveries concerning how pathogens modulate both host and self-autophagy machineries to colonize their host plants, delving into the arms race that determines the fate of interorganismal interaction.

Via Christophe Jacquet
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The transcription factor PstSTE12 is required for virulence of Puccinia striiformis f. sp. tritici - Zhu - 2018 - Molecular Plant Pathology -

The transcription factor PstSTE12 is required for virulence of Puccinia striiformis f. sp. tritici - Zhu - 2018 - Molecular Plant Pathology - | Plant pathogenic fungi | Scoop.it
Puccinia striiformis f. sp. tritici (Pst) is an obligate biotrophic fungus that causes extensive damage in wheat. The pathogen is now known to be a heteroecious fungus with an intricate life cycle containing sexual and asexual stages. Orthologues of the STE12 transcription factor that regulate mating and filamentation in Saccharomyces cerevisiae, as well as virulence in other fungi, have been extensively described. Because reliable transformation and gene disruption methods are lacking for Pst, knowledge about the function of its STE12 orthologue is limited. In this study, we identified a putative orthologue of STE12 from Pst in haustoria‐enriched transcripts and designated it as PstSTE12. The gene encodes a protein of 879 amino acids containing three helices in the homeodomain, conserved phenylalanine and tryptophan sites, and two C2/H2‐Zn2+ finger domains. Real‐time reverse transcription‐polymerase chain reaction (RT‐PCR) analyses revealed that the expression of PstSTE12 was highly induced during the early infection stages and peaked during haustorium formation and the pycniospore stage in the aecial host barberry. Subcellular localization assays indicated that PstSTE12 is localized in the nucleus and functions as a transcriptional activator. Yeast one‐hybrid assays revealed that PstSTE12 exhibits transcriptional activity, and that its C‐terminus is necessary for the activation of transcription. PstSTE12 complemented the mating defect in an α ste12 mutant of S. cerevisiae. In addition, it partially complemented the defects of the Magnaporthe oryzae mst12 mutant in plant infection. Knocking down PstSTE12 via host‐induced gene silencing (HIGS) mediated by Barley stripe mosaic virus (BSMV) resulted in a substantial reduction in the growth and spread of hyphae in Pst and weakened the virulence of Pst on wheat. Our results suggest that PstSTE12 probably acts at an intersection participating in the invasion and mating processes of Pst, and provide new insights into the comprehension of the variation of virulence in cereal rust fungi.

Via Christophe Jacquet
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Extracellular Vesicle RNA: A Universal Mediator of Microbial Communication?

Extracellular Vesicle RNA: A Universal Mediator of Microbial Communication? | Plant pathogenic fungi | Scoop.it
Both extracellular RNAs and extracellular vesicles (EVs) have recently garnered attention as novel mediators of intercellular communication in eukaryotes and prokaryotes alike. EVs not only permit export of RNA, but also facilitate delivery and trans-kingdom exchange of these and other biomolecules, for instance between microbes and their hosts. In this Opinion article, we propose that EV-mediated export of RNA represents a universal mechanism for interkingdom and intrakingdom communication that is conserved among bacterial, archaeal, and eukaryotic microbes. We speculate how microbes might use EV RNA to influence target cell gene expression or manipulate host immune responses.

Via Jonathan Plett
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Fungal G-protein-coupled receptors: mediators of pathogenesis and targets for disease control

Fungal G-protein-coupled receptors: mediators of pathogenesis and targets for disease control | Plant pathogenic fungi | Scoop.it

G-protein signalling pathways are involved in sensing the environment, enabling fungi to coordinate cell function, metabolism and development with their surroundings, thereby promoting their survival, propagation and virulence. G-protein-coupled receptors (GPCRs) are the largest class of cell surface receptors in fungi. Despite the apparent importance of GPCR signalling to fungal biology and virulence, relatively few GPCR–G-protein interactions, and even fewer receptor-binding ligands, have been identified. Approximately 40% of current pharmaceuticals target human GPCRs, due to their cell surface location and central role in cell signalling. Fungal GPCRs do not belong to any of the mammalian receptor classes, making them druggable targets for antifungal development. This Review Article evaluates developments in our understanding of fungal GPCR-mediated signalling, while substantiating the rationale for considering these receptors as potential antifungal targets. The need for insights into the structure–function relationship of receptor–ligand interactions is highlighted, which could facilitate the development of receptor-interfering compounds that could be used in disease control.

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LOVe across kingdoms: Blue light perception vital for growth and development in plant–fungal interactions

LOVe across kingdoms: Blue light perception vital for growth and development in plant–fungal interactions | Plant pathogenic fungi | Scoop.it
Highlights 
• Blue light plays an important role in fungal pathogenicity. 
• Fungi synchronise their circadian clocks to that of plants. 
• The fungal LOV domain evolved independently from that of plants. 
• The LOV domain is a likely target for Host Induced Gene Silencing (HIGS). 

Abstract
Blue light plays an important role in the growth and development of fungi. Environmental cues enable plant pathogenic fungi to synchronise essential metabolic pathways to that of their hosts to gain a competitive advantage. Phylogenetic analysis of the LOV domain present in blue light receptors across all three kingdoms suggests that these receptors in fungal lineages have undergone convergent evolution to use the same domain for control and regulation of similar cellular and metabolic processes. In this review, the genetic basis of blue light photoperception in fungi, and the functions it regulates, will be discussed. Furthermore, the evolution of the light sensing domain and its role in pathogenesis is hypothesised concluding with how knowledge of conserved LOV domains may be exploited for fungal disease control in crop plants.
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Why species delimitation matters for fungal ecology: Colletotrichum diversity on wild and cultivated cashew in Brazil

Why species delimitation matters for fungal ecology: Colletotrichum diversity on wild and cultivated cashew in Brazil | Plant pathogenic fungi | Scoop.it


• Several Colletotrichum species are associated with cashew anthracnose in Brazil
• Interpretation of Colletotrichum community diversity depends on how species are delimited
• C. gloeosporioides was rare, while C. siamense was the dominant species
• The cultivated cashew and leaves were the most diverse host-associated strata
• The Atlantic Forest and Pernambuco were the most diverse geographical strata


Via Serenella A Sukno
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GraftM: a tool for scalable, phylogenetically informed classification of genes within metagenomes | Nucleic Acids Research | Oxford Academic

GraftM: a tool for scalable, phylogenetically informed classification of genes within metagenomes | Nucleic Acids Research | Oxford Academic | Plant pathogenic fungi | Scoop.it

Large-scale metagenomic datasets enable the recovery of hundreds of population genomes from environmental samples. However, these genomes do not typically represent the full diversity of complex microbial communities. Gene-centric approaches can be used to gain a comprehensive view of diversity by examining each read independently, but traditional pairwise comparison approaches typically over-classify taxonomy and scale poorly with increasing metagenome and database sizes. Here we introduce GraftM, a tool that uses gene specific packages to rapidly identify gene families in metagenomic data using hidden Markov models (HMMs) or DIAMOND databases, and classifies these sequences using placement into pre-constructed gene trees. The speed and accuracy of GraftM was benchmarked with in silico and in vitro mock communities using taxonomic markers, and was found to have higher accuracy at the family level with a processing time 2.0–3.7× faster than currently available software. Exploration of a wetland metagenome using 16S rRNA- and methyl-coenzyme M reductase (McrA)-specific gpkgs revealed taxonomic and functional shifts across a depth gradient. Analysis of the NCBI nr database using the McrA gpkg allowed the detection of novel sequences belonging to phylum-level lineages. A growing collection of gpkgs is available online (https://github.com/geronimp/graftM_gpkgs), where curated packages can be uploaded and exchanged.

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Rescooped by Steve Marek from MycorWeb Plant-Microbe Interactions
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Fungal Phytotoxin Lasiojasmonate A Activates the Plant Jasmonic Acid Pathway | Journal of Experimental Botany | Oxford Academic

Fungal Phytotoxin Lasiojasmonate A Activates the Plant Jasmonic Acid Pathway | Journal of Experimental Botany | Oxford Academic | Plant pathogenic fungi | Scoop.it
Jasmonates are signaling compounds that regulate plant responses to stress. Jasmonic acid (JA) is the direct precursor of the bioactive plant hormone JA-Ile, the ligand of the COI1-JAZ co-receptor complex. JA, its methyl ester and three furanonyl esters were recently isolated from the grapevine pathogen Lasiodiplodia mediterannea sp. The JA ester lasiojasmonate A (LasA) is the first reported naturally occurring JA-furanone, whose mode of action is currently unexplored. Here we show that LasA activates many JA-regulated responses in planta, including protein degradation, gene expression, and physiological processes. These in vivo effects required LasA conversion into JA, formation of JA-Ile and its recognition by the plant JA-Ile perception complex. These data suggest a mode of action of the natural fungal LasA as an inactive JA pool that can be transformed into the bioactive JA-Ile form. We propose that fungal production of JA derivates such as LasA occur at late infection stages to induce plant JA responses such as cell death, and facilitate fungal infection.

Via Philip Carella, Francis Martin
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