Plant pathogenic fungi
28.6K views | +28 today
Follow
 
Rescooped by Steve Marek from Plant Breeding and Genomics News
onto Plant pathogenic fungi
Scoop.it!

PLOS ONE: RNA-Seq Reveals Infection-Related Gene Expression Changes in Phytophthora capsici

PLOS ONE: RNA-Seq Reveals Infection-Related Gene Expression Changes in Phytophthora capsici | Plant pathogenic fungi | Scoop.it

Phytophthora capsici is a soilborne plant pathogen capable of infecting a wide range of plants, including many solanaceous crops. However, genetic resistance and fungicides often fail to manage P. capsici due to limited knowledge on the molecular biology and basis of P. capsici pathogenicity. To begin to rectify this situation, Illumina RNA-Seq was used to perform massively parallel sequencing of three cDNA samples derived from P. capsici mycelia (MY), zoospores (ZO) and germinating cysts with germ tubes (GC). Over 11 million reads were generated for each cDNA library analyzed. After read mapping to the gene models of P. capsici reference genome, 13,901, 14,633 and 14,695 putative genes were identified from the reads of the MY, ZO and GC libraries, respectively. Comparative analysis between two of samples showed major differences between the expressed gene content of MY, ZO and GC stages. A large number of genes associated with specific stages and pathogenicity were identified, including 98 predicted effector genes. The transcriptional levels of 19 effector genes during the developmental and host infection stages of P. capsici were validated by RT-PCR. Ectopic expression in Nicotiana benthamiana showed that P. capsici RXLR and Crinkler effectors can suppress host cell death triggered by diverse elicitors including P. capsici elicitin and NLP effectors. This study provides a first look at the transcriptome and effector arsenal of P. capsici during the important pre-infection stages.


Via Plant Breeding and Genomics News
Steve Marek's insight:

Anti-death effectors expressed early during infection.  Sounds analogous to hemibiotroph Colletotrichum.

more...
No comment yet.
Plant pathogenic fungi
Your new post is loading...
Your new post is loading...
Scooped by Steve Marek
Scoop.it!

Quantifying airborne dispersal routes of pathogens over continents to safeguard global wheat supply

Quantifying airborne dispersal routes of pathogens over continents to safeguard global wheat supply | Plant pathogenic fungi | Scoop.it
Infectious crop diseases spreading over large agricultural areas pose a threat to food security. Aggressive strains of the obligate pathogenic fungus Puccinia graminis f.sp. tritici (Pgt), causing the crop disease wheat stem rust, have been detected in East Africa and the Middle East, where they lead to substantial economic losses and threaten livelihoods of farmers. The majority of commercially grown wheat cultivars worldwide are susceptible to these emerging strains, which pose a risk to global wheat production, because the fungal spores transmitting the disease can be wind-dispersed over regions and even continents1,2,3,4,5,6,7,8,9,10,11. Targeted surveillance and control requires knowledge about airborne dispersal of pathogens, but the complex nature of long-distance dispersal poses significant challenges for quantitative research12,13,14. We combine international field surveys, global meteorological data, a Lagrangian dispersion model and high-performance computational resources to simulate a set of disease outbreak scenarios, tracing billions of stochastic trajectories of fungal spores over dynamically changing host and environmental landscapes for more than a decade. This provides the first quantitative assessment of spore transmission frequencies and amounts amongst all wheat producing countries in Southern/East Africa, the Middle East and Central/South Asia. We identify zones of high air-borne connectivity that geographically correspond with previously postulated wheat rust epidemiological zones (characterized by endemic disease and free movement of inoculum)10,15, and regions with genetic similarities in related pathogen populations16,17. We quantify the circumstances (routes, timing, outbreak sizes) under which virulent pathogen strains such as ‘Ug99’5,6 pose a threat from long-distance dispersal out of East Africa to the large wheat producing areas in Pakistan and India. Long-term mean spore dispersal trends (predominant direction, frequencies, amounts) are summarized for all countries in the domain (Supplementary Data). Our mechanistic modelling framework can be applied to other geographic areas, adapted for other pathogens and used to provide risk assessments in real-time3.

more...
No comment yet.
Rescooped by Steve Marek from Publications
Scoop.it!

bioRxiv: Lessons in effector and NLR biology of plant-microbe systems (2017)

bioRxiv: Lessons in effector and NLR biology of plant-microbe systems (2017) | Plant pathogenic fungi | Scoop.it

A diversity of plant-associated organisms secrete effectors: proteins and metabolites that modulate plant physiology to favor host infection and colonization. However, effectors can also activate plant immune receptors, notably nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins, enabling plants to fight off invading organisms. This interplay between effectors, their host targets, and the matching immune receptors is shaped by intricate molecular mechanisms and exceptionally dynamic coevolution. In this article, we focus on three effectors, AVR-Pik, AVR-Pia, and AVR-Pii, from the rice blast fungus Magnaporthe oryzae (syn. Pyricularia oryzae), and their corresponding rice NLR immune receptors, Pik, Pia, and Pii, to highlight general concepts of plant-microbe interactions. We draw 12 lessons in effector and NLR biology that have emerged from studying these three little effectors and are broadly applicable to other plant-microbe systems.


Via Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Steve Marek from Adaptive Evolution and Speciation
Scoop.it!

Adaptation to the Host Environment by Plant-Pathogenic Fungi - Annual Review of Phytopathology

Adaptation to the Host Environment by Plant-Pathogenic Fungi - Annual Review of Phytopathology | Plant pathogenic fungi | Scoop.it
Many fungi can live both saprophytically and as endophyte or pathogen inside a living plant. In both environments, complex organic polymers are used as sources of nutrients. Propagation inside a living host also requires the ability to respond to immune responses of the host. We review current knowledge of how plant-pathogenic fungi do this. First, we look at how fungi change their global gene expression upon recognition of the host environment, leading to secretion of effectors, enzymes, and secondary metabolites; changes in metabolism; and defense against toxic compounds. Second, we look at what is known about the various cues that enable fungi to sense the presence of living plant cells. Finally, we review literature on transcription factors that participate in gene expression in planta or are suspected to be involved in that process because they are required for the ability to cause disease.

Via Ronny Kellner
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

Epidemiology: Past, Present, and Future Impacts on Understanding Disease Dynamics and Improving Plant Disease Management—A Summary of Focus Issue Articles | Phytopathology

Epidemiology: Past, Present, and Future Impacts on Understanding Disease Dynamics and Improving Plant Disease Management—A Summary of Focus Issue Articles | Phytopathology | Plant pathogenic fungi | Scoop.it
Epidemiology has made significant contributions to plant pathology by elucidating the general principles underlying the development of disease epidemics. This has resulted in a greatly improved theoretical and empirical understanding of the dynamics of disease epidemics in time and space, predictions of disease outbreaks or the need for disease control in real-time basis, and tactical and strategic solutions to disease problems. Availability of high-resolution experimental data at multiple temporal and spatial scales has now provided a platform to test and validate theories on the spread of diseases at a wide range of spatial scales ranging from the local to the landscape level. Relatively new approaches in plant disease epidemiology, ranging from network to information theory, coupled with the availability of large-scale datasets and the rapid development of computer technology, are leading to revolutionary thinking about epidemics that can result in considerable improvement of strategic and tactical decision making in the control and management of plant diseases. Methods that were previously restricted to topics such as population biology or evolution are now being employed in epidemiology to enable a better understanding of the forces that drive the development of plant disease epidemics in space and time. This Focus Issue of Phytopathology features research articles that address broad themes in epidemiology including social and political consequences of disease epidemics, decision theory and support, pathogen dispersal and disease spread, disease assessment and pathogen biology and disease resistance. It is important to emphasize that these articles are just a sample of the types of research projects that are relevant to epidemiology. Below, we provide a succinct summary of the articles that are published in this Focus Issue.

more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

Black Truffle, a Hermaphrodite with Forced Unisexual Behaviour - ScienceDirect

Black Truffle, a Hermaphrodite with Forced Unisexual Behaviour - ScienceDirect | Plant pathogenic fungi | Scoop.it
The life cycle of the black truffle (Tuber melanosporum) includes a mating before sporulation: although the species is hermaphroditic, mating turns out to involve parents with very different features, that mostly behave as male or female only, suggesting that this species undergoes forced dioecism.

more...
No comment yet.
Rescooped by Steve Marek from Plant-Microbe Symbiosis
Scoop.it!

PacBio metabarcoding of Fungi and other eukaryotes: errors, biases and perspectives

PacBio metabarcoding of Fungi and other eukaryotes: errors, biases and perspectives | Plant pathogenic fungi | Scoop.it
Second-generation, high-throughput sequencing methods have greatly improved our understanding of the ecology of soil microorganisms, yet the short barcodes (< 500 bp) provide limited taxonomic and phylogenetic information for species discrimination and taxonomic assignment.
Here, we utilized the third-generation Pacific Biosciences (PacBio) RSII and Sequel instruments to evaluate the suitability of full-length internal transcribed spacer (ITS) barcodes and longer rRNA gene amplicons for metabarcoding Fungi, Oomycetes and other eukaryotes in soil samples.
Metabarcoding revealed multiple errors and biases: Taq polymerase substitution errors and mis-incorporating indels in sequencing homopolymers constitute major errors; sequence length biases occur during PCR, library preparation, loading to the sequencing instrument and quality filtering; primer–template mismatches bias the taxonomic profile when using regular and highly degenerate primers.
The RSII and Sequel platforms enable the sequencing of amplicons up to 3000 bp, but the sequence quality remains slightly inferior to Illumina sequencing especially in longer amplicons. The full ITS barcode and flanking rRNA small subunit gene greatly improve taxonomic identification at the species and phylum levels, respectively. We conclude that PacBio sequencing provides a viable alternative for metabarcoding of organisms that are of relatively low diversity, require > 500-bp barcode for reliable identification or when phylogenetic approaches are intended.

Via Jean-Michel Ané
more...
No comment yet.
Rescooped by Steve Marek from Pathogens, speciation, domestication, genomics, fungi, biotic interactions
Scoop.it!

Habitat Predicts Levels of Genetic Admixture in Saccharomyces cerevisiae

Habitat Predicts Levels of Genetic Admixture in Saccharomyces cerevisiae | Plant pathogenic fungi | Scoop.it
Genetic admixture can provide material for populations to adapt to local environments, and this process has played a crucial role in the domestication of plants and animals. The model yeast, Saccharomyces cerevisiae , has been domesticated multiple times for the production of wine, sake, beer, and bread, but the high rate of admixture between yeast lineages has so far been treated as a complication for population genomic analysis. Here, we make use of the low recombination rate at centromeres to investigate admixture in yeast using a classic Bayesian approach and a locus-by-locus phylogenetic approach. Using both approaches, we find that S. cerevisiae from stable oak woodland habitats are less likely to show recent genetic admixture compared with those isolated from transient habitats such as fruits, wine, or human infections. When woodland yeast strains do show recent genetic admixture, the degree of admixture is lower than in strains from other habitats. Furthermore, S. cerevisiae populations from oak woodlands are genetically isolated from each other, with only occasional migration between woodlands and local fruit habitats. Application of the phylogenetic approach suggests that there is a previously undetected population in North Africa that is the closest outgroup to the European S. cerevisiae , including the domesticated Wine population. Careful testing for admixture in S. cerevisiae leads to a better understanding of the underlying population structure of the species and will be important for understanding the selective processes underlying domestication in this economically important species.

Via Pierre Gladieux
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

Discovering Protein-Coding Genes from the Environment: Time for the Eukaryotes?

Discovering Protein-Coding Genes from the Environment: Time for the Eukaryotes? | Plant pathogenic fungi | Scoop.it
Eukaryotic microorganisms from diverse environments encompass a large number of taxa, many of them still unknown to science. One strategy to mine these organisms for genes of biotechnological relevance is to use a pool of eukaryotic mRNA directly extracted from environmental samples. Recent reports demonstrate that the resulting metatranscriptomic cDNA libraries can be screened by expression in yeast for a wide range of genes and functions from many of the different eukaryotic taxa. In combination with novel emerging high-throughput technologies, we anticipate that this approach should contribute to exploring the functional diversity of the eukaryotic microbiota.

more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

In planta expression of hyperthermophilic enzymes as a strategy for accelerated lignocellulosic digestion

In planta expression of hyperthermophilic enzymes as a strategy for accelerated lignocellulosic digestion | Plant pathogenic fungi | Scoop.it
Conversion of lignocellulosic biomass to biofuels and biomaterials suffers from high production costs associated with biomass pretreatment and enzymatic hydrolysis. In-planta expression of lignocellulose-digesting enzymes is a promising approach to reduce these cost elements. However, this approach faces a number of challenges, including auto-hydrolysis of developing cell walls, plant growth and yield penalties, low expression levels and the limited stability of expressed enzymes at the high temperatures generally used for biomass processing to release fermentable sugars. To overcome these challenges we expressed codon-optimized recombinant hyperthermophilic endoglucanase (EG) and xylanase (Xyn) genes in A. thaliana. Transgenic Arabidopsis lines expressing EG and Xyn enzymes at high levels without any obvious plant growth or yield penalties were selected for further analysis. The highest enzyme activities were observed in the dry stems of transgenic lines, indicating that the enzymes were not degraded during stem senescence and storage. Biomass from transgenic lines exhibited improved saccharification efficiency relative to WT control plants. We conclude that the expression of hyperthermophilic enzymes in plants is a promising approach for combining pretreatment and enzymatic hydrolysis processes in lignocellulosic digestion. This study provides a valid foundation for further studies involving in planta co-expression of core and accessory lignocellulose-digesting enzymes.

more...
No comment yet.
Rescooped by Steve Marek from Plant-Microbe Symbiosis
Scoop.it!

Epichloë Fungal Endophytes and Plant Defenses: Not Just Alkaloids

Epichloë Fungal Endophytes and Plant Defenses: Not Just Alkaloids | Plant pathogenic fungi | Scoop.it
Although the role of fungal alkaloids in protecting grasses associated with Epichloë fungal endophytes has been extensively documented, the effects of the symbiont on the host plant’s immune responses have received little attention. We propose that, in addition to producing protective alkaloids, endophytes enhance plant immunity against chewing insects by promoting endogenous defense responses mediated by the jasmonic acid (JA) pathway. We advance a model that integrates this dual effect of endophytes on plant defenses and test its predictions by means of a standard meta-analysis. This analysis supports a role of Epichloë endophytes in boosting JA-mediated plant defenses. We discuss the ecological scenarios where this effect of endophytes on plant defenses would be most beneficial for increasing plant fitness.


Via Jean-Michel Ané
more...
No comment yet.
Rescooped by Steve Marek from Plant-Microbe Interactions: Pathogenesis & Symbiosis
Scoop.it!

Divergent LysM effectors contribute to the virulence of Beauveria bassiana by evasion of insect immune defenses

Divergent LysM effectors contribute to the virulence of Beauveria bassiana by evasion of insect immune defenses | Plant pathogenic fungi | Scoop.it
The lysin motif (LysM) containing proteins can bind chitin and are ubiquitous in various organisms including fungi. In plant pathogenic fungi, a few LysM proteins have been characterized as effectors to suppress chitin-induced immunity in plant hosts and therefore contribute to fungal virulence. The effector mechanism is still questioned in fungus-animal interactions. In this study, we found that LysM proteins are also present in animal pathogenic fungi and have evolved divergently. The genome of the insect pathogen Beauveria bassiana encodes 12 LysM proteins, and the genes were differentially transcribed by the fungus when grown in different conditions. Deletion of six genes that were expressed by the fungus growing in insects revealed that two, Blys2 and Blys5, were required for full fungal virulence. Both proteins could bind chitin and Blys5 (containing two LysM domains) could additionally bind chitosan and cellulose. Truncation analysis of Blys2 (containing five LysM domains) indicated that the combination of LysM domains could determine protein-binding affinity and specificity for different carbohydrates. Relative to the wild-type strain, loss of Blys2 or Blys5 could impair fungal propagation in insect hemocoels and lead to the upregulation of antifungal gene in insects. Interestingly, the virulence defects of ΔBlys2 and ΔBlys5 could be fully restored by complementation with the Slp1 effector from the rice blast fungus Magnaporthe oryzae. In contrast to Slp1 and Blys2, Blys5 could potentially protect fungal hyphae against chitinase hydrolysis. The results of this study not only advance the understanding of LysM protein evolution but also establish the effector mechanism of fungus-animal interactions.

Via Philip Carella
more...
Philip Carella's curator insight, September 11, 2:38 PM

ANOTHER example of plant biology informing animal researchers!

Rescooped by Steve Marek from Pathogens, speciation, domestication, genomics, fungi, biotic interactions
Scoop.it!

Fungal Genomes and Insights into the Evolution of the Kingdom

Fungal Genomes and Insights into the Evolution of the Kingdom | Plant pathogenic fungi | Scoop.it
The kingdom Fungi comprises species that inhabit nearly all ecosystems. Fungi exist as both free-living and symbiotic unicellular and multicellular organisms with diverse morphologies. The genomes of fungi encode genes that enable them to thrive in diverse environments, invade plant and animal cells, and participate in nutrient cycling in terrestrial and aquatic ecosystems. The continuously expanding databases of fungal genome sequences have been generated by individual and large-scale efforts such as Génolevures, Broad Institute’s Fungal Genome Initiative, and the 1000 Fungal Genomes Project (http://1000.fungalgenomes.org). These efforts have produced a catalog of fungal genes and genomic organization. The genomic datasets can be utilized to better understand how fungi have adapted to their lifestyles and ecological niches. Large datasets of fungal genomic and transcriptomic data have enabled the use of novel methodologies and improved the study of fungal evolution from a molecular sequence perspective. Combined with microscopes, petri dishes, and woodland forays, genome sequencing supports bioinformatics and comparative genomics approaches as important tools in the study of the biology and evolution of fungi.

Via Pierre Gladieux
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

Sterilizing immunity in the lung relies on targeting fungal apoptosis-like programmed cell death

Sterilizing immunity in the lung relies on targeting fungal apoptosis-like programmed cell death | Plant pathogenic fungi | Scoop.it
Humans inhale mold conidia daily and typically experience lifelong asymptomatic clearance. Conidial germination into tissue-invasive hyphae can occur in individuals with defects in myeloid function, although the mechanism of myeloid cell–mediated immune surveillance remains unclear. By monitoring fungal physiology in vivo, we demonstrate that lung neutrophils trigger programmed cell death with apoptosis-like features in Aspergillus fumigatus conidia, the most prevalent human mold pathogen. An antiapoptotic protein, AfBIR1, opposes this process by inhibiting fungal caspase activation and DNA fragmentation in the murine lung. Genetic and pharmacologic studies indicate that AfBIR1 expression and activity underlie conidial susceptibility to NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase-dependent killing and, in turn, host susceptibility to invasive aspergillosis. Immune surveillance exploits a fungal apoptosis-like programmed cell death pathway to maintain sterilizing immunity in the lung.
more...
No comment yet.
Rescooped by Steve Marek from MycorWeb Plant-Microbe Interactions
Scoop.it!

The importance of sourcing enzymes from non-conventional fungi for metabolic engineering & biomass breakdown

The importance of sourcing enzymes from non-conventional fungi for metabolic engineering & biomass breakdown | Plant pathogenic fungi | Scoop.it
A wealth of fungal enzymes has been identified from nature, which continue to drive strain engineering and bioprocessing for a range of industries. However, while a number of clades have been investigated, the vast majority of the fungal kingdom remains unexplored for industrial applications. Here, we discuss selected classes of fungal enzymes that are currently in biotechnological use, and explore more basal, non-conventional fungi and their underexploited biomass-degrading mechanisms as promising agents in the transition towards a bio-based society. Of special interest are anaerobic fungi like the Necocallimasticomycota, which were recently found to harbor the largest diversity of biomass-degrading enzymes among the fungal kingdom. Enzymes sourced from these basal fungi have been used to metabolically engineer substrate utilization in yeast, and may offer new paths to lignin breakdown and tunneled biocatalysis. We also contrast classic enzymology approaches with emerging ‘omics’-based tools to decipher function within novel fungal isolates and identify new promising enzymes. Recent developments in genome editing are expected to accelerate discovery and metabolic engineering within these systems, yet are still limited by a lack of high-resolution genomes, gene regulatory regions, and even appropriate culture conditions. Finally, we present new opportunities to harness the biomass-degrading potential of undercharacterized fungi via heterologous expression and engineered microbial consortia.

Via Francis Martin
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

Development of a versatile and conventional technique for gene disruption in filamentous fungi based on CRISPR - Cas9 technology

Development of a versatile and conventional technique for gene disruption in filamentous fungi based on CRISPR - Cas9 technology | Plant pathogenic fungi | Scoop.it
Filamentous fungi represent an invaluable source of pharmaceutically active compounds. The development of versatile methods to genetically manipulate filamentous fungi is of great value for improving the low yields of bioactive metabolites and expanding chemical diversity. The CRISPR-Cas9-based system has become a common platform for genome editing in a variety of organisms. However, recent application of this technology in filamentous fungi is limited to model strains, a versatile method for efficient gene disruption in different fungi is lacking. Here, we investigated the utility of the CRISPR-Cas9 system in a less-studied fungus Nodulisporium sp. (No. 65-12-7-1), and we have developed an efficient CRISPR-Cas9-based gene disruption strategy by simultaneous transformation of in vitro transcriptional gRNA and the linear maker gene cassette into the Cas9-expressing fungi. We found that the linear marker gene cassette could not only allow for selection of transformants, but also significantly enhance the gene disruption efficiency by inserting itself into the Cas9 cut site. Moreover, the above approach also demonstrated its efficiency in two other phylogenetically distinct strains Aspergillus oryzae NSAR1 and Sporormiella minima (No. 40-1-4-1) from two different classes of Ascomycota. These results suggested that a versatile CRISPR-Cas9-based gene disruption method in filamentous fungi was established.

more...
No comment yet.
Rescooped by Steve Marek from Plant Pathogens
Scoop.it!

Yellow sigatoka epidemics caused by a panmictic population of Mycosphaerella musicola in Brazil

Yellow sigatoka epidemics caused by a panmictic population of Mycosphaerella musicola in Brazil | Plant pathogenic fungi | Scoop.it

The genetic structure of Mycosphaerella musicola has never been investigated in Brazil to address epidemiologically related questions associated with yellow sigatoka. A total of 223 single-conidium isolates from four regions (North, South, Zona da Mata and Triângulo Mineiro) of Minas Gerais State, Brazil, were used to assess the population genetic structure of M. musicola. Isolates were characterized regarding the frequency of the MAT1-1-1 or MAT1-2-1 idiomorphs and polymorphism at nine microsatellite loci. The mating-type ratio in three of the four subpopulations was c. 1:1. A total of 87 alleles and 216 multilocus genotypes were identified. The overall population was in linkage equilibrium. Most (93.9%) genetic variation was detected within the subpopulations and there was weak differentiation between them. In total, eight genetic groups were detected and isolates of seven groups were present in all regions. The population of M. musicola in Minas Gerais seems to have high evolutionary potential: it is panmictic and both sexual reproduction and gene flow affect genetic variability. Strategies to avoid fungicide resistance should be enforced and breeding programmes need to consider quantitative resistance in the banana cultivars.

 

Via Yogesh Gupta
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

Ecological Insights into the Dynamics of Plant Biomass-Degrading Microbial Consortia - ScienceDirect

Ecological Insights into the Dynamics of Plant Biomass-Degrading Microbial Consortia - ScienceDirect | Plant pathogenic fungi | Scoop.it
Plant biomass (PB) is an important resource for biofuel production. However, the frequent lack of efficiency of PB saccharification is still an industrial bottleneck. The use of enzyme cocktails produced from PB-degrading microbial consortia (PB-dmc) is a promising approach to optimize this process. Nevertheless, the proper use and manipulation of PB-dmc depends on a sound understanding of the ecological processes and mechanisms that exist in these communities. This Opinion article provides an overview of arguments as to how spatiotemporal nutritional fluxes influence the successional dynamics and ecological interactions (synergism versus competition) between populations in PB-dmc. The themes of niche occupancy, ‘sugar cheaters’, minimal effective consortium, and the Black Queen Hypothesis are raised as key subjects that foster our appraisal of such systems. Here we provide a conceptual framework that describes the critical topics underpinning the ecological basis of PB-dmc, giving a solid foundation upon which further prospective experimentation can be developed.

more...
No comment yet.
Rescooped by Steve Marek from Pathogens, speciation, domestication, genomics, fungi, biotic interactions
Scoop.it!

Mitochondrial genomes reveal recombination in the presumed asexual Fusarium oxysporum species complex

Mitochondrial genomes reveal recombination in the presumed asexual Fusarium oxysporum species complex | Plant pathogenic fungi | Scoop.it
The Fusarium oxysporum species complex (FOSC) contains several phylogenetic lineages. Phylogenetic studies identified two to three major clades within the FOSC. The mitochondrial sequences are highly informative phylogenetic markers, but have been mostly neglected due to technical difficulties. A total of 61 complete mitogenomes of FOSC strains were de novo assembled and annotated. Length variations and intron patterns support the separation of three phylogenetic species. The variable region of the mitogenome that is typical for the genus Fusarium shows two new variants in the FOSC. The variant typical for Fusarium is found in members of all three clades, while variant 2 is found in clades 2 and 3 and variant 3 only in clade 2. The extended set of loci analyzed using a new implementation of the genealogical concordance species recognition method support the identification of three phylogenetic species within the FOSC. Comparative analysis of the mitogenomes in the FOSC revealed ongoing mitochondrial recombination within, but not between phylogenetic species. The recombination indicates the presence of a parasexual cycle in F. oxysporum. The obstacles hindering the usage of the mitogenomes are resolved by using next generation sequencing and selective genome assemblers, such as GRAbB. Complete mitogenome sequences offer a stable basis and reference point for phylogenetic and population genetic studies.

Via Pierre Gladieux
Steve Marek's insight:
evidence of parasexualism in FOSC
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

ASMscience | The Fungal Tree of Life: from Molecular Systematics to Genome-Scale Phylogenies

ASMscience | The Fungal Tree of Life: from Molecular Systematics to Genome-Scale Phylogenies | Plant pathogenic fungi | Scoop.it
The kingdom Fungi is one of the more diverse clades of eukaryotes in terrestrial ecosystems, where they provide numerous ecological services ranging from decomposition of organic matter and nutrient cycling to beneficial and antagonistic associations with plants and animals. The evolutionary relationships of the kingdom have represented some of the more recalcitrant problems in systematics and phylogenetics. The advent of molecular phylogenetics, and more recently phylogenomics, has greatly advanced our understanding of the patterns and processes associated with fungal evolution, however. In this article, we review the major phyla, subphyla, and classes of the kingdom Fungi and provide brief summaries of ecologies, morphologies, and exemplar taxa. We also provide examples of how molecular phylogenetics and evolutionary genomics have advanced our understanding of fungal evolution within each of the phyla and some of the major classes. In the current classification we recognize 8 phyla, 12 subphyla, and 46 classes within the kingdom. The ancestor of fungi is inferred to be zoosporic, and zoosporic fungi comprise three lineages that are paraphyletic to the remainder of fungi. Fungi historically classified as zygomycetes do not form a monophyletic group and are paraphyletic to Ascomycota and Basidiomycota. Ascomycota and Basidiomycota are each monophyletic and collectively form the subkingdom Dikarya.
more...
No comment yet.
Rescooped by Steve Marek from MycorWeb Plant-Microbe Interactions
Scoop.it!

Different waves of effector genes with contrasted genomic location are expressed by Leptosphaeria maculans during cotyledon and stem colonization of oilseed rape

Different waves of effector genes with contrasted genomic location are expressed by Leptosphaeria maculans during cotyledon and stem colonization of oilseed rape | Plant pathogenic fungi | Scoop.it
Leptosphaeria maculans, the causal agent of stem canker disease, colonizes oilseed rape (Brassica napus) in two stages: a short and early colonization stage corresponding to cotyledon or leaf colonization, and a late colonization stage during which the fungus colonizes systemically and symptomlessly the plant during several months before stem canker appears. To date, the determinants of the late colonization stage are poorly understood; L. maculans may either successfully escape plant defences, leading to stem canker development, or the plant may develop an ‘adult-stage’ resistance reducing canker incidence. To obtain an insight into these determinants, we performed an RNA-sequencing (RNA-seq) pilot project comparing fungal gene expression in infected cotyledons and in symptomless or necrotic stems. Despite the low fraction of fungal material in infected stems, sufficient fungal transcripts were detected and a large number of fungal genes were expressed, thus validating the feasibility of the approach. Our analysis showed that all avirulence genes previously identified are under-expressed during stem colonization compared with cotyledon colonization. A validation RNA-seq experiment was then performed to investigate the expression of candidate effector genes during systemic colonization. Three hundred and seven ‘late’ effector candidates, under-expressed in the early colonization stage and over-expressed in the infected stems, were identified. Finally, our analysis revealed a link between the regulation of expression of effectors and their genomic location: the ‘late’ effector candidates, putatively involved in systemic colonization, are located in gene-rich genomic regions, whereas the ‘early’ effector genes, over-expressed in the early colonization stage, are located in gene-poor regions of the genome.

Via Francis Martin
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

An atypical forkhead‐containing transcription factor SsFKH1 is involved in sclerotial formation and is essential for pathogenicity in Sclerotinia sclerotiorum

An atypical forkhead‐containing transcription factor SsFKH1 is involved in sclerotial formation and is essential for pathogenicity in Sclerotinia sclerotiorum | Plant pathogenic fungi | Scoop.it
Sclerotinia sclerotiorum (Lib.) de Bary is a necrotrophic plant pathogen with a worldwide distribution. The sclerotia of S. sclerotiorum are pigmented multicellular structures formed from the aggregation of vegetative hyphae. These survival structures play a central role in the life and infection cycles of this pathogen. Here, we characterized an atypical forkhead (FKH)-box-containing protein, SsFKH1, involved in sclerotial development and virulence. To investigate the role of SsFkh1 in S. sclerotiorum, the partial sequence of SsFkh1 was cloned and RNA interference (RNAi)-based gene silencing was employed to alter the expression of SsFkh1. RNA-silenced mutants with significantly reduced SsFkh1 RNA levels exhibited slow hyphal growth and sclerotial developmental defects. In addition, the expression levels of a set of putative melanin biosynthesis-related laccase genes and a polyketide synthase-encoding gene were significantly down-regulated in silenced strains. Disease assays demonstrated that pathogenicity in RNAi-silenced strains was significantly compromised with the development of a smaller infection lesion on tomato leaves. Collectively, the results suggest that SsFkh1 is involved in hyphal growth, virulence and sclerotial formation in S. sclerotiorum.
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

Characterization of an antimicrobial and phytotoxic ribonuclease secreted by the fungal wheat pathogen Zymoseptoria tritici

Characterization of an antimicrobial and phytotoxic ribonuclease secreted by the fungal wheat pathogen Zymoseptoria tritici | Plant pathogenic fungi | Scoop.it

The fungus Zymoseptoria tritici is the causal agent of Septoria Tritici Blotch (STB) disease of wheat leaves. Zymoseptoria tritici secretes many functionally uncharacterized effector proteins during infection. Here, we characterized a secreted ribonuclease (Zt6) with an unusual biphasic expression pattern.
Transient expression systems were used to characterize Zt6, and mutants thereof, in both host and non-host plants. Cell-free protein expression systems monitored the impact of Zt6 protein on functional ribosomes, and in vitro assays of cells treated with recombinant Zt6 determined toxicity against bacteria, yeasts and filamentous fungi.
We demonstrated that Zt6 is a functional ribonuclease and that phytotoxicity is dependent on both the presence of a 22-amino-acid N-terminal ‘loop’ region and its catalytic activity. Zt6 selectively cleaves both plant and animal rRNA species, and is toxic to wheat, tobacco, bacterial and yeast cells, but not to Z. tritici itself.
Zt6 is the first Z. tritici effector demonstrated to have a likely dual functionality. The expression pattern of Zt6 and potent toxicity towards microorganisms suggest that, although it may contribute to the execution of wheat cell death, it is also likely to have an important secondary function in antimicrobial competition and niche protection.
more...
No comment yet.
Rescooped by Steve Marek from MycorWeb Plant-Microbe Interactions
Scoop.it!

Functional Profiling of Transcription Factor Genes in Neurospora crassa

Functional Profiling of Transcription Factor Genes in Neurospora crassa | Plant pathogenic fungi | Scoop.it
Regulation of gene expression by DNA-binding transcription factors is essential for proper control of growth and development in all organisms. In this study, we annotate and characterize growth and developmental phenotypes for transcription factor genes in the model filamentous fungus Neurospora crassa . We identified 312 transcription factor genes, corresponding to 3.2% of the protein coding genes in the genome. The largest class was the fungal-specific Zn2Cys6 (C6) binuclear cluster, with 135 members, followed by the highly conserved C2H2 zinc finger group, with 61 genes. Viable knockout mutants were produced for 273 genes, and complete growth and developmental phenotypic data are available for 242 strains, with 64% possessing at least one defect. The most prominent defect observed was in growth of basal hyphae (43% of mutants analyzed), followed by asexual sporulation (38%), and the various stages of sexual development (19%). Two growth or developmental defects were observed for 21% of the mutants, while 8% were defective in all three major phenotypes tested. Analysis of available mRNA expression data for a time course of sexual development revealed mutants with sexual phenotypes that correlate with transcription factor transcript abundance in wild type. Inspection of this data also implicated cryptic roles in sexual development for several cotranscribed transcription factor genes that do not produce a phenotype when mutated.

Via Francis Martin
more...
No comment yet.
Rescooped by Steve Marek from MycorWeb Plant-Microbe Interactions
Scoop.it!

Genomic and transcriptomic analyses reveal differential regulation of diverse terpenoid and polyketides secondary metabolites in Hericium erinaceus

Genomic and transcriptomic analyses reveal differential regulation of diverse terpenoid and polyketides secondary metabolites in Hericium erinaceus | Plant pathogenic fungi | Scoop.it
The lion’s mane mushroom Hericium erinaceus is a famous traditional medicinal fungus credited with anti-dementia activity and a producer of cyathane diterpenoid natural products (erinacines) useful against nervous system diseases. To date, few studies have explored the biosynthesis of these compounds, although their chemical synthesis is known. Here, we report the first genome and tanscriptome sequence of the medicinal fungus H. erinaceus. The size of the genome is 39.35 Mb, containing 9895 gene models. The genome of H. erinaceus reveals diverse enzymes and a large family of cytochrome P450 (CYP) proteins involved in the biosynthesis of terpenoid backbones, diterpenoids, sesquiterpenes and polyketides. Three gene clusters related to terpene biosynthesis and one gene cluster for polyketides biosynthesis (PKS) were predicted. Genes involved in terpenoid biosynthesis were generally upregulated in mycelia, while the PKS gene was upregulated in the fruiting body. Comparative genome analysis of 42 fungal species of Basidiomycota revealed that most edible and medicinal mushroom show many more gene clusters involved in terpenoid and polyketide biosynthesis compared to the pathogenic fungi. None of the gene clusters for terpenoid or polyketide biosynthesis were predicted in the poisonous mushroom Amanita muscaria. Our findings may facilitate future discovery and biosynthesis of bioactive secondary metabolites from H. erinaceus and provide fundamental information for exploring the secondary metabolites in other Basidiomycetes.

Via Francis Martin
more...
No comment yet.
Scooped by Steve Marek
Scoop.it!

Legume LysM receptors mediate symbiotic and pathogenic signalling - ScienceDirect

Legume LysM receptors mediate symbiotic and pathogenic signalling - ScienceDirect | Plant pathogenic fungi | Scoop.it

• LysM receptor kinases differentiate symbiotic and pathogenic microbial signals.
• LysM receptor kinases perceive a wider range of ligands than previously anticipated.
• Receptor complex formation and signalling are modulated by interacting proteins.

more...
No comment yet.