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Plant Disease: Identification and Detection of Phytophthora: Reviewing Our Progress, Identifying Our Needs (2012)

Plant Disease: Identification and Detection of Phytophthora: Reviewing Our Progress, Identifying Our Needs (2012) | Pathogenomics | Scoop.it

With the increased attention given to the genus Phytophthora in the last decade in response to the ecological and economic impact of several invasive species (such as P. ramorum, P. kernoviae, and P. alni), there has been a significant increase in the number of described species. In part, this is due to the extensive surveys in historically underexplored ecosystems (e.g., forest and stream ecosystems) undertaken to determine the spread of invasive species and the involvement of Phytophthora species in forest decline worldwide (e.g., oak decline). The past decade has seen an approximate doubling in the number of described species within the genus Phytophthora, and the number will likely continue to increase as more surveys are completed and greater attention is devoted to clarifying phylogenetic relationships and delineating boundaries in species complexes. The development of molecular resources, the availability of credible sequence databases to simplify identification of new species, and the sequencing of several genomes have provided a solid framework to gain a better understanding of the biology, diversity, and taxonomic relationships within the genus. This information is much needed considering the impact invasive or exotic Phytophthora species have had on natural ecosystems and the regulatory issues associated with their management. While this work is improving our ability to identify species based on phylogenetic grouping, it has also revealed that the genus has a much greater diversity than previously appreciated.


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Rescooped by Guogen Yang from Plant-microbe interaction
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Plant Cell: Pipecolic Acid, an Endogenous Mediator of Defense Amplification and Priming, Is a Critical Regulator of Inducible Plant Immunity (2012)

Plant Cell: Pipecolic Acid, an Endogenous Mediator of Defense Amplification and Priming, Is a Critical Regulator of Inducible Plant Immunity (2012) | Pathogenomics | Scoop.it

Metabolic signals orchestrate plant defenses against microbial pathogen invasion. Here, we report the identification of the non-protein amino acid pipecolic acid (Pip), a common Lys catabolite in plants and animals, as a critical regulator of inducible plant immunity. Following pathogen recognition, Pip accumulates in inoculated Arabidopsis thaliana leaves, in leaves distal from the site of inoculation, and, most specifically, in petiole exudates from inoculated leaves. Defects of mutants in AGD2-LIKE DEFENSE RESPONSE PROTEIN1 (ALD1) in systemic acquired resistance (SAR) and in basal, specific, and β-aminobutyric acid–induced resistance to bacterial infection are associated with a lack of Pip production. Exogenous Pip complements these resistance defects and increases pathogen resistance of wild-type plants. We conclude that Pip accumulation is critical for SAR and local resistance to bacterial pathogens. Our data indicate that biologically induced SAR conditions plants to more effectively synthesize the phytoalexin camalexin, Pip, and salicylic acid and primes plants for early defense gene expression. Biological priming is absent in the pipecolate-deficient ald1 mutants. Exogenous pipecolate induces SAR-related defense priming and partly restores priming responses in ald1. We conclude that Pip orchestrates defense amplification, positive regulation of salicylic acid biosynthesis, and priming to guarantee effective local resistance induction and the establishment of SAR.


Via Kamoun Lab @ TSL, Suayib Üstün
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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Nature: Green hourglass - conserved downregulation of "young" genes in embryogenesis

Nature: Green hourglass - conserved downregulation of "young" genes in embryogenesis | Pathogenomics | Scoop.it

What's behind the pretty cover of this week's Nature? An interesting article that shows that like animals, plants have an "hourglass" pattern of gene expression during embryogenesis. That is, if you plot the stage of embryogenesis on the y axis, and on the x axis either evolutionary age or sequence divergence of transcribed genes, you find that in mid-embryogenesis (torpedo stage), the genes expressed are relatively old/ conserved. This finding is particularly interesting because a similar pattern has been found during animal embryogenesis. Of course, since animals and plants evolved embryos independently, this means that this pattern has arisen independently - it is convergent, not conserved.

 

In plants, the hourglass pattern forms in part because some young genes expressed during early embryogenesis shut off prior to the torpedo stage, and then other young genes involved in maturation switch on in late embryogenesis.

 

Here is how the authors interpret their results, ".. convergent evolution of a molecular hourglass pattern in animals and plants suggests operation of a fundamental developmental profile controlling the expression of evolutionarily young or rapidly evolving genes across kingdoms. We speculate that such a mechanism may be required for enabling spatio-temporal organization and differentiation of complex multicellular life."

 

Here is the new plant paper http://www.nature.com/nature/journal/v490/n7418/full/nature11394.html

and two animal papers http://www.nature.com/nature/journal/v468/n7325/full/nature09632.html

http://www.nature.com/nature/journal/v468/n7325/full/nature09634.html.


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Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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Genomic tillage and the harvest of fungal phytopathogens

Genomic tillage and the harvest of fungal phytopathogens | Pathogenomics | Scoop.it
Genome sequencing has been carried out on a small selection of major fungal ascomycete pathogens. These studies show that simple models whereby pathogens evolved from phylogenetically related saprobes by the acquisition or modification of a small number of key genes cannot be sustained.The genomes show that pathogens cannot be divided into three clearly delineated classes (biotrophs, hemibiotrophs and necrotrophs) but rather into a complex matrix of categories each with subtly different properties. It is clear that the evolution of pathogenicity is ancient, rapid and ongoing. Fungal pathogens have undergone substantial genomic rearrangements that can be appropriately described as ‘genomic tillage’. Genomic tillage underpins the evolution and expression of large families of genes – known as effectors – that manipulate and exploit metabolic and defence processes of plants so as to allow the proliferation of pathogens.

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DAD2 Is an α/β Hydrolase likely to Be Involved in the Perception of the Plant Branching Hormone, Strigolactone

DAD2 Is an α/β Hydrolase likely to Be Involved in the Perception of the Plant Branching Hormone, Strigolactone | Pathogenomics | Scoop.it

Strigolactones are a recently discovered class of plant hormone involved in branching, leaf senescence, root development, and plant-microbe interactions [1,2,3,4,5,6]. They are carotenoid-derived lactones, synthesized in the roots and transported acropetally to modulate axillary bud outgrowth (i.e., branching) [1,2]. However, a receptor for strigolactones has not been identified. We have identified the DAD2 gene from petunia, an ortholog of the rice and Arabidopsis D14 genes, and present evidence for its roles in strigolactone perception and signaling. DAD2 acts in the strigolactone pathway, and the dad2 mutant is insensitive to the strigolactone analog GR24. The crystal structure of DAD2 reveals an α/β hydrolase fold containing a canonical catalytic triad with a large internal cavity capable of accommodating strigolactones. In the presence of GR24 DAD2 interacts with PhMAX2A, a central component of strigolactone signaling, in a GR24 concentration-dependent manner. DAD2 can hydrolyze GR24, with mutants of the catalytic triad abolishing both this activity and the ability of DAD2 to interact with PhMAX2A. The hydrolysis products can neither stimulate the protein-protein interaction nor modulate branching. These observations suggest that DAD2 acts to bind the mobile strigolactone signal and then interacts with PhMAX2A during catalysis to initiate an SCF-mediated signal transduction pathway.


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Current Biology - Plant Cell Wall Homeostasis Is Mediated by Brassinosteroid Feedback Signaling

Brassinosteroid (BR) signaling is required for normal plant growth as shown by the dwarf phenotype of loss-of-function BR biosynthetic or perception mutants. Despite a detailed understanding of the BR signaling network [1,2,3], it is not clear how exactly BRs control growth. For instance, genetic sector analysis shows that BRs, in contrast to most other growth regulators, act locally, presumably in an autocrine and/or paracrine mode, suggesting that they have some role in feedback regulation [4,5]. Here, we show that at least one role for BRs in growth control is to ensure pectin-dependent cell wall homeostasis. Pectins are complex block cell wall polymers [6], which can be modified in the wall by the enzyme pectin methylesterase (PME) [7]. Genetic or pharmacological interference with PME activity causes dramatic changes in growth behavior, which are primarily the result of the activation of the BR signaling pathway. We propose that this activation of BR signaling is part of a compensatory response, which protects the plant against the loss of cell wall integrity caused by the imbalance in pectin modification. Thus, feedback signaling from the cell wall is integrated by the BR signaling module to ensure homeostasis of cell wall biosynthesis and remodeling.


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PLoS Genetics: The Aspergillus nidulans MAPK Module AnSte11-Ste50-Ste7-Fus3 Controls Development and Secondary Metabolism

PLoS Genetics: The Aspergillus nidulans MAPK Module AnSte11-Ste50-Ste7-Fus3 Controls Development and Secondary Metabolism | Pathogenomics | Scoop.it

Mitogen activated protein (MAP) kinase cascades are conserved from yeast to man to transmit an external signal to the nucleus and induce an appropriate cellular response. The yeast Fus3 MAP kinase module represents a textbook paradigm for signal transduction. The pathway is activated by external sexual hormones triggering several kinases that transmit the signal at the plasma membrane to Fus3. Phosphorylated Fus3 is released from the membrane-associated module, crosses the cytoplasm, and enters the nucleus to activate transcription factors for sexual development. We describe here the Fus3 MAPK pathway of a filamentous fungus that controls sexual development as well as secondary metabolism, which are coordinated processes in filamentous fungi. Aspergillus nidulans is able to release Fus3 as a complex from the membrane. Complexes of Fus3 can include two additional kinases and an adaptor protein, and these complexes can migrate from the membrane to the nuclear envelope where only A. nidulans Fus3 can enter the nucleus to control nuclear regulators. Revealing specific functions of cellular Aspergillus Fus3 complexes in signal transduction to control fungal development and secondary metabolism will be a fascinating future task.

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Plant Disease: Identification and Detection of Phytophthora: Reviewing Our Progress, Identifying Our Needs (2012)

Plant Disease: Identification and Detection of Phytophthora: Reviewing Our Progress, Identifying Our Needs (2012) | Pathogenomics | Scoop.it

With the increased attention given to the genus Phytophthora in the last decade in response to the ecological and economic impact of several invasive species (such as P. ramorum, P. kernoviae, and P. alni), there has been a significant increase in the number of described species. In part, this is due to the extensive surveys in historically underexplored ecosystems (e.g., forest and stream ecosystems) undertaken to determine the spread of invasive species and the involvement of Phytophthora species in forest decline worldwide (e.g., oak decline). The past decade has seen an approximate doubling in the number of described species within the genus Phytophthora, and the number will likely continue to increase as more surveys are completed and greater attention is devoted to clarifying phylogenetic relationships and delineating boundaries in species complexes. The development of molecular resources, the availability of credible sequence databases to simplify identification of new species, and the sequencing of several genomes have provided a solid framework to gain a better understanding of the biology, diversity, and taxonomic relationships within the genus. This information is much needed considering the impact invasive or exotic Phytophthora species have had on natural ecosystems and the regulatory issues associated with their management. While this work is improving our ability to identify species based on phylogenetic grouping, it has also revealed that the genus has a much greater diversity than previously appreciated.


Via Kamoun Lab @ TSL
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Trends in Plant Science: Catch me if you can: bacterial effectors and plant targets (2012)

Trends in Plant Science: Catch me if you can: bacterial effectors and plant targets (2012) | Pathogenomics | Scoop.it

To suppress plant defense responses and favor the establishment of disease, phytopathogenic bacteria have gained the ability to deliver effector molecules inside host cells through the type III secretion system. Inside plant cells, bacterial effector proteins may be addressed to different subcellular compartments where they are able to manipulate a variety of host cellular components and molecular functions. Here we review how the recent identification and functional characterization of plant components targeted by bacterial effectors, as well as the discovery of new pathogen recognition capabilities evolved in turn by plant cells, have significantly contributed to further our knowledge about the intricate molecular interactions that are established between plants and their invading bacteria.


Via Nicolas Denancé, Kamoun Lab @ TSL
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PLoS Genetics: Comparative Genomics of Plant-Associated Pseudomonas spp.: Insights into Diversity and Inheritance of Traits Involved in Multitrophic Interactions

PLoS Genetics: Comparative Genomics of Plant-Associated Pseudomonas spp.: Insights into Diversity and Inheritance of Traits Involved in Multitrophic Interactions | Pathogenomics | Scoop.it

We sequenced the genomes of seven strains of the Pseudomonas fluorescens group that colonize plant surfaces and function as biological control agents, protecting plants from disease. In this study, we demonstrated the genomic diversity of the group by comparing these strains to each other and to three other strains that were sequenced previously. Only about half of the genes in each strain are present in all of the other strains, and each strain has hundreds of unique genes that are not present in the other genomes. We mapped the genes that contribute to biological control in each genome and found that most of the biological control genes are in the variable regions of the genome, which are not shared by all of the other strains. This finding is consistent with our knowledge of the distinctive biology of each strain. Finally, we looked for new genes that are likely to confer antimicrobial traits needed to suppress plant pathogens, but have not been identified previously. In each genome, we discovered many of these new genes, which provide avenues for future discovery of new traits with the potential to manage plant diseases in agriculture or natural ecosystems.

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Rescooped by Guogen Yang from John Innes Centre on the web
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Tackling Drought Stress: RECEPTOR-LIKE KINASES Present New Approaches

Transient gene expression, in plant protoplasts or specific plant tissues, is a key technique in plant molecular cell biology, aimed at exploring gene products and their modifications to examine functional subdomains, their interactions with other biomolecules, and their subcellular localization. Here, we highlight some of the major advantages and potential pitfalls of the most commonly used transient gene expression models and illustrate how ectopic expression and the use of dominant mutants can provide insights into protein function.


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Role of actin cytoskeleton in brassinosteroid signaling and in its integration with the auxin response in plants (Developmental Cell)

Role of actin cytoskeleton in brassinosteroid signaling and in its integration with the auxin response in plants (Developmental Cell) | Pathogenomics | Scoop.it

In plants, developmental programs and tropisms are modulated by the phytohormone auxin. Auxin reconfigures the actin cytoskeleton, which controls polar localization of auxin transporters such as PIN2 and thus determines cell-type-specific responses. In conjunction with a second growth-promoting phytohormone, brassinosteroid (BR), auxin synergistically enhances growth and gene transcription. We show that BR alters actin configuration and PIN2 localization in a manner similar to that of auxin. We describe a BR constitutive-response mutant that bears an allele of the ACTIN2 gene and shows altered actin configuration, PIN2 delocalization, and a broad array of phenotypes that recapitulate BR-treated plants. Moreover, we show that actin filament reconfiguration is sufficient to activate BR signaling, which leads to an enhanced auxin response. Our results demonstrate that the actin cytoskeleton functions as an integration node for the BR signaling pathway and auxin responsiveness.


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Plant Cell: Chimeric FLS2 Receptors Reveal the Basis for Differential Flagellin Perception in Arabidopsis and Tomato (2012)

Plant Cell: Chimeric FLS2 Receptors Reveal the Basis for Differential Flagellin Perception in Arabidopsis and Tomato (2012) | Pathogenomics | Scoop.it

The flagellin receptor of Arabidopsis thaliana, At-FLAGELLIN SENSING2 (FLS2), has become a model for mechanistic and functional studies on plant immune receptors. Here, we started out with a comparison of At-FLS2 and the orthologous tomato (Solanum lycopersicum) receptor Sl-FLS2. Both receptors specifically responded to picomolar concentrations of the genuine flg22 ligand but proved insensitive to >106-fold higher concentrations of CLV3 peptides that have recently been reported as a second type of ligand for At-FLS2. At-FLS2 and Sl-FLS2 exhibit species-specific differences in the recognition of shortened or sequence-modified flg22 ligands. To map the sites responsible for these species-specific traits on the FLS2 receptors, we performed domain swaps, substituting subsets of the 28 leucine-rich repeats (LRRs) in At-FLS2 with the corresponding LRRs from Sl-FLS2. We found that the LRRs 7 to 10 of Sl-FLS2 determine the high affinity of Sl-FLS2 for the core part RINSAKDD of flg22. In addition, we discovered importance of the LRRs 19 to 24 for the responsiveness to C-terminally modified flagellin peptides. These results indicate that ligand perception in FLS2 is a complex molecular process that involves LRRs from both the outermost and innermost LRRs of the FLS2 ectodomain.


Via Kamoun Lab @ TSL
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simon's comment, May 30, 2012 5:00 PM
Cant wait for the "pirate peptide" Felix paper. Any possibility that something similar happened in the FLS2-Ax21 recognition Pam Ronald paper?
Rescooped by Guogen Yang from Plant Pathogenomics
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Trends in Plant Science: Obligate biotroph parasitism: can we link genomes to lifestyles? (2012)

Trends in Plant Science: Obligate biotroph parasitism: can we link genomes to lifestyles? (2012) | Pathogenomics | Scoop.it

Although the oomycetes and fungi are evolutionarily very distantly related, both taxa evolved biotrophy on plant hosts several times independently, giving rise to rust- and mildew-like phenotypes. Differences in host colonization and adaptation may be reflected in genome size and by gain and loss of genes. In this opinion article we combine classical knowledge with recently sequenced pathogen genomes and present new hypotheses about the convergent evolution that led to these two distinct phenotypes in obligate biotrophs.


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ScienceDirect.com - Trends in Plant Science - Brassinosteroids tailor stomatal production to different environments

ScienceDirect.com - Trends in Plant Science - Brassinosteroids tailor stomatal production to different environments | Pathogenomics | Scoop.it

Two recent reports show that brassinosteroids control stomata production by regulating the GSK3-like kinase BIN2-mediated phosphorylation of two different stomatal signalling components resulting in opposite stomatal phenotypes. We discuss how these two mechanisms might differentially control stomatal generation under diverse growth conditions.

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PLOS Pathogens: A Population Genomics Perspective on the Emergence and Adaptation of New Plant Pathogens in Agro-Ecosystems (2012)

PLOS Pathogens: A Population Genomics Perspective on the Emergence and Adaptation of New Plant Pathogens in Agro-Ecosystems (2012) | Pathogenomics | Scoop.it

Plants and pathogens evolve in response to each other. This co-evolutionary arms race is fueled by genetic variation underlying the recognition of pathogen proteins by the host and the defeat of host defenses by the pathogen. Together with new mutations, genetic diversity in populations of both the host and pathogen represent a pool of possible variants to maintain adaptation via natural selection.Drastic changes in genetic diversity in crop species have occurred as a consequence of domestication. Whether changes in the genetic composition of these host populations also have affected genetic diversity in pathogen species is, so far, poorly understood. Advances in comparative genomics and population genomic approaches open new avenues to study adaptive processes in plant pathogens and to infer the impact of agro-ecosystems on the evolution of pathogen populations. Here we summarize new insights gained from comparative genome studies and population genomics in host-pathogen systems.

 


Via Nicolas Denancé, Kamoun Lab @ TSL
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Molecular Cell - The Size of the Proteasomal Substrate Determines Whether Its Degradation Will Be Mediated by Mono- or Polyubiquitylation

Molecular Cell - The Size of the Proteasomal Substrate Determines Whether Its Degradation Will Be Mediated by Mono- or Polyubiquitylation | Pathogenomics | Scoop.it

Highlights

 

-Single ubiquitin is sufficient to target small proteins for proteasomal degradation
-Larger proteins require polyubiquitylation for their degradation
-The ubiquitin proteasomal signal is probably adaptive

 

Summary

 

A polyubiquitin chain anchored to the substrate has been the hallmark of proteasomal recognition. However, the degradation signal appears to be more complex and to contain also a substrate’s unstructured region. Recent reports have shown that the proteasome can degrade also monoubiquitylated proteins, which adds an additional layer of complexity to the signal. Here, we demonstrate that the size of the substrate is an important determinant in its extent of ubiquitylation: a single ubiquitin moiety fused to a tail of up to ∼150 residues derived from either short artificial repeats or from naturally occurring proteins, is sufficient to target them for proteasomal degradation. Importantly, chemically synthesized adducts, where ubiquitin is attached to the substrate via a naturally occurring isopeptide bond, display similar characteristics. Taken together, these findings suggest that the ubiquitin proteasomal signal is adaptive, and is not always made of a long polyubiquitin chain.


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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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Science: They mysteries of EIN2 signaling to the nucleus revealed

Science: They mysteries of EIN2 signaling to the nucleus revealed | Pathogenomics | Scoop.it

Put this in your ethylene folder!

EIN2 was identified through a loss-of-function ethyene-insensitive mutation in 1990 (http://www.plantcell.org/content/2/6/513.full.pdf+html), and the EIN2 gene was cloned in 1999 (http://www.sciencemag.org/content/284/5423/2148.full.pdf), but until now it's been unclear how EIN2 functions. 

This new paper "uncovers a mechanism of subcellular communication whereby ethylene stimulates phosphorylation-dependent cleavage and nuclear movement of the EIN2-C′ peptide, linking hormone perception and signaling components in the ER with nuclear-localized transcriptional regulators".

Nice work!

 


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Nature News: First evidence for photosynthesis in insects - Aphids may have a rudimentary sunlight-harvesting system

Nature News: First evidence for photosynthesis in insects - Aphids may have a rudimentary sunlight-harvesting system | Pathogenomics | Scoop.it

The biology of aphids is bizarre: they can be born pregnant and males sometimes lack mouths, causing them to die not long after mating. In an addition to their list of anomalies, work published this week indicates that they may also capture sunlight and use the energy for metabolic purposes.

 

Aphids are unique among animals in their ability to synthesize pigments called carotenoids. Many creatures rely on these pigments for a variety of functions, such as maintaining a healthy immune system and making certain vitamins, but all other animals must obtain them through their diet. Entomologist Alain Robichon at the Sophia Agrobiotech Institute in Sophia Antipolis, France, and his colleagues suggest that, in aphids, these pigments can absorb energy from the Sun and transfer it to the cellular machinery involved in energy production.


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PLoS Pathogens: Genome-Wide Identification of Pseudomonas aeruginosa Virulence-Related Genes Using a Caenorhabditis elegans Infection Model

PLoS Pathogens: Genome-Wide Identification of Pseudomonas aeruginosa Virulence-Related Genes Using a Caenorhabditis elegans Infection Model | Pathogenomics | Scoop.it

Pseudomonas aeruginosa is an opportunistic human pathogen that can also infect a wide range of model organisms, including the nematode Caenorhabditis elegans. To identify P. aeruginosa genes that play key roles in the pathogenic process, we performed a screen for mutants that exhibited reduced ability to kill C. elegans using a previously constructed non-redundant library representing approximately 80% of the non-essential P. aeruginosa PA14 genes. We defined a functionally diverse set of 180 P. aeruginosa mutants (representing 170 unique genes) necessary for normal levels of virulence that included both known and novel virulence factors. The major contributors to P. aeruginosa virulence in the C. elegans infection model were not secretion systems or their corresponding effectors, but rather regulators (particularly ones that are involved in quorum sensing) and genes likely to play key roles in survival of P. aeruginosa within the host intestine. Moreover, these putative P. aeruginosa virulence genes are neither overrepresented in strain-specific regions nor in horizontally acquired genomic islands and furthermore tend to have orthologs that are widely distributed across sequenced prokaryotic species. These data underscore the diversity of pathways involved in virulence, and especially the importance of highly conserved genes for P. aeruginosa virulence in the C. elegans host model.

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PLoS Genetics: Balancing Selection at the Tomato RCR3 Guardee Gene Family Maintains Variation in Strength of Pathogen Defense

PLoS Genetics: Balancing Selection at the Tomato RCR3 Guardee Gene Family Maintains Variation in Strength of Pathogen Defense | Pathogenomics | Scoop.it

Pathogens have a negative impact on the fitness of their hosts and are responsible for drastic epidemics in humans, animals, and plants. In plants, it has been thought that natural selection acts predominantly on so-called “resistance genes,” which recognize pathogens following a key-lock interaction. In this study, we demonstrate that the arms race between hosts and pathogens extends to other components of the immune system. We discovered a signature of balancing selection at the tomato RCR3 gene, which serves as a target for pathogen-derived molecules and facilitates recognition of the pathogen via interaction with a tomato resistance gene. Functional assays of 54 RCR3 alleles reveal that the polymorphisms underlying the observed pattern of balancing selection do not play a role in pathogen recognition, but are responsible for fine tuning the defense response of infected cells upon pathogen recognition. Therefore, the optimal RCR3 allele depends upon a delicate balance between sufficient activation in the presence of, but avoidance of auto-activation in the absence of, the pathogen. The optimization of defense activation is likely a very important aspect of immune system evolution, especially when the selection pressure by the pathogen is variable in time and space.

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Nature Reviews Microbiology: The Microbial Olympics

Nature Reviews Microbiology: The Microbial Olympics | Pathogenomics | Scoop.it

Every four years, the Olympic Games plays host to competitors who have built on their natural talent by training for many years to become the best in their chosen discipline. Similar spirit and endeavour can be found throughout the microbial world, in which every day is a competition to survive and thrive. Microorganisms are trained through evolution to become the fittest and the best adapted to a particular environmental niche or lifestyle, and to innovate when the 'rules of the game' are changed by alterations to their natural habitats. In this Essay, we honour the best competitors in the microbial world by inviting them to take part in the inaugural Microbial Olympics.

 

Plant pathogens among the Microbial Olympics medalists!


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Microbiol Mol Biol Rev: Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria (2012)

Microbiol Mol Biol Rev: Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria (2012) | Pathogenomics | Scoop.it

Flagellar and translocation-associated type III secretion (T3S) systems are present in most Gram-negative plant- and animal-pathogenic bacteria and are often essential for bacterial motility or pathogenicity. The architectures of the complex membrane-spanning secretion apparatuses of both systems are similar, but they are associated with different extracellular appendages, including the flagellar hook and filament or the needle/pilus structures of translocation-associated T3S systems. The needle/pilus is connected to a bacterial translocon that is inserted into the host plasma membrane and mediates the transkingdom transport of bacterial effector proteins into eukaryotic cells. During the last 3 to 5 years, significant progress has been made in the characterization of membrane-associated core components and extracellular structures of T3S systems. Furthermore, transcriptional and posttranscriptional regulators that control T3S gene expression and substrate specificity have been described. Given the architecture of the T3S system, it is assumed that extracellular components of the secretion apparatus are secreted prior to effector proteins, suggesting that there is a hierarchy in T3S. The aim of this review is to summarize our current knowledge of T3S system components and associated control proteins from both plant- and animal-pathogenic bacteria.


Via Nicolas Denancé, Freddy Monteiro, Kamoun Lab @ TSL
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The molecular basis of ubiquitin-like protein NEDD8 deamidation by the bacterial effector protein Cif

The cycle inhibiting factors (Cifs) are a family of translocated effector proteins, found in diverse pathogenic bacteria, that interfere with the host cell cycle by catalyzing the deamidation of a specific glutamine residue (Gln40) in NEDD8 and the related protein ubiquitin. This modification prevents recycling of neddylated cullin-RING ligases, leading to stabilization of various cullin-RING ligase targets, and also prevents polyubiquitin chain formation. Here, we report the crystal structures of two Cif/NEDD8 complexes, revealing a conserved molecular interface that defines enzyme/substrate recognition. Mutation of residues forming the interface suggests that shape complementarity, rather than specific individual interactions, is a critical feature for complex formation.


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The tomato genome sequence provides insights into fleshy fruit evolution : Nature

The tomato genome sequence provides insights into fleshy fruit evolution : Nature | Pathogenomics | Scoop.it
Tomato (Solanum lycopersicum) is a major crop plant and a model system for fruit development. Solanum is one of the largest angiosperm genera and includes annual and perennial plants from diverse habitats.

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Trends in Plant Science: Obligate biotroph parasitism: can we link genomes to lifestyles? (2012)

Trends in Plant Science: Obligate biotroph parasitism: can we link genomes to lifestyles? (2012) | Pathogenomics | Scoop.it

Although the oomycetes and fungi are evolutionarily very distantly related, both taxa evolved biotrophy on plant hosts several times independently, giving rise to rust- and mildew-like phenotypes. Differences in host colonization and adaptation may be reflected in genome size and by gain and loss of genes. In this opinion article we combine classical knowledge with recently sequenced pathogen genomes and present new hypotheses about the convergent evolution that led to these two distinct phenotypes in obligate biotrophs.


Via Kamoun Lab @ TSL
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