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Plant Cell: Spatio-Temporal Cellular Dynamics of the Arabidopsis Flagellin Receptor Reveal Activation Status-Dependent Endosomal Sorting (2012)

Plant Cell: Spatio-Temporal Cellular Dynamics of the Arabidopsis Flagellin Receptor Reveal Activation Status-Dependent Endosomal Sorting (2012) | Plants and Microbes | Scoop.it

The activity of surface receptors is location specific, dependent upon the dynamic membrane trafficking network and receptor-mediated endocytosis (RME). Therefore, the spatio-temporal dynamics of RME are critical to receptor function. The plasma membrane receptor FLAGELLIN SENSING2 (FLS2) confers immunity against bacterial infection through perception of flagellin (flg22). Following elicitation, FLS2 is internalized into vesicles. To resolve FLS2 trafficking, we exploited quantitative confocal imaging for colocalization studies and chemical interference. FLS2 localizes to bona fide endosomes via two distinct endocytic trafficking routes depending on its activation status. FLS2 receptors constitutively recycle in a Brefeldin A (BFA)–sensitive manner, while flg22-activated receptors traffic via ARA7/Rab F2b– and ARA6/Rab F1–positive endosomes insensitive to BFA. FLS2 endocytosis required a functional Rab5 GTPase pathway as revealed by dominant-negative ARA7/Rab F2b. Flg22-induced FLS2 endosomal numbers were increased by Concanamycin A treatment but reduced by Wortmannin, indicating that activated FLS2 receptors are targeted to late endosomes. RME inhibitors Tyrphostin A23 and Endosidin 1 altered but did not block induced FLS2 endocytosis. Additional inhibitor studies imply the involvement of the actin-myosin system in FLS2 internalization and trafficking. Altogether, we report a dynamic pattern of subcellular trafficking for FLS2 and reveal a defined framework for ligand-dependent endocytosis of this receptor.

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New Phytologist: Life, death and rebirth of avirulence effectors in a fungal pathogen of Brassica crops, Leptosphaeria maculans (2017)

New Phytologist: Life, death and rebirth of avirulence effectors in a fungal pathogen of Brassica crops, Leptosphaeria maculans (2017) | Plants and Microbes | Scoop.it

In agricultural systems, major (R) genes for resistance in plants exert strong selection pressure on cognate/corresponding avirulence effector genes of phytopathogens. However, a complex interplay often exists between trade-offs linked to effector function and the need to escape R gene recognition. Here, using the Leptosphaeria maculans–oilseed rape pathosystem we review evolution of effectors submitted to multiple resistance gene selection. Characteristics of this pathosystem include a crop in which resistance genes have been deployed intensively resulting in ‘boom and bust’ cycles; a fungal pathogen with a high adaptive potential in which seven avirulence genes are cloned and for which population surveys have been coupled with molecular analysis of events responsible for virulence. The mode of evolution of avirulence genes, all located in dispensable parts of the ‘two-speed’ genome, is a highly dynamic gene-specific process. In some instances, avirulence genes are readily deleted under selection. However, others, even when located in the most plastic genome regions, undergo only limited point mutations or their avirulence phenotype is ‘camouflaged’ by another avirulence gene. Thus, while hundreds of effector genes are present, some effectors are likely to have an important and nonredundant function, suggesting functional redundancy and dispensability of effectors might not be the rule.


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Plant Cell: Recognition of the Magnaporthe oryzae effector AVR-Pia by the decoy domain of the rice NLR immune receptor RGA5 (2017)

Plant Cell: Recognition of the Magnaporthe oryzae effector AVR-Pia by the decoy domain of the rice NLR immune receptor RGA5 (2017) | Plants and Microbes | Scoop.it

Nucleotide-binding domain and leucine-rich repeat proteins (NLRs) are important receptors in plant immunity that allow recognition of pathogen effectors. The rice NLR RGA5 recognizes the Magnaporthe oryzae effector AVR-Pia through direct interaction. Here, we gained detailed insights into the molecular and structural bases of AVR-Pia-RGA5 interaction and the role of the RATX1 decoy domain of RGA5. NMR titration combined with in vitro and in vivo protein-protein interaction analyses identified the AVR-Pia interaction surface that binds to the RATX1 domain. Structure-informed AVR-Pia mutants showed that, although AVR-Pia associates with additional sites in RGA5, binding to the RATX1 domain is necessary for pathogen recognition, but can be of moderate affinity. Therefore, RGA5-mediated resistance is highly resilient to mutations in the effector. We propose a model that explains such robust effector recognition as a consequence, and an advantage, of the combination of integrated decoy domains with additional independent effector-NLR interactions.

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Population Genomics of Fungal and Oomycete Diseases of Animals and Plants, Ascona, Switzerland, 7-11 May 2017

Population Genomics of Fungal and Oomycete Diseases of Animals and Plants, Ascona, Switzerland, 7-11 May 2017 | Plants and Microbes | Scoop.it

The population genomics of emerging fungal and oomycete pathogens is a dynamic and rapidly growing area of research. New datasets, new sequencing methodologies and new analytical methods are enabling a deeper understanding of the evolutionary processes driving the emergence of fungal and oomycete pathogens. This conference aims to enrich our understanding of the processes driving the evolution of plant, animal and human pathogens, with an over-riding goal of identifying the genomic changes responsible for adaptation to novel hosts and environments. A secondary goal will be to determine how the relevant genes (and their underlying functions) vary along ecological/agronomic gradients associated with host specialization, including quantitative adaptation to host resistance. Another important goal is to facilitate networking of key scientists working on fungal and oomycete diseases of plants, animals and humans. The conference will be oriented around genome-based approaches, including; 1) using population genomics to understand pathogen emergence and host specialization, 2) using genome-wide association studies to identify key genes and genomic regions associated with pathogen local adaptation, 3) using population genomics to understand pathogen divergence/speciation, 4) developing new analytical methods for population genomic analyses.

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15th Congress of the Mediterranean Phytopathological Union, Córdoba, Spain, June 20-23 2017

15th Congress of the Mediterranean Phytopathological Union, Córdoba, Spain, June 20-23 2017 | Plants and Microbes | Scoop.it

The upcoming Congress of the Mediterranean Phytopathological Union entitled Plant health sustaining Mediterranean Ecosystems” will be held in Córdoba, Spain, from June 20-23, 2017. The meeting promotes dissemination of the latest scientific advances and encourages dialogue and collaboration between researchers interested in all aspects of Phytopathology. The conference language is English.

 

A detailed scientific program will be available in January 2017. Plenary, concurrent and poster sessions will be held on key topics such as Genome Analysis; Invasive Emerging Pathogens; Integrated Disease Management; Food Safety, New Tools In Diagnostics And Management; Molecular Pathogen-Host Interactions; Impact Of Climate Change; Biocontrol, Natural Compounds And Plant Stimulants; Epidemiology And Modelling; and Microbiomes In Plant Health. The meeting proceedings will be published in the international journal Phytopathologia Mediterranea.

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PNAS: The CC domain structure from the wheat stem rust resistance protein Sr33 challenges paradigms for dimerization in plant NLR proteins (2016)

PNAS: The CC domain structure from the wheat stem rust resistance protein Sr33 challenges paradigms for dimerization in plant NLR proteins (2016) | Plants and Microbes | Scoop.it

Plants use intracellular immunity receptors, known as nucleotide-binding oligomerization domain-like receptors (NLRs), to recognize specific pathogen effector proteins and induce immune responses. These proteins provide resistance to many of the world’s most destructive plant pathogens, yet we have a limited understanding of the molecular mechanisms that lead to defense signaling. We examined the wheat NLR protein, Sr33, which is responsible for strain-specific resistance to the wheat stem rust pathogen, Puccinia graminis f. sp. tritici. We present the solution structure of a coiled-coil (CC) fragment from Sr33, which adopts a four-helix bundle conformation. Unexpectedly, this structure differs from the published dimeric crystal structure of the equivalent region from the orthologous barley powdery mildew resistance protein, MLA10, but is similar to the structure of the distantly related potato NLR protein, Rx. We demonstrate that these regions are, in fact, largely monomeric and adopt similar folds in solution in all three proteins, suggesting that the CC domains from plant NLRs adopt a conserved fold. However, larger C-terminal fragments of Sr33 and MLA10 can self-associate both in vitro and in planta, and this self-association correlates with their cell death signaling activity. The minimal region of the CC domain required for both cell death signaling and self-association extends to amino acid 142, thus including 22 residues absent from previous biochemical and structural protein studies. These data suggest that self-association of the minimal CC domain is necessary for signaling but is likely to involve a different structural basis than previously suggested by the MLA10 crystallographic dimer.

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Plant Cell: Plants Release Precursors of Histone Deacetylase Inhibitors to Suppress Growth of Competitors (2015)

Plant Cell: Plants Release Precursors of Histone Deacetylase Inhibitors to Suppress Growth of Competitors (2015) | Plants and Microbes | Scoop.it

To secure their access to water, light, and nutrients, many plant species have developed allelopathic strategies to suppress competitors. To this end, they release into the rhizosphere phytotoxic substances that inhibit the germination and growth of neighbors. Despite the importance of allelopathy in shaping natural plant communities and for agricultural production, the underlying molecular mechanisms are largely unknown. Here, we report that allelochemicals derived from the common class of cyclic hydroxamic acid root exudates directly affect the chromatin-modifying machinery in Arabidopsis thaliana. These allelochemicals inhibit histone deacetylases both in vitro and in vivo and exert their activity through locus-specific alterations of histone acetylation and associated gene expression. Our multilevel analysis collectively shows how plant-plant interactions interfere with a fundamental cellular process, histone acetylation, by targeting an evolutionarily highly conserved class of enzymes.

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bioRxiv: NLR signaling network mediates immunity to diverse plant pathogens (2016)

bioRxiv: NLR signaling network mediates immunity to diverse plant pathogens (2016) | Plants and Microbes | Scoop.it

Plant and animal nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins often function in pairs to mediate innate immunity to pathogens. However, the degree to which NLR proteins form signaling networks beyond genetically linked pairs is poorly understood. In this study, we discovered that a large NLR immune signaling network with a complex genetic architecture confers immunity to oomycetes, bacteria, viruses, nematodes, and insects. The network emerged over 100 million years ago from a linked NLR pair that diversified into up to one half of the NLR of asterid plants. We propose that this NLR network increases robustness of immune signaling to counteract rapidly evolving plant pathogens.

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Scientific Reports: CRISPR/Cas9-Mediated Immunity to Geminiviruses: Differential Interference and Evasion (2016)

Scientific Reports: CRISPR/Cas9-Mediated Immunity to Geminiviruses: Differential Interference and Evasion (2016) | Plants and Microbes | Scoop.it

The CRISPR/Cas9 system has recently been used to confer molecular immunity against several eukaryotic viruses, including plant DNA geminiviruses. Here, we provide a detailed analysis of the efficiencies of targeting different coding and non-coding sequences in the genomes of multiple geminiviruses. Moreover, we analyze the ability of geminiviruses to evade the CRISPR/Cas9 machinery. Our results demonstrate that the CRISPR/Cas9 machinery can efficiently target coding and non-coding sequences and interfere with various geminiviruses. Furthermore, targeting the coding sequences of different geminiviruses resulted in the generation of viral variants capable of replication and systemic movement. By contrast, targeting the noncoding intergenic region sequences of geminiviruses resulted in interference, but with inefficient recovery of mutated viral variants, which thus limited the generation of variants capable of replication and movement. Taken together, our results indicate that targeting noncoding, intergenic sequences provides viral interference activity and significantly limits the generation of viral variants capable of replication and systemic infection, which is essential for developing durable resistance strategies for long-term virus control.

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New Phytologist: Convergent evolution of filamentous microbes towards evasion of glycan-triggered immunity (2016)

New Phytologist: Convergent evolution of filamentous microbes towards evasion of glycan-triggered immunity (2016) | Plants and Microbes | Scoop.it

All filamentous microbes produce and release a wide range of glycans, which are essential determinants of microbe–microbe and microbe–host interactions. Major cell wall constituents, such as chitin and β-glucans, are elicitors of host immune responses. The widespread capacity for glycan perception in plants has driven the evolution of various strategies that help filamentous microbes to evade detection. Common strategies include structural and chemical modifications of cell wall components as well as the secretion of effector proteins that suppress chitin- and β-glucan-triggered immune responses. Thus, the necessity to avoid glycan-triggered immunity represents a driving force in the convergent evolution of filamentous microbes towards its suppression.

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Plant Physiol: Transcriptional analysis of serk1 and serk3 receptor-like kinase mutants (2016)

Plant Physiol: Transcriptional analysis of serk1 and serk3 receptor-like kinase mutants (2016) | Plants and Microbes | Scoop.it

Somatic Embryogenesis Receptor like Kinases (SERKs) are ligand binding co-receptors that are able to combine with different ligand perceiving receptors such as Brassinosteroid Insensitive 1 (BRI1) and Flagellin-Sensitive 2 (FLS2). Phenotypical analysis of serk single mutants is not straightforward because multiple pathways can be affected, while redundancy is observed for a single phenotype. For example, serk1serk3 double mutant roots are insensitive towards brassinosteroids but have a phenotype different from bri1 mutant roots. To decipher these effects, 4-day-old Arabidopsis roots were studied using microarray analysis. 698 genes, involved in multiple biological processes, were found to be differentially regulated in serk1-3serk3-2 double mutants. About half of these are related to BR signalling. The remainder appears to be unlinked to BRs and related to primary and secondary metabolism. In addition, methionine derived glucosinolate biosynthesis genes are upregulated, which was verified by metabolite profiling. The results also show that the gene expression pattern in serk3-2 mutant roots is similar to that of the serk1-3serk3-2 double mutant roots. This confirms the existence of partial redundancy between SERK3 and SERK1 as well as the promoting or repressive activity of a single co-receptor in multiple simultaneously active pathways.Click here to edit the content


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Somatic Embryogenesis Receptor like Kinases (SERKs) are ligand binding co-receptors that are able to combine with different ligand perceiving receptors such as Brassinosteroid Insensitive 1 (BRI1) and Flagellin-Sensitive 2 (FLS2). Phenotypical analysis of serk single mutants is not straightforward because multiple pathways can be affected, while redundancy is observed for a single phenotype. For example, serk1serk3 double mutant roots are insensitive towards brassinosteroids but have a phenotype different from bri1 mutant roots. To decipher these effects, 4-day-old Arabidopsis roots were studied using microarray analysis. 698 genes, involved in multiple biological processes, were found to be differentially regulated in serk1-3serk3-2 double mutants. About half of these are related to BR signalling. The remainder appears to be unlinked to BRs and related to primary and secondary metabolism. In addition, methionine derived glucosinolate biosynthesis genes are upregulated, which was verified by metabolite profiling. The results also show that the gene expression pattern in serk3-2 mutant roots is similar to that of the serk1-3serk3-2 double mutant roots. This confirms the existence of partial redundancy between SERK3 and SERK1 as well as the promoting or repressive activity of a single co-receptor in multiple simultaneously active pathways.
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Potato Research: Durable Late Blight Resistance in Potato Through Dynamic Varieties Obtained by Cisgenesis: Scientific and Societal Advances in the DuRPh Project (2016)

Potato Research: Durable Late Blight Resistance in Potato Through Dynamic Varieties Obtained by Cisgenesis: Scientific and Societal Advances in the DuRPh Project (2016) | Plants and Microbes | Scoop.it

From 2006 through 2015, a research project on Durable Resistance in potato against Phytophthora (DuRPh) was carried out at Wageningen University and Research Centre. Its objective was to develop a proof of principle for durable resistance against late blight by cisgenesis. This public-funded project aimed at stimulating research on genetic modification and public debate on innovative genetic techniques. It was decided to clone and transfer late blight resistance (R) genes of crossable wild potato species (cisgenes) by Agrobacterium tumefaciens-mediated transformation without non-potato genes. A stack of multiple R genes were planned to be inserted into established varieties, thereby creating a dynamic variety in which the composition of the stacks may vary over space and time. Cisgenic plants were selected based on the expression of all inserted R genes and trueness-to-type. Within the project, 13 Rgenes from wild potato species were genetically mapped and three of them were cloned. Four varieties were transformed with one to three R genes. This was initially done using kanamycin resistance provided by a selectable marker gene of synthetic origin in order to quickly test the performance and stability of the introduced R genes and stacked R gene combinations. Once the functioning thereof was confirmed, marker-free transformations were conducted; thus, true cisgenic events were selected. The results about the different R genes, their chromosomal location, their specificity, the background dependence, the maximum size of a stack, its regeneration time and associated somaclonal variation frequency and its stability were studied. After selection and characterisation in the laboratory, the best cisgenic events were assessed in field trials for late blight resistance. This showed that inserted R genes were capable of turning a susceptible variety into a resistant one. Maximising longevity of the resistance was assured through resistance management research. It was shown that stacking of multiple R genes and monitoring how to deploy these stacks spatially and temporally could reduce fungicide use by over 80%. Communications through media and field demonstrations were manifold to allow public and policymakers to decide if cisgenesis is an acceptable tool to make potato farming more sustainable. Future deployment of the DuRPh strategy will depend largely on its status as a genetically modified crop or its exemption thereof. Worldwide near eradication of late blight would increase global annual potato production by close to 80 million tons, thereby contributing considerably to the needed additional global future food supply.

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Current Opinion in Microbiology: The cell biology of late blight disease (2016)

Current Opinion in Microbiology: The cell biology of late blight disease (2016) | Plants and Microbes | Scoop.it

• The Phytophthora haustorium is a major site of secretion during infection.

• The host endocytic cycle contributes to biogenesis of the Extra-Haustorial Membrane.
• RXLR effectors manipulate host processes at diverse subcellular locations.

• They directly manipulate the activity or location of immune proteins.

• They also promote the activity of endogenous negative regulators of immunity.

 

Late blight, caused by the oomycete Phytophthora infestans, is a major global disease of potato and tomato. Cell biology is teaching us much about the developmental stages associated with infection, especially the haustorium, which is a site of intimate interaction and molecular exchange between pathogen and host. Recent observations suggest a role for the plant endocytic cycle in specific recruitment of host proteins to the Extra-Haustorial Membrane, emphasising the unique nature of this membrane compartment. In addition, there has been a strong focus on the activities of RXLR effectors, which are delivered into plant cells to modulate and manipulate host processes. RXLR effectors interact directly with diverse plant proteins at a range of subcellular locations to promote disease.

 

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PLOS Pathogens: Magnaporthe oryzae Glycine-Rich Secretion Protein, Rbf1 Critically Participates in Pathogenicity through the Focal Formation of the Biotrophic Interfacial Complex (2016)

PLOS Pathogens: Magnaporthe oryzae  Glycine-Rich Secretion Protein, Rbf1 Critically Participates in Pathogenicity through the Focal Formation of the Biotrophic Interfacial Complex (2016) | Plants and Microbes | Scoop.it

Magnaporthe oryzae, the fungus causing rice blast disease, should contend with host innate immunity to develop invasive hyphae (IH) within living host cells. However, molecular strategies to establish the biotrophic interactions are largely unknown. Here, we report the biological function of a Moryzae-specific gene, Required-for-Focal-BIC-Formation 1 (RBF1). RBF1expression was induced in appressoria and IH only when the fungus was inoculated to living plant tissues. Long-term successive imaging of live cell fluorescence revealed that the expression of RBF1 was upregulated each time the fungus crossed a host cell wall. Like other symplastic effector proteins of the rice blast fungus, Rbf1 accumulated in the biotrophic interfacial complex (BIC) and was translocated into the rice cytoplasm. RBF1-knockout mutants (Δrbf1) were severely deficient in their virulence to rice leaves, but were capable of proliferating in abscisic acid-treated or salicylic acid-deficient rice plants. In rice leaves, Δrbf1 inoculation caused necrosis and induced defense-related gene expression, which led to a higher level of diterpenoid phytoalexin accumulation than the wild-type fungus did. Δrbf1 showed unusual differentiation of IH and dispersal of the normally BIC-focused effectors around the short primary hypha and the first bulbous cell. In the Δrbf1-invaded cells, symplastic effectors were still translocated into rice cells but with a lower efficiency. These data indicate that RBF1 is a virulence gene essential for the focal BIC formation, which is critical for the rice blast fungus to suppress host immune responses.

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Phytochemistry: The bitter side of the nightshades: Genomics drives discovery in Solanaceae steroidal alkaloid metabolism (2015)

Phytochemistry: The bitter side of the nightshades: Genomics drives discovery in Solanaceae steroidal alkaloid metabolism (2015) | Plants and Microbes | Scoop.it

Steroidal alkaloids (SAs) and their glycosylated forms (SGAs) are toxic compounds largely produced by members of the Solanaceae and Liliaceae plant families. This class of specialized metabolites serves as a chemical barrier against a broad range of pest and pathogens. In humans and animals, SAs are considered anti-nutritional factors because they affect the digestion and absorption of nutrients from food and might even cause poisoning. In spite of the first report on SAs nearly 200 years ago, much of the molecular basis of their biosynthesis and regulation remains unknown. Aspects concerning chemical structures and biological activities of SAs have been reviewed extensively elsewhere; therefore, in this review the latest insights to the elucidation of the SAs biosynthetic pathway are highlighted. Recently, co-expression analysis combined with metabolic profiling revealed metabolic gene clusters in tomato and potato that contain core genes required for production of the prominent SGAs in these two species. Elaborating the knowledge regarding the SAs biosynthetic pathway, the subcellular transport of these molecules, as well as the identification of regulatory and signaling factors associated with SA metabolism will likely advance understanding of chemical defense mechanisms in Solanaceae and Liliaceae plants. It will also provide the means to develop, through classical breeding or genetic engineering, crops with modified levels of anti-nutritional SAs.

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Science: A paralogous decoy protects Phytophthora sojae apoplastic effector PsXEG1 from a host inhibitor (2017)

Science: A paralogous decoy protects Phytophthora sojae apoplastic effector PsXEG1 from a host inhibitor (2017) | Plants and Microbes | Scoop.it

The extracellular space (apoplast) of plant tissue represents a critical battleground between plants and attacking microbes. Here we show that a pathogen-secreted apoplastic Xyloglucan-specific EndoGlucanase PsXEG1 is a focus of this struggle in the Phytophthora sojae-soybean interaction. We show that soybean produces an apoplastic Glucanase Inhibitor Protein, (GmGIP1), that binds to PsXEG1 to block its contribution to virulence. P. sojae however, secretes a paralogous PsXEG1-Like Protein (PsXLP1) that has lost enzyme activity but binds to GmGIP1 more tightly than does PsXEG1, thus freeing PsXEG1 to support P. sojae infection. The PsXEG1 and PsXLP1gene pair is conserved in many Phytophthora species, and the P. parasitica orthologs PpXEG1 and PpXLP1 have similar functions. Thus this apoplastic decoy strategy maybe widely employed in Phytophthora pathosystems.

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MPMI: Current Understandings on Plant Nonhost Resistance (2016)

MPMI: Current Understandings on Plant Nonhost Resistance (2016) | Plants and Microbes | Scoop.it

Nonhost resistance, a resistance of plant species against all non-adapted pathogens, is considered the most durable and efficient immune system of plants but yet remains elusive. The underlying mechanism of nonhost resistance has been investigated at multiple levels of plant defense for several decades. In this review, we have comprehensively surveyed the latest literature on nonhost resistance in terms of pre-invasion, metabolic defense, pattern-triggered immunity, effector-triggered immunity, defense signaling, and possible application in crop protection. Overall, we summarize the current understanding of nonhost resistance mechanisms. Pre- and post-invasion is not much deviated from the knowledge on host resistance except for a few specific cases. Further insights on the roles of the pattern recognition receptor gene family, multiple interactions between effectors from non-adapted pathogen and plant factors, and plant secondary metabolites in host range determination could expand our knowledge on nonhost resistance and provide efficient tools for the future crop protection using combinational biotechnology approaches.


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Scienmag: Genome sequence reveals why the whitefly is such a formidable threat to food security (2016)

Scienmag: Genome sequence reveals why the whitefly is such a formidable threat to food security (2016) | Plants and Microbes | Scoop.it

ITHACA, NY–Researchers have sequenced the genome of the whitefly (Bemisia tabici), an invasive insect responsible for spreading plant viruses worldwide, causing billions of dollars in crop losses each year.

 

The genome study, led by Associate Professor Zhangjun Fei of the Boyce Thompson Institute (BTI), offers many clues to the insect's remarkable ability to resist pesticides, transmit more than 300 plant viruses, and to feed on at least 1,000 different plant species. Published today in the journal BMC Biology, the study will serve as a foundation for future work to combat this global pest.

"Whitefly is an economically important pest for agriculture crops. It causes direct damage and also is a major vector for viruses, like Tomato yellow leaf curl virus, Cassava mosaic virus and Cassava brown streak virus, so it creates huge crop losses and poses serious threats to food security, especially in Africa and other parts of the developing world," said Fei.

 

In collaboration with a group of international colleagues, BTI researchers created a high-quality draft genome sequence of the whitefly and identified genes that code for proteins. The genome sequence can be accessed at the whitefly genome database developed by the Fei lab.

 

An analysis showed that, compared to related species, the whitefly has expanded families of detoxification genes. It also has extra genes that code for proteins related to virus acquisition and transmission, as well as insecticide resistance.

 

In an impressive example of horizontal gene transfer, the whitefly has acquired 142 genes from bacteria or fungi, including some coding for enzymes that break down foreign chemicals. These genes likely allow the whitefly to feed on diverse types of plants and to rapidly evolve resistance to insecticides.

 

Because pesticides are ineffective at keeping whitefly populations in check, collaborators at USDA plan to use the genome sequence to develop a control strategy using RNA interference (RNAi). Once scientists pinpoint the genes necessary for virus transmission and survival in the whitefly genome, they can develop new varieties of crops that will produce RNA molecules that block the expression of those necessary genes, killing the whitefly or preventing it from spreading the virus .

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Science: Intracellular innate immune surveillance devices in plants and animals (2016)

Science: Intracellular innate immune surveillance devices in plants and animals (2016) | Plants and Microbes | Scoop.it
The innate immune systems of both plants and animals depend on the ability to recognize pathogen-derived molecules and stimulate a defense response. Jones et al. review how that common function is achieved in such diverse kingdoms by similar molecules. The recognition system is built for hair-trigger sensitivity and constructed in a modular manner. Understanding such features could be useful in building new pathways through synthetic biology, whether for broadening disease defenses or constructing new signal-response circuits.Empty description

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The Sainsbury Lab's curator insight, December 2, 2016 4:06 AM
The innate immune systems of both plants and animals depend on the ability to recognize pathogen-derived molecules and stimulate a defense response. Jones et al. review how that common function is achieved in such diverse kingdoms by similar molecules. The recognition system is built for hair-trigger sensitivity and constructed in a modular manner. Understanding such features could be useful in building new pathways through synthetic biology, whether for broadening disease defenses or constructing new signal-response circuits.
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eLife: A complete toolset for the study of Ustilago bromivora and Brachypodium sp. as a fungal-temperate grass pathosystem (2016)

eLife: A complete toolset for the study of Ustilago bromivora and Brachypodium sp. as a fungal-temperate grass pathosystem (2016) | Plants and Microbes | Scoop.it

Due to their economic relevance, the study of plant pathogen interactions is of importance. However, elucidating these interactions and their underlying molecular mechanisms remains challenging since both host and pathogen need to be fully genetically accessible organisms. Here we present milestones in the establishment of a new biotrophic model pathosystem: Ustilago bromivora and Brachypodium sp. We provide a complete toolset, including an annotated fungal genome and methods for genetic manipulation of the fungus and its host plant. This toolset will enable researchers to easily study biotrophic interactions at the molecular level on both the pathogen and the host side. Moreover, our research on the fungal life cycle revealed a mating type bias phenomenon. U. bromivora harbors a haplo-lethal allele that is linked to one mating type region. As a result, the identified mating type bias strongly promotes inbreeding, which we consider to be a potential speciation driver.


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Science: Regulation of sugar transporter activity for antibacterial defense in Arabidopsis (2016)

Science: Regulation of sugar transporter activity for antibacterial defense in Arabidopsis (2016) | Plants and Microbes | Scoop.it

Microbial pathogens strategically acquire metabolites from their hosts during infection. Here we show that the host can intervene to prevent such metabolite loss to pathogens. Phosphorylation-dependent regulation of sugar transporter 13 (STP13) is required for antibacterial defense in the plant Arabidopsis thaliana. STP13 physically associates with the flagellin receptor flagellin-sensitive 2 (FLS2) and its co-receptor BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1 (BAK1). BAK1 phosphorylates STP13 at threonine 485, which enhances its monosaccharide uptake activity to compete with bacteria for extracellular sugars. Limiting the availability of extracellular sugar deprives bacteria of an energy source and restricts virulence factor delivery. Our results reveal that control of sugar uptake, managed by regulation of a host sugar transporter, is a defense strategy deployed against microbial infection. Competition for sugar thus shapes host-pathogen interactions.

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Nature: Bacteria establish an aqueous living space in plants crucial for virulence (2016)

Nature: Bacteria establish an aqueous living space in plants crucial for virulence (2016) | Plants and Microbes | Scoop.it

High humidity has a strong influence on the development of numerous diseases affecting the above-ground parts of plants (the phyllosphere) in crop fields and natural ecosystems, but the molecular basis of this humidity effect is not understood. Previous studies have emphasized immune suppression as a key step in bacterial pathogenesis. Here we show that humidity-dependent, pathogen-driven establishment of an aqueous intercellular space (apoplast) is another important step in bacterial infection of the phyllosphere. Bacterial effectors, such as Pseudomonas syringae HopM1, induce establishment of the aqueous apoplast and are sufficient to transform non-pathogenic P. syringae strains into virulent pathogens in immunodeficient Arabidopsis thaliana under high humidity. Arabidopsis quadruple mutants simultaneously defective in a host target (AtMIN7) of HopM1 and in pattern-triggered immunity could not only be used to reconstitute the basic features of bacterial infection, but also exhibited humidity-dependent dyshomeostasis of the endophytic commensal bacterial community in the phyllosphere. These results highlight a new conceptual framework for understanding diverse phyllosphere–bacterial interactions.

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EMBO Reports: Plants get on PAR with poly(ADP‐ribosyl)action (2016)

EMBO Reports: Plants get on PAR with poly(ADP‐ribosyl)action (2016) | Plants and Microbes | Scoop.it

Poly(ADP-ribosyl)ation, or PARylation, was first described over 50 years ago. Since then, our understanding of the biochemistry and enzymology of this protein modification has significantly progressed. PARylation has long been associated with DNA damage and DNA repair as well as genotoxic stress [1,2]. However, over the last two decades this has expanded to chromatin remodelling, DNA replication, transcriptional regulation, telomere cohesion and mitotic spindle formation during cell division, intracellular trafficking and energy metabolism [1]. Most eukaryotes, except yeasts, have genes encoding poly (ADP-ribose) polymerases (PARPs) and poly (ADP-ribose) glycohydrolases (PARGs), and our knowledge on PARylation is primarily based on studies in metazoans. In plants, however, mechanistic understanding of the role of ADP-ribosylation in stress response is still lacking. In this issue of EMBO Reports, Feng et al [3] identify the first set of PARylated plant proteins and show that in vivo PARylation of one of these proteins, a factor named DAWDLE, is important for its role in plant immunity. See also: B Feng et al


Via Frank Menke, The Sainsbury Lab
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Advances in Botanical Research: Effector-Mediated Communication of Filamentous Plant Pathogens With Their Hosts (2016)

Advances in Botanical Research: Effector-Mediated Communication of Filamentous Plant Pathogens With Their Hosts (2016) | Plants and Microbes | Scoop.it

Pathogenic fungi and oomycetes can establish intimate associations with plants. These interactions underlie a molecular dialogue that leads to the successful colonization of host tissues. Major questions driving research in plant pathology these last decades are how pathogenic microorganisms circumvent preformed or induced defences and how pathogens manipulate host physiology to promote virulence. One key actor in this dialogue relies on a class of molecules secreted by pathogens termed effectors. Effectors perturb host processes by targeting a variety of host functions either in the apoplast or in the cytosol of host cells. This chapter focuses on fungal and oomycetal cytoplasmic effectors by reviewing methods to predict and to characterize effectors as well as their activities and role during infection. We provide current knowledge regarding their evolution and their putative role in the shaping of plant-associated microbial communities.

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3rd Adam Kondorosi Symposium: Frontiers in Beneficial Plant-Microbe Interactions, 24-25 April 2017, Gif-sur-Yvette, France

3rd Adam Kondorosi Symposium: Frontiers in Beneficial Plant-Microbe Interactions, 24-25 April 2017, Gif-sur-Yvette, France | Plants and Microbes | Scoop.it

The objective of this symposium is to create a scientific event that is at the forefront of fundamental research in beneficial plant-microbe interactions.

 

The symposium will bring together about 150 participants in a rather informal atmosphere, facilitating exchanges. We also aim at proposing a highly attractive program at a moderate inscription fee to give the opportunity to researchers - in particular those at the early stage of their career – to participate to an exciting top-level scientific event. Young researchers will have the opportunity to present their work with a poster.

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Jean-Michel Ané's comment, October 20, 2016 1:06 PM
That's a picture I took as postdoc 15 years ago :-)
Jean-Michel Ané's curator insight, October 20, 2016 1:06 PM

That's a picture that I took as a postdoc 15 years ago :-)

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Phytopathology: Evolution of Compatibility Range in the Rice−Magnaporthe oryzae System: An Uneven Distribution of R Genes Between Rice Subspecies (2016)

Phytopathology: Evolution of Compatibility Range in the Rice−Magnaporthe oryzae System: An Uneven Distribution of R Genes Between Rice Subspecies (2016) | Plants and Microbes | Scoop.it

Efficient strategies for limiting the impact of pathogens on crops require a good understanding of the factors underlying the evolution of compatibility range for the pathogens and host plants, i.e., the set of host genotypes that a particular pathogen genotype can infect and the set of pathogen genotypes that can infect a particular host genotype. Until now, little is known about the evolutionary and ecological factors driving compatibility ranges in systems implicating crop plants. We studied the evolution of host and pathogen compatibility ranges for rice blast disease, which is caused by the ascomycete Magnaporthe oryzae. We challenged 61 rice varieties from three rice subspecies with 31 strains of M. oryzae collected worldwide from all major known genetic groups. We determined the compatibility range of each plant variety and pathogen genotype and the severity of each plant−pathogen interaction. Compatibility ranges differed between rice subspecies, with the most resistant subspecies selecting for pathogens with broader compatibility ranges and the least resistant subspecies selecting for pathogens with narrower compatibility ranges. These results are consistent with a nested distribution of R genes between rice subspecies.

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