Plant-Microbe Interaction
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plant-microbe interaction
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Rescooped by Guogen Yang from Rice Blast
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Structure-activity relationship study for fungicidal activity of 1-(4-phenoxymethyl-2-phenyl-[1,3]dioxolan-2-ylmethyl)-1H-1,2,4-triazole derivatives against rice blast

Structure-activity relationship study for fungicidal activity of 1-(4-phenoxymethyl-2-phenyl-[1,3]dioxolan-2-ylmethyl)-1H-1,2,4-triazole derivatives against rice blast | Plant-Microbe Interaction | Scoop.it
To explore new antifungal agents for rice blast control, the antifungal activity of a series of novel 1,2,4-triazole derivatives against Magnaporthe oryzae has been evaluated. The antifungal activity was determined by using in vitro mycelial growth inhibition tests. Among the 19 test compounds, we found that the compound 1-(4-phenoxymethyl-2-phenyl-[1,3]dioxolan-2-ylmethyl)-1H-1,2,4- triazole (Gj) displayed potent antifungal activity against M. oryzae. The IC50 value was found approximately 3.8±0.5 μM and the IC50 value of propiconazole was found to be approximately 3.7±0.2 μM, respectively. Structure-activity relationship studies on aromatic ring structures provided insight and information about the structural requirements for antifungal activity of this synthetic series against M. oryzae.

Via Elsa Ballini
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Living fossils: the plants holding the key to ancient and modern climate change

Living fossils: the plants holding the key to ancient and modern climate change | Plant-Microbe Interaction | Scoop.it
Despite being (somewhat surprisingly) named after a pubic triangle, Ginkgo biloba can help us understand atmosphere changes over nearly 300 million years

Via Mary Williams
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PLOS Genetics: Retromer Is Essential for Autophagy-Dependent Plant Infection by the Rice Blast Fungus

PLOS Genetics: Retromer Is Essential for Autophagy-Dependent Plant Infection by the Rice Blast Fungus | Plant-Microbe Interaction | Scoop.it
The retromer mediates protein trafficking through recycling cargo from endosomes to the trans-Golgi network in eukaryotes. However, the role of such trafficking events during pathogen-host interaction remains unclear. Here, we report that the cargo-recognition complex (MoVps35, MoVps26 and MoVps29) of the retromer is essential for appressorium-mediated host penetration by Magnaporthe oryzae, the causal pathogen of the blast disease in rice. Loss of retromer function blocked glycogen distribution and turnover of lipid bodies, delayed nuclear degeneration and reduced turgor during appressorial development. Cytological observation revealed dynamic MoVps35-GFP foci co-localized with autophagy-related protein RFP-MoAtg8 at the periphery of autolysosomes. Furthermore, RFP-MoAtg8 interacted with MoVps35-GFP in vivo, RFP-MoAtg8 was mislocalized to the vacuole and failed to recycle from the autolysosome in the absence of the retromer function, leading to impaired biogenesis of autophagosomes. We therefore conclude that retromer is essential for autophagy-dependent plant infection by the rice blast fungus.
Author Summary

The rice blast fungus Magnaporthe oryzae utilizes key infection structures, called appressoria, elaborated at the tips of the conidial germ tubes to gain entry into the host tissue. Development of the appressorium is accompanied with autophagy in the conidium leading to programmed cell death. This work highlights the significance of the Vps35/retromer membrane-trafficking machinery in the regulation of autophagy during appressorium-mediated host penetration, and thus sheds light on a novel molecular mechanism underlying autophagy-based membrane trafficking events during pathogen-host interaction in rice blast disease. Our findings provide the first genetic evidence that the retromer controls the initiation of autophagy in filamentous fungi.

Via Christophe Jacquet, Elsa Ballini
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Rescooped by Guogen Yang from Publications
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Cell Host & Microbe: Fungal Sex Receptors Recalibrated to Detect Host Plants (2015)

Cell Host & Microbe: Fungal Sex Receptors Recalibrated to Detect Host Plants (2015) | Plant-Microbe Interaction | Scoop.it

Secreted peroxidases are well-known components of damage-induced defense responses in plants. A recent study in Nature ( Turrà et al., 2015) has revealed that these enzymes can inadvertently serve as reporters of wounded sites and constitute an “Achilles heel,” allowing adapted pathogens to track and enter host tissue.


Via The Sainsbury Lab, Kamoun Lab @ TSL
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The Sainsbury Lab's curator insight, December 10, 2015 9:47 AM

Secreted peroxidases are well-known components of damage-induced defense responses in plants. A recent study in Nature ( Turrà et al., 2015) has revealed that these enzymes can inadvertently serve as reporters of wounded sites and constitute an “Achilles heel,” allowing adapted pathogens to track and enter host tissue.

Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Frontiers | Elevated Temperature Differentially Influences Effector-Triggered Immunity Outputs in Arabidopsis | Plant Biotic Interactions

Frontiers | Elevated Temperature Differentially Influences Effector-Triggered Immunity Outputs in Arabidopsis | Plant Biotic Interactions | Plant-Microbe Interaction | Scoop.it
Pseudomonas syringae is a Gram-negative bacterium that infects multiple plant species by manipulating cellular processes via injection of type three secreted effectors (T3SEs) into host cells. Nucleotide-binding leucine-rich repeat (NLR) resistance (R) proteins recognize specific T3SEs and trigger a robust immune response, called effector-triggered immunity (ETI), which limits pathogen proliferation and is often associated with localized programmed cell death, known as the hypersensitive response (HR). In this study, we examine the influence of elevated temperature on two ETI outputs: HR and pathogen virulence suppression. We found that in the Arabidopsis thaliana accession Col-0, elevated temperatures suppress the HR, but have minimal influence on ETI-associated P. syringae virulence suppression, thereby uncoupling these two ETI responses. We also identify accessions of Arabidopsis that exhibit impaired P. syringae virulence suppression at elevated temperature, highlighting the natural variation that exists in coping with biotic and abiotic stresses. These results not only reinforce the influence of abiotic factors on plant immunity but also emphasize the importance of carefully documented environmental conditions in studies of plant immunity.

Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant-Microbe Symbiosis
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CYTOKININ OXIDASE/DEHYDROGENASE3 maintains cytokinin homeostasis during root and nodule development in Lotus japonicus

Cytokinins are required for symbiotic nodule development in legumes and cytokinin signalling responses occur locally in nodule primordia and in developing nodules. Here we show that the Lotus japonicus Ckx3 cytokinin oxidase/dehydrogenase gene is induced by Nod Factor during the early phase of nodule initiation. At the cellular level, pCkx3::YFP reporter-gene studies revealed that the Ckx3 promoter is active during the first cortical cell divisions of the nodule primordium and in growing nodules. Cytokinin measurements in ckx3 mutants confirmed that CKX3 activity negatively regulates root cytokinin levels. Particularly tZ and DHZ type cytokinins in both inoculated and uninoculated roots were elevated in ckx3 mutants suggesting that these are targets for degradation by the CKX3 cytokinin oxidase/dehydrogenase. The effect of CKX3 on the positive and negative roles of cytokinin in nodule development, infection and regulation was further clarified using ckx3 insertion mutants. Phenotypic analysis indicated that ckx3 mutants have reduced nodulation, infection thread formation and root growth. We also identify a role for cytokinin in regulating nodulation and nitrogen fixation in response to nitrate as ckx3 phenotypes are exaggerated at increased nitrate levels. Together, these findings show that cytokinin accumulation is tightly regulated during nodulation in order to balance the requirement for cell divisions with negative regulatory effects of cytokinin on infection events and root development.

Via Jean-Michel Ané
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Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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Pore-forming toxins: ancient, but never really out of fashion : Nature Reviews Microbiology

Pore-forming toxins: ancient, but never really out of fashion : Nature Reviews Microbiology | Plant-Microbe Interaction | Scoop.it

Pore-forming toxins (PFTs) are virulence factors produced by many pathogenic bacteria and have long fascinated structural biologists, microbiologists and immunologists. Interestingly, pore-forming proteins with remarkably similar structures to PFTs are found in vertebrates and constitute part of their immune system. Recently, structural studies of several PFTs have provided important mechanistic insights into the metamorphosis of PFTs from soluble inactive monomers to cytolytic transmembrane assemblies. In this Review, we discuss the diverse pore architectures and membrane insertion mechanisms that have been revealed by these studies, and we consider how these features contribute to binding specificity for different membrane targets. Finally, we explore the potential of these structural insights to enable the development of novel therapeutic strategies that would prevent both the establishment of bacterial resistance and an excessive immune response.


Via IPM Lab
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Metal induction of a Pisolithus albus metallothionein and its potential involvement in heavy metal tolerance during mycorrhizal symbiosis

Metal induction of a Pisolithus albus metallothionein and its potential involvement in heavy metal tolerance during mycorrhizal symbiosis | Plant-Microbe Interaction | Scoop.it
Metallothioneins (MTs) are small, cysteine-rich peptides involved in intracellular sequestration of heavy metals in eukaryotes. We examined the role in metal homeostasis and detoxification of a MT from the ectomycorrhizal fungus Pisolithus albus (PaMT1). PaMT1 encodes a 35 amino acid-long polypeptide, with seven cysteine residues; most of them part of a C-x-C motif found in other known basidiomycete MTs. The expression levels of PaMT1 increased as a function of increased external Cu and Cd concentrations and were higher with Cu than with Cd. Heterologous complementation assays in metal-sensitive yeast mutants indicated that PaMT1 encodes a polypeptide capable of conferring higher tolerance to both Cu and Cd. Eucalyptus tereticornis plantlets colonized with P. albus grown in presence of Cu and Cd showed better growth compared to non-mycorrhizal plants. Higher PaMT1 expression levels were recorded in mycorrhizal plants grown in presence of Cu and Cd compared to control mycorrhizal plants not exposed to heavy metals. These data provide the first evidence to our knowledge that fungal metallothioneins could protect ectomycorrhizal fungi from heavy metal stress and in turn help the plants to establish in metal contaminated sites.

Via Francis Martin
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Rescooped by Guogen Yang from Rice Blast
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Transcriptomic Analysis and the Expression of Disease-Resistant Genes in Oryza meyeriana under Native Condition

Transcriptomic Analysis and the Expression of Disease-Resistant Genes in  Oryza meyeriana  under Native Condition | Plant-Microbe Interaction | Scoop.it
Oryza meyeriana (O. meyeriana), with a GG genome type (2n = 24), accumulated plentiful excellent characteristics with respect to resistance to many diseases such as rice shade and blast, even immunity to bacterial blight. It is very important to know if the diseases-resistant genes exist and express in this wild rice under native conditions. However, limited genomic or transcriptomic data of O. meyeriana are currently available. In this study, we present the first comprehensive characterization of the O. meyeriana transcriptome using RNA-seq and obtained 185,323 contigs with an average length of 1,692 bp and an N50 of 2,391 bp. Through differential expression analysis, it was found that there were most tissue-specifically expressed genes in roots, and next to stems and leaves. By similarity search against protein databases, 146,450 had at least a significant alignment to existed gene models. Comparison with the Oryza sativa (japonica-type Nipponbare and indica-type 93–11) genomes revealed that 13% of the O. meyeriana contigs had not been detected in O. sativa. Many diseases-resistant genes, such as bacterial blight resistant, blast resistant, rust resistant, fusarium resistant, cyst nematode resistant and downy mildew gene, were mined from the transcriptomic database. There are two kinds of rice bacterial blight-resistant genes (Xa1 and Xa26) differentially or specifically expressed in O. meyeriana. The 4 Xa1 contigs were all only expressed in root, while three of Xa26 contigs have the highest expression level in leaves, two of Xa26 contigs have the highest expression profile in stems and one of Xa26 contigs was expressed dominantly in roots. The transcriptomic database of O. meyeriana has been constructed and many diseases-resistant genes were found to express under native condition, which provides a foundation for future discovery of a number of novel genes and provides a basis for studying the molecular mechanisms associated with disease resistance in O. meyeriana.

Via Elsa Ballini
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Rhizobial peptidase HrrP cleaves host-encoded signaling peptides and mediates symbiotic compatibility

Rhizobial peptidase HrrP cleaves host-encoded signaling peptides and mediates symbiotic compatibility | Plant-Microbe Interaction | Scoop.it
Significance

The agriculturally important symbiosis between nitrogen-fixing bacteria (rhizobia) and their legume hosts occurs within root nodules. This partnership requires a molecular dialogue that ensures specificity and directs the codevelopment of the two organisms during nodule formation. This paper characterizes a protein, host range restriction peptidase (HrrP), which plays a role in this dialogue. Rhizobial strains that express HrrP tend to exhibit more parasitic properties, such as failing to provide fixed nitrogen for their hosts and proliferating more abundantly within nodule tissue. HrrP likely exhibits these properties by actively degrading plant-derived chemical signals that normally stimulate symbiotic cooperation.

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Abstract

Legume–rhizobium pairs are often observed that produce symbiotic root nodules but fail to fix nitrogen. Using the Sinorhizobium meliloti and Medicago truncatula symbiotic system, we previously described several naturally occurring accessory plasmids capable of disrupting the late stages of nodule development while enhancing bacterial proliferation within the nodule. We report here that host range restriction peptidase (hrrP), a gene found on one of these plasmids, is capable of conferring both these properties. hrrP encodes an M16A family metallopeptidase whose catalytic activity is required for these symbiotic effects. The ability of hrrP to suppress nitrogen fixation is conditioned upon the genotypes of both the host plant and the hrrP-expressing rhizobial strain, suggesting its involvement in symbiotic communication. Purified HrrP protein is capable of degrading a range of nodule-specific cysteine-rich (NCR) peptides encoded by M. truncatula. NCR peptides are crucial signals used by M. truncatula for inducing and maintaining rhizobial differentiation within nodules, as demonstrated in the accompanying article [Horváth B, et al. (2015) Proc Natl Acad Sci USA, 10.1073/pnas.1500777112]. The expression pattern of hrrP and its effects on rhizobial morphology are consistent with the NCR peptide cleavage model. This work points to a symbiotic dialogue involving a complex ensemble of host-derived signaling peptides and bacterial modifier enzymes capable of adjusting signal strength, sometimes with exploitative outcomes.

Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Mechanisms of developmentally controlled cell death in plants

Mechanisms of developmentally controlled cell death in plants | Plant-Microbe Interaction | Scoop.it
Highlights



Programmed cell death (PCD) is a vital aspect of plant development.


PCD is the ultimate differentiation step of specific plant cell types.


PCD is gradually prepared in tight coordination with differentiation.


The actual cell death is a highly controlled and rapidly executed process.


Cell-autonomous partial or complete cell clearance is completed post mortem.

During plant development various forms of programmed cell death (PCD) are implemented by a number of cell types as inherent part of their differentiation programmes. Differentiation-induced developmental PCD is gradually prepared in concert with the other cell differentiation processes. As precocious or delayed PCD can have detrimental consequences for plant development, the actual execution of PCD has to be tightly controlled. Once triggered, PCD is irrevocably and rapidly executed accompanied by the breakdown of cellular compartments. In most developmental PCD forms, cell death is followed by cell corpse clearance. Devoid of phagocytic mechanisms, dying plant cells have to prepare their own demise in a cell-autonomous fashion before their deaths, ensuring the completion of cell clearance post mortem. Depending on the cell type, cell clearance can be complete or rather selective, and persistent corpses of particular cells accomplish vital functions in the plant body. The present review attempts to give an update on the molecular mechanisms that coordinate differentiation-induced PCD as vital part of plant development.

Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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Nature: Save our soils

Nature: Save our soils | Plant-Microbe Interaction | Scoop.it

There are several good articles and comments in this week's Nature (3 December 2015) on the topic of soil management, including a very good Open Access overview of the hows and whys of nutrient reclamation from wastewater, "Chemistry: Reuse water pollutants"

http://www.nature.com/news/chemistry-reuse-water-pollutants-1.18899.

One of the major problems with applying fertilizers to crops is the downstream contamination of wastewaters. Extracting these nutrient contaminants both extends nutrient reserves (particularly important for P) and decreases environmental harm. It's an interesting topic for discussion in your Plant Nutrition lessons.


Via Mary Williams
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Deciphering durable resistance one R gene at a time : Nature Genetics : Nature Publishing Group

Deciphering durable resistance one R gene at a time : Nature Genetics : Nature Publishing Group | Plant-Microbe Interaction | Scoop.it
Characterizations of durable resistance genes in crop plants are coming to the fore. A new study characterizing the wheat gene Lr67 shows that how a plant manages sugar transport affects the ability of a broad group of fungal pathogens to colonize their host.

Via Christophe Jacquet
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Proteomic analysis of symbiotic proteins of Glomus mosseae and Amorpha fruticosa

Proteomic analysis of symbiotic proteins of Glomus mosseae and Amorpha fruticosa | Plant-Microbe Interaction | Scoop.it
Arbuscular mycorrhiza fungi (AMF) can colonize the roots of Amorpha fruticosa, a perennial leguminous woody shrub, and form arbuscular mycorrhiza (AM). AMF have significant promoting effects on A. fruticosa growth as the intensity of fungal colonization increases. Taking AMF-A. fruticosa symbionts as the experimental material, gel-free isobaric tags for relative and absolute quantification (iTRAQ) coupled with two-dimensional liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to investigate the expression of A. fruticosa mycorrhizal proteins at the maturation stage. A total of 3,473 proteins were identified, of which 77 showed dramatic changes in their root expression levels; 33 increased, and 44 decreased. We also found nine AMF proteins that were expressed with AMF treatment. The 77 proteins were classified according to function. Plant proteins were assigned into 11 categories: metabolism-related (32%), protein folding and degradation-related (22%), energy-related (10%), protein synthesis-related (8%), stress and defense-related (24%), transcription-related (6%), membrane and transport-related (4%), cellular structure-related (2.5%), signaling transduction-related (11%) and unknown proteins (5%). The results of the study provide a foundation for further investigation of the metabolic characteristics and molecular mechanisms of AM.

Via Jean-Michel Ané
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PLOS Genetics: Skp1 Independent Function of Cdc53/Cul1 in F-box Protein Homeostasis

PLOS Genetics: Skp1 Independent Function of Cdc53/Cul1 in F-box Protein Homeostasis | Plant-Microbe Interaction | Scoop.it
Abundance of substrate receptor subunits of Cullin-RING ubiquitin ligases (CRLs) is tightly controlled to maintain the full repertoire of CRLs. Unbalanced levels can lead to sequestration of CRL core components by a few overabundant substrate receptors. Numerous diseases, including cancer, have been associated with misregulation of substrate receptor components, particularly for the largest class of CRLs, the SCF ligases. One relevant mechanism that controls abundance of their substrate receptors, the F-box proteins, is autocatalytic ubiquitylation by intact SCF complex followed by proteasome-mediated degradation. Here we describe an additional pathway for regulation of F-box proteins on the example of yeast Met30. This ubiquitylation and degradation pathway acts on Met30 that is dissociated from Skp1. Unexpectedly, this pathway required the cullin component Cdc53/Cul1 but was independent of the other central SCF component Skp1. We demonstrated that this non-canonical degradation pathway is critical for chromosome stability and effective defense against heavy metal stress. More importantly, our results assign important biological functions to a sub-complex of cullin-RING ligases that comprises Cdc53/Rbx1/Cdc34, but is independent of Skp1.
Author Summary

Protein ubiquitylation is the covalent attachment of the small protein ubiquitin onto other proteins and is a key regulatory pathway for most biological processes. The central components of the ubiquitylation process are the E3 ligases, which recognize substrate proteins. The best-studied E3 complexes are the SCF ligases, which are composed of 3 core components—Cdc53, Skp1, Rbx1—that assemble to the functional ligase complex by binding to one of the multiple substrate adaptors—the F-box proteins. Maintaining a balanced repertoire of diverse SCF complexes that represent the entire cellular panel of substrate adapters is challenging. Depending on the cell type, hundreds of different F-box proteins can compete for the single binding site on the common SCF core complex. Rapid degradation of F-box proteins helps in maintaining a critical level of unoccupied Cdc53/Skp1/Rbx1 core, complexes and alterations in levels of F-box proteins has been linked to diseases including cancer. Studying the yeast F-box protein Met30 as a model, we have uncovered a novel mechanism for degradation of F-box proteins. This pathway targets free F-box proteins and requires part of the SCF core. These findings add an additional layer to our understanding of regulation of multisubunit E3 ligase.

Via Christophe Jacquet
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Developmental and metabolic plasticity of white-skinned grape berries in response to Botrytis cinerea during noble rot

Developmental and metabolic plasticity of white-skinned grape berries in response to Botrytis cinerea during noble rot | Plant-Microbe Interaction | Scoop.it
Noble rot results from exceptional infections of ripe grape (Vitis vinifera) berries by Botrytis cinerea. Unlike bunch rot, noble rot promotes favorable changes in grape berries and accumulation of secondary metabolites that enhance wine grape composition. Noble rot-infected berries of Sémillon, a white-skinned variety, were collected over three years from a commercial vineyard at the same time fruit were harvested for botrytized wine production. Using an integrated transcriptomics and metabolomics approach, we demonstrate that noble rot alters the metabolism of Sémillon berries by inducing biotic and abiotic stress responses as well as ripening processes. During noble rot, Botrytis induced the expression of key regulators of ripening-associated pathways, some of which are distinctive to normal ripening of red-skinned cultivars. Enhancement of phenylpropanoid metabolism, characterized by a restricted flux in white-skinned berries, was a common outcome of noble rot and red-skinned berry ripening. Transcript and metabolite analyses together with enzymatic assays determined that the biosynthesis of anthocyanins is a consistent hallmark of noble rot in Sémillon berries. The biosynthesis of terpenes and fatty acid aroma precursors also increased during noble rot. We finally characterized the impact of noble rot in botrytized wines. Altogether the results of this work demonstrate that noble rot causes a major reprogramming of berry development and metabolism. This desirable interaction between a fruit and a fungus stimulates pathways otherwise inactive in white-skinned berries, leading to greater accumulation of compounds involved in the unique flavor and aroma of botrytized wines.

Via Francis Martin
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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A recently evolved hexose transporter variant confers resistance to multiple pathogens in wheat : Nature Genetics : Nature Publishing Group

A recently evolved hexose transporter variant confers resistance to multiple pathogens in wheat : Nature Genetics : Nature Publishing Group | Plant-Microbe Interaction | Scoop.it
As there are numerous pathogen species that cause disease and limit yields of crops, such as wheat (Triticum aestivum), single genes that provide resistance to multiple pathogens are valuable in crop improvement1, 2. The mechanistic basis of multi-pathogen resistance is largely unknown. Here we use comparative genomics, mutagenesis and transformation to isolate the wheat Lr67 gene, which confers partial resistance to all three wheat rust pathogen species and powdery mildew. The Lr67 resistance gene encodes a predicted hexose transporter (LR67res) that differs from the susceptible form of the same protein (LR67sus) by two amino acids that are conserved in orthologous hexose transporters. Sugar uptake assays show that LR67sus, and related proteins encoded by homeoalleles, function as high-affinity glucose transporters. LR67res exerts a dominant-negative effect through heterodimerization with these functional transporters to reduce glucose uptake. Alterations in hexose transport in infected leaves may explain its ability to reduce the growth of multiple biotrophic pathogen species.

Via Christophe Jacquet
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Secretome analysis of the mycoparasitic fungus Trichoderma harzianum ALL 42 cultivated in different media supplemented with Fusarium solani cell wall or glucose

Secretome analysis of the mycoparasitic fungus Trichoderma harzianum ALL 42 cultivated in different media supplemented with Fusarium solani cell wall or glucose | Plant-Microbe Interaction | Scoop.it
Trichoderma harzianum is a fungus well known for its potential as a biocontrol agent against many fungal phytopathogens. The aim of this study was to characterize the proteins secreted by T. harzianum ALL42 when its spores were inoculated and incubated for 48 hours in culture media supplemented with glucose (GLU) or with cell walls from Fusarium solani (FSCW), a phytopathogen that causes severe losses in common bean and soy crops in Brazil, as well as other crop diseases around the world. T. harzianum was able to grow in Trichoderma Liquid Enzyme Production medium (TLE) and Minimal medium (MM) supplemented with FSCW and in TLE+GLU, but was unable to grow in MM+GLU medium. Protein quantification showed that TLE+FSCW and MM+FSCW had 45- and 30- fold, respectively, higher protein concentration on supernatant when compared to TLE+GLU, and this difference was observable on 2-D gel electrophoresis (2-DE). A total of 94 out of 105 proteins excised from 2-DE maps were identified. The only protein observed in all three conditions was epl1. In the media supplemented with FSCW, different hydrolases such as chitinases, β-1,3-glucanases, glucoamylases, α-1,3-glucanases, and proteases were identified, along with other proteins with no known functions in mycoparasitism, such as npp1 and cys. T. harzianum showed a complex and diverse arsenal of proteins that are secreted in response to the presence of FSCW, with novel proteins not previously described in mycoparasitic-related studies.

Via Francis Martin
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Influence of zygomycete-derived D'orenone on IAA signaling in Tricholoma-spruce ectomycorrhiza

Influence of zygomycete-derived D'orenone on IAA signaling in Tricholoma-spruce ectomycorrhiza | Plant-Microbe Interaction | Scoop.it
Despite the rising interest in microbial communication, only few studies relate to mycorrhization and the pool of potential morphogenic substances produced by the surrounding soil community. Here, we investigated the effect exerted by the C18- ketone β-apo-13-carotenone, D'orenone, on the ectomycorrhizal basidiomycete Tricholoma vaccinum and its symbiosis with the economically important host tree, spruce (Picea abies). D'orenone is an early intermediate in the biosynthesis of morphogens in sexual development of mucoromycetes, the trisporoids. In the ectomycorrhizal fungus T. vaccinum, D'orenone increased the production and/or release of the phytohormone indole-3-acetic acid (IAA) which had been proposed to be involved in the mutual symbiosis. The induced expression of the fungal aldehyde dehydrogenase, Ald5 is associated with IAA synthesis and excretion. In the host tree, D'orenone modulated root architecture by increasing lateral root length and hypertrophy of root cortex cells, likely via changed IAA concentrations and flux. Thus, we report for the first time on carotenoid metabolites from soil fungi affecting both ectomycorrhizal partners. The data imply a complex network of functions for secondary metabolites which act in an inter-kingdom signaling in soil.

Via Francis Martin
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In Vitro Morphogenesis of Arabidopsis to Search for Novel Endophytic Fungi Modulating Plant Growth

In Vitro  Morphogenesis of  Arabidopsis  to Search for Novel Endophytic Fungi Modulating Plant Growth | Plant-Microbe Interaction | Scoop.it
Fungal endophytes have shown to affect plant growth and to confer stress tolerance to the host; however, effects of endophytes isolated from water plants have been poorly investigated. In this study, fungi isolated from stems (stem-E) and roots (root-E) of Mentha aquatica L. (water mint) were identified, and their morphogenetic properties analysed on in vitro cultured Arabidopsis (L.) Heynh., 14 and 21 days after inoculation (DAI). Nineteen fungi were analysed and, based on ITS analysis, 17 isolates showed to be genetically distinct. The overall effect of water mint endophytes on Arabidopsis fresh (FW) and dry weight (DW) was neutral and positive, respectively, and the increased DW, mainly occurring 14 DAI, was possibly related to plant defence mechanism. Only three fungi increased both FW and DW of Arabidopsis at 14 and 21 DAI, thus behaving as plant growth promoting (PGP) fungi. E-treatment caused a reduction of root depth and primary root length in most cases and inhibition-to-promotion of root area and lateral root length, from 14 DAI. Only Phoma macrostoma, among the water mint PGP fungi, increased both root area and depth, 21 DAI. Root depth and area 14 DAI were shown to influence DWs, indicating that the extension of the root system, and thus nutrient uptake, was an important determinant of plant dry biomass. Reduction of Arabidopsis root depth occurred to a great extent when plants where treated with stem-E while root area decreased or increased under the effects of stem-E and root-E, respectively, pointing to an influence of the endophyte origin on root extension. M. aquatica and many other perennial hydrophytes have growing worldwide application in water pollution remediation. The present study provided a model for directed screening of endophytes able to modulate plant growth in the perspective of future field applications of these fungi.

Via Jean-Michel Ané, Francis Martin
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Rescooped by Guogen Yang from WU_Phyto-Publications
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Frontiers in Microbiology (2015): Diversity and Activity of Lysobacter Species from Disease Suppressive Soils

Frontiers in Microbiology (2015): Diversity and Activity of Lysobacter Species from Disease Suppressive Soils | Plant-Microbe Interaction | Scoop.it
The genus Lysobacter includes several species that produce a range of extracellular enzymes and other metabolites with activity against bacteria, fungi, oomycetes and nematodes. Lysobacter species were found to be more abundant in soil suppressive against the fungal root pathogen Rhizoctonia solani, but their actual role in disease suppression is still unclear. Here, the antifungal and plant growth-promoting activities of 18 Lysobacter strains, including 11 strains from Rhizoctonia-suppressive soils, were studied both in vitro and in vivo. Based on 16S rRNA sequencing, the Lysobacter strains from the Rhizoctonia-suppressive soil belonged to the four species L. antibioticus, L. capsici, L. enzymogenes and L. gummosus. Most strains showed strong in vitro activity against R. solani and several other pathogens, including Pythium ultimum, Aspergillus niger, Fusarium oxysporum and Xanthomonas campestris. When the Lysobacter strains were introduced into soil, however, no significant and consistent suppression of R. solani damping-off disease of sugar beet and cauliflower was observed. Subsequent bioassays further revealed that none of the Lysobacter strains was able to promote growth of sugar beet, cauliflower, onion and Arabidopsis thaliana, either directly or via volatile compounds. The lack of in vivo activity is most likely attributed to poor colonization of the rhizosphere by the introduced Lysobacter strains. In conclusion, our results demonstrated that Lysobacter species have strong antagonistic activities against a range of pathogens, making them an important source for putative new enzymes and antimicrobial compounds. However, their potential role in R. solani disease suppressive soil could not be confirmed. In-depth omics’- based analyses will be needed to shed more light on the potential contribution of Lysobacter species to the collective activities of microbial consortia in disease suppressive soils.

Via WU_Phyto
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Phylogenetic analysis of fungal heterotrimeric G protein-encoding genes and their expression during dimorphism in Mucor circinelloides

Phylogenetic analysis of fungal heterotrimeric G protein-encoding genes and their expression during dimorphism in Mucor circinelloides | Plant-Microbe Interaction | Scoop.it

In fungi, heterotrimeric G proteins are key regulators of biological processes such as mating, virulence, morphology, among others. Mucor circinelloides is a model organism for many biological processes, and its genome contains the largest known repertoire of genes that encode putative heterotrimeric G protein subunits in the fungal kingdom: twelve Gα (McGpa1–12), three Gβ (McGpb1–3), and three Gγ (McGpg1–3). Phylogenetic analysis of fungal Gα showed that they are divided into four distinct groups as reported previously. Fungal Gβ and Gγ are also divided into four phylogenetic groups, and to our understanding this is the first report of a phylogenetic classification for fungal Gβ and Gγ subunits.

Almost all genes that encode putative heterotrimeric G subunits in M. circinelloides are differentially expressed during dimorphic growth, except for McGpg1 (Gγ) that showed very low mRNA levels at all developmental stages. Moreover, several of the subunits are expressed in a similar pattern and at the same level, suggesting that they constitute discrete complexes. For example, McGpb3 (Gβ), and McGpg2 (Gγ), are co-expressed during mycelium growth, and McGpa1, McGpb2, and McGpg2, are co-expressed during yeast development. These findings provide the conceptual framework to study the biological role of these genes during M. circinelloides morphogenesis.


Via Francis Martin
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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New insights into an RNAi approach for plant defence against piercing-sucking and stem-borer insect pests - Plant, Cell & Environment -

Insect double-stranded (ds)RNA expression in transgenic crops can increase plant resistance to biotic stress; however, creating transgenic crops to defend against every insect pest is impractical. Arabidopsis Mob1A is required for organ growth and reproduction. When Arabidopsis roots were soaked in dsMob1A, the root lengths and numbers were significantly suppressed and plants could not bolt or flower. Twenty-four hours after rice roots were immersed in fluorescent-labelled dsEYFP (enhanced yellow fluorescent protein), fluorescence was observed in the rice sheath and stem and in planthoppers feeding on the rice. The expression levels of Ago and Dicer in rice and planthoppers were induced by dsEYFP. When rice roots were soaked in dsActin, their growth was also significantly suppressed. When planthoppers or Asian corn borers fed on rice or maize that had been irrigated with a solution containing the dsRNA of an insect target gene, the insect's mortality rate increased significantly. Our results demonstrate that dsRNAs can be absorbed by crop roots, trigger plant and insect RNAi and enhance piercing-sucking and stem-borer insect mortality rates. We also confirmed that dsRNA was stable under outdoor conditions. These results indicate that the root dsRNA soaking can be used as a bioinsecticide strategy during crop irrigation.

Via Christophe Jacquet
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Rescooped by Guogen Yang from TAL effector science
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Three technologies that changed genetics : Nature : Nature Publishing Group

Three technologies that changed genetics : Nature : Nature Publishing Group | Plant-Microbe Interaction | Scoop.it
Genome editing uses enzymes that are targeted to sequences of DNA to make cuts. These cuts are then repaired by the cell's machinery. This technology allows scientists to disrupt or modify genes with unprecedented precision. By Amy Maxmen, infographic by Denis Mallet.

Via dromius
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