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Plant-Microbe Interaction
plant-microbe interaction
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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Why start from scratch when you can recycle and adapt?

Why start from scratch when you can recycle and adapt? | Plant-Microbe Interaction | Scoop.it

Leaf development is such a fascinating topic, because it reveals the molecular processes the are involved in pattern formation. Interestingly, several genes and small molecules (e.g., auxin) are used repeatedly during the initiation and elaboration of leaves. A pair of papers out in Plant Cell highlights this thrifty genetic strategy.
In the first, we see how the development of the ligule in a maize leaf involves the redeployment of several genes that are involved in leaf initiation, a process that occurs much earlier in the developmental pathway.


Transcriptomic Analyses Indicate That Maize Ligule Development Recapitulates Gene Expression Patterns That Occur during Lateral Organ Initiation (www.plantcell.org/…/early/2014/12/16/tpc.114.132688.abstract).
In the second, we see the KNOX1 / GA module that is so important in leaf developmental patterning also contributes to the environtmental responsiveness of leaf shape (heterophylly), as found in aquatic plants such as Rorippa aquatica.
Regulation of the KNOX-GA Gene Module Induces Heterophyllic Alteration in North American Lake Cress (http://www.plantcell.org/…/20…/12/16/tpc.114.130229.abstract).
These studies also reinforce our understanding of process of evolution; why start from scratch when you can just tweak something that aleady works in another context?

 


Via Mary Williams
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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First evidence of mutualism between ancient plant lineages (Haplomitriopsida liverworts) and Mucoromycotina fungi and its response to simulated Palaeozoic changes in atmospheric CO2

First evidence of mutualism between ancient plant lineages (Haplomitriopsida liverworts) and Mucoromycotina fungi and its response to simulated Palaeozoic changes in atmospheric CO2 | Plant-Microbe Interaction | Scoop.it

The discovery that Mucoromycotina, an ancient and partially saprotrophic fungal lineage, associates with the basal liverwort lineage Haplomitriopsida casts doubt on the widely held view that Glomeromycota formed the sole ancestral plant–fungus symbiosis. Whether this association is mutualistic, and how its functioning was affected by the fall in atmospheric CO2 concentration that followed plant terrestrialization in the Palaeozoic, remains unknown.We measured carbon-for-nutrient exchanges between Haplomitriopsida liverworts and Mucoromycotina fungi under simulated mid-Palaeozoic (1500 ppm) and near-contemporary (440 ppm) CO2 concentrations using isotope tracers, and analysed cytological differences in plant–fungal interactions. Concomitantly, we cultured both partners axenically, resynthesized the associations in vitro, and characterized their cytology.We demonstrate that liverwort–Mucoromycotina symbiosis is mutualistic and mycorrhiza-like, but differs from liverwort–Glomeromycota symbiosis in maintaining functional efficiency of carbon-for-nutrient exchange between partners across CO2 concentrations. Inoculation of axenic plants with Mucoromycotina caused major cytological changes affecting the anatomy of plant tissues, similar to that observed in wild-collected plants colonized by Mucoromycotina fungi.By demonstrating reciprocal exchange of carbon for nutrients between partners, our results provide support for Mucoromycotina establishing the earliest mutualistic symbiosis with land plants. As symbiotic functional efficiency was not compromised by reduced CO2, we suggest that other factors led to the modern predominance of the Glomeromycota symbiosis.


Via Francis Martin
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Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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Patellins 3 and 6, two members of the Plant Patellin family, interact with the movement protein of Alfalfa mosaic virus and interfere with viral movement

Patellins 3 and 6, two members of the Plant Patellin family, interact with the movement protein of Alfalfa mosaic virus and interfere with viral movement | Plant-Microbe Interaction | Scoop.it
Movement proteins (MPs) encoded by plant viruses interact with host proteins to facilitate or interfere with intra- and/or intercellular viral movement. Using yeast two-hybrid and bimolecular fluorescence complementation assays, we herein present in vivo evidence for the interaction between Alfalfa mosaic virus (AMV) MP and Arabidopsis Patellin 3 (atPATL3) and Patellin 6 (atPATL6), two proteins containing a Sec14 domain. Proteins with Sec14 domains are implicated in membrane trafficking, cytoskeleton dynamics, lipid metabolism and lipid-mediated regulatory functions. Interestingly, the overexpression of atPATL3 and/or atPATL6 interfered with the plasmodesmata targeting of AMV MP and correlated with reduced infection foci size. Consistently, the viral RNA levels increased in the single and double Arabidopsis knockout mutants for atPATL3 and atPATL6. Our results indicate that, in general, MP–PATL interactions interfere with the correct subcellular targeting of MP, thus rendering the intracellular transport of viral MP-containing complexes less efficient and diminishing cell-to-cell movement.

Via Christophe Jacquet
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Rescooped by Guogen Yang from Publications
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New Phytologist: Meetings - A snapshot of molecular plant–microbe interaction research (2014)

New Phytologist: Meetings - A snapshot of molecular plant–microbe interaction research (2014) | Plant-Microbe Interaction | Scoop.it

Plants and microbes are in a continuous arms race to maintain their predominance within their particular niche. Understanding the complexity of these plant–microbe interactions is of utmost importance as it can provide new insights into the mechanisms mediating disease processes and in turn inspire new plant breeding strategies. The International Society for Molecular Plant–Microbe Interactions (IS-MPMI) invited scientists from around the world to share their findings during the XVI International Congress on Molecular Plant–Microbe Interactions, which was held on the beautiful island of Rhodes in Greece. The congress was organized by the Agricultural University of Athens, the Hellenic Phytopathology Society, and the Hellenic Society of Phytiatry and provided over 1100 participants from 55 countries with the opportunity to present and discuss their current and future research. A great number of talks and posters were presented, however our aim within this report is to provide a snapshot of the discipline by focusing on just some of the exciting research and discussions which took place. The key topics discussed were virulence factors, epigenetic regulation, hormones, symbiosis factors, toxins, signaling pathways, microbe recognition, immunity, and pathogen diagnostics. Effector biology was also a recurrent theme in many plenary and concurrent sessions, indicating the importance of a topic that was also highlighted recently by a Virtual Special Issue in New Phytologist (see Kuhn & Panstruga, 2014). In addition to this, throughout the meeting next generation sequencing (NGS) techniques were described and shown to be shedding new light on long-standing issues in microbial ecology.


Via Kamoun Lab @ TSL
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Ectomycorrhizal fungi – potential organic matter decomposers, yet not saprotrophs

Ectomycorrhizal fungi – potential organic matter decomposers, yet not saprotrophs | Plant-Microbe Interaction | Scoop.it
Although hypothesized for many years, the involvement of ectomycorrhizal fungi in decomposition of soil organic matter remains controversial and has not yet been fully acknowledged as an important factor in the regulation of soil carbon (C) storage. Here, we review recent findings, which support the view that some ectomycorrhizal fungi have the capacity to oxidize organic matter, either by ‘brown-rot’ Fenton chemistry or using ‘white-rot’ peroxidases. We propose that ectomycorrhizal fungi benefit from organic matter decomposition primarily through increased nitrogen mobilization rather than through release of metabolic C and question the view that ectomycorrhizal fungi may act as facultative saprotrophs. Finally, we discuss how mycorrhizal decomposition may influence organic matter storage in soils and mediate responses of ecosystem C sequestration to environmental changes.

Via Jean-Michel Ané, Francis Martin
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Analysis of the Phlebiopsis gigantea Genome, Transcriptome and Secretome Provides Insight into Its Pioneer Colonization Strategies of Wood

Analysis of the Phlebiopsis gigantea Genome, Transcriptome and Secretome Provides Insight into Its Pioneer Colonization Strategies of Wood | Plant-Microbe Interaction | Scoop.it
Collectively classified as white-rot fungi, certain basidiomycetes efficiently degrade the major structural polymers of wood cell walls. A small subset of these Agaricomycetes, exemplified by Phlebiopsis gigantea, is capable of colonizing freshly exposed conifer sapwood despite its high content of extractives, which retards the establishment of other fungal species. The mechanism(s) by which P. gigantea tolerates and metabolizes resinous compounds have not been explored. Here, we report the annotated P. gigantea genome and compare profiles of its transcriptome and secretome when cultured on fresh-cut versus solvent-extracted loblolly pine wood. The P. gigantea genome contains a conventional repertoire of hydrolase genes involved in cellulose/hemicellulose degradation, whose patterns of expression were relatively unperturbed by the absence of extractives. The expression of genes typically ascribed to lignin degradation was also largely unaffected. In contrast, genes likely involved in the transformation and detoxification of wood extractives were highly induced in its presence. Their products included an ABC transporter, lipases, cytochrome P450s, glutathione S-transferase and aldehyde dehydrogenase. Other regulated genes of unknown function and several constitutively expressed genes are also likely involved in P. gigantea's extractives metabolism. These results contribute to our fundamental understanding of pioneer colonization of conifer wood and provide insight into the diverse chemistries employed by fungi in carbon cycling processes.

Via Francis Martin
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Rescooped by Guogen Yang from Plants and Microbes
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PLOS Pathogens: Apoplastic Venom Allergen-like Proteins of Cyst Nematodes Modulate the Activation of Basal Plant Innate Immunity by Cell Surface Receptors (2014)

PLOS Pathogens: Apoplastic Venom Allergen-like Proteins of Cyst Nematodes Modulate the Activation of Basal Plant Innate Immunity by Cell Surface Receptors (2014) | Plant-Microbe Interaction | Scoop.it

Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes most likely utilize venom allergen-like proteins to suppress the activation of defenses by immunogenic breakdown products in damaged host tissue.


Via Kamoun Lab @ TSL
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Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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The Evolution of Fungal Metabolic Pathways

The Evolution of Fungal Metabolic Pathways | Plant-Microbe Interaction | Scoop.it

Fungi contain a remarkable range of metabolic pathways, sometimes encoded by gene clusters, enabling them to digest most organic matter and synthesize an array of potent small molecules. Although metabolism is fundamental to the fungal lifestyle, we still know little about how major evolutionary processes, such as gene duplication (GD) and horizontal gene transfer (HGT), have interacted with clustered and non-clustered fungal metabolic pathways to give rise to this metabolic versatility. We examined the synteny and evolutionary history of 247,202 fungal genes encoding enzymes that catalyze 875 distinct metabolic reactions from 130 pathways in 208 diverse genomes. We found that gene clustering varied greatly with respect to metabolic category and lineage; for example, clustered genes in Saccharomycotina yeasts were overrepresented in nucleotide metabolism, whereas clustered genes in Pezizomycotina were more common in lipid and amino acid metabolism. The effects of both GD and HGT were more pronounced in clustered genes than in their non-clustered counterparts and were differentially distributed across fungal lineages; specifically, GD, which was an order of magnitude more abundant than HGT, was most frequently observed in Agaricomycetes, whereas HGT was much more prevalent in Pezizomycotina. The effect of HGT in some Pezizomycotina was particularly strong; for example, we identified 111 HGT events associated with the 15 Aspergillus genomes, which sharply contrasts with the 60 HGT events detected for the 48 genomes from the entire Saccharomycotina subphylum. Finally, the impact of GD within a metabolic category was typically consistent across all fungal lineages, whereas the impact of HGT was variable. These results indicate that GD is the dominant process underlying fungal metabolic diversity, whereas HGT is episodic and acts in a category- or lineage-specific manner. Both processes have a greater impact on clustered genes, suggesting that metabolic gene clusters represent hotspots for the generation of fungal metabolic diversity.


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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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The population biology of fungal invasions

The population biology of fungal invasions | Plant-Microbe Interaction | Scoop.it
Fungal invasions are increasingly recognized as a significant component of global changes, threatening ecosystem health and damaging food production. Invasive fungi also provide excellent models to evaluate the generality of results based on other eukaryotes. We first consider here the reasons why fungal invasions have long been overlooked: they tend to be inconspicuous and inappropriate methods have been used for species recognition. We then review the information available on the patterns and mechanisms of fungal invasions. We examine the biological features underlying invasion success of certain fungal species. We review population structure analyses, revealing native source populations and strengths of bottlenecks. We highlight the documented ecological and evolutionary changes in invaded regions, including adaptation to temperature, increased virulence, hybridization, shifts to clonality and association with novel hosts. We discuss how the huge census size of most fungi allows adaptation even in bottlenecked, clonal invaders. We also present new analyses of the invasion of the anther smut pathogen on white campion in North America, as a case study illustrating how an accurate knowledge of species limits and phylogeography of fungal populations can be used to decipher the origin of invasions. This case study shows that successful invasions can occur even when life-history traits are particularly unfavorable to long-distance dispersal and even with a strong bottleneck. We conclude that fungal invasions are valuable models to contribute to our view of biological invasions, in particular by providing insights into the traits as well as ecological and evolutionary processes allowing successful introductions.

Via Jean-Michel Ané, Francis Martin
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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C2-domain Abscisic acid-Related (CAR) proteins mediate the interaction of ABA receptors with the plasma membrane

C2-domain Abscisic acid-Related (CAR) proteins mediate the interaction of ABA receptors with the plasma membrane | Plant-Microbe Interaction | Scoop.it

"We show that transient calcium-dependent interactions of PYR/PYL ABA receptors with membranes are mediated through a 10-member family of C2-domain ABA-related (CAR) proteins in Arabidopsis thaliana. Specifically, we found that PYL4 interacted in an ABA-independent manner with CAR1 in both the plasma membrane and nucleus of plant cells. CAR1 belongs to a plant-specific gene family encoding CAR1 to CAR10 proteins, and bimolecular fluorescence complementation and coimmunoprecipitation assays showed that PYL4-CAR1 as well as other PYR/PYL-CAR pairs interacted in plant cells. The crystal structure of CAR4 was solved, which revealed that, in addition to a classical calcium-dependent lipid binding C2 domain, a specific CAR signature is likely responsible for the interaction with PYR/PYL receptors and their recruitment to phospholipid vesicles."


Read the In Brief here (opens PDF) http://www.plantcell.org/content/early/2014/12/02/tpc.114.134411.full.pdf+html


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Rescooped by Guogen Yang from Rice Blast
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Over-expression of a glutamate dehydrogenase gene, MgGDH , from Magnaporthe grisea confers tolerance to dehydration stress in transgenic rice

Over-expression of a glutamate dehydrogenase gene, MgGDH , from Magnaporthe grisea confers tolerance to dehydration stress in transgenic rice | Plant-Microbe Interaction | Scoop.it

Main conclusionHeterologous expression of a fungal NADP(H)-GDH gene ( MgGDH ) from Magnaporthe grisea can improve dehydration stress tolerance in rice by preventing toxic accumulation of ammonium.Glutamate dehydrogenase (GDH; EC 1.4.1.2 and EC 1.4.1.4) may act as a stress-responsive enzyme in detoxification of high intracellular ammonia and production of glutamate for proline synthesis under stress conditions. In present study, a fungal NADP(H)-GDH gene (MgGDH) from Magnaporthe grisea was over-expressed in rice (Oryza sativa L. cv. ‘kitaake’), and the transgenic plants showed the improvement of tolerance to dehydration stress. The kinetic analysis showed that His-TF-MgGDH preferentially utilizes ammonium to produce l-glutamate. Moreover, the affinity of His-TF-MgGDH for ammonium was dramatically higher than that of His-TF-OsGDH for ammonium. Over-expressing MgGDH transgenic rice plants showed lower water-loss rate and higher completely close stomata than the wild-type plants under dehydration stress conditions. In transgenic plants, the NADP(H)-GDH activities were markedly higher than those in wild-type plants and the amination activity was significantly higher than the deamination activity. Compared with wild-type plants, the transgenic plants accumulated much less NH4 + but higher amounts of glutamate, proline and soluble sugar under dehydration stress conditions. These results indicate that heterologous expression of MgGDH can prevent toxic accumulation of ammonium and in return improve dehydration stress tolerance in rice.


Via Christophe Jacquet, Elsa Ballini
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Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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A novel Arabidopsis CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) mutant with enhanced pathogen-induced cell death and altered receptor processing

A novel Arabidopsis CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) mutant with enhanced pathogen-induced cell death and altered receptor processing | Plant-Microbe Interaction | Scoop.it

Plants detect pathogens by sensing microbe-associated molecular patterns (MAMPs) through pattern recognition receptors. Pattern recognition receptor complexes also have roles in cell death control, but the underlying mechanisms are poorly understood. Here, we report isolation of cerk1-4, a novel mutant allele of the Arabidopsis chitin receptor CERK1 with enhanced defense responses.We identified cerk1-4 in a forward genetic screen with barley powdery mildew and consequently characterized it by pathogen assays, mutant crosses and analysis of defense pathways. CERK1 and CERK1-4 proteins were analyzed biochemically.The cerk1-4 mutation causes an amino acid exchange in the CERK1 ectodomain. Mutant plants maintain chitin signaling capacity but exhibit hyper-inducible salicylic acid concentrations and deregulated cell death upon pathogen challenge. In contrast to chitin signaling, the cerk1-4 phenotype does not require kinase activity and is conferred by the N-terminal part of the receptor. CERK1 undergoes ectodomain shedding, a well-known process in animal cell surface proteins. Wild-type plants contain the full-length CERK1 receptor protein as well as a soluble form of the CERK1 ectodomain, whereas cerk1-4 plants lack the N-terminal shedding product.Our work suggests that CERK1 may have a chitin-independent role in cell death control and is the first report of ectodomain shedding in plants.


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Rescooped by Guogen Yang from WU_Phyto-Publications
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PhD Thesis Yan Wang (2014): Understanding the role of L-type lectin receptor kinases in Phytophthora resistance

PhD Thesis Yan Wang (2014): Understanding the role of L-type lectin receptor kinases in Phytophthora resistance | Plant-Microbe Interaction | Scoop.it

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Rescooped by Guogen Yang from TAL effector science
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Genome-wide detection of DNA double-stranded breaks induced by engineered nucleases - Nature Biotech.

Genome-wide detection of DNA double-stranded breaks induced by engineered nucleases - Nature Biotech. | Plant-Microbe Interaction | Scoop.it

Frock et al, 2014

Although great progress has been made in the characterization of the off-target effects of engineered nucleases, sensitive and unbiased genome-wide methods for the detection of off-target cleavage events and potential collateral damage are still lacking. Here we describe a linear amplification–mediated modification of a previously published high-throughput, genome-wide, translocation sequencing (HTGTS) method that robustly detects DNA double-stranded breaks (DSBs) generated by engineered nucleases across the human genome based on their translocation to other endogenous or ectopic DSBs. HTGTS with different Cas9:sgRNA or TALEN nucleases revealed off-target hotspot numbers for given nucleases that ranged from a few or none to dozens or more, and extended the number of known off-targets for certain previously characterized nucleases more than tenfold. We also identified translocations between bona fide nuclease targets on homologous chromosomes, an undesired collateral effect that has not been described previously. Finally, HTGTS confirmed that the Cas9D10A paired nickase approach suppresses off-target cleavage genome-wide.


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Fesquet didier's curator insight, December 19, 5:53 AM

off target ou pas off targets...the debate is still on going...hope the wt has reported does not induce that much OT...can't believe

Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Overexpression of Laccaria bicolor aquaporin JQ585595 alters root water transport properties in ectomycorrhizal white spruce (Picea glauca) seedlings

Overexpression of Laccaria bicolor aquaporin JQ585595 alters root water transport properties in ectomycorrhizal white spruce (Picea glauca) seedlings | Plant-Microbe Interaction | Scoop.it
The contribution of hyphae to water transport in ectomycorrhizal (ECM) white spruce (Picea glauca) seedlings was examined by altering expression of a major water-transporting aquaporin in Laccaria bicolor.
Picea glauca was inoculated with wild-type (WT), mock transgenic or L. bicolor aquaporin JQ585595-overexpressing (OE) strains and exposed to root temperatures ranging from 5 to 20°C to examine the root water transport properties, physiological responses and plasma membrane intrinsic protein (PIP) expression in colonized plants.
Mycorrhization increased shoot water potential, transpiration, net photosynthetic rates, root hydraulic conductivity and root cortical cell hydraulic conductivity in seedlings. At 20°C, OE plants had higher root hydraulic conductivity compared with WT plants and the increases were accompanied by higher expression of P. glauca PIP GQ03401_M18.1 in roots. In contrast to WT L. bicolor, the effects of OE fungi on root and root cortical cell hydraulic conductivities were abolished at 10 and 5°C in the absence of major changes in the examined transcript levels of P. glauca root PIPs.
The results provide evidence for the importance of fungal aquaporins in root water transport of mycorrhizal plants. They also demonstrate links between hyphal water transport, root aquaporin expression and root water transport in ECM plants.

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Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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Do pathogen effectors play peek-a-boo?

Guus Bakkeren and Barbara Valent

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Loss of Arabidopsis thaliana Dynamin-Related Protein 2B Reveals Separation of Innate Immune Signaling Pathways

Loss of Arabidopsis thaliana Dynamin-Related Protein 2B Reveals Separation of Innate Immune Signaling Pathways | Plant-Microbe Interaction | Scoop.it
Vesicular trafficking has emerged as an important means by which eukaryotes modulate responses to microbial pathogens, likely by contributing to the correct localization and levels of host components necessary for effective immunity. However, considering the complexity of membrane trafficking in plants, relatively few vesicular trafficking components with functions in plant immunity are known. Here we demonstrate that Arabidopsis thaliana Dynamin-Related Protein 2B (DRP2B), which has been previously implicated in constitutive clathrin-mediated endocytosis (CME), functions in responses to flg22 (the active peptide derivative of bacterial flagellin) and immunity against flagellated bacteria Pseudomonas syringae pv. tomato (Pto) DC3000. Consistent with a role of DRP2B in Pattern-Triggered Immunity (PTI), drp2b null mutant plants also showed increased susceptibility to Pto DC3000 hrcC−, which lacks a functional Type 3 Secretion System, thus is unable to deliver effectors into host cells to suppress PTI. Importantly, analysis of drp2b mutant plants revealed three distinct branches of the flg22-signaling network that differed in their requirement for RESPIRATORY BURST OXIDASE HOMOLOGUE D (RBOHD), the NADPH oxidase responsible for flg22-induced apoplastic reactive oxygen species production. Furthermore, in drp2b, normal MAPK signaling and increased immune responses via the RbohD/Ca2+-branch were not sufficient for promoting robust PR1 mRNA expression nor immunity against Pto DC3000 and Pto DC3000 hrcC−. Based on live-cell imaging studies, flg22-elicited internalization of the plant flagellin-receptor, FLAGELLIN SENSING 2 (FLS2), was found to be partially dependent on DRP2B, but not the closely related protein DRP2A, thus providing genetic evidence for a component, implicated in CME, in ligand-induced endocytosis of FLS2. Reduced trafficking of FLS2 in response to flg22 may contribute in part to the non-canonical combination of immune signaling defects observed in drp2b. In conclusion, this study adds DRP2B to the relatively short list of known vesicular trafficking proteins with roles in flg22-signaling and PTI in plants.

Via Suayib Üstün
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bioRxiv: Phytophthora infestans RXLR-WY effector AVR3a associates with a Dynamin-Related Protein involved in endocytosis of a plant pattern recognition receptor (2014)

bioRxiv: Phytophthora infestans RXLR-WY effector AVR3a associates with a Dynamin-Related Protein involved in endocytosis of a plant pattern recognition receptor (2014) | Plant-Microbe Interaction | Scoop.it

Perception of pathogen associated molecular patterns (PAMPs) by cell surface localized pattern recognition receptors (PPRs), activates plant basal defense responses in a process known as PAMP/PRR–triggered immunity (PTI). In turn, pathogens deploy effector proteins that interfere with different steps in PTI signaling. However, our knowledge of PTI suppression by filamentous plant pathogens, i.e. fungi and oomycetes, remains fragmentary. Previous work revealed that BAK1/SERK3, a regulatory receptor of several PRRs, contributes to basal immunity against the Irish potato famine pathogen Phytophthora infestans. Moreover BAK1/SERK3 is required for the cell death induced by P. infestans elicitin INF1, a protein with characteristics of PAMPs. The P. infestans host-translocated RXLR-WY effector AVR3a is known to supress INF1-mediated defense by binding the E3 ligase CMPG1. In contrast, AVR3aKI-Y147del, a deletion mutant of the C-terminal tyrosine of AVR3a, fails to bind CMPG1 and suppress INF1 cell death. Here we studied the extent to which AVR3a and its variants perturb additional BAK1/SERK3 dependent PTI responses using the plant PRR FLAGELLIN SENSING 2 (FLS2). We found that all tested variants of AVR3a, including AVR3aKI-Y147del, suppress early defense responses triggered by the bacterial flagellin-derived peptide flg22 and reduce internalization of activated FLS2 from the plasma membrane without disturbing its nonactivated localization. Consistent with this effect of AVR3a on FLS2 endocytosis, we discovered that AVR3a associates with the Dynamin-Related Protein DRP2, a plant GTPase implicated in receptor-mediated endocytosis. Interestingly, DRP2 is required for ligand-induced FLS2 internalization but does not affect internalization of the growth receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1). Furthermore, overexpression of DRP2 suppressed accumulation of reactive oxygen species triggered by PAMP treatment. We conclude that AVR3a associates with a key cellular trafficking and membrane-remodeling complex involved in immune receptor-mediated endocytosis and signaling. AVR3a is a multifunctional effector that can suppress BAK1/SERK3 mediated immunity through at least two different pathways.


Via Kamoun Lab @ TSL, Suayib Üstün
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fundoshi's curator insight, December 22, 3:10 AM
Arabidopsis dynamin-related proteins, DRP2A and DRP2B, function coordinately in post-Golgi trafficking.

http://www.sciencedirect.com/science/article/pii/S0006291X14020956

Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Extensive Error in the Number of Genes Inferred from Draft Genome Assemblies

Extensive Error in the Number of Genes Inferred from Draft Genome Assemblies | Plant-Microbe Interaction | Scoop.it
Current sequencing methods produce large amounts of data, but genome assemblies based on these data are often woefully incomplete. These incomplete and error-filled assemblies result in many annotation errors, especially in the number of genes present in a genome. In this paper we investigate the magnitude of the problem, both in terms of total gene number and the number of copies of genes in specific families. To do this, we compare multiple draft assemblies against higher-quality versions of the same genomes, using several new assemblies of the chicken genome based on both traditional and next-generation sequencing technologies, as well as published draft assemblies of chimpanzee. We find that upwards of 40% of all gene families are inferred to have the wrong number of genes in draft assemblies, and that these incorrect assemblies both add and subtract genes. Using simulated genome assemblies of Drosophila melanogaster, we find that the major cause of increased gene numbers in draft genomes is the fragmentation of genes onto multiple individual contigs. Finally, we demonstrate the usefulness of RNA-Seq in improving the gene annotation of draft assemblies, largely by connecting genes that have been fragmented in the assembly process.

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Francis Martin's curator insight, December 20, 11:02 AM

Good that JGI is using RNA-Seq to support gene prediction of our fungal genomes.

Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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Rapid identification of the Leptosphaeria maculans avirulence gene AvrLm2, using an intraspecific comparative genomics approach

Summary
Five avirulence genes from Leptosphaeria maculans, the causal agent of blackleg of canola (Brassica napus), have previously been identified through map-based cloning.

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Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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Adaptive genomic structural variation in the grape powdery mildew pathogen, Erysiphe necator

Background:
Powdery mildew, caused by the obligate biotrophic fungus Erysiphe necator, is an economically important disease of grapevines worldwide.

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Rescooped by Guogen Yang from Virology and Bioinformatics from Virology.ca
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Not Just a Theory—The Utility of Mathematical Models in Evolutionary Biology

Not Just a Theory—The Utility of Mathematical Models in Evolutionary Biology | Plant-Microbe Interaction | Scoop.it
PLOS Biology is an open-access, peer-reviewed journal that features works of exceptional significance in all areas of biological science, from molecules to ecosystems, including works at the interface with other disciplines.

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Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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Cytosolic calcium signals elicited by the pathogen-associated molecular pattern flg22 in stomatal guard cells are of an oscillatory nature - Thor - 2014 - New Phytologist - Wiley Online Library

Cytosolic calcium signals elicited by the pathogen-associated molecular pattern flg22 in stomatal guard cells are of an oscillatory nature - Thor - 2014 - New Phytologist - Wiley Online Library | Plant-Microbe Interaction | Scoop.it

Changes in cytosolic free calcium ([Ca2+]cyt) are an early and essential element of signalling networks activated by the perception of pathogen-associated molecular patterns (PAMPs), such as flg22. The flg22-induced calcium signal has been described on whole-plant, but not on single-cell scale so far. Also, the Ca2+ sources and channels contributing to its generation are still obscure.Ratiometric fluorescence imaging employing the calcium reporter Yellow Cameleon 3.6 was performed to analyse the flg22-induced calcium signature in single guard cells of Arabidopsis thaliana. Calcium stores and channel types involved in its generation were determined by a pharmacological approach.In contrast to the calcium signal determined on whole-plant level, the signature on single-cell level is not characterized by one sustained response, but by oscillations in [Ca2+]cyt. These oscillations were abolished by EGTA and lanthanum, as well as by U73122, neomycin and TMB-8, but only partially or not at all affected by inhibitors of glutamate receptor-like channels and cyclic nucleotide-gated channels.Our analyses suggest that the response observed on whole-plant level is the summary of oscillations occurring in single cells. Parallel to external calcium, influx via channels located at internal stores contributes to the signal.


Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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Pepper Heat Shock Protein 70a Interacts with the Type III Effector AvrBsT and Triggers Plant Cell Death and Immunity

Pepper Heat Shock Protein 70a Interacts with the Type III Effector AvrBsT and Triggers Plant Cell Death and Immunity | Plant-Microbe Interaction | Scoop.it
Heat shock proteins (HSPs) function as molecular chaperones and are essential for the maintenance and/or restoration of protein homeostasis. The Xanthomonas type III effector AvrBsT induces hypersensitive cell death in pepper (Capsicum annuum). Here, we report the identification of the pepper CaHSP70a as an AvrBsT-interacting protein. Bimolecular fluorescence complementation and co-immunoprecipitation assays confirm the specific interaction between CaHSP70a and AvrBsT in planta. The CaHSP70a peptide-binding domain is essential for its interaction with AvrBsT. Heat stress (37°C) and Xanthomonas campestris pv. vesicatoria (Xcv) infection distinctly induce CaHSP70a in pepper leaves. Cytoplasmic CaHSP70a proteins significantly accumulate in pepper leaves to induce the hypersensitive cell death response by Xcv (avrBsT) infection. Transient CaHSP70a overexpression induces hypersensitive cell death under heat stress, which is accompanied by strong induction of defense- and cell death-related genes. CaHSP70a peptide-binding domain and ATPase-binding domain are required to trigger cell death under heat stress. Transient co-expression of CaHSP70a and avrBsT leads to cytoplasmic localization of the CaHSP70a-AvrBsT complex, and significantly enhances avrBsT-triggered cell death in Nicotiana benthamiana. CaHSP70a silencing in pepper enhances Xcv growth, but disrupts the reactive oxygen species burst and cell death response during Xcv infection. Expression of some defense marker genes is significantly reduced in CaHSP70a-silenced leaves, with lower levels of the defense hormones salicylic acid and jasmonic acid. Together, these results suggest that CaHSP70a interacts with the type III effector AvrBsT and is required for cell death and immunity in plants.

Via Suayib Üstün, Christophe Jacquet
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