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Molecular Cell - Substrates of IAP Ubiquitin Ligases Identified with a Designed Orthogonal E3 Ligase, the NEDDylator

Molecular Cell - Substrates of IAP Ubiquitin Ligases Identified with a Designed Orthogonal E3 Ligase, the NEDDylator | Plant-Microbe Interaction | Scoop.it

Inhibitors of Apoptosis Protein (IAPs) are guardian ubiquitin ligases that keep classic proapoptotic proteins in check. Systematic identification of additional IAP substrates is challenged by the heterogeneity and sheer number of ubiquitinated proteins (>5,000). Here we report a powerful catalytic tagging tool, the NEDDylator, which fuses a NEDD8 E2-conjugating enzyme, Ubc12, to the ubiquitin ligase, XIAP or cIAP1. This permits transfer of the rare ubiquitin homolog NEDD8 to the ubiquitin E3 substrates, allowing them to be efficiently purified for LC-MS/MS identification. We have identified >50 potential IAP substrates of both cytosolic and mitochondrial origin that bear hallmark N-terminal IAP binding motifs. These substrates include the recently discovered protein phosphatase PGAM5, which we show is proteolytically processed, accumulates in cytosol during apoptosis, and sensitizes cells to death. These studies reveal mechanisms and antagonistic partners for specific IAPs, and provide a powerful technology for labeling binding partners in transient protein-protein complexes.


Via Suayib Üstün
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Random mutagenesis of the nucleotide-binding domain of NRC1 (NB-LRR Required for Hypersensitive Response-Associated Cell Death-1), a downstream signalling nucleotide-binding, leucine-rich repeat (N...

Random mutagenesis of the nucleotide-binding domain of NRC1 (NB-LRR Required for Hypersensitive Response-Associated Cell Death-1), a downstream signalling nucleotide-binding, leucine-rich repeat (N... | Plant-Microbe Interaction | Scoop.it
Plant nucleotide-binding, leucine-rich repeat (NB-LRR) proteins confer immunity to pathogens possessing the corresponding avirulence proteins. Activation of NB-LRR proteins is often associated with induction of the hypersensitive response (HR), a form of programmed cell death.
NRC1 (NB-LRR Required for HR-Associated Cell Death-1) is a tomato (Solanum lycopersicum) NB-LRR protein that participates in the signalling cascade leading to resistance to the pathogens Cladosporium fulvum and Verticillium dahliae.
To identify mutations in NRC1 that cause increased signalling activity, we generated a random library of NRC1 variants mutated in their nucleotide-binding domain and screened them for the ability to induce an elicitor-independent HR in Nicotiana tabacum. Screening of 1920 clones retrieved 11 gain-of-function mutants, with 10 of them caused by a single amino acid substitution.
All substitutions are located in or very close to highly conserved motifs within the nucleotide-binding domain, suggesting modulation of the signalling activity of NRC1. Three-dimensional modelling of the nucleotide-binding domain of NRC1 revealed that the targeted residues are centred around the bound nucleotide. Our mutational approach has generated a wide set of novel gain-of-function mutations in NRC1 and provides insight into how the activity of this NB-LRR is regulated.

Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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An introduction to synthetic biology in plant systems - Carmichael - 2015 - New Phytologist - Wiley Online Library

...Plant synthetic biology is a burgeoning field that is attracting attention from both the synthetic biology and plant science communities (Osbourn et al., 2012; Cook et al., 2014), as illustrated by the recent funding of OpenPlant by the UK government through the Biotechnology and Biological Sciences Research Council (BBSRC) and Engineering and Physical Sciences Research Council (EPSRC), to develop foundational technologies for plant synthetic biology. The development of this new field is in part due to rapid technological advances allowing quick, easy and efficient manipulation of genomic and transgenic plant DNA, and therefore the summer school mainly focussed on these cutting-edge tools and applications, with the aim of encouraging their use by up-and-coming researchers.

The 20 summer school participants had a variety of research backgrounds and levels of experience, from theorists and computer scientists to molecular, plant and synthetic biologists, and from new PhD students to postdoctoral researchers. Some of the participants had no previous plant science knowledge, so the major challenge was to devise a programme that would be engaging and instructive. As a result, participants were trained through a diverse course of lectures, practical sessions and group projects, covering a wide range of theoretical, technical and ethical content in this expanding discipline.
Lectures: cutting-edge training from world-leading experts

The lecture programme was designed to teach the participants about synthetic biology concepts and new technologies both in theory and application, as well as introducing them to several model plant systems. In addition, technical talks provided practical details including plant transformation, bioinformatics and metabolite analysis. Discussion was encouraged following the talks, with participants taking the opportunity to meet and question world-leading experts.

Claes Gustafsson, from the San Francisco-based DNA synthesis company DNA2.0, set the scene by introducing the theory behind the application of engineering values to synthetic biology, including the experimental cycle of designing, building, testing and learning that underpins effective synthetic biology research. Consistent with recent developments in plant synthetic biology, DNA assembly and genome engineering techniques were at the forefront of the more technical talks, and, importantly, illustrated with recent applications. Golden Gate cloning, a newly developed technique for assembling multigene DNA constructs in a modular fashion, was highlighted by several speakers, including Aymeric Leveau (Osbourn Laboratory, John Innes Centre, UK), who discussed its use in his work in metabolic engineering of wheat, whilst Samantha Fox (Coen laboratory, John Innes Centre, UK) explained how she had used Golden Gate cloning to develop a modular Cre-Lox system for inducible expression of a gene of interest in Arabidopsis thaliana. The talks were compiled to introduce the participants to cutting-edge methodologies driving the development of the plant synthetic biology field – notably, Diego Orzaez (Technical University of Valencia, Spain) outlined the GoldenBraid cloning system he has developed, based on Golden Gate, for iterative modular DNA assembly for plant biotechnology applications (Sarrion-Perdigones et al., 2011), and Jim Haseloff (University of Cambridge/OpenPlant, UK) promoted the simple liverwort plant Marchantia polymorpha as a new, tractable model system for plant synthetic biology.

Genome editing in plants was also emphasized in the lectures as an increasingly invaluable and widespread synthetic biology tool, due to its relatively straightforward and efficient application. Sebastian Schornack (University of Cambridge, UK) described how the code for recognition of target DNA by TAL effectors was discovered (Boch et al., 2009) and how TAL effector proteins have been repurposed for genome engineering functions, while the extension of the ubiquitous CRISPR/Cas9 system to plants was outlined in a technical talk from Kate Caves (DNA2.0, USA), and exemplified in work described by Jen Sheen (Havard University, MA, USA) (Li et al., 2013)....


Via Christophe Jacquet, Mary Williams
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Differential Function of Arabidopsis SERK Family Receptor-like Kinases in Stomatal Patterning: Current Biology

Differential Function of Arabidopsis SERK Family Receptor-like Kinases in Stomatal Patterning: Current Biology | Plant-Microbe Interaction | Scoop.it
Highlights

•SERK family receptor-like kinases redundantly regulate stomatal patterning
•SERKs act downstream of EPF ligands and upstream of the YDA MAPKKK
•SERKs associate with ERECTA family receptors in a ligand-induced manner
•SERKs regulate stomatal patterning independent of brassinosteroid signaling

Summary

Plants use cell-surface-resident receptor-like kinases (RLKs) to sense diverse extrinsic and intrinsic cues and elicit distinct biological responses. In Arabidopsis, ERECTA family RLKs recognize EPIDERMAL PATTERNING FACTORS (EPFs) to specify stomatal patterning. However, little is known about the molecular link between ERECTA activation and intracellular signaling. We report here that the SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK) family RLKs regulate stomatal patterning downstream of EPF ligands and upstream of a MAP kinase cascade. EPF ligands induce the heteromerization of ERECTA and SERK family RLKs. SERK and ERECTA family RLKs transphosphorylate each other. In addition, SERKs associate with the receptor-like protein (RLP) TMM, a signal modulator of stomata development, in a ligand-independent manner, suggesting that ERECTA, SERKs, and TMM form a multiprotein receptorsome consisting of different RLKs and RLP perceiving peptide ligands to regulate stomatal patterning. In contrast to the differential requirement of individual SERK members in plant immunity, cell-death control, and brassinosteroid (BR) signaling, all four functional SERKs are essential but have unequal genetic contributions to stomatal patterning, with descending order of importance from SERK3/BAK1 to SERK2 to SERK1 to SERK4. Although BR signaling connects stomatal development via multiple components, the function of SERKs in stomatal patterning is uncoupled from their involvement in BR signaling. Our results reveal that the SERK family is a shared key module in diverse Arabidopsis signaling receptorsomes and that different combinatorial codes of individual SERK members regulate distinct functions.

Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Differential Function of Arabidopsis SERK Family Receptor-like Kinases in Stomatal Patterning: Current Biology

Differential Function of Arabidopsis SERK Family Receptor-like Kinases in Stomatal Patterning: Current Biology | Plant-Microbe Interaction | Scoop.it
Highlights

•SERK family receptor-like kinases redundantly regulate stomatal patterning
•SERKs act downstream of EPF ligands and upstream of the YDA MAPKKK
•SERKs associate with ERECTA family receptors in a ligand-induced manner
•SERKs regulate stomatal patterning independent of brassinosteroid signaling

Summary

Plants use cell-surface-resident receptor-like kinases (RLKs) to sense diverse extrinsic and intrinsic cues and elicit distinct biological responses. In Arabidopsis, ERECTA family RLKs recognize EPIDERMAL PATTERNING FACTORS (EPFs) to specify stomatal patterning. However, little is known about the molecular link between ERECTA activation and intracellular signaling. We report here that the SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK) family RLKs regulate stomatal patterning downstream of EPF ligands and upstream of a MAP kinase cascade. EPF ligands induce the heteromerization of ERECTA and SERK family RLKs. SERK and ERECTA family RLKs transphosphorylate each other. In addition, SERKs associate with the receptor-like protein (RLP) TMM, a signal modulator of stomata development, in a ligand-independent manner, suggesting that ERECTA, SERKs, and TMM form a multiprotein receptorsome consisting of different RLKs and RLP perceiving peptide ligands to regulate stomatal patterning. In contrast to the differential requirement of individual SERK members in plant immunity, cell-death control, and brassinosteroid (BR) signaling, all four functional SERKs are essential but have unequal genetic contributions to stomatal patterning, with descending order of importance from SERK3/BAK1 to SERK2 to SERK1 to SERK4. Although BR signaling connects stomatal development via multiple components, the function of SERKs in stomatal patterning is uncoupled from their involvement in BR signaling. Our results reveal that the SERK family is a shared key module in diverse Arabidopsis signaling receptorsomes and that different combinatorial codes of individual SERK members regulate distinct functions.

Via Christophe Jacquet
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Fungal endophyte infection of ryegrass reprograms host metabolism and alters development

Fungal endophyte infection of ryegrass reprograms host metabolism and alters development | Plant-Microbe Interaction | Scoop.it

Beneficial associations between plants and microbes play an important role in both natural and agricultural ecosystems. For example, associations between fungi of the genus Epichloë, and cool-season grasses are known for their ability to increase resistance to insect pests, fungal pathogens and drought. However, little is known about the molecular changes induced by endophyte infection.To study the impact of endophyte infection, we compared the expression profiles, based on RNA sequencing, of perennial ryegrass infected with Epichloë festucae with noninfected plants.We show that infection causes dramatic changes in the expression of over one third of host genes. This is in stark contrast to mycorrhizal associations, where substantially fewer changes in host gene expression are observed, and is more similar to pathogenic interactions. We reveal that endophyte infection triggers reprogramming of host metabolism, favouring secondary metabolism at a cost to primary metabolism. Infection also induces changes in host development, particularly trichome formation and cell wall biogenesis.Importantly, this work sheds light on the mechanisms underlying enhanced resistance to drought and super-infection by fungal pathogens provided by fungal endophyte infection. Finally, our study reveals that not all beneficial plant–microbe associations behave the same in terms of their effects on the host.


Via Francis Martin
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Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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Fungal endophyte infection of ryegrass reprograms host metabolism and alters development

Fungal endophyte infection of ryegrass reprograms host metabolism and alters development | Plant-Microbe Interaction | Scoop.it
Summary
Beneficial associations between plants and microbes play an important role in both natural and agricultural ecosystems.

Via IPM Lab
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Rescooped by Guogen Yang from Plants and Microbes
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BMC Evolutionary Biology: Phylogeography and virulence structure of the powdery mildew population on its 'new' host triticale (2012)

BMC Evolutionary Biology: Phylogeography and virulence structure of the powdery mildew population on its 'new' host triticale (2012) | Plant-Microbe Interaction | Scoop.it

Background - Powdery mildew, caused by the obligate biotrophic fungus Blumeria graminis, is a major problem in cereal production as it can reduce quality and yield. B. graminis has evolved eight distinct formae speciales (f.sp.) which display strict host specialization. In the last decade, powdery mildew has emerged on triticale, the artificial intergeneric hybrid between wheat and rye. This emergence is probably triggered by a host range expansion of the wheat powdery mildew B. graminis f.sp. tritici. To gain more precise information about the evolutionary processes that led to this host range expansion, we pursued a combined pathological and genetic approach.

 

Results - B. graminis isolates were sampled from triticale, wheat and rye from different breeding regions in Europe. Pathogenicity tests showed that isolates collected from triticale are highly pathogenic on most of the tested triticale cultivars. Moreover, these isolates were also able to infect several wheat cultivars (their previous hosts), although a lower aggressiveness was observed compared to isolates collected from wheat. Phylogenetic analysis of nuclear gene regions identified two statistically significant clades, which to a certain extent correlated with pathogenicity. No differences in virulence profiles were found among the sampled regions, but the distribution of genetic variation demonstrated to be geography dependent. A multilocus haplotype network showed that haplotypes pathogenic on triticale are distributed at different sites in the network, but always clustered at or near the tips of the network.

 

Conclusions - This study reveals a genetic structure in B. graminis with population differentiation according to geography and host specificity. In addition, evidence is brought forward demonstrating that the host range expansion of wheat isolates to the new host triticale occurred recently and multiple times at different locations in Europe.


Via Kamoun Lab @ TSL
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New Disease Reports: A bacterial leaf spot of aquilegia caused by Pseudomonas syringae (2014)

New Disease Reports: A bacterial leaf spot of aquilegia caused by Pseudomonas syringae (2014) | Plant-Microbe Interaction | Scoop.it

Aquilegia vulgaris (Ranunculaceae) (Columbine) is a flowering herbaceous perennial native to Europe and widely cultivated in UK gardens. It is an important crop for some commercial nurseries that produce large numbers of potted plants for retail sale in garden centres. In 2008, 100% crop loss due to a bacterial disease was reported by one grower. Subsequently, during a survey of bacterial diseases of herbaceous perennials on commercial nurseries carried out during 2010 (Roberts, 2011), symptoms consisting of black spots or larger lesions with a water-soaked margin were observed on the leaves and stems of plants at two nurseries in different regions of the UK.


Via Kamoun Lab @ TSL
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Plant microbiome blueprints

Plant microbiome blueprints | Plant-Microbe Interaction | Scoop.it
Just as the number of petals in a flower or the number of limbs on an animal follow predictable rules, host-associated microbial communities (“microbiomes”) have predictable compositions. At the level of bacterial phylum, the structure of the host-associated microbiome is conserved across individuals of a species (1, 2). The consistency and predictability of host-associated microbiomes—like many of the phenotypes of a particular multicellular organism—suggest that they too may, in part, be under the regulation of a genetic blueprint. Indeed, evidence in animals shows that through production of broad-spectrum antimicrobials, the innate immune system shapes the composition of the gut microbiome (3, 4). On page 860 of this issue, Lebeis et al. (5) reveal a critical role of the plant hormone salicylic acid in determining the higher-order organization of the root-associated microbiome of the reference plant Arabidopsis thaliana.

Via Francis Martin
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Salicylic acid modulates colonization of the root microbiome by specific bacterial taxa

Salicylic acid modulates colonization of the root microbiome by specific bacterial taxa | Plant-Microbe Interaction | Scoop.it

Immune systems distinguish “self” from “nonself” to maintain homeostasis and must differentially gate access to allow colonization by potentially beneficial, nonpathogenic microbes. Plant roots grow within extremely diverse soil microbial communities but assemble a taxonomically limited root-associated microbiome. We grew isogenic Arabidopsis thaliana mutants with altered immune systems in a wild soil and also in recolonization experiments with a synthetic bacterial community. We established that biosynthesis of, and signaling dependent on, the foliar defense phytohormone salicylic acid is required to assemble a normal root microbiome. Salicylic acid modulates colonization of the root by specific bacterial families. Thus, plant immune signaling drives selection from the available microbial communities to sculpt the root microbiome.


Via Francis Martin
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Rescooped by Guogen Yang from Plant-Microbe Symbioses
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Genome-wide identification, phylogeny and expression analysis of GRAS gene family in tomato

Genome-wide identification, phylogeny and expression analysis of GRAS gene family in tomato | Plant-Microbe Interaction | Scoop.it
Background
GRAS transcription factors usually act as integrators of multiple growth regulatory and environmental signals, including axillary shoot meristem formation, root radial pattering, phytohormones, light signaling, and abiotic/biotic stress. However, little is known about this gene family in tomato (Solanum lycopersicum), the most important model plant for crop species with fleshy fruits.

Results
In this study, 53 GRAS genes were identified and renamed based on tomato whole-genome sequence and their respective chromosome distribution except 19 members were kept as their already existed name. Multiple sequence alignment showed typical GRAS domain in these proteins. Phylogenetic analysis of GRAS proteins from tomato, Arabidopsis, Populus, P.mume, and Rice revealed that SlGRAS proteins could be divided into at least 13 subfamilies. SlGRAS24 and SlGRAS40 were identified as target genes of miR171 using5’-RACE (Rapid amplification of cDNA ends). qRT-PCR analysis revealed tissue-/organ- and development stage-specific expression patterns of SlGRAS genes. Moreover, their expression patterns in response to different hormone and abiotic stress treatments were also investigated.

Conclusions
This study provides the first comprehensive analysis of GRAS gene family in the tomato genome. The data will undoubtedly be useful for better understanding the potential functions of GRAS genes, and their possible roles in mediating hormone cross-talk and abiotic stress in tomato as well as in some other relative species.

Via Jean-Michel Ané
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Jean-Michel Ané's curator insight, August 27, 1:35 AM

Neighbor-Joining method... seriously... Did someone review this paper?

Rescooped by Guogen Yang from Plants and Microbes
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News: How plant sensors detect pathogens (2015)

News: How plant sensors detect pathogens (2015) | Plant-Microbe Interaction | Scoop.it

In the mid-20th century, an American scientist named Harold Henry Flor helped explain how certain varieties of plants can fight off some plant killers (pathogens), but not others, with a model called the “gene-for-gene” hypothesis. Seventy years later, an international team of scientists describes precisely how a plant senses a pathogen, bringing an unprecedented level of detail to Flor’s model.

 

“We know that plants have sensors to detect pathogens but we knew little about how they work,” says Professor Banfield from the John Innes Centre (UK).

 

In a study published in eLife, the team led by Professor Mark Banfield, in collaboration with the Iwate Biotechnology Research Centre (Japan) and The Sainsbury Laboratory (UK), investigated how one sensor protein from rice called Pik binds AVR-Pik, a protein from the rice blast pathogen. This fungus causes the most devastating disease of rice crops. Using X-ray crystallography facilities at Diamond Light Source in Oxfordshire, the team succeeded in imaging the contact points between the plant and pathogen proteins at the molecular level – the first time this has been done for a pair of plant and pathogen proteins that follow the gene-for-gene model.

 

Dr Abbas Maqbool from the JIC, first author of the study added, “Harold Flor predicted that plant sensors discriminate between different pathogen types, but at the time he had no knowledge of the molecules involved. It is remarkable that his ideas have now crystallized into detailed molecular models.”

 

Dr Maqbool, Professor Banfield and colleagues went on to discover that the strength at which the Pik sensor binds the pathogen AVR-Pik protein correlates with the strength of the plant’s response. This opens up new avenues for engineering better plant responses against pathogens by building sensors with increased strength of binding to pathogen proteins, and therefore conferring enhanced resistance to disease.

 

“Once we understand how these plant sensors detect invading pathogens, we can devise strategies to ‘boost’ the plant immune system and help protect rice and other important food crops from disease,” says Professor Banfield.

 

Maqbool et al. eLife http://elifesciences.org/content/4/e08709


Via Kamoun Lab @ TSL
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Microbial effectors target multiple steps in the salicylic acid production and signaling pathway

Microbial effectors target multiple steps in the salicylic acid production and signaling pathway | Plant-Microbe Interaction | Scoop.it
Microbes attempting to colonize plants are recognized through the plant immune surveillance system. This leads to a complex array of global as well as specific defense responses, which are often associated with plant cell death and subsequent arrest of the invader. The responses also entail complex changes in phytohormone signaling pathways. Among these, salicylic acid (SA) signaling is an important pathway because of its ability to trigger plant cell death. As biotrophic and hemibiotrophic pathogens need to invade living plant tissue to cause disease, they have evolved efficient strategies to downregulate SA signaling by virulence effectors, which can be proteins or secondary metabolites. Here we review the strategies prokaryotic pathogens have developed to target SA biosynthesis and signaling, and contrast this with recent insights into how plant pathogenic eukaryotic fungi and oomycetes accomplish the same goal.

Via Francis Martin
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PeerJ Collection: Top Microbiology Papers - August 2015

PeerJ Collection: Top Microbiology Papers - August 2015 | Plant-Microbe Interaction | Scoop.it
Microbiology is the study of microscopic organisms and includes many sub-disciplines such as virology, mycology, parasitology, and bacteriology. PeerJ is pleased to have published some outstanding work in microbiology and this Collection represents some of the most noteworthy papers we have published, as of August 2015.

Via Francis Martin
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Planted forest health: The need for a global strategy

Planted forest health: The need for a global strategy | Plant-Microbe Interaction | Scoop.it

Several key tree genera are used in planted forests worldwide, and these represent valuable global resources. Planted forests are increasingly threatened by insects and microbial pathogens, which are introduced accidentally and/or have adapted to new host trees. Globalization has hastened tree pest emergence, despite a growing awareness of the problem, improved understanding of the costs, and an increased focus on the importance of quarantine. To protect the value and potential of planted forests, innovative solutions and a better-coordinated global approach are needed. Mitigation strategies that are effective only in wealthy countries fail to contain invasions elsewhere in the world, ultimately leading to global impacts. Solutions to forest pest problems in the future should mainly focus on integrating management approaches globally, rather than single-country strategies. A global strategy to manage pest issues is vitally important and urgently needed.


Via Francis Martin
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Rescooped by Guogen Yang from WU_Phyto-Publications
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MPMI (2015): Haustorium formation in Medicago truncatula roots infected by Phytophthora palmivora does not involve the common endosymbiotic program shared by AM fungi and rhizobia

MPMI (2015): Haustorium formation in Medicago truncatula roots infected by Phytophthora palmivora does not involve the common endosymbiotic program shared by AM fungi and rhizobia | Plant-Microbe Interaction | Scoop.it

In biotrophic plant-microbe interactions, microbes infect living plant cells where they are hosted in a novel membrane compartment; the host-microbe interface. To create a host-microbe interface, arbuscular mycorrhizal (AM) fungi and rhizobia make use of the same endosymbiotic program. It is a long-standing hypothesis that pathogens make use of plant proteins that are dedicated to mutualistic symbiosis to infect plants and form haustoria. In this report, we developed a Phytophthora palmivora pathosystem to study haustorium formation in Medicago truncatula (Medicago) roots. We show that P. palmivora does not require host genes that are essential for symbiotic infection and host-microbe interface formation to infect Medicago roots and form haustoria. Based on these findings, we conclude that P. palmivora does not hijack the ancient intracellular accommodation program used by symbiotic microbes to form a biotrophic host-microbe interface.


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Quantitative assessment of the differential impacts of arbuscular and ectomycorrhiza on soil carbon cycling

Quantitative assessment of the differential impacts of arbuscular and ectomycorrhiza on soil carbon cycling | Plant-Microbe Interaction | Scoop.it
A significant fraction of carbon stored in the Earth's soil moves through arbuscular mycorrhiza (AM) and ectomycorrhiza (EM). The impacts of AM and EM on the soil carbon budget are poorly understood.
We propose a method to quantify the mycorrhizal contribution to carbon cycling, explicitly accounting for the abundance of plant-associated and extraradical mycorrhizal mycelium. We discuss the need to acquire additional data to use our method, and present our new global database holding information on plant species-by-site intensity of root colonization by mycorrhizas. We demonstrate that the degree of mycorrhizal fungal colonization has globally consistent patterns across plant species. This suggests that the level of plant species-specific root colonization can be used as a plant trait.
To exemplify our method, we assessed the differential impacts of AM : EM ratio and EM shrub encroachment on carbon stocks in sub-arctic tundra. AM and EM affect tundra carbon stocks at different magnitudes, and via partly distinct dominant pathways: via extraradical mycelium (both EM and AM) and via mycorrhizal impacts on above- and belowground biomass carbon (mostly AM).
Our method provides a powerful tool for the quantitative assessment of mycorrhizal impact on local and global carbon cycling processes, paving the way towards an improved understanding of the role of mycorrhizas in the Earth's carbon cycle.

Via Francis Martin
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Subversion of plant cellular functions by bacterial type-III effectors: beyond suppression of immunity - New Phytologist

Subversion of plant cellular functions by bacterial type-III effectors: beyond suppression of immunity - New Phytologist | Plant-Microbe Interaction | Scoop.it

Most bacterial plant pathogens employ a type-III secretion system to inject type-III effector (T3E) proteins directly inside plant cells. These T3Es manipulate host cellular processes in order to create a permissive niche for bacterial proliferation, allowing development of the disease. An important role of T3Es in plant pathogenic bacteria is the suppression of plant immune responses. However, in recent years, research has uncovered T3E functions different from direct immune suppression, including the modulation of plant hormone signaling, metabolism or organelle function. This insight article discusses T3E functions other than suppression of immunity, which may contribute to the modulation of plant cells in order to promote bacterial survival, nutrient release, and bacterial replication and dissemination.


Via Max-Bernhard Ballhausen, Suayib Üstün
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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A CRISPR/Cas9 toolbox for multiplexed plant genome editing and transcriptional regulation (OPEN)

A CRISPR/Cas9 toolbox for multiplexed plant genome editing and transcriptional regulation (OPEN) | Plant-Microbe Interaction | Scoop.it

" we developed and implemented a comprehensive molecular toolbox for multifaceted CRISPR/Cas9 applications in plants. This toolbox provides researchers with a protocol and reagents to quickly and efficiently assemble functional CRISPR/Cas9 T-DNA constructs for monocots and dicots using Golden Gate and Gateway cloning methods. It comes with a full suite of capabilities, including multiplexed gene editing and transcriptional activation or repression of plant endogenous genes. We report the functionality and effectiveness of this toolbox in model plants such as tobacco, Arabidopsis and rice, demonstrating its utility for basic and applied plant research."


Via Mary Williams
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Boron bridging of rhamnogalacturonan-II is promoted in vitro by cationic chaperones, including polyhistidine and wall glycoproteins

Boron bridging of rhamnogalacturonan-II is promoted in vitro by cationic chaperones, including polyhistidine and wall glycoproteins | Plant-Microbe Interaction | Scoop.it
Summary
Dimerization of rhamnogalacturonan-II (RG-II) via boron cross-links contributes to the assembly and biophysical properties of the cell wall.

Via IPM Lab
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Probing strigolactone receptors in Striga hermonthica with fluorescence

Probing strigolactone receptors in Striga hermonthica with fluorescence | Plant-Microbe Interaction | Scoop.it
Elucidating the signaling mechanism of strigolactones has been the key to controlling the devastating problem caused by the parasitic plant Striga hermonthica. To overcome the genetic intractability that has previously interfered with identification of the strigolactone receptor, we developed a fluorescence turn-on probe, Yoshimulactone Green (YLG), which activates strigolactone signaling and illuminates signal perception by the strigolactone receptors. Here we describe how strigolactones bind to and act via ShHTLs, the diverged family of α/β hydrolase-fold proteins in Striga. Live imaging using YLGs revealed that a dynamic wavelike propagation of strigolactone perception wakes up Striga seeds. We conclude that ShHTLs function as the strigolactone receptors mediating seed germination in Striga. Our findings enable access to strigolactone receptors and observation of the regulatory dynamics for strigolactone signal transduction in Striga.

Via Francis Martin
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Native root-associated bacteria rescue a plant from a sudden-wilt disease that emerged during continuous cropping

Plants maintain microbial associations whose functions remain largely unknown. For the past 15 y, we have planted the annual postfire tobacco Nicotiana attenuata into an experimental field plot in the plant’s native habitat, and for the last 8 y the number of plants dying from a sudden wilt disease has increased, leading to crop failure. Inadvertently we had recapitulated the common agricultural dilemma of pathogen buildup associated with continuous cropping for this native plant. Plants suffered sudden tissue collapse and black roots, symptoms similar to a Fusarium–Alternaria disease complex, recently characterized in a nearby native population and developed into an in vitro pathosystem for N. attenuata. With this in vitro disease system, different protection strategies (fungicide and inoculations with native root-associated bacterial and fungal isolates), together with a biochar soil amendment, were tested further in the field. A field trial with more than 900 plants in two field plots revealed that inoculation with a mixture of native bacterial isolates significantly reduced disease incidence and mortality in the infected field plot without influencing growth, herbivore resistance, or 32 defense and signaling metabolites known to mediate resistance against native herbivores. Tests in a subsequent year revealed that a core consortium of five bacteria was essential for disease reduction. This consortium, but not individual members of the root-associated bacteria community which this plant normally recruits during germination from native seed banks, provides enduring resistance against fungal diseases, demonstrating that native plants develop opportunistic mutualisms with prokaryotes that solve context-dependent ecological problems.

Via Stéphane Hacquard, Jean-Michel Ané
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Rescooped by Guogen Yang from WU_Phyto-Publications
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Annual Review of Phytopathology (2015): Genomics Spurs Rapid Advances in Our Understanding of the Biology of Vascular Wilt Pathogens in the Genus Verticillium

Annual Review of Phytopathology (2015): Genomics Spurs Rapid Advances in Our Understanding of the Biology of Vascular Wilt Pathogens in the Genus Verticillium | Plant-Microbe Interaction | Scoop.it

The availability of genomic sequences of several Verticillium species triggered an explosion of genome-scale investigations of mechanisms fundamental to the Verticillium life cycle and disease process. Comparative genomics studies have revealed evolutionary mechanisms, such as hybridization and interchromosomal rearrangements, that have shaped these genomes. Functional analyses of a diverse group of genes encoding virulence factors indicate that successful host xylem colonization relies on specific Verticillium responses to various stresses, including nutrient deficiency and host defense–derived oxidative stress. Regulatory pathways that control responses to changes in nutrient availability also appear to positively control resting structure development. Conversely, resting structure development seems to be repressed by pathways, such as those involving effector secretion, which promote responses to host defenses. The genomics-enabled functional characterization of responses to the challenges presented by the xylem environment, accompanied by identification of novel virulence factors, has rapidly expanded our understanding of niche adaptation in Verticillium species.


Via WU_Phyto
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Structural basis of pathogen recognition by an integrated HMA domain in a plant NLR immune receptor

Structural basis of pathogen recognition by an integrated HMA domain in a plant NLR immune receptor | Plant-Microbe Interaction | Scoop.it

Plants have evolved intracellular immune receptors to detect pathogen proteins known as effectors. How these immune receptors detect effectors remains poorly understood. Here we describe the structural basis for direct recognition of AVR-Pik, an effector from the rice blast pathogen, by the rice intracellular NLR immune receptor Pik. AVR-PikD binds a dimer of the Pikp-1 HMA integrated domain with nanomolar affinity. The crystal structure of the Pikp-HMA/AVR-PikD complex enabled design of mutations to alter protein interaction in yeast and in vitro, and perturb effector-mediated response both in a rice cultivar containing Pikp and upon expression of AVR-PikD and Pikp in the model plant Nicotiana benthamiana. These data reveal the molecular details of a recognition event, mediated by a novel integrated domain in an NLR, which initiates a plant immune response and resistance to rice blast disease. Such studies underpin novel opportunities for engineering disease resistance to plant pathogens in staple food crops.


Via Francis Martin
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Rescooped by Guogen Yang from Publications
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eLife: Structural basis of pathogen recognition by an integrated HMA domain in a plant NLR immune receptor (2015)

eLife: Structural basis of pathogen recognition by an integrated HMA domain in a plant NLR immune receptor (2015) | Plant-Microbe Interaction | Scoop.it

Plants have evolved intracellular immune receptors to detect pathogen proteins known as effectors. How these immune receptors detect effectors remains poorly understood. Here we describe the structural basis for direct recognition of AVR-Pik, an effector from the rice blast pathogen, by the rice intracellular NLR immune receptor Pik. AVR-PikD binds a dimer of the Pikp-1 HMA integrated domain with nanomolar affinity. The crystal structure of the Pikp-HMA/AVR-PikD complex enabled design of mutations to alter protein interaction in yeast and in vitro, and perturb effector-mediated response both in a rice cultivar containing Pikp and upon expression of AVR-PikD and Pikp in the model plant Nicotiana benthamiana. These data reveal the molecular details of a recognition event, mediated by a novel integrated domain in an NLR, which initiates a plant immune response and resistance to rice blast disease. Such studies underpin novel opportunities for engineering disease resistance to plant pathogens in staple food crops.


Via Kamoun Lab @ TSL
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