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A really useful pathogen, Agrobacterium tumefaciens. New Teaching Tool.

A really useful pathogen, Agrobacterium tumefaciens. New Teaching Tool. | Plant-Microbe Interaction | Scoop.it

The soil bacterium Agrobacterium tumefaciens has a special place in plant biology. Through a rare inter-kingdom DNA transfer, the bacteria move some of their genes into their host's genome, thereby inducing the host cells to proliferate and produce opines, which are nutrients sources for the pathogen. Agrobacterium's ability to transfer DNA makes can be adapted to introduce other genes, such as those encoding useful traits, into plant genomes. The development of Agrobacterium as a tool to transform plants is a landmark event in modern plant biology. This new "Teaching Tool in Plant Biology" provides an introduction to Agrobacterium tumefaciens and related species, focusing on their modes of pathogenicity, their usefulness as tools for plant transformation, and their use as a model for the study of plant-pathogen interactions.

Find it here: http://www.plantcell.org/site/teachingtools/TTPB23.xhtml (subscription to Plant Cell or ASPB membership required).


Via Mary Williams, Nicolas Denancé, Suayib Üstün
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Lidia Pérez de Obanos's curator insight, November 27, 2013 9:15 AM

Agrobacterium tumefaciens es un vector muy útil para muchos tipos de genes que se quieren introducir en distintas plantas. Gracias a ella hemos podido realizar múltiples experimentos y es muy fácil de realizar.

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Rescooped by Guogen Yang from Virology and Bioinformatics from Virology.ca
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PLOS Computational Biology: Ten Simple Rules for a Bioinformatics Journal Club

PLOS Computational Biology: Ten Simple Rules for a Bioinformatics Journal Club | Plant-Microbe Interaction | Scoop.it

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RS-1 enhances CRISPR/Cas9- and TALEN-mediated knock-in efficiency - Nature Comm.

RS-1 enhances CRISPR/Cas9- and TALEN-mediated knock-in efficiency - Nature Comm. | Plant-Microbe Interaction | Scoop.it

(via T. Lahaye & T Schreiber, thx)

Song et al, 2016

Zinc-finger nuclease, transcription activator-like effector nuclease and CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9) are becoming major tools for genome editing. Importantly, knock-in in several non-rodent species has been finally achieved thanks to these customizable nucleases; yet the rates remain to be further improved. We hypothesize that inhibiting non-homologous end joining (NHEJ) or enhancing homology-directed repair (HDR) will improve the nuclease-mediated knock-in efficiency. Here we show that the in vitro application of an HDR enhancer, RS-1, increases the knock-in efficiency by two- to five-fold at different loci, whereas NHEJ inhibitor SCR7 has minimal effects. We then apply RS-1 for animal production and have achieved multifold improvement on the knock-in rates as well. Our work presents tools to nuclease-mediated knock-in animal production, and sheds light on improving gene-targeting efficiencies on pluripotent stem cells.


Via dromius
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Filamentous brown algae infected by the marine, holocarpic oomycete Eurychasma dicksonii: first results on the organization and the role of cytoskeleton in both host and parasite

Filamentous brown algae infected by the marine, holocarpic oomycete Eurychasma dicksonii:  first results on the organization and the role of cytoskeleton in both host and parasite | Plant-Microbe Interaction | Scoop.it
The important role of the cytoskeletal scaffold is increasingly recognized in host-pathogen interactions. The cytoskeleton potentially functions as a weapon for both the plants defending themselves against fungal or oomycete parasites, and for the pathogens ...

Via GlobalSeaweed, Christophe Jacquet
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Rescooped by Guogen Yang from Plant-Microbe Symbiosis
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The birth of cooperation

The birth of cooperation | Plant-Microbe Interaction | Scoop.it
Mutually beneficial associations between individuals of different species, called mutualistic symbioses, have enabled major ecological innovations and underlie some of the major transitions in evolution (1). For example, the ancestor of plants domesticated endosymbiotic photosynthetic bacteria, today's chloroplasts, for carbon fixation. This association dramatically increased the habitat of these photosynthetic bacteria from the sea to terrestrial ecosystems. However, the colonization of land by plants required an additional symbiotic association, with fungal root symbionts that facilitate nutrient uptake (2). Yet, surprisingly little is known about how mutualistic symbioses evolved and persist. On page 94 of this issue, Hom and Murray show how mutualism may arise without prior coevolution (see the photo) (3).

Via Jean-Michel Ané
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Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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bioRxiv: Cell re-entry assays do not support models of pathogen- independent translocation of AvrM and AVR3a effectors into plant cells (2016)

bioRxiv: Cell re-entry assays do not support models of pathogen- independent translocation of AvrM and AVR3a effectors into plant cells (2016) | Plant-Microbe Interaction | Scoop.it

The cell re-entry assay is widely used to evaluate pathogen effector protein uptake into plant cells. The assay is based on the premise that effector proteins secreted out of a leaf cell would translocate back into the cytosol of the same cell via a yet unknown host-derived uptake mechanism. Here, we critically assess this assay by expressing domains of the effector proteins AvrM-A of Melampsora lini and AVR3a of Phytophthora infestans fused to a signal peptide and fluorescent proteins in Nicotiana benthamiana. We found that the secreted fusion proteins do not re-enter plant cells from the apoplast and that the assay is prone to false-positives. We therefore emit a cautionary note on the use of the cell re-entry assay for protein trafficking studies.


Via Kamoun Lab @ TSL, IPM Lab
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Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana

Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana | Plant-Microbe Interaction | Scoop.it
Background

Host RNA-dependent RNA polymerases (RDRs) 1 and 6 contribute to antiviral RNA silencing in plants. RDR6 is constitutively expressed and was previously shown to limit invasion of Nicotiana benthamiana meristem tissue by potato virus X and thereby inhibit disease development. RDR1 is inducible by salicylic acid (SA) and several other phytohormones. But although it contributes to basal resistance to tobacco mosaic virus (TMV) it is dispensable for SA-induced resistance in inoculated leaves. The laboratory accession of N. benthamiana is a natural rdr1 mutant and highly susceptible to TMV. However, TMV-induced symptoms are ameliorated in transgenic plants expressing Medicago truncatula RDR1.
Results

In MtRDR1-transgenic N. benthamiana plants the spread of TMV expressing the green fluorescent protein (TMV.GFP) into upper, non-inoculated, leaves was not inhibited. However, in these plants exclusion of TMV.GFP from the apical meristem and adjacent stem tissue was greater than in control plants and this exclusion effect was enhanced by SA. TMV normally kills N. benthamiana plants but although MtRDR1-transgenic plants initially displayed virus-induced necrosis they subsequently recovered. Recovery from disease was markedly enhanced by SA treatment in MtRDR1-transgenic plants whereas in control plants SA delayed but did not prevent systemic necrosis and death. Following SA treatment of MtRDR1-transgenic plants, extractable RDR enzyme activity was increased and Western blot analysis of RDR extracts revealed a band cross-reacting with an antibody raised against MtRDR1. Expression of MtRDR1 in the transgenic N. benthamiana plants was driven by a constitutive 35S promoter derived from cauliflower mosaic virus, confirmed to be non-responsive to SA. This suggests that the effects of SA on MtRDR1 are exerted at a post-transcriptional level.
Conclusions

MtRDR1 inhibits severe symptom development by limiting spread of virus into the growing tips of infected plants. Thus, RDR1 may act in a similar fashion to RDR6. MtRDR1 and SA acted additively to further promote recovery from disease symptoms in MtRDR1-transgenic plants. Thus it is possible that SA promotes MtRDR1 activity and/or stability through post-transcriptional effects.

Via Christophe Jacquet
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Rules and Self-Organizing Properties of Post-embryonic Plant Organ Cell Division Patterns: Current Biology

Rules and Self-Organizing Properties of Post-embryonic Plant Organ Cell Division Patterns: Current Biology | Plant-Microbe Interaction | Scoop.it
Plants form new organs with patterned tissue organization throughout their lifespan. It is unknown whether this robust post-embryonic organ formation results from stereotypic dynamic processes, in which the arrangement of cells follows rigid rules. Here, we combine modeling with empirical observations of whole-organ development to identify the principles governing lateral root formation in Arabidopsis. Lateral roots derive from a small pool of founder cells in which some take a dominant role as seen by lineage tracing. The first division of the founders is asymmetric, tightly regulated, and determines the formation of a layered structure. Whereas the pattern of subsequent cell divisions is not stereotypic between different samples, it is characterized by a regular switch in division plane orientation. This switch is also necessary for the appearance of patterned layers as a result of the apical growth of the primordium. Our data suggest that lateral root morphogenesis is based on a limited set of rules. They determine cell growth and division orientation. The organ-level coupling of the cell behavior ensures the emergence of the lateral root’s characteristic features. We propose that self-organizing, non-deterministic modes of development account for the robustness of plant organ morphogenesis.

Via Francis Martin
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Rescooped by Guogen Yang from Plants and Microbes
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Science Signaling: Rosmarinic acid is a homoserine lactone mimic produced by plants that activates a bacterial quorum-sensing regulator (2016)

Science Signaling: Rosmarinic acid is a homoserine lactone mimic produced by plants that activates a bacterial quorum-sensing regulator (2016) | Plant-Microbe Interaction | Scoop.it

Quorum sensing is a bacterial communication mechanism that controls genes, enabling bacteria to live as communities, such as biofilms. Homoserine lactone (HSL) molecules function as quorum-sensing signals for Gram-negative bacteria. Plants also produce previously unidentified compounds that affect quorum sensing. We identified rosmarinic acid as a plant-derived compound that functioned as an HSL mimic. In vitro assays showed that rosmarinic acid bound to the quorum-sensing regulator RhlR of Pseudomonas aeruginosaPAO1 and competed with the bacterial ligand N-butanoyl-homoserine lactone (C4-HSL). Furthermore, rosmarinic acid stimulated a greater increase in RhlR-mediated transcription in vitro than that of C4-HSL. In P. aeruginosa, rosmarinic acid induced quorum sensing–dependent gene expression and increased biofilm formation and the production of the virulence factors pyocyanin and elastase. Because P. aeruginosa PAO1 infection induces rosmarinic acid secretion from plant roots, our results indicate that rosmarinic acid secretion is a plant defense mechanism to stimulate a premature quorum-sensing response. P. aeruginosa is a ubiquitous pathogen that infects plants and animals; therefore, identification of rosmarinic acid as an inducer of premature quorum-sensing responses may be useful in agriculture and inform human therapeutic strategies.


Via Kamoun Lab @ TSL
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A proposed regulatory framework for genome-edited crops - Nature Genetics

A proposed regulatory framework for genome-edited crops - Nature Genetics | Plant-Microbe Interaction | Scoop.it

Huang et al, 2016

Crop breeding is being revolutionized by rapid progress in DNA sequencing and targeted alteration of DNA sequences by genome editing. Here we propose a regulatory framework for precision breeding with 'genome-edited crops' (GECs) so that society can fully benefit from the latest advances in plant genetics and genomics.


Via dromius
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Fesquet didier's curator insight, February 10, 4:22 AM

l'OGM propre...genome editing of the gliadin loci in wheat is wellcome

Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Infection of the brown alga Ectocarpus siliculosus by the oomycete Eurychasma dicksonii induces oxidative stress and halogen metabolism - Plant, Cell & Environment -

Infection of the brown alga Ectocarpus siliculosus by the oomycete Eurychasma dicksonii induces oxidative stress and halogen metabolism - Plant, Cell & Environment - | Plant-Microbe Interaction | Scoop.it
Pathogens are increasingly being recognized as key evolutionary and ecological drivers in marine ecosystems. Defence mechanisms of seaweeds, however, have mostly been investigated by mimicking infection using elicitors. We have established an experimental pathosystem between the genome brown model seaweed Ectocarpus siliculosus and the oomycete Eurychasma dicksonii as a powerful new tool to investigate algal responses to infection. Using proteomics, we identified 21 algal proteins differentially accumulated in response to Eu. dicksonii infection. These include classical algal stress response proteins such as a manganese superoxide dismutase, heat shock proteins 70 and a vanadium bromoperoxidase. Transcriptional profiling by qPCR confirmed the induction of the latter during infection. The accumulation of hydrogen peroxide was observed at different infection stages via histochemical staining. Inhibitor studies confirmed that the main source of hydrogen peroxide is superoxide converted by superoxide dismutase. Our data give an unprecedented global overview of brown algal responses to pathogen infection, and highlight the importance of oxidative stress and halogen metabolism in these interactions. This suggests overlapping defence pathways with herbivores and abiotic stresses. We also identify previously unreported actors, in particular a Rad23 and a plastid–lipid-associated protein, providing novel insights into the infection and defence processes in brown algae.

Via Christophe Jacquet
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Interspecies gene transfer provides soybean resistance to a fungal pathogen - Plant Biotechnology Journal

Interspecies gene transfer provides soybean resistance to a fungal pathogen - Plant Biotechnology Journal | Plant-Microbe Interaction | Scoop.it
Fungal pathogens pose a major challenge to global crop production. Crop varieties that resist disease present the best defence and offer an alternative to chemical fungicides. Exploiting durable nonhost resistance (NHR) for crop protection often requires identification and transfer of NHR-linked genes to the target crop. Here, we identify genes associated with NHR of Arabidopsis thaliana to Phakopsora pachyrhizi, the causative agent of the devastating fungal disease called Asian soybean rust. We transfer selected Arabidopsis NHR-linked genes to the soybean host and discover enhanced resistance to rust disease in some transgenic soybean lines in the greenhouse. Interspecies NHR gene transfer thus presents a promising strategy for genetically engineered control of crop diseases.

Via Christophe Jacquet
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Frontiers | Plant Ribosomal Proteins, RPL12 and RPL19, Play a Role in Nonhost Disease Resistance against Bacterial Pathogens | Plant Biotic Interactions

Frontiers | Plant Ribosomal Proteins, RPL12 and RPL19, Play a Role in Nonhost Disease Resistance against Bacterial Pathogens | Plant Biotic Interactions | Plant-Microbe Interaction | Scoop.it
haracterizing the molecular mechanism involved in nonhost disease resistance is important to understand the adaptations of plant-pathogen interactions. In this study, virus-induced gene silencing (VIGS)-based forward genetics screen was utilized to identify genes involved in nonhost resistance in Nicotiana benthamiana. Genes encoding ribosomal proteins, RPL12 and RPL19, were identified in the screening. These genes when silenced in N. benthamiana caused a delay in nonhost bacteria induced hypersensitive response (HR) with concurrent increase in nonhost bacterial multiplication. Arabidopsis mutants of AtRPL12 and AtRPL19 also compromised nonhost resistance. The studies on NbRPL12 and NbRPL19 double silenced plants suggested that both RPL12 and RPL19 act in the same pathway to confer nonhost resistance. Our work suggests a role for RPL12 and RPL19 in nonhost disease resistance in N. benthamiana and Arabidopsis. In addition, we show that these genes also play a minor role in basal resistance against virulent pathogens.

Via Christophe Jacquet
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Serotonin attenuates biotic stress and leads to lesion browning caused by a hypersensitive response to Magnaporthe oryzae penetration in rice - - The Plant Journal -

Serotonin attenuates biotic stress and leads to lesion browning caused by a hypersensitive response to Magnaporthe oryzae penetration in rice - - The Plant Journal - | Plant-Microbe Interaction | Scoop.it
The hypersensitive response (HR) of plants is one of the earliest responses to prevent pathogen invasion. A brown dot lesion on a leaf is visual evidence of the HR against the blast fungus Magnaporthe oryzae in rice, but tracking the browning process has been difficult. In this study, we induced the HR in rice cultivars harboring the blast resistance gene Pit by inoculation of an incompatible M. oryzae strain, which generated a unique resistance lesion with a brown ring (halo) around the brown fungal penetration site. Inoculation analysis using a plant harboring Pit but lacking an enzyme that catalyzes tryptamine to serotonin showed that high accumulation of the oxidized form of serotonin was the cause of the browning at the halo and penetration site. Our analysis of the halo browning process in the rice leaf revealed that abscisic acid enhanced biosynthesis of serotonin under light conditions, and serotonin changed to the oxidized form via hydrogen peroxide produced by light. The dramatic increase in serotonin, which has a high antioxidant activity, suppressed leaf damage outside the halo, blocked expansion of the browning area and attenuated inhibition of plant growth. These results suggest that serotonin helps to reduce biotic stress in the plant by acting as a scavenger of oxygen radicals to protect uninfected tissues from oxidative damage caused by the HR. The deposition of its oxide at the HR lesion is observed as lesion browning.

Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Autophagy in Plants – What's New on the Menu?

Autophagy in Plants – What's New on the Menu? | Plant-Microbe Interaction | Scoop.it
Autophagy is a major cellular degradation pathway in eukaryotes. Recent studies have revealed the importance of autophagy in many aspects of plant life, including seedling establishment, plant development, stress resistance, metabolism, and reproduction. This is manifested by the dual ability of autophagy to execute bulk degradation under severe environmental conditions, while simultaneously to be highly selective in targeting specific compartments and protein complexes to regulate key cellular processes, even during favorable growth conditions. Delivery of cellular components to the vacuole enables their recycling, affecting the plant metabolome, especially under stress. Recent research in Arabidopsis has further unveiled fundamental mechanistic aspects in autophagy which may have relevance in non-plant systems. We review the most recent discoveries concerning autophagy in plants, touching upon all these aspects.

Via Christophe Jacquet
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Rescooped by Guogen Yang from Virology and Bioinformatics from Virology.ca
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PLOS Computational Biology: A Quick Introduction to Version Control with Git and GitHub

PLOS Computational Biology: A Quick Introduction to Version Control with Git and GitHub | Plant-Microbe Interaction | Scoop.it

Share Your Code Once you have your files saved in a Git repository, you can share it with your collaborators and the wider scientific community by putting your code online (Fig 3).


Via Chris Upton + helpers
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Asela Wijeratne's curator insight, February 4, 11:41 AM

Nice overview of version control!

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Keystone Herbivores and the Evolution of Plant Defenses: Trends in Plant Science

Keystone Herbivores and the Evolution of Plant Defenses: Trends in Plant Science | Plant-Microbe Interaction | Scoop.it
Plants need to defend themselves against a diverse and dynamic herbivore community. Such communities may be shaped by keystone herbivores that through their feeding alter the plant phenotype as well as the likelihood of attack by other herbivores. Here, we discuss such herbivores that have a large effect on the interaction network structure with associated fitness consequences for the plant, as dominant agents of selection on plant defense traits. Merging the keystone herbivore concept with plant fitness and trait selection frameworks will provide an approach to identify which herbivores drive selection in complex multispecies interactions in natural and agricultural systems.
Trends

Keystone herbivores affect the composition of plant-associated communities through plant-mediated species interactions and thus affect the integrative effect of the herbivore community on plant fitness.

Through their role in mediating the outcomes of plant–herbivore community interactions, keystone herbivores are expected to be major agents of natural selection on constitutive and induced direct and indirect resistance although they may individually not significantly affect plant fitness. Thus, they are key to understanding evolution of plant defenses.

Identifying keystone herbivores and measuring their plant fitness effects would be equivalent to identifying the fitness effect of plant-associated interaction networks and provide a shortcut to understanding diffuse (co)-evolution.
Keywords:

Via Christophe Jacquet
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New Phytologist: Mycorrhizal symbioses: today and tomorrow (2016)

New Phytologist: Mycorrhizal symbioses: today and tomorrow (2016) | Plant-Microbe Interaction | Scoop.it

The 2nd International Molecular Mycorrhiza Meeting, Cambridge, UK, September 2015The 2nd International Molecular Mycorrhiza Meeting, Cambridge, UK, September 2015Symbiotic interactions between plants and mycorrhizal fungi have a major impact on plant growth, development and evolution. Among them, the ectomycorrhizal (ECM) symbiosis formed between a large variety of phylogenetically diverse fungi and trees, and the arbuscular mycorrhizal (AM) symbiosis involving almost all land plants and the monophyletic Glomeromycota, are critical players of most ecosystems. Beyond their ecological functions, these associations offer a unique opportunity to improve the productivity and sustainability of current forest and agricultural systems. Over the last two decades, genetics conducted in model legumes has allowed the identification of a first set of genes and molecular mechanisms required for the efficient establishment of the AM symbiosis but also highlighted how scarce and incomplete our understanding of this association is at the molecular level. The 2nd international Molecular Mycorrhiza Meeting (2nd iMMM) brought together researchers who work on the molecular characterization of AM and ECM symbioses in a variety of contexts including root colonization, cell dynamics, nutrient exchange and metabolism, molecular evolution, genomics, effectors, plant–fungal communication, hormonal regulation or signal transduction. During this year's meeting many presenters outlined novel discoveries, concepts and models that are likely to take the research on mycorrhizal associations into new realms.


Via Kamoun Lab @ TSL
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A Phytophthora infestans RXLR effector targets plant PP1c isoforms that promote late blight disease : Nature Communications : Nature Publishing Group

A Phytophthora infestans RXLR effector targets plant PP1c isoforms that promote late blight disease : Nature Communications : Nature Publishing Group | Plant-Microbe Interaction | Scoop.it

RT @jfgumarc: A Phytophthora infestans RXLR effector targets plant PP1c https://t.co/sVVDc7lHJV


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Streptomyces thermoautotrophicus does not fix nitrogen

Streptomyces thermoautotrophicus does not fix nitrogen | Plant-Microbe Interaction | Scoop.it
Streptomyces thermoautotrophicus UBT1 has been described as a moderately thermophilic chemolithoautotroph with a novel nitrogenase enzyme that is oxygen-insensitive. We have cultured the UBT1 strain, and have isolated two new strains (H1 and P1-2) of very similar phenotypic and genetic characters. These strains show minimal growth on ammonium-free media, and fail to incorporate isotopically labeled N2 gas into biomass in multiple independent assays. The sdn genes previously published as the putative nitrogenase of S. thermoautotrophicus have little similarity to anything found in draft genome sequences, published here, for strains H1 and UBT1, but share >99% nucleotide identity with genes from Hydrogenibacillus schlegelii, a draft genome for which is also presented here. H. schlegelii similarly lacks nitrogenase genes and is a non-diazotroph. We propose reclassification of the species containing strains UBT1, H1, and P1-2 as a non-Streptomycete, non-diazotrophic, facultative chemolithoautotroph and conclude that the existence of the previously proposed oxygen-tolerant nitrogenase is extremely unlikely.

Via Jean-Michel Ané
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Jean-Michel Ané's curator insight, February 1, 1:05 PM

Setting the record right...

Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Sci Reports: Msp40 effector of root-knot nematode manipulates plant immunity to facilitate parasitism

Sci Reports: Msp40 effector of root-knot nematode manipulates plant immunity to facilitate parasitism | Plant-Microbe Interaction | Scoop.it
Root-knot nematodes (RKNs) are obligate biotrophic parasites that invade plant roots and engage in prolonged and intimate relationships with their hosts. Nematode secretions, some of which have immunosuppressing activity, play essential roles in successful parasitism; however, their mechanisms of action remain largely unknown. Here, we show that the RKN-specific gene MiMsp40, cloned from Meloidogyne incognita, is expressed exclusively in subventral oesophageal gland cells and is strongly upregulated during early parasitic stages. Arabidopsis plants overexpressing MiMsp40 were more susceptible to nematode infection than were wild type plants. Conversely, the host-derived MiMsp40 RNAi suppressed nematode parasitism and/or reproduction. Moreover, overexpression of MiMsp40 in plants suppressed the deposition of callose and the expression of marker genes for bacterial elicitor elf18-triggered immunity. Transient expression of MiMsp40 prevented Bax-triggered defence-related programmed cell death. Co-agroinfiltration assays indicated that MiMsp40 also suppressed macroscopic cell death triggered by MAPK cascades or by the ETI cognate elicitors R3a/Avr3a. Together, these results demonstrate that MiMsp40 is a novel Meloidogyne-specific effector that is injected into plant cells by early parasitic stages of the nematode and that plays a role in suppressing PTI and/or ETI signals to facilitate RKN parasitism.

Via Christophe Jacquet, Jim Alfano, Francis Martin
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A widespread plant-fungal-bacterial symbiosis promotes plant biodiversity, plant nutrition and seedling recruitment

A widespread plant-fungal-bacterial symbiosis promotes plant biodiversity, plant nutrition and seedling recruitment | Plant-Microbe Interaction | Scoop.it
Highly diverse microbial assemblages colonize plant roots. It is still poorly understood whether different members of this root microbiome act synergistically by supplying different services (for example, different limiting nutrients) to plants and plant communities. In order to test this, we manipulated the presence of two widespread plant root symbionts, arbuscular mycorrhizal fungi and nitrogen-fixing rhizobia bacteria in model grassland communities established in axenic microcosms. Here, we demonstrate that both symbionts complement each other resulting in increased plant diversity, enhanced seedling recruitment and improved nutrient acquisition compared with a single symbiont situation. Legume seedlings obtained up to 15-fold higher productivity if they formed an association with both symbionts, opposed to productivity they reached with only one symbiont. Our results reveal the importance of functional diversity of symbionts and demonstrate that different members of the root microbiome can complement each other in acquiring different limiting nutrients and in driving important ecosystem functions.

Via Ryohei Thomas Nakano, Jean-Michel Ané
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Diversity of genetic backgrounds modulating the durability of a major resistance gene. Analysis of a core collection of pepper landraces resistant to Potato virus Y - Molecular Plant Pathol...

Diversity of genetic backgrounds modulating the durability of a major resistance gene. Analysis of a core collection of pepper landraces resistant to Potato virus Y - Molecular Plant Pathol... | Plant-Microbe Interaction | Scoop.it
The evolution of resistance-breaking capacity in pathogen populations has been shown to depend on the plant genetic background surrounding the resistance genes. We evaluated a core collection of pepper (Capsicum annuum) landraces, representing the worldwide genetic diversity, for its ability to modulate the breakdown frequency by Potato virus Y of major resistance alleles at the pvr2 locus encoding the eukaryotic initiation factor 4E (eIF4E). Depending on the pepper landrace, the breakdown frequency of a given resistance allele varied from 0% to 52.5%, attesting to their diversity and the availability of genetic backgrounds favourable to resistance durability in the plant germplasm. The mutations in the virus genome involved in resistance breakdown also differed between plant genotypes, indicating differential selection effects exerted on the virus population by the different genetic backgrounds. The breakdown frequency was positively correlated with the level of virus accumulation, confirming the impact of quantitative resistance loci on resistance durability. Among these loci, pvr6, encoding an isoform of eIF4E, was associated with a major effect on virus accumulation and on the breakdown frequency of the pvr2-mediated resistance. This exploration of plant genetic diversity delivered new resources for the control of pathogen evolution and the increase in resistance durability.

Via Christophe Jacquet
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The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea : Nature : Nature Publishing Group

The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea : Nature : Nature Publishing Group | Plant-Microbe Interaction | Scoop.it

"Seagrasses colonized the sea on at least three independent occasions to form the basis of one of the most productive and widespread coastal ecosystems on the planet. Here we report the genome of Zostera marina (L.), the first, to our knowledge, marine angiosperm to be fully sequenced. This reveals unique insights into the genomic losses and gains involved in achieving the structural and physiological adaptations required for its marine lifestyle, arguably the most severe habitat shift ever accomplished by flowering plants. Key angiosperm innovations that were lost include the entire repertoire of stomatal genes, genes involved in the synthesis of terpenoids and ethylene signalling, and genes for ultraviolet protection and phytochromes for far-red sensing."


Via Mary Williams
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Mary Williams's curator insight, January 28, 4:38 AM

This is a really interesting paper! Seagrass - the dolphins of the plant kingdom (from sea to land and back to sea).

Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Science Signaling: 2015: Signaling Breakthroughs of the Year

Science Signaling: 2015: Signaling Breakthroughs of the Year | Plant-Microbe Interaction | Scoop.it

Plants are subject to attack by pathogens, and, like animals, the plant innate immune response involves both surface and cytoplasmic receptors. Intracellular nucleotide-binding leucine-rich repeat receptors involved in the plant innate immune response are structurally and functionally similar to animal Nod-like receptors (NLRs), which play a key role in inflammasome activation. Plant NLRs, which detect pathogen-derived virulence factors (effectors) frequently directed against plant defenses triggered by the plasma membrane-localized immune receptors, can function in pairs, with both partners required for activation of an immune response. In work that he described as representing “a paradigmatic shift in our understanding of how immune receptors work,” Cyril Zipfel nominated three papers (24–26) describing an intriguing twist on effector detection. Le Roux et al. (24) and Sarris et al. (25) showed how integration of a “decoy” or “sensor” domain that mimics host targets baits pathogenic virulence factors to one member of a plant NLR pair, thereby activating the partner NLR to initiate defense signaling. In a third breakthrough paper on this theme, Maqbool et al. (26) determined the structural basis for effector interaction with a different class of integrated domain and demonstrated that a high binding affinity between the NLR domain and the effector is required to activate immunity. The emerging theme from these papers is that the very mechanisms that enable pathogen virulence factors to cripple the initial wave of the immune response have been turned to their own destruction.


Via Kamoun Lab @ TSL, Christophe Jacquet
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The Arabidopsis microtubule-associated protein MAP65-3 supports infection by filamentous biotrophic pathogens by down-regulating salicylic acid-dependent defenses

The Arabidopsis microtubule-associated protein MAP65-3 supports infection by filamentous biotrophic pathogens by down-regulating salicylic acid-dependent defenses | Plant-Microbe Interaction | Scoop.it
The oomycete Hyaloperonospora arabidopsidis and the ascomycete Erysiphe cruciferarum are obligate biotrophic pathogens causing downy mildew and powdery mildew, respectively, on Arabidopsis. Upon infection, the filamentous pathogens induce the formation of intracellular bulbous structures called haustoria, which are required for the biotrophic lifestyle. We previously showed that the microtubule-associated protein AtMAP65-3 plays a critical role in organizing cytoskeleton microtubule arrays during mitosis and cytokinesis. This renders the protein essential for the development of giant cells, which are the feeding sites induced by root knot nematodes. Here, we show that AtMAP65-3 expression is also induced in leaves upon infection by the downy mildew oomycete and the powdery mildew fungus. Loss of AtMAP65-3 function in the map65-3 mutant dramatically reduced infection by both pathogens, predominantly at the stages of leaf penetration. Whole-transcriptome analysis showed an over-represented, constitutive activation of genes involved in salicylic acid (SA) biosynthesis, signaling, and defense execution in map65-3, whereas jasmonic acid (JA)-mediated signaling was down-regulated. Preventing SA synthesis and accumulation in map65-3 rescued plant susceptibility to pathogens, but not the developmental phenotype caused by cytoskeleton defaults. AtMAP65-3 thus has a dual role. It positively regulates cytokinesis, thus plant growth and development, and negatively interferes with plant defense against filamentous biotrophs. Our data suggest that downy mildew and powdery mildew stimulate AtMAP65-3 expression to down-regulate SA signaling for infection.

Via Christophe Jacquet
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