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ScienceDirect.com - Journal of Proteomics - In-depth insight into in vivo apoplastic secretome of rice-Magnaporthe oryzae interaction

ScienceDirect.com - Journal of Proteomics - In-depth insight into in vivo apoplastic secretome of rice-Magnaporthe oryzae interaction | Plant-Microbe Interaction | Scoop.it

The in vivo apoplastic fluid secretome of rice-blast fungus interaction remains largely uncharacterized. Here, we report a proteomics investigation of in vivo secreted proteins of rice leaves infected with incompatible (KJ401) and compatible (KJ301) races of Magnaporthe oryzae (M. oryzae) using 2-DGE and MudPIT coupled with MALDI-TOF-MS and/or nESI-LC–MS/MS analyses. Prepared fractions of secretory proteins were essentially free from cytoplasmic contamination. Two-DGE and MudPIT identified 732 secretory proteins, where 291 (40%) and 441 (60%) proteins were derived from rice and M. oryzae, respectively. Of these, 39.2% (rice) and 38.9% (M. oryzae) of proteins were predicted by SignalP as retaining signal peptides. Among these, rice secreted more proteins related to stress response, ROS and energy metabolism, whereas, M. oryzae secreted more proteins involved in metabolism and cell wall hydrolyses. Semi-quantitative RT-PCR revealed their differential expression under compatible/incompatible interactions. In vivo expression of M. oryzae glycosyl hydrolase (GH) protein family members using particle bombardment driven transient expression system showed that four GH genes could act as effectors within host apoplast possibly via interaction with host membrane bound receptor. The established in vivo secretome serves as a valuable resource toward secretome analysis of rice-M. oryzae interaction.

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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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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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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.

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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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Rescooped by Guogen Yang from Plant-Microbe Symbioses
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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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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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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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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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Activation of Big Grain1 significantly improves grain size by regulating auxin transport in rice

Activation of Big Grain1 significantly improves grain size by regulating auxin transport in rice | Plant-Microbe Interaction | Scoop.it

Here's an interesting OPEN paper in PNAS. The gene was identified by activation tagging, meaning that the mutant overexpresses a normal protein, resulting in big rice grains. The overexpressed gene encodes an uncharacterized membrane-localized protein that affects auxin transport. Lots more work to do, but an interesting and potentially useful phenotype!


Via Mary Williams
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Rescooped by Guogen Yang from Plant immunity and legume symbiosis
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Genome Biology | Full text | Chromatin in 3D: progress and prospects for plants

Genome Biology | Full text | Chromatin in 3D: progress and prospects for plants | Plant-Microbe Interaction | Scoop.it
Methods that use high-throughput sequencing have begun to reveal features of the three-dimensional structure of genomes at a resolution that goes far beyond that of traditional microscopy. Integration of these methods with other molecular tools has advanced our knowledge of both global and local chromatin packing in plants, and has revealed how patterns of chromatin packing correlate with the genomic and epigenomic landscapes. This update reports recent progress made in this area in plants, and suggests new research directions.

Via Christophe Jacquet
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Frontiers | The battle in the apoplast: further insights into the roles of proteases and their inhibitors in plant–pathogen interactions | Plant Biotic Interactions

Frontiers | The battle in the apoplast: further insights into the roles of proteases and their inhibitors in plant–pathogen interactions | Plant Biotic Interactions | Plant-Microbe Interaction | Scoop.it
Upon host penetration, fungal pathogens secrete a plethora of effectors to promote disease, including proteases that degrade plant antimicrobial proteins, and protease inhibitors (PIs) that inhibit plant proteases with antimicrobial activity. Conversely, plants secrete proteases and PIs to protect themselves against pathogens or to mediate recognition of pathogen proteases and PIs, which leads to induction of defense responses. Many examples of proteases and PIs mediating effector-triggered immunity in host plants have been reported in the literature, but little is known about their role in compromising basal defense responses induced by microbe-associated molecular patterns. Recently, several reports appeared in literature on secreted fungal proteases that modify or degrade pathogenesis-related proteins, including plant chitinases or PIs that compromise their activities. This prompted us to review the recent advances on proteases and PIs involved in fungal virulence and plant defense. Proteases and PIs from plants and their fungal pathogens play an important role in the arms race between plants and pathogens, which has resulted in co-evolutionary diversification and adaptation shaping pathogen lifestyles.

Via Christophe Jacquet
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Current Biology: Functional Divergence of Two Secreted Immune Proteases of Tomato (2015)

Current Biology: Functional Divergence of Two Secreted Immune Proteases of Tomato (2015) | Plant-Microbe Interaction | Scoop.it

• Rcr3 and Pip1 are paralogous secreted tomato proteases that diverged >36 mya
• Rcr3 and Pip1 differ in expression levels and solvent-exposed residues
• Pip1 depletion increases susceptibility to unrelated apoplastic pathogens
• Without Cf-2, Rcr3 depletion increases susceptibility only to oomycete infection

 

Rcr3 and Pip1 are paralogous secreted papain-like proteases of tomato. Both proteases are inhibited by Avr2 from the fungal pathogen Cladosporium fulvum, but only Rcr3 acts as a co-receptor for Avr2 recognition by the tomato Cf-2 immune receptor [ 1–4 ]. Here, we show that Pip1-depleted tomato plants are hyper-susceptible to fungal, bacterial, and oomycete plant pathogens, demonstrating that Pip1 is an important broad-range immune protease. By contrast, in the absence of Cf-2, Rcr3 depletion does not affect fungal and bacterial infection levels but causes increased susceptibility only to the oomycete pathogen Phytophthora infestans. Rcr3 and Pip1 reside on a genetic locus that evolved over 36 million years ago. These proteins differ in surface-exposed residues outside the substrate-binding groove, and Pip1 is 5- to 10-fold more abundant than Rcr3. We propose a model in which Rcr3 and Pip1 diverged functionally upon gene duplication, possibly driven by an arms race with pathogen-derived inhibitors or by coevolution with the Cf-2 immune receptor detecting inhibitors of Rcr3, but not of Pip1.


Via Kamoun Lab @ TSL
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Davell Logan's curator insight, August 25, 2:55 AM

Reading about this topic is very educational I'm all aspects.

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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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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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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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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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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Jasmonates: biosynthesis, perception, signal transduction and action in plant stress response, growth and development. An update to the 2007 review in Annals of Botany

Jasmonates: biosynthesis, perception, signal transduction and action in plant stress response, growth and development. An update to the 2007 review in Annals of Botany | Plant-Microbe Interaction | Scoop.it
Background Jasmonates are important regulators in plant responses to biotic and abiotic stresses as well as in development. Synthesized from lipid-constituents, the initially formed jasmonic acid is converted to different metabolites including the conjugate with isoleucine. Important new components of jasmonate signalling including its receptor were identified, providing deeper insight into the role of jasmonate signalling pathways in stress responses and development.

Scope The present review is an update of the review on jasmonates published in this journal in 2007. New data of the last five years are described with emphasis on metabolites of jasmonates, on jasmonate perception and signalling, on cross-talk to other plant hormones and on jasmonate signalling in response to herbivores and pathogens, in symbiotic interactions, in flower development, in root growth and in light perception.

Conclusions The last few years have seen breakthroughs in the identification of JASMONATE ZIM DOMAIN (JAZ) proteins and their interactors such as transcription factors and co-repressors, and the crystallization of the jasmonate receptor as well as of the enzyme conjugating jasmonate to amino acids. Now, the complex nature of networks of jasmonate signalling in stress responses and development including hormone cross-talk can be addressed.

Via Christophe Jacquet
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Caspases in plants: metacaspase gene family in plant stress responses

Caspases in plants: metacaspase gene family in plant stress responses | Plant-Microbe Interaction | Scoop.it
Programmed cell death (PCD) is an ordered cell suicide that removes unwanted or damaged cells, playing a role in defense to environmental stresses and pathogen invasion. PCD is component of the life cycle of plants, occurring throughout development from embryogenesis to the death. Metacaspases are cysteine proteases present in plants, fungi, and protists. In certain plant–pathogen interactions, the PCD seems to be mediated by metacaspases. We adopted a comparative genomic approach to identify genes coding for the metacaspases in Viridiplantae. We observed that the metacaspase was divided into types I and II, based on their protein structure. The type I has a metacaspase domain at the C-terminus region, presenting or not a zinc finger motif in the N-terminus region and a prodomain rich in proline. Metacaspase type II does not feature the prodomain and the zinc finger, but has a linker between caspase-like catalytic domains of 20 kDa (p20) and 10 kDa (p10). A high conservation was observed in the zinc finger domain (type I proteins) and in p20 and p10 subunits (types I and II proteins). The phylogeny showed that the metacaspases are divided into three principal groups: type I with and without zinc finger domain and type II metacaspases. The algae and moss are presented as outgroup, suggesting that these three classes of metacaspases originated in the early stages of Viridiplantae, being the absence of the zinc finger domain the ancient condition. The study of metacaspase can clarify their assignment and involvement in plant PCD mechanisms.

Via Elsa Ballini
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Elsa Ballini's curator insight, August 24, 3:04 AM

Rice (Oryza sativa) metacaspase (OsMC) genes are also expressed under abiotic and biotic stresses. OsMC5 is expressed in Magnaporthe oryzae-infected resistant plants, OsMC1 in plants under cold stress, OsMC6 and OsMC8 in plants under drought stress, and OsMC6 is expressed when rice leaves were damaged by beef armyworms

Rescooped by Guogen Yang from Rice Blast
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VIGS, HIGS and FIGS: small RNA silencing in the interactions of viruses or filamentous organisms with their plant hosts

VIGS, HIGS and FIGS: small RNA silencing in the interactions of viruses or filamentous organisms with their plant hosts | Plant-Microbe Interaction | Scoop.it

• RNA produced in a host plant can affect gene expression in an interacting fungus or oomycete.
• RNA produced in a fungus can affect the defense system of a host plant.
• Proteins produced in an oomycete (and possibly a fungus) may prevent host encoded siRNA and miRNA from regulation of the innate immune system.


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