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PLOS Pathogens: Transcription Factor Amr1 Induces Melanin Biosynthesis and Suppresses Virulence in Alternaria brassicicola

PLOS Pathogens: Transcription Factor Amr1 Induces Melanin Biosynthesis and Suppresses Virulence in Alternaria brassicicola | Plant-Microbe Interaction | Scoop.it

Induction of cell wall-degrading enzymes, secretion of toxins, enforcement of fungal cell wall architecture, and detoxification of host defense molecules are important or essential for the fungal infection of plants. Genes important for each of these functions have been identified in various fungal species. Understanding how these genes are coordinately regulated and how many regulators are involved in the process is a challenge. We recently discovered a transcription factor gene, AbVf19, which positively regulates hydrolytic enzyme-coding genes. Here, we report on another transcription factor gene, Amr1, which negatively regulates a subset of these genes during late-stage pathogenesis and positively regulates melanin biosynthesis during conidiogenesis. This study adds another dimension to the complex regulation and overall importance of hydrolytic enzyme genes during plant pathogenesis by necrotrophic fungi. In addition, this study provides an example on the evolutionary implication of virulence in the necrotrophic fungus, A. brassicicola. One transcription factor essential for long-term survival because of its role in melanin biosynthesis is used instead to suppress virulence. We speculate that the suppressive functions of Amr1 contribute to the specialized adaptation of A. brassicicola as an efficient and successful facultative parasite.

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

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

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

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

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

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

Via Chris Upton + helpers
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Cytosolic calcium signals elicited by the pathogen-associated molecular pattern flg22 in stomatal guard cells are of an oscillatory nature - Thor - 2014 - New Phytologist - Wiley Online Library

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

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


Via Christophe Jacquet
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Pepper Heat Shock Protein 70a Interacts with the Type III Effector AvrBsT and Triggers Plant Cell Death and Immunity

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

Via Suayib Üstün, Christophe Jacquet
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Rescooped by Guogen Yang from Plants and Microbes
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Video: Fifi The Oomycete (2014)

Happy holidays from the @KamounLab!

 

FiFi (Phytophthora) The Oomycete


(adapted from Frosty The Snowman)

 

Fifi the oomycete is a scary parasite,
With flagellated spores and hyphal threads
She kills crops and triggers blight.

 

Fifi the oomycete is a heterokont, they say,
She’s fungus-like but the scientists
Know how she had plastids one day.

 

There must have been some magic in those
Transposons they found.
For when they mapped ‘em on the genome
They began to jump around.

 

Fifi the oomycete has a big genome, they say,
Full of repeats but don’t call it junk
‘cause can be handy one day.

 

O, Fifi the oomycete
Was as virulent as she’s been;
and scientists say she secretes her way
Inside potatoes and bean.

 

Fifi the oomycete found
A resistant plant that day,
So she said, "Let's run and
There’ll be no fun
Until I mutate away."

 

There must have been some magic in those
Transposons they found.
For when they mapped ‘em on the genome
They began to jump around.

 

For Fifi the oomycete
Keeps evolving in her way,
But don’t wave her goodbye,
Don't you even try,
She’ll be back again some day.

 


Via Kamoun Lab @ TSL
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Mary Williams's curator insight, December 10, 12:46 PM

She's adorable (or maybe not...). Nice song though!

Rescooped by Guogen Yang from Plants and Microbes
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BMC Plant Biology: Mutations in the Arabidopsis homoserine kinase gene DMR1 confer enhanced resistance to Fusarium culmorum and F. graminearum (2014)

BMC Plant Biology: Mutations in the Arabidopsis homoserine kinase gene DMR1 confer enhanced resistance to Fusarium culmorum and F. graminearum (2014) | Plant-Microbe Interaction | Scoop.it

Background - Mutation of Arabidopsis DMR1, encoding homoserine kinase, leads to elevation in homoserine and foliar resistance to the biotrophic pathogens Hyaloperonospora arabidopsidis and Oidium neolycopersici through activation of an unidentified defence mechanism. This study investigates the effect of mutation of dmr1 on resistance to the ascomycete pathogens Fusarium graminearum and F. culmorum, which cause Fusarium Ear Blight (FEB) disease on small grain cereals.


Results - We initially found that the dmr1-2 mutant allele confers increased resistance to F. culmorum and F. graminearum silique infection, and decreased colonisation of rosette leaves. Meanwhile the dmr1-1 allele supports less rosette leaf colonisation but has wild type silique resistance. Three additional dmr1 alleles were subsequently examined for altered F. culmorum susceptibility and all showed increased silique resistance, while leaf colonisation was reduced in two (dmr1-3 and dmr1-4). Amino acid analysis of dmr1 siliques revealed homoserine accumulation, which is undetectable in wild type plants. Exogenous application of L-homoserine reduced bud infection in both dmr1 and wild type plants, whilst D-homoserine application did not. Delayed leaf senescence was also observed in dmr1 plants compared to wild type and correlated with reduced Fusarium leaf colonisation.


Conclusions - These findings suggest that common Arabidopsis DMR1 mediated susceptibility mechanisms occur during infection by both obligate biotrophic oomycete and hemi-biotrophic fungal pathogens, not only in vegetative but also in reproductive plant tissues. This has the potential to aid the development of cereal crops with enhanced resistance to FEB.


Via Kamoun Lab @ TSL
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BMC Genomics | Abstract | Dynamics in the resistant and susceptible peanut (Arachis hypogaea L.) root transcriptome on infection with the Ralstonia solanacearum

BMC Genomics | Abstract | Dynamics in the resistant and susceptible peanut (Arachis hypogaea L.) root transcriptome on infection with the Ralstonia solanacearum | Plant-Microbe Interaction | Scoop.it
Background

Bacterial wilt caused by Ralstonia solanacearum is a serious soil-borne disease of peanut (Arachis hypogaea L). The molecular basis of peanut response to R. solanacearum remains unknown. To understand the resistance mechanism behind peanut resistance to R. solanacearum, we used RNA-Seq to perform global transcriptome profiling on the roots of peanut resistant (R) and susceptible (S) genotypes under R. solanacearum infection.
Results

A total of 4.95 x 108 raw sequence reads were generated and subsequently assembled into 271, 790 unigenes with an average length of 890 bp and a N50 of 1, 665 bp. 179, 641 unigenes could be annotated by public protein databases. The pairwise transcriptome comparsions of time course (6, 12, 24, 48 and 72 h post inoculation) were conducted 1) between inoculated and control samples of each genotype, 2) between inoculated samples of R and S genotypes. The linear dynamics of transcriptome profile was observed between adjacent samples for each genotype, two genotypes shared similar transcriptome pattern at early time points with most significant up regulation at 12 hour, and samples from R genotype at 24 h and S genotype at 48 h showed similar transcriptome pattern, significant differences of transcriptional profile were observed in pairwise comparisons between R and S genotypes. KEGG analysis showed that the primary metabolisms were inhibited in both genotypes and stronger inhibition in R genotype post inoculation. The defense related genes (R gene, LRR-RLK,cell wall genes, etc.) generally showed a genotype-specific down regulation and different expression between both genotypes.
Conclusion

This transcriptome profiling provided the largest data set that explores the dynamic in crosstalk between peanut and R. solanacearum. The results suggested that the down-regulation of primary metabolism is contributed to the resistance difference between R and S genotypes. The genotype-specific expression pattern of defense related DEGs also contributed to the resistance difference between R and S genotype. This study will strongly contribute to better understand the molecular interaction between plant and R. solanacearum.

Via Christophe Jacquet
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Suppression of xylan endotransglycosylase PtxtXyn10A affects cellulose microfibril angle in secondary wall in aspen wood

Suppression of xylan endotransglycosylase PtxtXyn10A affects cellulose microfibril angle in secondary wall in aspen wood | Plant-Microbe Interaction | Scoop.it
Certain xylanases from family GH10 are highly expressed during secondary wall deposition, but their function is unknown. We carried out functional analyses of the secondary-wall specific PtxtXyn10A in hybrid aspen (Populus tremula × tremuloides).
PtxtXyn10A function was analysed by expression studies, overexpression in Arabidopsis protoplasts and by downregulation in aspen.
PtxtXyn10A overexpression in Arabidopsis protoplasts resulted in increased xylan endotransglycosylation rather than hydrolysis. In aspen, the enzyme was found to be proteolytically processed to a 68 kDa peptide and residing in cell walls. Its downregulation resulted in a corresponding decrease in xylan endotransglycosylase activity and no change in xylanase activity. This did not alter xylan molecular weight or its branching pattern but affected the cellulose-microfibril angle in wood fibres, increased primary growth (stem elongation, leaf formation and enlargement) and reduced the tendency to form tension wood. Transcriptomes of transgenic plants showed downregulation of tension wood related genes and changes in stress-responsive genes.
The data indicate that PtxtXyn10A acts as a xylan endotransglycosylase and its main function is to release tensional stresses arising during secondary wall deposition. Furthermore, they suggest that regulation of stresses in secondary walls plays a vital role in plant development.

Via Francis Martin
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Rescooped by Guogen Yang from Plant-Microbe Symbioses
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Arctic fungal communities associated with roots of Bistorta vivipara do not respond to the same fine-scale edaphic gradients as the aboveground vegetation

Arctic fungal communities associated with roots of Bistorta vivipara do not respond to the same fine-scale edaphic gradients as the aboveground vegetation | Plant-Microbe Interaction | Scoop.it
Soil conditions and microclimate are important determinants of the fine-scale distribution of plant species in the Arctic, creating locally heterogeneous vegetation. We hypothesize that root-associated fungal (RAF) communities respond to the same fine-scale environmental gradients as the aboveground vegetation, creating a coherent pattern between aboveground vegetation and RAF.
We explored how RAF communities of the ectomycorrhizal (ECM) plant Bistorta vivipara and aboveground vegetation structure of arctic plants were affected by biotic and abiotic variables at 0.3–3.0-m scales. RAF communities were determined using pyrosequencing. Composition and spatial structure of RAF and aboveground vegetation in relation to collected biotic and abiotic variables were analysed by ordination and semi-variance analyses.
The vegetation was spatially structured along soil C and N gradients, whereas RAF lacked significant spatial structure. A weak relationship between RAF community composition and the cover of two ECM plants, B. vivipara and S. polaris, was found, and RAF richness increased with host root length and root weight.
Results suggest that the fine-scale spatial structure of RAF communities of B. vivipara and the aboveground vegetation are driven by different factors. At fine spatial scales, neighbouring ECM plants may affect RAF community composition, whereas soil nutrients gradients structure the vegetation.

Via Jean-Michel Ané
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Simultaneous transcriptome analysis of Colletotrichum gloeosporioides and tomato fruit pathosystem reveals novel fungal pathogenicity and fruit defense strategies -

Simultaneous transcriptome analysis of Colletotrichum gloeosporioides and tomato fruit pathosystem reveals novel fungal pathogenicity and fruit defense strategies - | Plant-Microbe Interaction | Scoop.it
The fungus Colletotrichum gloeosporioides breaches the fruit cuticle but remains quiescent until fruit ripening signals a switch to necrotrophy, culminating in devastating anthracnose disease. There is a need to understand the distinct fungal arms strategy and the simultaneous fruit response.
Transcriptome analysis of fungal–fruit interactions was carried out concurrently in the appressoria, quiescent and necrotrophic stages.
Conidia germinating on unripe fruit cuticle showed stage-specific transcription that was accompanied by massive fruit defense responses. The subsequent quiescent stage showed the development of dendritic-like structures and swollen hyphae within the fruit epidermis. The quiescent fungal transcriptome was characterized by activation of chromatin remodeling genes and unsuspected environmental alkalization. Fruit response was portrayed by continued highly integrated massive up-regulation of defense genes. During cuticle infection of green or ripe fruit, fungi recapitulate the same developmental stages but with differing quiescent time spans. The necrotrophic stage showed a dramatic shift in fungal metabolism and up-regulation of pathogenicity factors. Fruit response to necrotrophy showed activation of the salicylic acid pathway, climaxing in cell death.
Transcriptome analysis of C. gloeosporioides infection of fruit reveals its distinct stage-specific lifestyle and the concurrent changing fruit response, deepening our perception of the unfolding fungal–fruit arms and defenses race.

Via Christophe Jacquet
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Rescooped by Guogen Yang from TAL effector science
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TALEN Gene Knockouts Reveal No Requirement for the Conserved Human Shelterin Protein Rap1 in Telomere Protection and Length Regulation: Cell Reports

TALEN Gene Knockouts Reveal No Requirement for the Conserved Human Shelterin Protein Rap1 in Telomere Protection and Length Regulation: Cell Reports | Plant-Microbe Interaction | Scoop.it

(via T. Lahaye, thx)

Kabir et al, 2014

The conserved protein Rap1 functions at telomeres in fungi, protozoa, and vertebrates. Like yeast Rap1, human Rap1 has been implicated in telomere length regulation and repression of nonhomologous end-joining (NHEJ) at telomeres. However, mouse telomeres lacking Rap1 do not succumb to NHEJ. To determine the functions of human Rap1, we generated several transcription activator-like effector nuclease (TALEN)-mediated human cell lines lacking Rap1. Loss of Rap1 did not affect the other components of shelterin, the modification of telomeric histones, the subnuclear position of telomeres, or the 3′ telomeric overhang. Telomeres lacking Rap1 did not show a DNA damage response, NHEJ, or consistent changes in their length, indicating that Rap1 does not have an important function in protection or length regulation of human telomeres. As human Rap1, like its mouse and unicellular orthologs, affects gene expression, we propose that the conservation of Rap1 reflects its role in transcriptional regulation rather than a function at telomeres.


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Stem-cell-triggered immunity safeguards cytokinin enriched plant shoot apexes from pathogen infection

Stem-cell-triggered immunity safeguards cytokinin enriched plant shoot apexes from pathogen infection | Plant-Microbe Interaction | Scoop.it
Intricate mechanisms discriminate between friends and foes in plants. Plant organs deploy overlapping and distinct protection strategies. Despite vulnerability to a plethora of pathogens, the growing tips of plants grow bacteria free. The shoot apical meristem (SAM) is among three stem cells niches, a self-renewable reservoir for the future organogenesis of leaf, stem, and flowers. How plants safeguard this high value growth target from infections was not known until now. Recent reports find the stem cell secreted 12-amino acid peptide CLV3p (CLAVATA3 peptide) is perceived by FLS2 (FLAGELLIN SENSING 2) receptor and activates the transcription of immunity and defense marker genes. No infection in the SAM of wild type plants and bacterial infection in clv3 and fls2 mutants illustrate this natural protection against infections. Cytokinins (CKs) are enriched in the SAM and regulate meristem activities by their involvement in stem cell signaling networks. Auxin mediates plant susceptibility to pathogen infections while CKs boost plant immunity. Here, in addition to the stem-cell-triggered immunity we also highlight a potential link between CK signaling and CLV3p mediated immune response in the SAM.

Via Christophe Jacquet
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The Evolution of Fungal Metabolic Pathways

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

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


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

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

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

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

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


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


Via Mary Williams
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Over-expression of a glutamate dehydrogenase gene, MgGDH , from Magnaporthe grisea confers tolerance to dehydration stress in transgenic rice

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

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


Via Christophe Jacquet, Elsa Ballini
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A novel Arabidopsis CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) mutant with enhanced pathogen-induced cell death and altered receptor processing

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

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


Via Christophe Jacquet
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Who owns CRISPR-Cas9 in Europe? - Nature Biotech.

Kupecz, 2014

Recent developments in the prosecution of the CRISPR-Cas9 patent in Europe highlight the differences between the intellectual property regimes of Europe and the United States.


Via dromius
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dromius's curator insight, December 10, 12:46 PM

Andras: "So what do you do if you want to use
CRISPR-Cas9 in Europe? ... Third parties that need to assess their freedom to operate should take due account of the many patent applications that have been filed"

Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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Discovery of genes affecting resistance of barley to adapted and non-adapted powdery mildew fungi

Discovery of genes affecting resistance of barley to adapted and non-adapted powdery mildew fungi | Plant-Microbe Interaction | Scoop.it

Background

Nonhost resistance, NHR, to non-adapted pathogens and quantitative host resistance, QR, confer durable protection to plants and are important for securing yield in a longer perspective. However, a more targeted exploitation of the trait usually possessing a complex mode of inheritance by many quantitative trait loci, QTLs, will require a better understanding of the most important genes and alleles.

Results

Here we present results from a transient-induced gene silencing, TIGS, approach of candidate genes for NHR and QR in barley against the powdery mildew fungus Blumeria graminis. Genes were selected based on transcript regulation, multigene-family membership or genetic map position. Out of 1,144 tested RNAi-target genes, 96 significantly affected resistance to the non-adapted wheat- or the compatible barley powdery mildew fungus, with an overlap of four genes. TIGS results for QR were combined with transcript regulation data, allele-trait associations, QTL co-localization and copy number variation resulting in a Meta-dataset of 51 strong candidate genes with convergent evidence for a role in QR

.Conclusions

This study represents an initial, functional inventory of approximately 3% of the barley transcriptome for a role in NHR or QR against the powdery mildew pathogen. The discovered candidate genes support the idea that QR in this Triticeae host is primarily based on pathogen-associated molecular pattern-triggered immunity, which is compromised by effector molecules produced by the compatible pathogen. The overlap of four genes with significant TIGS effects both in the NHR and QR screens also indicates shared components for both forms of durable pathogen resistance.

 

 


Via Pierre-Marc Delaux, Christophe Jacquet
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New Phytologist: Arctic fungal communities associated with roots of Bistorta vivipara do not respond to the same fine-scale edaphic gradients as the aboveground vegetation

New Phytologist: Arctic fungal communities associated with roots of Bistorta vivipara do not respond to the same fine-scale edaphic gradients as the aboveground vegetation | Plant-Microbe Interaction | Scoop.it

Soil conditions and microclimate are important determinants of the fine-scale distribution of plant species in the Arctic, creating locally heterogeneous vegetation. We hypothesize that root-associated fungal (RAF) communities respond to the same fine-scale environmental gradients as the aboveground vegetation, creating a coherent pattern between aboveground vegetation and RAF.
We explored how RAF communities of the ectomycorrhizal (ECM) plant Bistorta vivipara and aboveground vegetation structure of arctic plants were affected by biotic and abiotic variables at 0.3–3.0-m scales. RAF communities were determined using pyrosequencing. Composition and spatial structure of RAF and aboveground vegetation in relation to collected biotic and abiotic variables were analysed by ordination and semi-variance analyses.
The vegetation was spatially structured along soil C and N gradients, whereas RAF lacked significant spatial structure. A weak relationship between RAF community composition and the cover of two ECM plants, B. vivipara and S. polaris, was found, and RAF richness increased with host root length and root weight.
Results suggest that the fine-scale spatial structure of RAF communities of B. vivipara and the aboveground vegetation are driven by different factors. At fine spatial scales, neighbouring ECM plants may affect RAF community composition, whereas soil nutrients gradients structure the vegetation.


Via Stéphane Hacquard, Alejandro Rojas
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Rescooped by Guogen Yang from TAL effector science
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A multicolor panel of TALE-KRAB based transcriptional repressor vectors enabling knockdown of multiple gene targets - Sci. Reports

A multicolor panel of TALE-KRAB based transcriptional repressor vectors enabling knockdown of multiple gene targets - Sci. Reports | Plant-Microbe Interaction | Scoop.it

(via T. Schreiber, thx)

Zhang et al, 2014

Stable and efficient knockdown of multiple gene targets is highly desirable for dissection of molecular pathways. Because it allows sequence-specific DNA binding, transcription activator-like effector (TALE) offers a new genetic perturbation technique that allows for gene-specific repression. Here, we constructed a multicolor lentiviral TALE-Kruppel-associated box (KRAB) expression vector platform that enables knockdown of multiple gene targets. This platform is fully compatible with the Golden Gate TALEN and TAL Effector Kit 2.0, a widely used and efficient method for TALE assembly. We showed that this multicolor TALE-KRAB vector system when combined together with bone marrow transplantation could quickly knock down c-kit and PU.1 genes in hematopoietic stem and progenitor cells of recipient mice. Furthermore, our data demonstrated that this platform simultaneously knocked down both c-Kit and PU.1 genes in the same primary cell populations. Together, our results suggest that this multicolor TALE-KRAB vector platform is a promising and versatile tool for knockdown of multiple gene targets and could greatly facilitate dissection of molecular pathways.


Via dromius
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SRB's curator insight, December 12, 4:27 PM

PMID: 25475013 

Rescooped by Guogen Yang from Virology and Bioinformatics from Virology.ca
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A Top Ten list for economically important plant viruses

A Top Ten list for economically important plant viruses | Plant-Microbe Interaction | Scoop.it

The concept of “Top Ten” lists of plant pathogens is in vogue in recent years, and plant viruses are no exception. However, the only list available has more to do with historical and scientific worth than it has to do with economic impact on humans and their animals. This review will discuss the most important plant viruses that cause serious harm to food plants that sustain the bulk of humankind.

 


Via Ed Rybicki, Chris Upton + helpers
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Ed Rybicki's curator insight, December 1, 6:08 AM

I offered it to them over at Molecular Plant Pathology; I did...B-)

Rescooped by Guogen Yang from Plant-Microbe Symbioses
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A quinol oxidase, encoded by cyoABCD, is utilized to adapt to lower O2 concentrations in Rhizobium etli CFN42.

A quinol oxidase, encoded by cyoABCD, is utilized to adapt to lower O2 concentrations in Rhizobium etli CFN42. | Plant-Microbe Interaction | Scoop.it

Bacteria have branched aerobic respiratory chains that terminate at different terminal oxidases. These terminal oxidases have varying properties such as their affinity for oxygen, transcriptional regulation, and proton pumping ability. The focus of this study was on a quinol oxidase, encoded by cyoABCD. Although this oxidase (Cyo) is widespread among bacteria, not much is known about its role in the cell, particularly in bacteria that contain both cytochrome c oxidases and quinol oxidases. Using Rhizobium etli CFN42 as a model organism, a Cyo- mutant was analyzed for its ability to grow in batch cultures at high (21%) and low (1% and 0.1%) ambient oxygen concentrations. In comparison to other oxidase mutants, the Cyo- had a significantly longer lag phase at low oxygen conditions. Using a cyo:lacZ transcriptional fusion, it was shown that cyo expression in the wild type peaks between 1-2.5% oxygen. In addition, it was shown with q-RT-PCR that cyoB is up-regulated approximately 5-fold in 1% oxygen compared to fully aerobic (21%) conditions. Analysis of the Cyo- mutant during symbiosis with Phaseolous vulgaris indicated that Cyo is utilized during early development of the symbiosis. Although Cyo is commonly thought to be utilized only in higher oxygen concentrations, the results from this study indicate Cyo is important for adaptation to and sustained growth at low oxygen.


Lunak ZR, Noel KD (2014). Microbiology. Nov 4. [Epub ahead of print]

 


Via IvanOresnik, Jean-Michel Ané
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Assessing the gene regulatory properties of Argonaute-bound small RNAs of diverse genomic origin

Assessing the gene regulatory properties of Argonaute-bound small RNAs of diverse genomic origin | Plant-Microbe Interaction | Scoop.it
High-throughput sequencing reveals an abundance of microRNA-sized fragments derived from larger non-coding RNAs. Roles for these small RNAs in gene silencing are suggested by their co-precipitation with Argonaute, the microRNA effector protein, though the extent to which they suppress gene expression endogenously remains unclear. To address this, we used luciferase reporters to determine the endogenous functionality of small RNAs from a diverse range of sources. We demonstrate small RNAs derived from snoRNAs have the capacity to act in a microRNA-like manner, though we note the vast majority of these are bound to Argonaute at levels below that required for detectable silencing activity. We show Argonaute exhibits a high degree of selectivity for the small RNAs with which it interacts and note that measuring Argonaute-associated levels is a better indicator of function than measuring total expression. Although binding to Argonaute at sufficient levels is necessary for demonstrating microRNA functionality in our reporter assay, this alone is not enough as some small RNAs derived from other non-coding RNAs (tRNAs, rRNAs, Y-RNAs) are associated with Argonaute at very high levels yet do not serve microRNA-like roles.
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