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The Arabidopsis ROP GTPase AtROP6 functions in developmental and pathogen response pathways

The Arabidopsis ROP GTPase AtROP6 functions in developmental and pathogen response pathways | Plant-Microbe Interaction | Scoop.it

How plants coordinate developmental processes and environmental stress responses is a pressing question. Here, we show that Arabidopsis AtROP6 integrates developmental and pathogen response signaling. AtROP6 expression is induced by auxin and detected in the root meristem, lateral root initials, and leaf hydathodes. Plants expressing a dominant negative AtROP6 (rop6DN) under regulation of its endogenous promoter are small, have multiple inflorescence stems, twisted leaves, deformed leaf epidermis pavement cells, and differentially organized cytoskeleton. Microarrays analyses of rop6DN plants revealed that major changes in gene expression are associated with constitutive salicylic acid (SA)-mediated defense responses. In agreement, the free and total SA levels resembled that of wild-type plants inoculated with a virulent powdery mildew pathogen. The constitutive SA-associated response in rop6DN was suppressed in mutant backgrounds defective in SA signaling (npr1) or biosynthesis (sid2). However, the rop6DN npr1 or rop6DN sid2 double mutants retained the aberrant developmental phenotypes, indicating that the constitutive SA response can be uncoupled from ROP function(s) in development. rop6DN plants exhibited enhanced pre-invasive defense responses to a host-adapted virulent powdery mildew fungus, but were impaired in pre-invasive defenses upon inoculation with a non-adapted powdery mildew. The host-adapted powdery mildew had a reduced reproductive fitness on rop6DN plants, which was retained in mutant backgrounds defective in SA biosynthesis or signaling. Our findings indicate that both the morphological aberrations and altered sensitivity to powdery mildews of rop6DN plants result from perturbations that are independent from the SA-associated response. These perturbations uncouple SA-dependent defense signaling from disease resistance execution.


Via Suayib Üstün
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Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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The polyadenylation factor subunit CPSF30: a key factor of programmed cell death and a regulator of immunity in Arabidopsis

The polyadenylation factor subunit CPSF30: a key factor of programmed cell death and a regulator of immunity in Arabidopsis | Plant-Microbe Interaction | Scoop.it

Programmed cell death (PCD) is essential for several aspects of plant life, including development and stress responses. Indeed, incompatible plant-pathogen interactions are well known to induce the hypersensitive response (HR), a localized cell death. Mutational analyses have identified several key PCD components and we recently identified the mips1 mutant of Arabidopsis thaliana, which is deficient for the key enzyme catalysing the limiting step of myo-inositol (MI) synthesis. One of the most striking features of mips1 is the light-dependent formation of lesions on leaves due to Salicylic Acid (SA)-dependent PCD, revealing roles for MI or inositol derivatives in the regulation of PCD. Here, we identified a regulator of plant PCD by screening for mutants that display transcriptomic profiles opposing that of the mips1 mutant. Our screen identified the oxt6 mutant, which has been described previously as being tolerant to oxidative stress. In the oxt6 mutant, a T-DNA is inserted in the CPSF30 gene, which encodes a polyadenylation factor subunit homolog. We show that CPSF30 is required for lesion formation in mips1 via SA-dependant signalling, that the pro-death function of CPSF30 is not mediated by changes in the glutathione status and that CPSF30 activity is required for Pseudomonas syringae resistance. We also show that the oxt6 mutation suppresses cell death in other lesion mimic mutants, including lsd1, mpk4, cpr5 and cat2, suggesting that CPSF30 and, thus, the control of mRNA 3’ end processing, through the regulation of SA production, is a key component of plant immune responses.


Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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Central Cell–Derived Peptides Regulate Early Embryo Patterning in Flowering Plants

Central Cell–Derived Peptides Regulate Early Embryo Patterning in Flowering Plants | Plant-Microbe Interaction | Scoop.it

Plant embryogenesis initiates with the establishment of an apical-basal axis; however, the molecular mechanisms accompanying this early event remain unclear. Here, we show that a small cysteine-rich peptide family is required for formation of the zygotic basal cell lineage and proembryo patterning in Arabidopsis. EMBRYO SURROUNDING FACTOR 1 (ESF1) peptides accumulate before fertilization in central cell gametes and thereafter in embryo-surrounding endosperm cells. Biochemical and structural analyses revealed cleavage of ESF1 propeptides to form biologically active mature peptides. Further, these peptides act in a non–cell-autonomous manner and synergistically with the receptor-like kinase SHORT SUSPENSOR to promote suspensor elongation through the YODA mitogen-activated protein kinase pathway. Our findings demonstrate that the second female gamete and its sexually derived endosperm regulate early embryonic patterning in flowering plants.


Via Francis Martin, Mary Williams
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Botany: Special issue: The microbiota of plants

In this Special Issue, we have tried to capture the diversity of plant–microbe research that is on-going, and that might not normally be marketed under the banner of “plant microbiome research”. Nevertheless, it belongs under this banner and we highlight some of this research here, including a variety of plant “habitats” such as roots, leaves, and floral parts, as well as a variety of microbes, from bacteria and arbuscular mycorrhizal fungi to dark septate fungi. Of course, the field is broader than what we are able present in a single issue, but we hope that it inspires researchers of overlooked aspects of plant microbiota research to get in on the game, and contribute to a more complete picture of this complex “ecosystem”.


Via Stéphane Hacquard, Francis Martin
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Rescooped by Guogen Yang from Rice Blast
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Multiple functional polymorphisms in a single disease resistance gene in rice enhance durable resistance to blast

Multiple functional polymorphisms in a single disease resistance gene in rice enhance durable resistance to blast | Plant-Microbe Interaction | Scoop.it

Here we show that map-based cloning of Pi35 identifies multiple functional polymorphisms that allow effective control of the disease, and thatPi35 is allelic to Pish, which mediates race-specific resistance to blast and encodes a protein containing a nucleotide-binding site (NBS) and leucine-rich repeats (LRRs). Analysis using Pish–Pi35 chimeric genes demonstrated that multiple functional polymorphisms cumulatively enhance resistance, and that an amino acid residue in a LRR of Pi35 is strongly associated with the gene's mediation of quantitative but consistent resistance to pathogen isolates in Japan, in contrast to Pish, which mediates resistance to only a single isolate. Our results reinforce the substantial importance of mining allelic variation for crop breeding.


Via Elsa Ballini
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Rescooped by Guogen Yang from Rice Blast
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Disruption and Molecular Characterization of Calpains-Related (MoCAPN1, MoCAPN3 and MoCAPN4) Genes in Magnaporthe oryzae

Disruption and Molecular Characterization of Calpains-Related (MoCAPN1, MoCAPN3 and MoCAPN4) Genes in Magnaporthe oryzae | Plant-Microbe Interaction | Scoop.it

Calpains-related MoCAPN1 (MGG_14872), MoCAPN3 (MGG_15810) and MoCAPN4 (MGG_04818) genes from M. oryzae genome. All the mutants except those for MoCAPN1 showed normal phenotypes. In pathogenicity test, the mutants did not lead to any visible changes in phenotypes causing similar blast lesions on blast susceptible rice . Germ tubes formation, appressorium formation, mycelium radial growth and mating with 2539 strain were indistinguishable among the mutants . Cell wall integrity (congo red) test, stress response under chemical pressure (ZnSO4, CuSO4 and CdCl2), osmotic and oxidative (NaCl and H2O2) stress response, growth response on glucose and nitrogen deficient media resulted in similar results in the mutants and Guy-11 strains. However, mutants for ΔMoCAPN1 gene produced reduced (0.57 ± 0.15B and 0.54 ± 0.05B) conidia compared to that (1.69 ± 0.13A) of the Guy-11 strain showing its involvement in conidiation.


Via Elsa Ballini
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Rescooped by Guogen Yang from TAL effector science
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A guide to genome engineering with programmable nucleases - Nature Rev. Gen.

A guide to genome engineering with programmable nucleases - Nature Rev. Gen. | Plant-Microbe Interaction | Scoop.it

(via T. Lahaye, thx)

Kim & Kim 2014

Programmable nucleases — including zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and RNA-guided engineered nucleases (RGENs) derived from the bacterial clustered regularly interspaced short palindromic repeat (CRISPR)–Cas (CRISPR-associated) system — enable targeted genetic modifications in cultured cells, as well as in whole animals and plants. The value of these enzymes in research, medicine and biotechnology arises from their ability to induce site-specific DNA cleavage in the genome, the repair (through endogenous mechanisms) of which allows high-precision genome editing. However, these nucleases differ in several respects, including their composition, targetable sites, specificities and mutation signatures, among other characteristics. Knowledge of nuclease-specific features, as well as of their pros and cons, is essential for researchers to choose the most appropriate tool for a range of applications.


Via dromius
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Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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Effects of elevated [CO2] on maize defense against mycotoxigenic Fusarium verticillioides

Effects of elevated [CO2] on maize defense against mycotoxigenic Fusarium verticillioides | Plant-Microbe Interaction | Scoop.it

Maize is by quantity the most important C4 cereal crop; however, future climate changes are expected to increase maize susceptibility to mycotoxigenic fungal pathogens and reduce productivity. While rising atmospheric [CO2] is a driving force behind the warmer temperatures and drought, which aggravate fungal disease and mycotoxin accumulation, our understanding of how elevated [CO2] will effect maize defenses against such pathogens is limited. Here we report that elevated [CO2] increases maize susceptibility to Fusarium verticillioides proliferation but mycotoxin levels are unaltered. Fumonisin production is not proportional to the increase in F. verticillioides biomass, and the amount of fumonisin produced per unit pathogen is reduced at elevated [CO2]. Following F. verticillioides stalk inoculation, the accumulation of sugars, free fatty acids, lipoxygenase (LOX) transcripts, phytohormones and downstream phytoalexins is dampened in maize grown at elevated [CO2]. The attenuation of maize 13-LOXs and JA production correlates with reduced terpenoid phytoalexins and increased susceptibility. Furthermore, the attenuated induction of 9-LOXs, which have been suggested to stimulate mycotoxin biosynthesis, is consistent with reduced fumonisin per unit fungal biomass at elevated [CO2]. Our findings suggest that elevated [CO2] will compromise maize LOX-dependent signaling which will influence the interactions between maize and mycotoxigenic fungi.

 

 


Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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Plant peptides in defense and signaling

Plant peptides in defense and signaling | Plant-Microbe Interaction | Scoop.it

This review focuses on plant peptides involved in defense against pathogen infection and those involved in the regulation of growth and development. Defense peptides, defensins, cyclotides and anti-microbial peptides are compared and contrasted. Signaling peptides are classified according to their major sites of activity. Finally, a network approach to creating an interactomic peptide map is described.


Via Jean-Michel Ané, Christophe Jacquet
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Brachypodium distachyon is a pathosystem model for the study of the wheat disease Rhizoctonia root rot - Schneebeli - Plant Pathology - Wiley Online Library

Brachypodium distachyon is a pathosystem model for the study of the wheat disease Rhizoctonia root rot - Schneebeli - Plant Pathology - Wiley Online Library | Plant-Microbe Interaction | Scoop.it

Brachypodium distachyon (Bd) is increasingly being used as a model for cereal diseases and to study cereal root architecture. Rhizoctonia solani AG 8 is a necrotrophic root pathogen that infects wheat soon after germination resulting in reduced plant growth and yield loss. Genetic resistance to R. solani AG 8 is not available in commercial wheat cultivars, although some quantitative levels of resistance have previously been found in mutant lines and grass relatives. Resistance mechanisms in cereals remain unknown. The ability to use Bd as a model to study the wheat - R. solani AG 8 pathosystem was investigated. The results presented show that Bd is susceptible to R. solani AG 8 and that the pathogen infects both species to a similar degree, producing comparable disease symptoms. Root length reduction was the primary indicator of disease, with shoots also affected. The second objective was to develop a repeatable phenotyping method to screen Bd populations for resistance to R. solani AG 8. Results of a preliminary experiment provide evidence for variation in resistance between Bd inbred lines. This is the first report showing the potential of Bd as a model plant for discovery of quantitative genetic variation in resistance to a necrotrophic cereal root pathogen.


Via Christophe Jacquet
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N-Glycosylation of Effector Proteins by an α-1,3-Mannosyltransferase Is Required for the Rice Blast Fungus to Evade Host Innate Immunity

N-Glycosylation of Effector Proteins by an α-1,3-Mannosyltransferase Is Required for the Rice Blast Fungus to Evade Host Innate Immunity | Plant-Microbe Interaction | Scoop.it

Plant pathogenic fungi deploy secreted effectors to suppress plant immunity responses. These effectors operate either in the apoplast or within host cells, so they are putatively glycosylated, but the posttranslational regulation of their activities has not been explored. In this study, the ASPARAGINE-LINKED GLYCOSYLATION3 (ALG3)-mediated N-glycosylation of the effector, Secreted LysM Protein1 (Slp1), was found to be essential for its activity in the rice blast fungus Magnaporthe oryzae. ALG3 encodes an α-1,3-mannosyltransferase for protein N-glycosylation. Deletion of ALG3 resulted in the arrest of secondary infection hyphae and a significant reduction in virulence. We observed that Δalg3 mutants induced massive production of reactive oxygen species in host cells, in a similar manner to Δslp1 mutants, which is a key factor responsible for arresting infection hyphae of the mutants. Slp1 sequesters chitin oligosaccharides to avoid their recognition by the rice (Oryza sativa) chitin elicitor binding protein CEBiP and the induction of innate immune responses, including reactive oxygen species production. We demonstrate that Slp1 has three N-glycosylation sites and that simultaneous Alg3-mediated N-glycosylation of each site is required to maintain protein stability and the chitin binding activity of Slp1, which are essential for its effector function. These results indicate that Alg3-mediated N-glycosylation of Slp1 is required to evade host innate immunity.


Via Suayib Üstün
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Arabidopsis DELLA and JAZ Proteins Bind the WD-Repeat/bHLH/MYB Complex to Modulate Gibberellin and Jasmonate Signaling Synergy

Integration of diverse environmental and endogenous signals to coordinately regulate growth, development, and defense is essential for plants to survive in their natural habitat. The hormonal signals gibberellin (GA) and jasmonate (JA) antagonistically and synergistically regulate diverse aspects of plant growth, development, and defense. GA and JA synergistically induce initiation of trichomes, which assist seed dispersal and act as barriers to protect plants against insect attack, pathogen infection, excessive water loss, and UV irradiation. However, the molecular mechanism underlying such synergism between GA and JA signaling remains unclear. In this study, we revealed a mechanism for GA and JA signaling synergy and identified a signaling complex of the GA pathway in regulation of trichome initiation. Molecular, biochemical, and genetic evidence showed that the WD-repeat/bHLH/MYB complex acts as a direct target of DELLAs in the GA pathway and that both DELLAs and JAZs interacted with the WD-repeat/bHLH/MYB complex to mediate synergism between GA and JAsignaling in regulating trichome development. GA and JA induce degradation of DELLAs and JASMONATE ZIM-domain proteins to coordinately activate the WD-repeat/bHLH/MYB complex and synergistically and mutually dependently induce trichome initiation. This study provides deep insights into the molecular mechanisms for integration of different hormonal signals to synergistically regulate plant development.

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Rescooped by Guogen Yang from Plant-Microbe Symbioses
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Rhizosphere microbiome assemblage is affected by plant development

There is a concerted understanding of the ability of root exudates to influence the structure of rhizosphere microbial communities. However, our knowledge of the connection between plant development, root exudation and microbiome assemblage is limited. Here, we analyzed the structure of the rhizospheric bacterial community associated with Arabidopsis at four time points corresponding to distinct stages of plant development: seedling, vegetative, bolting and flowering. Overall, there were no significant differences in bacterial community structure, but we observed that the microbial community at the seedling stage was distinct from the other developmental time points. At a closer level, phylum such as Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria and specific genera within those phyla followed distinct patterns associated with plant development and root exudation. These results suggested that the plant can select a subset of microbes at different stages of development, presumably for specific functions. Accordingly, metatranscriptomics analysis of the rhizosphere microbiome revealed that 81 unique transcripts were significantly (P<0.05) expressed at different stages of plant development. For instance, genes involved in streptomycin synthesis were significantly induced at bolting and flowering stages, presumably for disease suppression. We surmise that plants secrete blends of compounds and specific phytochemicals in the root exudates that are differentially produced at distinct stages of development to help orchestrate rhizosphere microbiome assemblage.

Via Jean-Michel Ané
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Rescooped by Guogen Yang from Publications
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Frontiers Plant Science: The genome sequence and effector complement of the flax rust pathogen Melampsora lini (2014)

Frontiers Plant Science: The genome sequence and effector complement of the flax rust pathogen Melampsora lini (2014) | Plant-Microbe Interaction | Scoop.it

Rust fungi cause serious yield reductions on crops, including wheat, barley, soybean, coffee, and represent real threats to global food security. Of these fungi, the flax rust pathogen Melampsora lini has been developed extensively over the past 80 years as a model to understand the molecular mechanisms that underpin pathogenesis. During infection, M. lini secretes virulence effectors to promote disease. The number of these effectors, their function and their degree of conservation across rust fungal species is unknown. To assess this, we sequenced and assembled de novo the genome of M. lini isolate CH5 into 21,130 scaffolds spanning 189 Mbp (scaffold N50 of 31 kbp). Global analysis of the DNA sequence revealed that repetitive elements, primarily retrotransposons, make up at least 45% of the genome. Using ab initio predictions, transcriptome data and homology searches, we identified 16,271 putative protein-coding genes. An analysis pipeline was then implemented to predict the effector complement of M. lini and compare it to that of the poplar rust, wheat stem rust and wheat stripe rust pathogens to identify conserved and species-specific effector candidates. Previous knowledge of four cloned M. lini avirulence effector proteins and two basidiomycete effectors was used to optimise parameters of the effector prediction pipeline. Markov clustering based on sequence similarity was performed to group effector candidates from all four rust pathogens. Clusters containing at least one member from M. lini were further analysed and prioritized based on features including expression in isolated haustoria and infected leaf tissue and conservation across rust species. Herein, we describe 200 of 940 clusters that ranked highest on our priority list, representing 725 flax rust candidate effectors. Our findings on this important model rust species provide insight into how effectors of rust fungi are conserved across species and how they may act to promote infection on their hosts.


Via Francis Martin, Kamoun Lab @ TSL
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Francis Martin's curator insight, March 4, 2:30 PM

A long awaited genome! More rust genomes needed.

Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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Bacterial tricks for turning plants into zombies

Bacterial tricks for turning plants into zombies | Plant-Microbe Interaction | Scoop.it
Microbe deploys proteins that manipulate both the plant it infects and the insects that spread it.

Via Mary Williams
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Mary Williams's curator insight, April 9, 2:41 AM

Here's the article in PLOS Biology http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001835

And an article about the research in the local Norwich newspaper

http://www.edp24.co.uk/news/graphic_scientists_solve_mystery_of_the_zombie_plants_1_3533805

Rescooped by Guogen Yang from Plant-microbe interactions (on the plant's side)
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RbohB, a Phaseolus vulgaris NADPH oxidase gene, enhances symbiosome number, bacteroid size, and nitrogen fixation in nodules and impairs mycorrhizal colonization -

RbohB, a Phaseolus vulgaris NADPH oxidase gene, enhances symbiosome number, bacteroid size, and nitrogen fixation in nodules and impairs mycorrhizal colonization - | Plant-Microbe Interaction | Scoop.it

Via Christophe Jacquet
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Rescooped by Guogen Yang from Plant Immunity And Microbial Effectors
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Host-to-Pathogen Gene Transfer Facilitated Infection of Insects by a Pathogenic Fungus

Host-to-Pathogen Gene Transfer Facilitated Infection of Insects by a Pathogenic Fungus | Plant-Microbe Interaction | Scoop.it
by Hong Zhao, Chuan Xu, Hsiao-Ling Lu, Xiaoxuan Chen, Raymond J. St. Leger, Weiguo Fang
Metarhizium robertsii is a plant root colonizing fungus that is also an insect pathogen.

Via IPM Lab
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Microbial Pathogens Trigger Host DNA Double-Strand Breaks Whose Abundance Is Reduced by Plant Defense Responses

Microbial Pathogens Trigger Host DNA Double-Strand Breaks Whose Abundance Is Reduced by Plant Defense Responses | Plant-Microbe Interaction | Scoop.it

Immune responses and DNA damage repair are two fundamental processes that have been characterized extensively, but the links between them remain largely unknown. We report that multiple bacterial, fungal and oomycete plant pathogen species induce double-strand breaks (DSBs) in host plant DNA. DNA damage detected by histone γ-H2AX abundance or DNA comet assays arose hours before the disease-associated necrosis caused by virulent Pseudomonas syringae pv. tomato. Necrosis-inducing paraquat did not cause detectable DSBs at similar stages after application. Non-pathogenic E. coli and Pseudomonas fluorescens bacteria also did not induce DSBs. Elevation of reactive oxygen species (ROS) is common during plant immune responses, ROS are known DNA damaging agents, and the infection-induced host ROS burst has been implicated as a cause of host DNA damage in animal studies. However, we found that DSB formation in Arabidopsis in response to P. syringae infection still occurs in the absence of the infection-associated oxidative burst mediated by AtrbohD and AtrbohF. Plant MAMP receptor stimulation or application of defense-activating salicylic acid or jasmonic acid failed to induce a detectable level of DSBs in the absence of introduced pathogens, further suggesting that pathogen activities beyond host defense activation cause infection-induced DNA damage. The abundance of infection-induced DSBs was reduced by salicylic acid and NPR1-mediated defenses, and by certain R gene-mediated defenses. Infection-induced formation of γ-H2AX still occurred in Arabidopsis atr/atm double mutants, suggesting the presence of an alternative mediator of pathogen-induced H2AX phosphorylation. In summary, pathogenic microorganisms can induce plant DNA damage. Plant defense mechanisms help to suppress rather than promote this damage, thereby contributing to the maintenance of genome integrity in somatic tissues.

 


Via Suayib Üstün
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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Planta: Plant systems biology: insights, advances and challenges (review)

Planta: Plant systems biology: insights, advances and challenges  (review) | Plant-Microbe Interaction | Scoop.it

"Systems biology offers a comprehensive view of plant systems, by employing a holistic approach integrating the molecular data at various hierarchical levels. In this  review, we discuss the basics of systems biology including the various ‘omics’ approaches and their integration, the modeling aspects and the tools needed for the plant systems research. A particular emphasis is given to the recent analytical advances, updated published examples of plant systems biology studies and the future trends."


Via Mary Williams
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Rescooped by Guogen Yang from Effectors and Plant Immunity
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The Pepper SGT1 Interacts with the Receptor-Like Cytoplasmic Kinase 1 and AvrBsT and Promotes Hypersensitive Cell Death Response in a Phosphorylation-Dependent Manner

The Pepper SGT1 Interacts with the Receptor-Like Cytoplasmic Kinase 1 and AvrBsT and Promotes Hypersensitive Cell Death Response in a Phosphorylation-Dependent Manner | Plant-Microbe Interaction | Scoop.it

Xanthomonas campestris pv. vesicatoria type III effector protein, AvrBsT, triggers hypersensitive cell death in pepper (Capsicum annuum). Here, we have identified the pepper SGT1 (suppressor of the G2 allele of skp1) as a host interactor of AvrBsT and also the pepper PIK1 (receptor-like cytoplasmic kinase 1). PIK1 specifically phosphorylates SGT1 and AvrBsT in vitro. AvrBsT specifically binds to the CS domain of SGT1, resulting in the inhibition of PIK1-mediated SGT1 phosphorylation and subsequent nuclear transport of the SGT1-PIK1 complex. Liquid chromatography-tandom mass spectrometry (LC/MS/MS) of the proteolytic peptides of SGT1 identified the residues Serine 98 and Serine 279 of SGT1 as the major PIK1-mediated phosphorylation sites. Site directed mutagenesis of SGT1 revealed that the identified SGT1 phosphorylation sites are responsible for the activation of AvrBsT-triggered cell death in planta. SGT1 forms a heterotrimeric complex with both AvrBsT and PIK1 exclusively in the cytoplasm. Agrobacterium-mediated co-expression of SGT1 and PIK1 with avrBsT promotes avrBsT-triggered cell death in Nicotiana benthamiana, dependent on PIK1. Virus-induced silencing of SGT1 and/or PIK1 compromises avrBsT-triggered cell death, H2O2 production, defense gene induction and salicylic acid accumulation, leading to the enhanced bacterial pathogen growth in pepper. Together, these results suggest that SGT1 interacts with PIK1 and bacterial effector protein AvrBsT and promotes hypersensitive cell death associated with PIK1-mediated phosphorylation in plants.


Via Suayib Üstün, Nicolas Denancé
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NASA news: Satellite Shows High Productivity from U.S. Corn Belt

NASA news: Satellite Shows High Productivity from U.S. Corn Belt | Plant-Microbe Interaction | Scoop.it
During the U.S. Midwest's growing season, the region boasts more photosynthetic activity than any other spot on Earth.

Via Mary Williams
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Mary Williams's curator insight, April 1, 12:01 PM

This is a summary of a new paper in PNAS that shows "that chlorophyll fluorescence data can be used as a unique benchmark to improve our global models, thus providing more reliable projections of agricultural productivity and climate impact on crop yields."


www.pnas.org/content/early/2014/03/24/1320008111.abstract

creditrepairaid's comment, April 3, 3:26 AM
<br>Its fabulous
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MPMI: Single amino acid mutations in the potato immune receptor R3a expand response to Phytophthora effectors (2014)

MPMI: Single amino acid mutations in the potato immune receptor R3a expand response to Phytophthora effectors (2014) | Plant-Microbe Interaction | Scoop.it

Both plants and animals rely on nucleotide-binding domain and leucine-rich repeat-containing proteins (NB-LRRs or NLRs) to respond to invading pathogens and activate immune responses. How plant NB-LRR proteins respond to pathogens is poorly understood. We undertook a gain-of-function random mutagenesis screen of the potato NB-LRR immune receptor R3a to study how this protein responds to the effector protein AVR3a from the oomycete pathogen Phytophthora infestans. R3a response can be extended to the stealthy AVR3aEM isoform of the effector while retaining recognition of AVR3aKI. Each one of 8 single amino acid mutations is sufficient to expand the R3a response to AVR3aEM and other AVR3a variants. These mutations occur across the R3a protein, from the N-terminus to different regions of the LRR domain. Further characterization of these R3a mutants revealed that at least one of them was sensitized, exhibiting a stronger response than the wild-type R3a protein to AVR3aKI. Remarkably, the N336Y mutation, near the R3a nucleotide-binding pocket, conferred response to the effector protein PcAVR3a4 from the vegetable pathogen Phytophthora capsici. This work contributes to understanding how NB-LRR receptor specificity can be modulated. Together with knowledge of pathogen effector diversity, this strategy can be exploited to develop synthetic immune receptors.


Via Kamoun Lab @ TSL
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Stephen Bolus's curator insight, March 30, 2:09 AM

I just really love the idea of synthetic immune receptors!

nosehound's comment, April 7, 1:21 AM
Its striking
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Monoubiquitination of Histone 2B at the disease resistance gene locus regulates its expression and impacts immune responses in Arabidopsis

Monoubiquitination of Histone 2B at the disease resistance gene locus regulates its expression and impacts immune responses in Arabidopsis | Plant-Microbe Interaction | Scoop.it

Disease resistance (R) genes are key components in plant immunity. Here we show that Arabidopsis E3 ubiquitin ligase genes HUB1 (HISTONE MONOUBIQUITINATION1) and HUB2 regulate the expression of the R genes SNC1 (SUPPRESSOR OF npr1-1, CONSTITUTIVE1)and RPP4 (RESISTANCE TO PERONOSPORA PARASITICA 4). An increase of SNC1 expression induces constitutive immune responses in the bon1 (bonzai1) mutant, and the loss of HUB1 or HUB2 function reduces SNC1 upregulation and suppresses the bon1 autoimmune phenotypes. HUB1 and HUB2 mediate H2B monoubiquitination directly at the SNC1 R gene locus to regulate its expression. In addition, SNC1 and HUB1 transcripts are moderately up-regulated by pathogen infection and H2B monoubiquitination at SNC1 is enhanced by pathogen infection. Together, this study indicates that H2B monoubiquitination at the R gene locus regulates its expression and this histone modification at the R gene locus has an impact on immune responses in plants.


Via Suayib Üstün
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Rescooped by Guogen Yang from Plant Biology Teaching Resources (Higher Education)
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New Phyt Tansley Review. Putting the brakes on: abscisic acid as a central environmental regulator of stomatal development

"Mature leaves detect environmental signals and relay messages to immature leaves to tell them how to adapt and grow. Stomata on mature leaves may act as stress signal-sensing and transduction centres, locally by aperture adjustment, and at long distance by optimizing stomatal density to maximize future carbon gain while minimizing water loss."


Via Mary Williams
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The Arabidopsis thaliana LYSM-CONTAINING RECEPTOR-LIKE KINASE 3 regulates the cross talk between immunity and abscisic acid responses.

The Arabidopsis thaliana LYSM-CONTAINING RECEPTOR-LIKE KINASE 3 regulates the cross talk between immunity and abscisic acid responses. | Plant-Microbe Interaction | Scoop.it

Transmembrane receptor-like kinases characterized by the presence of one or more LysM domains in the extracytoplasmic portion (LysM-containing receptor-like kinase, LYKs) mediate recognition of symbiotic and pathogenic microorganisms in plants. The Arabidopsis thaliana genome encodes five putative LYKs; among them, LYSM RLK1/CHITIN ELICITOR RECEPTOR KINASE 1 is required for response to chitin and peptidoglycan, and AtLYK4 contributes to chitin perception. More recently, AtLYK3 has been shown to be required for full repression, mediated by Nod factors, of Arabidopsis innate immune responses. In this work we show that AtLYK3 negatively regulates also basal expression of defence genes and resistance to Botrytis cinerea and Pectobacterium carotovorum infection. Enhanced resistance of atlyk3 mutants requires PHYTOALEXIN-DEFICIENT 3, which is crucial for camalexin biosynthesis. The expression of AtLYK3 is strongly repressed by elicitors and fungal infection, and is induced by the hormone abscisic acid (ABA), which has a negative impact on resistance against B. cinerea and P. carotovorum. Plants lacking a functional AtLYK3 also show reduced physiological responses to ABA, and are partially resistant to ABA-induced inhibition of PAD3 expression. These results indicate that AtLYK3 is important for the cross-talk between signaling pathways activated by ABA and pathogens.


Via Olivier ANDRE, Christophe Jacquet
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Rescooped by Guogen Yang from MycorWeb Plant-Microbe Interactions
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Nature's microbiome: introduction - Molecular Ecology Special Issue

Nature's microbiome: introduction - Molecular Ecology Special Issue | Plant-Microbe Interaction | Scoop.it

In this special issue of Molecular Ecology, we present 28 articles incorporating molecular and bioinformatics tools to dissect the intimate and prolonged associations that define symbioses. We have organized these studies into three sections, focused on (i) the composition of symbiotic communities and how this varies across hosts, tissues and development, and in response to environmental change (‘The Dynamic Microbiome’); (ii) the roles that microbes play for their hosts and the underlying mechanisms behind these functions (‘Microbiome Function’); and (iii) the nature and mechanisms of interactions between hosts and symbionts and between the co-inhabiting symbionts themselves (‘The Interactive Microbiome’). These articles highlight the state-of-the-art in microbiome research, with novel discoveries for well-developed models and for other budding systems beyond the human realm.


Via Francis Martin
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