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Rescooped by linzhang from Plant Pathogens
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Evolution of protein phosphorylation across 18 fungal species

Evolution of protein phosphorylation across 18 fungal species | Stories of plants and its enermies | Scoop.it

Living organisms have evolved protein phosphorylation, a rapid and versatile mechanism that drives signaling and regulates protein function. We report the phosphoproteomes of 18 fungal species and a phylogenetic-based approach to study phosphosite evolution. We observe rapid divergence, with only a small fraction of phosphosites conserved over hundreds of millions of years. Relative to recently acquired phosphosites, ancient sites are enriched at protein interfaces and are more likely to be functionally important, as we show for sites on H2A1 and eIF4E. We also observe a change in phosphorylation motif frequencies and kinase activities that coincides with the whole-genome duplication event. Our results provide an evolutionary history for phosphosites and suggest that rapid evolution of phosphorylation can contribute strongly to phenotypic diversity.


Via Yogesh Gupta
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Rescooped by linzhang from Plant pathogenic fungi
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Advances in Botanical Research: Effector-Mediated Communication of Filamentous Plant Pathogens With Their Hosts (2016)

Advances in Botanical Research: Effector-Mediated Communication of Filamentous Plant Pathogens With Their Hosts (2016) | Stories of plants and its enermies | Scoop.it

Pathogenic fungi and oomycetes can establish intimate associations with plants. These interactions underlie a molecular dialogue that leads to the successful colonization of host tissues. Major questions driving research in plant pathology these last decades are how pathogenic microorganisms circumvent preformed or induced defences and how pathogens manipulate host physiology to promote virulence. One key actor in this dialogue relies on a class of molecules secreted by pathogens termed effectors. Effectors perturb host processes by targeting a variety of host functions either in the apoplast or in the cytosol of host cells. This chapter focuses on fungal and oomycetal cytoplasmic effectors by reviewing methods to predict and to characterize effectors as well as their activities and role during infection. We provide current knowledge regarding their evolution and their putative role in the shaping of plant-associated microbial communities.


Via Kamoun Lab @ TSL, Steve Marek
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The hijacking of a receptor kinase–driven pathway by a wheat fungal pathogen leads to disease

The hijacking of a receptor kinase–driven pathway by a wheat fungal pathogen leads to disease | Stories of plants and its enermies | Scoop.it

Necrotrophic pathogens live and feed on dying tissue, but their interactions with plants are not well understood compared to biotrophic pathogens. The wheat Snn1 gene confers susceptibility to strains of the necrotrophic pathogen Parastagonospora nodorum that produce the SnTox1 protein. We report the positional cloning of Snn1 , a member of the wall-associated kinase class of receptors, which are known to drive pathways for biotrophic pathogen resistance. Recognition of SnTox1 by Snn1 activates programmed cell death, which allows this necrotroph to gain nutrients and sporulate. These results demonstrate that necrotrophic pathogens such as P. nodorum hijack host molecular pathways that are typically involved in resistance to biotrophic pathogens, revealing the complex nature of susceptibility and resistance in necrotrophic and biotrophic pathogen interactions with plants.


Via Giannis Stringlis, Steve Marek
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Rescooped by linzhang from Plant & Evolution
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The Cardamine hirsuta genome offers insight into the evolution of morphological diversity

Finding causal relationships between genotypic and phenotypic variation is a key focus of evolutionary biology, human genetics and plant breeding. To identify genome-wide patterns underlying trait diversity, we assembled a high-quality reference genome of Cardamine hirsuta, a close relative of the model plant Arabidopsis thaliana. We combined comparative genome and transcriptome analyses with the experimental tools available in C. hirsuta to investigate gene function and phenotypic diversification. Our findings highlight the prevalent role of transcription factors and tandem gene duplications in morphological evolution. We identified a specific role for the transcriptional regulators PLETHORA5/7 in shaping leaf diversity and link tandem gene duplication with differential gene expression in the explosive seed pod of C. hirsuta. Our work highlights the value of comparative approaches in genetically tractable species to understand the genetic basis for evolutionary change.

Via Pierre-Marc Delaux
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Rescooped by linzhang from Plant immunity and legume symbiosis
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The Multivesicular Bodies (MVBs)-Localized AAA ATPase LRD6-6 Inhibits Immunity and Cell Death Likely through Regulating MVBs-Mediated Vesicular Trafficking in Rice

The Multivesicular Bodies (MVBs)-Localized AAA ATPase LRD6-6 Inhibits Immunity and Cell Death Likely through Regulating MVBs-Mediated Vesicular Trafficking in Rice | Stories of plants and its enermies | Scoop.it
Previous studies have shown that multivesicular bodies (MVBs)/endosomes-mediated vesicular trafficking may play key roles in plant immunity and cell death. However, the molecular regulation is poorly understood in rice. Here we report the identification and characterization of a MVBs-localized AAA ATPase LRD6-6 in rice. Disruption of LRD6-6 leads to enhanced immunity and cell death in rice. The ATPase activity and homo-dimerization of LRD6-6 is essential for its regulation on plant immunity and cell death. An ATPase inactive mutation (LRD6-6E315Q) leads to dominant-negative inhibition in plants. The LRD6-6 protein co-localizes with the MVBs marker protein RabF1/ARA6 and interacts with ESCRT-III components OsSNF7 and OsVPS2. Further analysis reveals that LRD6-6 is required for MVBs-mediated vesicular trafficking and inhibits the biosynthesis of antimicrobial compounds. Collectively, our study shows that the AAA ATPase LRD6-6 inhibits plant immunity and cell death most likely through modulating MVBs-mediated vesicular trafficking in rice.

Via Christophe Jacquet
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Rescooped by linzhang from Plant immunity and legume symbiosis
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The Diversification of Plant NBS-LRR Defense Genes Directs the Evolution of MicroRNAs That Target Them

The Diversification of Plant NBS-LRR Defense Genes Directs the Evolution of MicroRNAs That Target Them | Stories of plants and its enermies | Scoop.it
High expression of plant nucleotide binding site leucine-rich repeat (NBS-LRR) defense genes is often lethal to plant cells, a phenotype perhaps associated with fitness costs. Plants implement several mechanisms to control the transcript level of NBS-LRR defense genes. As negative transcriptional regulators, diverse miRNAs target NBS-LRRs in eudicots and gymnosperms. To understand the evolutionary benefits of this miRNA-NBS-LRR regulatory system, we investigated the NBS-LRRs of 70 land plants, coupling this analysis with extensive small RNA data. A tight association between the diversity of NBS-LRRs and miRNAs was found. The miRNAs typically target highly duplicated NBS-LRRs. In comparison, families of heterogeneous NBS-LRRs were rarely targeted by miRNAs in Poaceae and Brassicaceae genomes. We observed that duplicated NBS-LRRs from different gene families periodically gave birth to new miRNAs. Most of these newly emerged miRNAs target the same conserved, encoded protein motif of NBS-LRRs, consistent with a model of convergent evolution for these miRNAs. By assessing the interactions between miRNAs and NBS-LRRs, we found nucleotide diversity in the wobble position of the codons in the target site drives the diversification of miRNAs. Taken together, we propose a co-evolutionary model of plant NBS-LRRs and miRNAs hypothesizing how plants balance the benefits and costs of NBS-LRR defense genes.

Via Christophe Jacquet
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Rescooped by linzhang from Rice Blast
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A new automatic method for disease symptom segmentation in digital photographs of plant leaves

A new automatic method for disease symptom segmentation in digital photographs of plant leaves | Stories of plants and its enermies | Scoop.it
The segmentation of symptoms during image analysis of diseased plant leaves is an essential process for detection and classification of diseases. However, there are challenges involved in the task, many of them related to the variability of image and host/symptom characteristics and conditions. As a result of those challenges, the methods proposed in the literature so far focus on a specific problem and are usually bounded by tight constraints regarding image capture conditions. This research explores a new automatic method for segmenting disease symptoms on plant leaves that was designed to be applicable in a wide range of situations. The proposed technique employs only color channel manipulations and Boolean operations applied on binary masks, thus being simpler and more robust compared to many previously described automatic methods. Its effectiveness is demonstrated by tests performed over a large database containing images of 77 different diseases of 11 plant species. A comparison with manual segmentation is also presented, further reinforcing the advantages of the proposed approach.

Via Elsa Ballini
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Elsa Ballini's curator insight, August 4, 3:36 AM
This protocol was used for wheat blast
Rescooped by linzhang from MycorWeb Plant-Microbe Interactions
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Mannitol in Plants, Fungi, and Plant–Fungal Interactions

Mannitol in Plants, Fungi, and Plant–Fungal Interactions | Stories of plants and its enermies | Scoop.it
Although the presence of mannitol in organisms as diverse as plants and fungi clearly suggests that this compound has important roles, our understanding of fungal mannitol metabolism and its interaction with mannitol metabolism in plants is far from complete. Despite recent inroads into understanding the importance of mannitol and its metabolic roles in salt, osmotic, and oxidative stress tolerance in plants and fungi, our current understanding of exactly how mannitol protects against reactive oxygen is also still incomplete. In this opinion, we propose a new model of the interface between mannitol metabolism in plants and fungi and how it impacts plant–pathogen interactions.

Via Christophe Jacquet, Francis Martin
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Rescooped by linzhang from Plant & Evolution
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Large-scale analyses of angiosperm nucleotide-binding site-leucine-rich repeat (NBS-LRR) genes reveal three anciently diverged classes with distinct evolutionary patterns

Nucleotide binding site-leucine-rich repeat (NBS-LRR) genes comprise the largest plant disease resistance gene family (R genes), with hundreds of copies occurring in individual angiosperm genomes. However, the expansion history of NBS-LRR genes during angiosperm evolution is largely unknown. By identifying over 6,000 NBS-LRR genes in 22 representative angiosperms and reconstructing their phylogenies, we present a potential framework of NBS-LRR gene evolution in the angiosperm. Three anciently diverged NBS-LRR classes (TNLs, CNLs and RNLs) were distinguished with unique exon-intron structures and DNA motif sequences. A total of 7 ancient TNL, 14 CNL and 2 RNL lineages were discovered in the ancestral angiosperm, from which all current NBS-LRR gene repertoires were evolved. A pattern of 'gradual expansion' during the first 100 million years evolution of the angiosperm clade was observed for CNLs. TNL numbers remained stable during this period, which were eventually deleted in three divergent angiosperm lineages. We inferred that an intense expansion of both TNL and CNL genes was started from the 'Cretaceous-Paleogene (K-P) boundary'. Because dramatic environmental changes and an explosion in fungal diversity occurred during this period, the observed expansions of R genes probably reflect convergent adaptive responses of various angiosperm families. An ancient whole genome duplication event that occurred in an angiosperm ancestor resulted in two RNL lineages, which were conservatively evolved and acted as scaffold proteins for defense signal transduction. Overall, the reconstructed framework of angiosperm NBS-LRR gene evolution in the present study may serve as a fundamental reference for better understanding angiosperm NBS-LRR genes.


Via Pierre-Marc Delaux
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Rescooped by linzhang from Rice Blast
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Live-cell fluorescence imaging to investigate the dynamics of plant cell death during infection by the rice blast fungus Magnaporthe oryzae

Live-cell fluorescence imaging to investigate the dynamics of plant cell death during infection by the rice blast fungus Magnaporthe oryzae | Stories of plants and its enermies | Scoop.it
Background

Plant cell death plays important roles during plant-pathogen interactions. To study pathogen-induced cell death, there is a need for cytological tools that allow determining not only host cell viability, but also cellular events leading to cell death with visualization of pathogen development. Here we describe a live cell imaging method to provide insights into the dynamics of cell death in rice (Oryza sativa). This method uses live-cell confocal microscopy of rice sheath cells mechanically damaged or invaded by fluorescently-tagged Magnaporthe oryzae together with fluorescent dyes fluorescein diacetate (FDA) and propidium iodide (PI). FDA stains the cytoplasm of live cells exclusively, thus also visualizing the vacuole, whereas PI stains nuclei of dead cells.
Results

We first demonstrated that confocal microscopy of rice leaf sheaths stained with FDA and PI discriminated between live cells and mechanically-killed cells. FDA-derived fluorescein was confined to the cytoplasm of live cells, indicating the intact vacuolar and plasma membranes. We also observed previously unreported fluorescein patterns in mechanically damaged cells. These patterns include: (1) homogeneous distribution of fluorescein in the increased area of the cytoplasm due to the shrunken vacuole; (2) the increase of the fluorescein intensity; and (3) containment of the brighter fluorescein signal only in affected cells likely due to closure of plasmodesmata. We refer to these as novel fluorescein patterns in this study. Simultaneous imaging of fluorescently-tagged M. oryzae (red) and FDA staining (green) in rice cells revealed characteristic features of the hemibiotrophic interaction. That is, newly invaded cells are alive but subsequently become dead when the fungus spreads into neighbor cells, and biotrophic interfacial complexes are associated with the host cytoplasm. This also revealed novel fluorescein patterns in invaded cells. Time-lapse imaging suggested that the FDA staining pattern in the infected host cell progressed from typical cytoplasmic localization (live cell with the intact vacuole), to novel patterns (dying cell with closed plasmodesmata with the shrunken or ruptured vacuole), to lack of fluorescence (dead cell).
Conclusion

We have developed a method to visualize cellular events leading to host cell death during rice blast disease. This method can be used to compare and contrast host cell death associated with disease resistance and susceptibility in rice-M. oryzae and other host-pathogen interactions.

Via Christophe Jacquet, CP, Elsa Ballini
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Rescooped by linzhang from Plant immunity and legume symbiosis
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MicroRNAs in Rice Innate Immunity

MicroRNAs in Rice Innate Immunity | Stories of plants and its enermies | Scoop.it
MicroRNAs (miRNAs) are short regulatory non-coding RNAs that guide gene silencing in most eukaryotes. They regulate gene expression by triggering sequence-specific cleavage or translational repression of target transcripts. Plant miRNAs are known to play important roles in a wide range of developmental processes. Increasing evidence also supports that the modulation of miRNA levels plays an important role in reprogramming plant responses to abiotic stress (drought, cold, salinity and nutrient deficiency) and biotic stress (antibacterial resistance). Most of these studies were carried out in the model plant Arabidopsis thaliana. During the last years, the adoption of high-throughput sequencing technologies has significantly contributed to uncover multiple miRNAs while allowing miRNA profiling in plants. However, although a plethora of rice miRNAs have been shown to be regulated by pathogen infection, the biological function remains largely unknown for most of them. In this review, we summarize our current understanding on the contribution of miRNAs to rice immunity and discuss their potential applications in rice biotechnology. A better understanding of the miRNA species controlling rice immunity may lead to practical biotechnological applications leading to the development of appropriate strategies for rice protection.

Via Elsa Ballini, Christophe Jacquet
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Rescooped by linzhang from Plant immunity and legume symbiosis
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Bioinformatic Identification and Analysis of Extensins in the Plant Kingdom

Bioinformatic Identification and Analysis of Extensins in the Plant Kingdom | Stories of plants and its enermies | Scoop.it
Extensins (EXTs) are a family of plant cell wall hydroxyproline-rich glycoproteins (HRGPs) that are implicated to play important roles in plant growth, development, and defense. Structurally, EXTs are characterized by the repeated occurrence of serine (Ser) followed by three to five prolines (Pro) residues, which are hydroxylated as hydroxyproline (Hyp) and glycosylated. Some EXTs have Tyrosine (Tyr)-X-Tyr (where X can be any amino acid) motifs that are responsible for intramolecular or intermolecular cross-linkings. EXTs can be divided into several classes: classical EXTs, short EXTs, leucine-rich repeat extensins (LRXs), proline-rich extensin-like receptor kinases (PERKs), formin-homolog EXTs (FH EXTs), chimeric EXTs, and long chimeric EXTs. To guide future research on the EXTs and understand evolutionary history of EXTs in the plant kingdom, a bioinformatics study was conducted to identify and classify EXTs from 16 fully sequenced plant genomes, including Ostreococcus lucimarinus, Chlamydomonas reinhardtii, Volvox carteri, Klebsormidium flaccidum, Physcomitrella patens, Selaginella moellendorffii, Pinus taeda, Picea abies, Brachypodium distachyon, Zea mays, Oryza sativa, Glycine max, Medicago truncatula, Brassica rapa, Solanum lycopersicum, and Solanum tuberosum, to supplement data previously obtained from Arabidopsis thaliana and Populus trichocarpa. A total of 758 EXTs were newly identified, including 87 classical EXTs, 97 short EXTs, 61 LRXs, 75 PERKs, 54 FH EXTs, 38 long chimeric EXTs, and 346 other chimeric EXTs. Several notable findings were made: (1) classical EXTs were likely derived after the terrestrialization of plants; (2) LRXs, PERKs, and FHs were derived earlier than classical EXTs; (3) monocots have few classical EXTs; (4) Eudicots have the greatest number of classical EXTs and Tyr-X-Tyr cross-linking motifs are predominantly in classical EXTs; (5) green algae have no classical EXTs but have a number of long chimeric EXTs that are absent in embryophytes. Furthermore, phylogenetic analysis was conducted of LRXs, PERKs and FH EXTs, which shed light on the evolution of three EXT classes.

Via Christophe Jacquet
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Rescooped by linzhang from Plant-microbe interaction
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Science: Using decoys to expand the recognition specificity of a plant disease resistance protein

Science: Using decoys to expand the recognition specificity of a plant disease resistance protein | Stories of plants and its enermies | Scoop.it

Maintaining high crop yields in an environmentally sustainable manner requires the development of disease-resistant crop varieties. We describe a method to engineer disease resistance in plants by means of an endogenous disease resistance gene from Arabidopsis thaliana named RPS5, which encodes a nucleotide-binding leucine-rich repeat (NLR) protein. RPS5 is normally activated when a second host protein, PBS1, is cleaved by the pathogen-secreted protease AvrPphB. We show that the AvrPphB cleavage site within PBS1 can be substituted with cleavage sites for other pathogen proteases, which then enables RPS5 to be activated by these proteases, thereby conferring resistance to new pathogens. This “decoy” approach may be applicable to other NLR proteins and should enable engineering of resistance in plants to diseases for which we currently lack robust genetic resistance.

Science Vol 351, Issue 6274 12 February 2016


Via Jim Alfano, Suayib Üstün
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Rescooped by linzhang from Plant & Evolution
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Draft Genome Sequence of Mentha longifolia (L.) and Development of Resources for Mint Cultivar Improvement

The genus Mentha encompasses species cultivated for their essential oils, which are formulated into a vast array of consumer products. Desirable oil characteristics and resistance to the fungal disease Verticillium wilt are top priorities for the mint industry. However, cultivated mints have complex polyploid genomes and are sterile. Breeding efforts, therefore, require the development of genomic resources for fertile mint species. Here, we present draft de novo genome and plastome assemblies for a wilt-resistant South African accession of Mentha longifolia (L.) Huds., a diploid species ancestral to cultivated peppermint and spearmint. The 353 Mb contained 35,597 predicted protein-coding genes, including 292 disease resistance gene homologs, and nine genes determining essential oil characteristics. A genetic linkage map ordered 1,397 genome scaffolds on 12 pseudochromosomes. Over two million simple sequence repeats were identified, which will aid molecular marker development. The M. longifolia genome is a valuable resource for both metabolic engineering and molecular breeding. This is exemplified by employing the genome sequence to clone and functionally characterize promoters in a peppermint cultivar, and demonstrating the utility of a glandular trichome-specific promoter to increase expression of a biosynthetic gene, thereby modulating essential oil composition.

Via Pierre-Marc Delaux
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Rescooped by linzhang from Plant pathogenic fungi
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Genome Biology and Evolution: A Tale of Genome Compartmentalization: The Evolution of Virulence Clusters in Smut Fungi (2016)

Genome Biology and Evolution: A Tale of Genome Compartmentalization: The Evolution of Virulence Clusters in Smut Fungi (2016) | Stories of plants and its enermies | Scoop.it

Smut fungi are plant pathogens mostly parasitizing wild species of grasses as well as domesticated cereal crops. Genome analysis of several smut fungi including Ustilago maydis revealed a singular clustered organization of genes encoding secreted effectors. In U. maydis, many of these clusters have a role in virulence. Reconstructing the evolutionary history of clusters of effector genes is difficult because of their intrinsically fast evolution, which erodes the phylogenetic signal and homology relationships. Here, we describe the use of comparative evolutionary analyses of quality draft assemblies of genomes to study the mechanisms of this evolution. We report the genome sequence of a South African isolate of Sporisorium scitamineum, a smut fungus parasitizing sugar cane with a phylogenetic position intermediate to the two previously sequenced species U. maydisand Sporisorium reilianum. We show that the genome of S. scitamineumcontains more and larger gene clusters encoding secreted effectors than any previously described species in this group. We trace back the origin of the clusters and find that their evolution is mainly driven by tandem gene duplication. In addition, transposable elements play a major role in the evolution of the clustered genes. Transposable elements are significantly associated with clusters of genes encoding fast evolving secreted effectors. This suggests that such clusters represent a case of genome compartmentalization that restrains the activity of transposable elements on genes under diversifying selection for which this activity is potentially beneficial, while protecting the rest of the genome from its deleterious effect.


Via Kamoun Lab @ TSL, Steve Marek
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Rescooped by linzhang from Plant & Evolution
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A transcription factor hierarchy defines an environmental stress response network

INTRODUCTION Transcription factors (TFs) are often studied one by one or in clusters of a few related factors. However, the integration and networks of transcriptional changes to response to environmental stresses often involve many related TFs. In many organisms, such as plants, overlapping functions can make it difficult to understand how a biologically relevant end result can be achieved via the complex signaling networks controlled by these TFs. To better understand how the reference plant Arabidopsis deals with the stresses incurred by water limitation via the hormone abscisic acid (ABA), we characterized all DNA sequences that bind to the 21 ABA-related TFs in vivo. 


RATIONALE There have been limited systematic studies of stress-responsive TF networks in multicellular organisms. We chose ABA, an essential plant hormone that is required for both development and responses to osmotic stress, as an elicitor to investigate complex gene regulatory networks under stress. Combining differential binding (DB) of 21 ABA-related TFs at a single time point measured by chromatin immunoprecipitation sequencing (ChIP-seq) with differentially expressed genes from a time-series RNA sequencing (RNA-seq) data set, we analyzed the relationship between DB of TFs and differential expression (DE) of target genes, the determinants of DB, and the combinatorial effects of multi-TF binding. These data sets also provide a framework to construct an ABA TF network and to predict genes and cis-regulatory elements important to ABA responses and related environmental stresses. 


RESULTS We found that, in general, DNA binding is correlated with transcript and protein levels of TFs. Most TFs in our study are induced by ABA and gain binding sites (termed “peaks”) after the hormone treatment. ABA also increases the binding of the TFs at most peaks. However, in some peaks, TF binding may be static or even decrease after ABA exposure, revealing the complexity of locus-specific gene regulation. De novo motif discovery enabled us to identify distinct, primary motifs often centrally localized in the ChIP-seq peaks for most TFs. However, it is not uncommon to find motifs, such as the G-box, that are shared by peaks from multiple TFs and may contribute to binding dynamics at these sites. DB of multiple TFs is a robust predictor of both the DE and ABA-related functions of the target genes. Using the DB and DE data, we constructed a network of TFs and canonical ABA pathway genes and demonstrated a regulatory hierarchy of TFs and extensive feedback of ABA responses. On the basis of a “guilt-by-association” paradigm, we further predicted genes whose functions were previously not linked to ABA responses, and we thus functionally characterized a new family of transcriptional regulators. 


CONCLUSION These data sets will provide the plant community with a roadmap of ABA-elicited transcriptional regulation by 21 ABA-related TFs. We propose that dynamic, multi-TF binding could be a criterion for prioritizing the characterization of TF binding events, cis-regulatory elements, and functionally unknown genes in both plants and other species. In our proof-of-principle experiments, ectopic expression of the transcriptional regulators ranked highly in our model results in altered sensitivity to both ABA and high salinity. Together with the fact that our modeling recovered genes related to seed development and osmotic stresses, we believe such predictions are likely applicable to a broad range of developmental stages and osmotic stresses.


Via Pierre-Marc Delaux
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Rescooped by linzhang from SEED DEV LAB Biblio
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PlantTFDB 4.0: toward a central hub for transcription factors and regulatory interactions in plants

PlantTFDB 4.0: toward a central hub for transcription factors and regulatory interactions in plants | Stories of plants and its enermies | Scoop.it

Via Loïc Lepiniec
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Rescooped by linzhang from Plant immunity and legume symbiosis
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Plasma membrane order and fluidity are diversely triggered by elicitors of plant defence

Plasma membrane order and fluidity are diversely triggered by elicitors of plant defence | Stories of plants and its enermies | Scoop.it
Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence.

Via Christophe Jacquet
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Immunity to Rice Blast Disease by Suppression of Effector-Triggered Necrosis

Immunity to Rice Blast Disease by Suppression of Effector-Triggered Necrosis | Stories of plants and its enermies | Scoop.it
Highlights

•AvrPiz-t interacts and co-localizes with APIP5 in the cytoplasm
•AvrPiz-t suppresses APIP5 transcriptional activity and protein accumulation
•APIP5, a negative regulator of cell death, interacts with the NLR receptor Piz-t
•Piz-t suppresses the AvrPiz-t-mediated APIP5 turnover

Summary

Hemibiotrophic pathogens are some of the most destructive plant pathogens, causing huge economic losses and threatening global food security. Infection with these organisms often involves an initial biotrophic infection phase, during which the pathogen spreads in host tissue asymptomatically, followed by a necrotrophic phase, during which host-cell death is induced. How hemibiotrophic pathogens trigger host necrosis and how plants inhibit the transition from the biotrophic stage to the necrotrophic stage in disease symptom expression are mainly unknown. The rice blast fungus Magnaporthe oryzae spreads in rice biotrophically early during infection, but this biotrophic stage is followed by a pronounced switch to cell death and lesion formation. Here, we show that the M. oryzae effector AvrPiz-t interacts with the bZIP-type transcription factor APIP5 in the cytoplasm and suppresses its transcriptional activity and protein accumulation at the necrotrophic stage. Silencing of APIP5 in transgenic rice leads to cell death, and the phenotype is enhanced by the expression of AvrPiz-t. Conversely, Piz-t interacts with and stabilizes APIP5 to prevent necrosis at the necrotrophic stage. At the same time, APIP5 is essential for Piz-t stability. These results demonstrate a novel mechanism for the suppression of effector-triggered necrosis at the necrotrophic stage by an NLR receptor in plants.

Via Christophe Jacquet
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Rescooped by linzhang from Publications from The Sainsbury Laboratory
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Science: Detection of the plant parasite Cuscuta reflexa by a tomato cell surface receptor (2016)

Science: Detection of the plant parasite Cuscuta reflexa by a tomato cell surface receptor (2016) | Stories of plants and its enermies | Scoop.it
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Via The Sainsbury Lab
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The Sainsbury Lab's curator insight, July 29, 4:05 AM
Parasitic plants are a constraint on agriculture worldwide. Cuscuta reflexa is a stem holoparasite that infests most dicotyledonous plants. One exception is tomato, which is resistant to C. reflexa. We discovered that tomato responds to a small peptide factor occurring in Cuscuta spp. with immune responses typically activated after perception of microbe-associated molecular patterns. We identified the cell surface receptor-like protein CUSCUTA RECEPTOR 1 (CuRe1) as essential for the perception of this parasite-associated molecular pattern. CuRe1 is sufficient to confer responsiveness to the Cuscuta factor and increased resistance to parasitic C. reflexa when heterologously expressed in otherwise susceptible host plants. Our findings reveal that plants recognize parasitic plants in a manner similar to perception of microbial pathogens.
Rescooped by linzhang from MycorWeb Plant-Microbe Interactions
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Independent Origins of Yeast Associated with Coffee and Cacao Fermentation: Current Biology

Independent Origins of Yeast Associated with Coffee and Cacao Fermentation: Current Biology | Stories of plants and its enermies | Scoop.it
Modern transportation networks have facilitated the migration and mingling of previously isolated populations of plants, animals, and insects. Human activities can also influence the global distribution of microorganisms. The best-understood example is yeasts associated with winemaking. Humans began making wine in the Middle East over 9,000 years ago [ 1, 2 ]. Selecting favorable fermentation products created specialized strains of Saccharomyces cerevisiae [ 3, 4 ] that were transported along with grapevines. Today, S. cerevisiae strains residing in vineyards around the world are genetically similar, and their population structure suggests a common origin that followed the path of human migration [ 3–7 ]. Like wine, coffee and cacao depend on microbial fermentation [ 8, 9 ] and have been globally dispersed by humans. Theobroma cacao originated in the Amazon and Orinoco basins of Colombia and Venezuela [ 10 ], was cultivated in Central America by Mesoamerican peoples, and was introduced to Europeans by Hernán Cortés in 1530 [ 11 ]. Coffea, native to Ethiopia, was disseminated by Arab traders throughout the Middle East and North Africa in the 6th century and was introduced to European consumers in the 17th century [ 12 ]. Here, we tested whether the yeasts associated with coffee and cacao are genetically similar, crop-specific populations or genetically diverse, geography-specific populations. Our results uncovered populations that, while defined by niche and geography, also bear signatures of admixture between major populations in events independent of the transport of the plants. Thus, human-associated fermentation and migration may have affected the distribution of yeast involved in the production of coffee and chocolate.

Via Francis Martin
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Rescooped by linzhang from Rice Blast
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Inspirational decoys: a new hunt for effector targets

Inspirational decoys: a new hunt for effector targets | Stories of plants and its enermies | Scoop.it
Understanding recognition mechanisms of pathogenic microbes by plants is not only pivotal to crop protection programs, but has also revealed fascinating examples of co-evolutionary biology. A new phase has been initiated with a series of exciting discoveries on ‘integrated decoys’. In this issue of New Phytologist, Kroj et al. (pp. 618–626) show that the integrated decoys are diverse, but common in plants and illustrate that this model predicts novel components in plant immunity.

Via Christophe Jacquet, Elsa Ballini
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Comparative Analysis of the Flax Immune Receptors L6 and L7 Suggests an Equilibrium-Based Switch Activation Model

Comparative Analysis of the Flax Immune Receptors L6 and L7 Suggests an Equilibrium-Based Switch Activation Model | Stories of plants and its enermies | Scoop.it
NOD-like receptors (NLRs) are central components of the plant immune system. L6 is a Toll/interleukin-1 receptor (TIR) domain-containing NLR from flax (Linum usitatissimum) conferring immunity to the flax rust fungus. Comparison of L6 to the weaker allele L7 identified two polymorphic regions in the TIR and the nucleotide binding (NB) domains that regulate both effector ligand-dependent and -independent cell death signaling as well as nucleotide binding to the receptor. This suggests that a negative functional interaction between the TIR and NB domains holds L7 in an inactive/ADP-bound state more tightly than L6, hence decreasing its capacity to adopt the active/ATP-bound state and explaining its weaker activity in planta. L6 and L7 variants with a more stable ADP-bound state failed to bind to AvrL567 in yeast two-hybrid assays, while binding was detected to the signaling active variants. This contrasts with current models predicting that effectors bind to inactive receptors to trigger activation. Based on the correlation between nucleotide binding, effector interaction, and immune signaling properties of L6/L7 variants, we propose that NLRs exist in an equilibrium between ON and OFF states and that effector binding to the ON state stabilizes this conformation, thereby shifting the equilibrium toward the active form of the receptor to trigger defense signaling.

Via Christophe Jacquet
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Rescooped by linzhang from Plant immunity and legume symbiosis
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The LysM receptor-like kinase SlLYK10 regulates the arbuscular mycorrhizal symbiosis in tomato - New Phytologist -

The LysM receptor-like kinase SlLYK10 regulates the arbuscular mycorrhizal symbiosis in tomato -  New Phytologist - | Stories of plants and its enermies | Scoop.it
Most plants have the ability to establish a symbiosis with arbuscular mycorrhizal (AM) fungi, which allows better plant nutrition. A plant signaling pathway, called the common symbiosis signaling pathway (CSSP), is essential for the establishment of both AM and root nodule symbioses. The CSSP is activated by microbial signals. Plant receptor(s) for AM fungal signals required for the activation of the CSSP and initial fungal penetration are currently unknown.
We set up conditions to use virus-induced gene silencing (VIGS) in Solanum lycopersicum to study the genes potentially involved in AM.
We show that the lysin motif receptor-like kinase SlLYK10, whose orthologs in legumes are essential for nodulation, but not for AM, and SlCCaMK, a component of the CSSP, are required for penetration of the AM fungus Rhizophagus irregularis into the roots of young tomato plants.
Our results support the hypothesis that the SILYK10 ancestral gene originally played a role in AM and underwent duplication and neofunctionalization for a role in nodulation in legumes. Moreover, we conclude that VIGS is an efficient method for fast screening of genes playing major roles in AM.

Via Christophe Jacquet
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Rescooped by linzhang from MycorWeb Plant-Microbe Interactions
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Mildew-Omics: How Global Analyses Aid the Understanding of Life and Evolution of Powdery Mildews

Mildew-Omics: How Global Analyses Aid the Understanding of Life and Evolution of Powdery Mildews | Stories of plants and its enermies | Scoop.it
The common powdery mildew plant diseases are caused by ascomycete fungi of the order Erysiphales. Their characteristic life style as obligate biotrophs renders functional analyses in these species challenging, mainly because of experimental constraints to genetic manipulation. Global large-scale (“-omics”) approaches are thus particularly valuable and insightful for the characterisation of the life and evolution of powdery mildews. Here we review the knowledge obtained so far from genomic, transcriptomic and proteomic studies in these fungi. We consider current limitations and challenges regarding these surveys and provide an outlook on desired future investigations on the basis of the various –omics technologies

Via Francis Martin
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