The Experts below are selected from a list of 981 Experts worldwide ranked by ideXlab platform

Jan Lochman - One of the best experts on this subject based on the ideXlab platform.

  • Elicitins' Oligomeric States Affect The Hypersensitive Response And Resistance In Tobacco
    Journal of experimental botany, 2021
    Co-Authors: Martin Solanský, Zbyněk Zdráhal, Marek Petřivalský, Kamil Mikulášek, Martina Zapletalová, Annick Chiltz, Nathalie Leborgne-castel, Jan Lochman
    Abstract:

    Successful plant defence against microbial pathogens is based on early recognition and fast activation of inducible responses. Key mechanisms include detection of microbe-associated molecular patterns by membrane-localized Pattern Recognition Receptors that induce a basal resistance response. A well-described model of such responses to pathogens involves interaction between Solanaceae plants with proteinaceous elicitors secreted by oomycetes, called Elicitins. It has been hypothesised that Elicitins' formation of oligomeric structures could be involved in their recognition and activation of defensive transduction cascades. In tests of this hypothesis reported here, using several approaches, we observed differences in tobacco plant responses induced by the Elicitin β-cryptogein (β-CRY) and its homodimer (β-CRY DIM). We also found that the C-terminal domain of Elicitins of other ELI clades plays a significant role in stabilization of their oligomeric structure and restraint in the cell wall. In addition, covalently crosslinking β-CRY DIM impaired formation of signalling complexes, thereby reducing its capacity to elicit the hypersensitive response and resistance in the host plant, with no significant changes in pathogenesis-related protein expression. The results illuminate the poorly understood role of Elicitins' oligomeric structures in oomycetes' interaction with plants, by revealing details of effects of β-CRY dimerization on tobacco plants' recognition and defence responses.

  • ELR is a true pattern recognition receptor that associates with Elicitins from diverse Phytophthora species
    2020
    Co-Authors: Emmanouil Domazakis, Jan Lochman, Doret Wouters, Richard G. F. Visser, Matthieu H. A. J. Joosten, Vivianne G A A Vleeshouwers
    Abstract:

    The first layer of plant immunity against pathogens is mediated by cell surface pattern recognition receptors (PRRs) that recognize pathogen molecules in the apoplast. Several pairs of PRRs and their matching extracellular ligands have been described but, in many cases, actual evidence for ligand binding by the PRR is lacking. The receptor-like protein ELR from Solanum microdontum, which triggers cell death upon co-expression with Elicitins of various Phytophthora species and enhances resistance to late blight caused by Phytophthora infestans, was previously identified as the Elicitin receptor by forward genetic screenings employing the INF1 Elicitin of P. infestans. In this study, we investigated whether ELR associates with INF1 and other Elicitins that are secreted by diverse Phytophthora spp. We performed in planta and in vitro co-immunoprecipitation of ELR with several affinity-tagged Elicitins, as well as in planta transient co-expression assays. We found that ELR physically interacts with the class I Elicitins INF1 and ParA1, from P. infestans and Phytophthora parasitica, respectively, which is in line with their ability to cause cell death when co-expressed with ELR in potato. Together, we demonstrate that ELR is a genuine PRR that binds Elicitins of Phytophthora species.

  • Biological effects of oomycetes Elicitins
    Plant Protection Science, 2019
    Co-Authors: Martina Janků, Jan Lochman, Lucie Činčalová, Lenka Luhová, Marek Petřivalský
    Abstract:

    Successful plant defence responses to pathogen challenges are based on fast and specific pathogen recognition and plant reaction mechanisms. Elicitins, proteinaceous elicitors secreted by the Phytophthora and Pythium species, were first described in Phytophthora culture filtrates as proteins able to induce a hypersensitive response (HR) and resistance in tobacco at low concentrations. Later, they were classified as microbial-associated molecular patterns (MAMPs) able to induce defences in a variety of plant species. In this review, we present a comprehensive summary of the actual knowledge on the representative Elicitins and their structure, perception and activation of plant signalling pathways. The current research of Elicitins has been focused on a detailed understanding of the molecular mechanisms of the Elicitin recognition by plant cells. Moreover, the possibility of Elicitin involvement in the establishment and enhancement of plant host resistance to a broad spectrum of pathogens has been intensively studied.

  • The Elicitin β-cryptogein's activity in tomato is mediated by jasmonic acid and ethylene signalling pathways independently of Elicitin-sterol interactions.
    Planta, 2018
    Co-Authors: Tomáš Starý, Tomáš Kašparovský, Lenka Luhová, Marek Petřivalský, Pavla Satková, Jana Piterková, B. Mieslerová, Jaromír Mikulík, Jan Lochman
    Abstract:

    Main conclusion The level of resistance induced in different tomato genotypes after β-CRY treatment correlated with the upregulation of defence genes, but not sterol binding and involved ethylene and jasmonic acid signalling. Elicitins, a family of small proteins secreted by Phytophthora and Pythium spp., are the most well-known microbe-associated molecular patterns of oomycetes, a lineage of fungus-like organisms that include many economically significant crop pathogens. The responses of tomato plants to Elicitin INF1 produced by Phytophthora infestans have been studied extensively. Here, we present studies on the responses of three tomato genotypes to β-cryptogein (β-CRY), a potent Elicitin secreted by Phytophthora cryptogea that induces hypersensitive response (HR) cell death in tobacco plants and confers greater resistance to oomycete infection than acidic Elicitins like INF1. We also studied β-CRY mutants impaired in sterol binding (Val84Phe) and interaction with the binding site on tobacco plasma membrane (Leu41Phe), because sterol binding was suggested to be important in INF1-induced resistance. Treatment with β-CRY or the Val84Phe mutant induced resistance to powdery mildew caused by the pathogen Pseudoidium neolycopersici, but not the HR cell death observed in tobacco and potato plants. The level of resistance induced in different tomato genotypes correlated with the upregulation of defence genes including defensins, β-1,3-glucanases, heveins, chitinases, osmotins, and PR1 proteins. Treatment with the Leu41Phe mutant did not induce this upregulation, suggesting similar Elicitin recognition in tomato and tobacco. However, here β-CRY activated ethylene and jasmonic acid signalling, but not salicylic acid signalling, demonstrating that Elicitins activate different downstream signalling processes in different plant species. This could potentially be exploited to enhance the resistance of Phytophthora-susceptible crops.

  • Elicititns Oligomerization: What Could Clarify in Elicitins Actvity
    2018
    Co-Authors: Martin Solanský, Matěj Sklenář, Vojtěch Pětroš, Nathalie Leborne-castel, Jan Lochman
    Abstract:

    A well described and accessible model of plant-pathogen interaction is represented by Elicitins and Solanaceae plants. Elicitins, a family of small proteins secreted by Phytophthora and Pythium spp., are the most well-known microbe-associated molecular patterns of oomycetes (MAMPs). Recently, it has been described that one of the factors affecting Elicitins activity in plants could be represented by their ability to form dimer/oligomer under normal conditions. To clear up in details the role of dimer within Elicitins biological activity we prepared covalently crosslinked dimer of highly necrotising Elicitin ?-cryptogein (?-CRY) and its variants D21N and K13V carrying mutations in the region likely involved in dimerization. By analytical ultracentrifugation we proved different KD of homodimer complexes formation in both mutants and wt ?-CRY. Further, we found a pretty relation between proteins KD of dimer formation and response of tobacco plants and cell suspension to their treatment. Noticeable, we found that ?-CRY dimer is affected in interaction with receptor-like protein ELR from S. microdontum and in triggering of ROS production in tobacco cells but not in activation of WIPK/SIPK kinases leading to defense genes expression. Consequently, we studied on the model of BY2 cells and GP3 cells, impaired in NADPH oxidase, the exact role of ROS in early and late phase of plant-Elicitin interaction.

Daniel F Klessig - One of the best experts on this subject based on the ideXlab platform.

  • Multiple levels of tobacco WIPK activation during the induction of cell death by fungal Elicitins.
    The Plant journal : for cell and molecular biology, 2000
    Co-Authors: Shuqun Zhang, Yidong Liu, Daniel F Klessig
    Abstract:

    Three protein kinases of 48, 44 and 40 kDa are activated at different stages in tobacco cells treated with fungal Elicitins. Previously we demonstrated that the rapidly activated 48 kDa protein kinase is encoded by SIPK. Here we report that the Elicitin-activated 44 kDa kinase is encoded by WIPK. Activation of this kinase occurred 2-4 h after Elicitin treatment and was preceded by dramatic increases in WIPK mRNA and protein levels. Studies using actinomycin D and cycloheximide demonstrated that de novo transcription and translation were required for this activation of the kinase activity. Strikingly, the kinetics of WIPK activation following Elicitin treatment correlated with the onset of hypersensitive response (HR)-like cell death. Moreover, staurosporine and K-252a, two Ser/Thr protein kinase inhibitors that blocked WIPK activation, suppressed cell death. The timing for Elicitin-treated cells to commit to a death program correlated with the appearance of high levels of WIPK activity. These correlative data suggest that WIPK may play a role during HR development in tobacco. Interestingly, a fungal cell-wall elicitor that does not cause cell death induced WIPK mRNA and protein to similar levels as those observed with the Elicitins. However, no corresponding increase in WIPK activity was detected. Thus WIPK appears to be controlled at multiple levels.

  • activation of the tobacco sip kinase by both a cell wall derived carbohydrate elicitor and purified proteinaceous Elicitins from phytophthora spp
    The Plant Cell, 1998
    Co-Authors: Shuqun Zhang, Daniel F Klessig
    Abstract:

    Two purified proteinaceous fungal elicitors, parasiticein (an α Elicitin) and cryptogein (a β Elicitin), as well as a fungal cell wall–derived carbohydrate elicitor all rapidly activated a 48-kD kinase in tobacco suspension cells. The maximum activation of this kinase paralleled or preceded medium alkalization and activation of the defense gene phenylalanine ammonia–lyase ( PAL ). In addition, the two Elicitins, which also induced hypersensitive cell death, activated a 44- and a 40-kD kinase with delayed kinetics. By contrast, the cell wall–derived elicitor only weakly activated the 44-kD kinase and failed to activate the 40-kD kinase. The size and substrate preference of the 48-kD kinase are reminiscent of the recently purified and cloned salicylic acid–induced protein (SIP) kinase, which is a member of the mitogen-activated protein kinase family. Antibodies raised against a peptide corresponding to the unique N terminus of SIP kinase immunoreacted with the 48-kD kinase activated by all three elicitors from Phytophthora spp. In addition, the cell wall elicitor and the salicylic acid–activated 48-kD kinase copurified through several chromatography steps and comigrated on two-dimensional gels. Based on these results, all three fungal elicitors appear to activate the SIP kinase. In addition, inhibition of SIP kinase activation by kinase inhibitors correlated with the suppression of cell wall elicitor–induced medium alkalization and PAL gene activation, suggesting a regulatory function for the SIP kinase in these defense responses.

  • Activation of the Tobacco SIP Kinase by Both a Cell Wall–Derived Carbohydrate Elicitor and Purified Proteinaceous Elicitins from Phytophthora spp
    The Plant cell, 1998
    Co-Authors: Shuqun Zhang, Daniel F Klessig
    Abstract:

    Two purified proteinaceous fungal elicitors, parasiticein (an α Elicitin) and cryptogein (a β Elicitin), as well as a fungal cell wall–derived carbohydrate elicitor all rapidly activated a 48-kD kinase in tobacco suspension cells. The maximum activation of this kinase paralleled or preceded medium alkalization and activation of the defense gene phenylalanine ammonia–lyase ( PAL ). In addition, the two Elicitins, which also induced hypersensitive cell death, activated a 44- and a 40-kD kinase with delayed kinetics. By contrast, the cell wall–derived elicitor only weakly activated the 44-kD kinase and failed to activate the 40-kD kinase. The size and substrate preference of the 48-kD kinase are reminiscent of the recently purified and cloned salicylic acid–induced protein (SIP) kinase, which is a member of the mitogen-activated protein kinase family. Antibodies raised against a peptide corresponding to the unique N terminus of SIP kinase immunoreacted with the 48-kD kinase activated by all three elicitors from Phytophthora spp. In addition, the cell wall elicitor and the salicylic acid–activated 48-kD kinase copurified through several chromatography steps and comigrated on two-dimensional gels. Based on these results, all three fungal elicitors appear to activate the SIP kinase. In addition, inhibition of SIP kinase activation by kinase inhibitors correlated with the suppression of cell wall elicitor–induced medium alkalization and PAL gene activation, suggesting a regulatory function for the SIP kinase in these defense responses.

Jean-claude Pernollet - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of Elicitin-like phospholipases isolated from Phytophthora capsici culture filtrate.
    FEBS letters, 1999
    Co-Authors: Claude Nespoulous, Jean-claude Huet, Odile Gaudemer, Jean-claude Pernollet
    Abstract:

    The phytopathogenic oomycete Phytophthora capsici secretes in culture a phospholipase activity. Two enzyme isoforms exhibiting a high phospholipase B activity were isolated by chromatography and electrophoresis. They differ in their apparent molar masses (22 and 32 kDa). Both proteins are glycosylated and share the same N-terminal amino acid sequence up to the 39th residue with a high homology with capsicein, the P. capsici Elicitin. Although devoid of phospholipase activity, capsicein was shown by circular dichroism to specifically interact with negatively charged phospholipids, suggesting that the membrane lipids could be a potential target for Elicitins.

  • The 2.1 A structure of an Elicitin-ergosterol complex: a recent addition to the Sterol Carrier Protein family.
    Protein science : a publication of the Protein Society, 1999
    Co-Authors: Guillaume Boissy, Jean-claude Pernollet, Odile Gaudemer, Valérie Perez, Michael J. O’donohue, Simone Brunie
    Abstract:

    Elicitins, produced by most of the phytopathogenic fungi of the genus Phytophthora, provoke in tobacco both remote leaf necrosis and the induction of a resistance against subsequent attack by various microorganisms. Despite the recent description of the three-dimensional crystal structure of cryptogein (CRY), the molecular basis of the interactions between Phytophthora and plants largely remains unknown. The X-ray crystal structure, refined at 2.1 A, of a ligand complexed, mutated CRY, K13H, is reported. Analysis of this structure reveals that CRY is able to encapsulate a ligand that induces only a minor conformational change in the protein structure. The ligand has been identified as an ergosterol by gas chromatographic analysis coupled with mass spectrometry analysis. This result is consistent with biochemical data that have shown that Elicitins are a distinct class of Sterol Carrier Proteins (SCP). Data presented here provide the first structural description of the pertinent features of the Elicitin sterol interaction and permit a reassessment of the importance of both the key residue 13 and the mobility of the omega loop for the accessibility of the sterol to the cavity. The biological implications thereof are discussed. This paper reports the first structure of a SCP/sterol complex.

  • Mapping the Elicitor and Necrotic Sites of Phytophthora Elicitins with Synthetic Peptides and Reporter Genes Controlled by Tobacco Defense Gene Promoters
    Molecular plant-microbe interactions : MPMI, 1997
    Co-Authors: Valérie Perez, Jean-claude Huet, Claude Nespoulous, Jean-claude Pernollet
    Abstract:

    Elicitins are 10-kDa proteins secreted by Phytophthora and Pythium fungi that elicit a hypersensitive-like necrotic reaction, leading to resistance against fungal and bacterial plant pathogens. Induction of necrosis and resistance were previously shown to be borne by different sites of the molecule. Furthermore, sequence comparison indicated several potential residues necessary for necrosis. The role of one of these residues was previously evidenced with site-directed mutagenesis. In order to locate other necrosis-determining sites and reveal the defense-Eliciting sites, we synthesized a series of synthetic peptides. Tests were performed on two types of transgenic tobacco plants, both transformed with a construction containing the beta-glucuronidase reporter gene, in one case controlled by the promoter of the multiple stimulus response gene str 246C and in the other by the promoter of the pathogenesis-related gene PR1a. We report that only certain peptides were found to be active. Whereas PR1a induction was consistently correlated with induction of necrosis, four peptides were observed to induce only str 246C expression without necrosis, which led to differentiate the defense-Eliciting sites from the necrotic sites. From the structure-function relationship thus obtained, two different defense pathways were inferred to be independently induced by Elicitins.

  • Crystal structure of a fungal elicitor secreted by Phytophthora cryptogea, a member of a novel class of plant necrotic proteins
    Structure, 1996
    Co-Authors: Guillaume Boissy, Jean-claude Huet, Jean-claude Pernollet, Eric De La Fortelle, Richard A. Kahn, Gérard Bricogne, Simone Brunie
    Abstract:

    Abstract Background: Elicitins form a novel class of plant necrotic proteins which are secreted by Phytophthora and Pythium fungi , parasites of many economically important crops. These proteins induce leaf necrosis in infected plants and elicit an incompatible hypersensitive-like reaction, leading to the development of a systemic acquired resistance against a range of fungal and bacterial plant pathogens. No crystal structures of this class of protein are available. The crystal structure determination of β -cryptogein (CRY), secreted by Phytophthora cryptogea , was undertaken to identify structural features important for the necrotic activity of Elicitins. Results: The structure of CRY was determined using the multiwavelength anomalous diffraction technique and refined to 2.2 a resolution. The overall structure has a novel fold consisting of six α helices and a beak-like motif, whose sequence is highly conserved within the family, composed of an antiparallel two-stranded β sheet and an Ω loop. This motif is assumed to be a major recognition site for a putative receptor and/or ligand. Two other distinct binding sites seem to be correlated to the level of necrotic activity of Elicitins. Conclusions: The determination of the crystal structure of a member of the Elicitin family may make it possible to separate the activity that causes leaf necrosis from that inducing systemic acquired resistance to pathogens, making it feasible to engineer a non-toxic Elicitin that only elicits plant defences. Such studies should aid the development of non-toxic agricultural pest control.

  • chemical synthesis expression and mutagenesis of a gene encoding β cryptogein an Elicitin produced by phytophthora cryptogea
    Plant Molecular Biology, 1995
    Co-Authors: Michael J Odonohue, Jean-claude Huet, H. Gousseau, David Tepfer, Jean-claude Pernollet
    Abstract:

    Elicitins are 10 kDa holoproteins secreted by Phytophthora fungi, that elicit an incompatible hypersensitive reaction, leading to resistance against fungal and bacterial plant pathogens. Comparison of primary sequences of α-Elicitins and β-Elicitins indicated several potential necrotic activity-determining residues. All of the highly necrotic β-Elicitins have a hydrophilic residue (usually lysine) at position 13, whereas in the less necrotic α-Elicitins this residue is replaced by a valine. Here, we report the synthesis and expression of a gene encoding a highly necrotic Elicitin, β-cryptogein, and we show that the substitution of Lys-13 of this recombinant protein by a valine leads to a drastic alteration to the necrotic activity of the recombinant protein.

Sophien Kamoun - One of the best experts on this subject based on the ideXlab platform.

  • Agroinfection-based high-throughput screening reveals specific recognition of INF Elicitins in Solanum
    Molecular plant pathology, 2006
    Co-Authors: Vivianne G A A Vleeshouwers, Francine Govers, Richard G. F. Visser, Jan‐david Driesprong, Lars G. Kamphuis, Trudy Torto-alalibo, Klaas A. E. Van 't Slot, Evert Jacobsen, Sophien Kamoun
    Abstract:

    SUMMARY We adapted and optimized the use of the Agrobacterium tumefaciens binary PVX expression system (PVX agroinfection) to screen Solanum plants for response to pathogen elicitors and applied the assay to identify a total of 11 clones of Solanum huancabambense and Solanum microdontum, out of 31 species tested, that respond to the Elicitins INF1, INF2A and INF2B of Phytophthora infestans. Prior to this study, response to INF Elicitins was only known in Nicotiana spp. within the Solanaceae. The identified S. huancabambense and S. microdontum clones also exhibited hypersensitivity-like cell death following infiltration with purified recombinant INF1, INF2A and INF2B, thereby validating the screening protocol. Comparison of INF Elicitin activity revealed that Nicotiana plants responded to significantly lower concentrations than Solanum, suggesting variable levels of sensitivity to INF Elicitins. We exploited natural variation in response to INF Elicitins in the identified Solanum accessions to evaluate the relationship between INF recognition and late blight resistance. Interestingly, several INF-responsive Solanum plants were susceptible to P. infestans. Also, an S. microdontum xSolanum tuberosum (potato) population that segregates for INF response was generated but failed to identify a measurable contribution of INF response to resistance. These results suggest that in Solanum, INF Elicitins are recognized as general elicitors and do not have a measurable contribution to disease resistance.

  • differences in intensity and specificity of hypersensitive response induction in nicotiana spp by inf1 inf2a and inf2b of phytophthora infestans
    Molecular Plant-microbe Interactions, 2005
    Co-Authors: Edgar Huitema, Vivianne G A A Vleeshouwers, Cahit Cakir, Sophien Kamoun, Francine Govers
    Abstract:

    Elicitins form a family of structurally related proteins that induce the hypersensitive response (HR) in plants, particularly Nicotiana spp. The Elicitin family is composed of several classes. Most species of the plant-pathogenic oomycete genus Phytophthora produce the well-characterized 10-kDa canonical Elicitins (class I), such as INF1 of the potato and tomato pathogen Phytophthora infestans. Two genes, inf2A and inf2B, encoding a distinct class (class III) of Elicitinlike proteins, also occur in P. infestans. Unlike secreted class I Elicitins, class III Elicitins are thought to be cell-surface-anchored polypeptides. Molecular characterization of the inf2 genes indicated that they are widespread in Phytophthora spp. and occur as a small gene family. In addition, Southern blot and Northern blot hybridizations using gene-specific probes showed that inf2A and inf2B genes and transcripts can be detected in 17 different P. infestans isolates. Functional secreted expression in plant cells of the Elicitin domain of the inf1 and inf2 genes was conducted using a binary Potato virus X (PVX) vector (agroinfection) and Agrobacterium tumefaciens transient transformation assays (agroinfiltration), and resulted in HR-like necrotic symptoms and induction of defense response genes in tobacco. However, comparative analyses of elicitor activity of INF1, INF2A, and INF2B revealed significant differences in intensity, specificity, and consistency of HR induction. Whereas INF1 induced the HR in Nicotiana benthamiana, INF2A induced weak symptoms and INF2B induced no symptoms on this plant. Nonetheless, similar to INF1, HR induction by INF2A in N. benthamiana required the ubiquitin ligase-associated protein SGT1. Overall, these results suggest that variation in the resistance of Nicotiana spp. to P. infestans is shadowed by variation in the response to INF Elicitins. The ability of tobacco, but not N. benthamiana, to respond to INF2B could explain differences in resistance to P. infestans observed for these two species.

  • Variation in structure and activity among Elicitins from Phytophthora sojae.
    Molecular plant pathology, 2003
    Co-Authors: Dinah Qutob, Edgar Huitema, Mark Gijzen, Sophien Kamoun
    Abstract:

    SUMMARY Transcripts encoding Elicitin-like protein domains were identified from similarity searches of Phytophthora sojae expressed sequence tags and were characterized with regard to molecular structure and elicitor activity. The P. sojae Elicitin family consists of at least nine genes with products similar to previously described Elicitins (SOJA-2, SOJB, SOJ2, SOJ3, SOJ5, SOJ6 and SOJ7) or highly diverged from known sequences (SOJX and SOJY). The predicted structural features of seven (SOJA-2, SOJB, SOJ2, SOJ3, SOJ6, SOJX and SOJY) of the Elicitin preproteins were compared. All of the predicted Elicitins possess a leader signal sequence and a core Elicitin domain. Five (SOJ2, SOJ3, SOJ6, SOJX and SOJY) of the characterized Elicitins also contain a variable C-terminal region. In addition, SOJX and SOJY contain a C-terminal hydrophobic membrane-spanning domain. An analysis of expression patterns of the Elicitin transcripts showed that SOJA-2, SOJB, SOJ2, SOJ3 and SOJ6 were expressed in axenically grown mycelia and during infection, but not in zoospores. In contrast, SOJX and SOJY were predominantly and specifically expressed in zoospores. Selected Elicitin domains were also tested for the induction of the hypersensitive response (HR) in Nicotiana spp. All of the Elicitin protein domains tested induced the HR, except for SOJX and SOJY. Overall, the results show that the P. sojae Elicitin gene family is large and diverse, with varying patterns of expression and HR-inducing activity.

  • independent pathways leading to apoptotic cell death oxidative burst and defense gene expression in response to Elicitin in tobacco cell suspension culture
    FEBS Journal, 2000
    Co-Authors: Michiko Sasabe, Sophien Kamoun, Francine Govers, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose, Kasumi Takeuchi, Tetsuji Yamada
    Abstract:

    We characterized pharmacologically the hypersensitive cell death of tobacco BY-2 cells that followed treatments with Escherichia coli preparations of INF1, the major secreted Elicitin of the late blight pathogen Phytophthora infestans. INF1 Elicitin treatments resulted in fragmentation and 180 bp laddering of tobacco DNA as early as 3 h post-treatment. INF1 Elicitin also induced rapid accumulation of H2O2 typical of oxidative burst, and the expression of defense genes such as phenylalanine ammonia-lyase (PAL) gene at 1 h and 3 h after Elicitin treatment, respectively. To investigate the involvement of the oxidative burst and/or the expression of defense genes in the signal transduction pathways leading to hypersensitive cell death, we analyzed the effect of several chemical inhibitors of signal transduction pathways on the various responses. The results indicated that (a) the cell death required serine proteases, Ca2+ and protein kinases, (b) the oxidative burst was involved in Ca2+ and protein kinase mediated pathways, but Elicitin-induced AOS was neither necessary nor sufficient for cell death and PAL gene expression, and (c) the signaling pathway of PAL gene expression required protein kinases. These results suggest that the three signal transduction pathways leading to cell death, oxidative burst and expression of defense genes branch in the early stages that follow Elicitin recognition by tobacco cells.

  • initial assessment of gene diversity for the oomycete pathogen phytophthora infestans based on expressed sequences
    Fungal Genetics and Biology, 1999
    Co-Authors: Sophien Kamoun, Peter Hraber, Bruno W S Sobral, Donald L Nuss, Francine Govers
    Abstract:

    A total of 1000 expressed sequence tags (ESTs) corresponding to 760 unique sequence sets were identified using random sequencing of clones from a cDNA library constructed from mycelial RNA of Phytophthora infestans. A number of software programs, represented by a relational database and an analysis pipeline, were developed for the automated analysis and storage of the EST sequence data. A set of 419 nonredundant sequences, which correspond to a total of 632 ESTs (63.2%), were identified as showing significant matches to sequences deposited in public databases. A putative cellular identity and role was assigned to all 419 sequences. All major functional categories were represented by at least several ESTs. Four novel cDNAs containing sequences related to Elicitins, a family of structurally related proteins that induce the hypersensitive response and condition avirulence of P. infestans on Nicotiana plants, were among the most notable genes identified. Two of these Elicitin-like cDNAs were among the most abundant cDNAs examined. The set also contained several ESTs with high sequence similarity to unique plant genes.

Pierre Ricci - One of the best experts on this subject based on the ideXlab platform.

  • Elicitin Genes Expressed In Vitro by Certain Tobacco Isolates of Phytophthora parasitica Are Down Regulated During Compatible Interactions
    Molecular Plant-Microbe Interactions, 2001
    Co-Authors: F Colas, Pierre Ricci, Franck Panabières, Paul Venard, Harald Keller, Sandrine Conrod, Virginie Colas
    Abstract:

    Phytophthora spp. secrete proteins called Elicitins in vitro that can specifically induce hypersensitive response and systemic acquired resistance in tobacco. In Phytophthora parasitica, the causal agent of black shank, most isolates virulent on tobacco are unable to produce Elicitins in vitro. Recently, however, a few Elicitin-producing P. parasitica strains virulent on tobacco have been isolated. We investigated the potential diversity of Elicitin genes in P. parasitica isolates belonging to different genotypes and with various virulence levels toward tobacco as well as Elicitin expression pattern in vitro and in planta. Although Elicitins are encoded by a multigene family, parAl is the main Elicitin gene expressed. This gene is highly conserved among isolates, regardless of the Elicitin production and virulence levels toward tobacco. Moreover, we show that Elicitin-producing P. parasitica isolates virulent on tobacco down regulate parAl expression during compatible interactions, whichever host plant is tested. Conversely, one Elicitin-producing P. parasitica isolate that is pathogenic on tomato and avirulent on tobacco still expresses parAl in the compatible interaction. Therefore, some P. parasitica isolates may evade tobacco recognition by down regulating parA1 in planta. The in planta down regulation of parA1 may constitute a suitable mechanism for P. parasitica to infect tobacco without deleterious consequences for the pathogen.

  • Heterologous expression of a basic Elicitin from Phytophthora cryptogea in Phytophthora infestans increases its ability to cause leaf necrosis in tobacco
    Microbiology, 1998
    Co-Authors: Franck Panabières, Michel Ponchet, Pierre Ricci, Paul R. J. Birch, Shiela E. Unkles, Isabelle Lacourt, Paul Venard, Harald Keller, Valérie Allasia, James M. Duncan
    Abstract:

    Summary: The cry-b sequence, encoding a basic Elicitin (cryptogein B) from Phytophthora cryptogea, was co-transformed into Phytophthora infestans. The copy number of the cry-b sequence varied in co-transformants. Nevertheless, in all cases the alien Elicitin gene was transcribed, translated and the protein secreted in vitro from such transformants. Moreover, the secreted cryptogein B from P. infestans co-transformants increased their ability to cause a hypersensitive-response-like necrosis of tobacco leaves. It was thus concluded that the transfer of a single gene encoding a basic Elicitin from one Phytophthora species to another can dramatically alter the phenotypic interaction of the transformed species with tobacco.

  • Comparison of Binding Properties and Early Biological Effects of Elicitins in Tobacco Cells
    Plant physiology, 1998
    Co-Authors: Stéphane Bourque, Michel Ponchet, Pierre Ricci, Marie-noëlle Binet, Alain Pugin, Angela Lebrun-garcia
    Abstract:

    Elicitins are a family of small proteins secreted by Phytophthora species that have a high degree of homology and elicit defense reactions in tobacco (Nicotiana tabacum). They display acidic or basic characteristics, the acidic Elicitins being less efficient in inducing plant necrosis. In this study we compared the binding properties of four Elicitins (two basic and two acidic) and early-induced signal transduction events (Ca2+ influx, extracellular medium alkalinization, and active oxygen species production). The affinity for tobacco plasma membrane-binding sites and the number of binding sites were similar for all four Elicitins. Furthermore, Elicitins compete with one another for binding sites, suggesting that they interact with the same receptor. The four Elicitins induced Ca2+ influx, extracellular medium alkalinization, and the production of active oxygen species in tobacco cell suspensions, but the intensity and kinetics of these effects were different from one Elicitin to another. As a general observation the concentrations that induce similar levels of biological activities were lower for basic Elicitins (with the exception of cinnamomin-induced Ca2+ uptake). The qualitative similarity of early events induced by Elicitins indicates a common transduction scheme, whereas fine signal transduction tuning is different in each Elicitin.

  • Sesquiterpene cyclase is not a determining factor for elicitor and pathogen induced capsidiol accumulation in tobacco
    Planta, 1998
    Co-Authors: Harald Keller, Michel Ponchet, Pierre Ricci, Pierre Czernic, Paul Henri Ducrot, Kyoungwhan Back, Joseph Chappell, Yves Marco
    Abstract:

    The induction of sesquiterpene cyclase, a key phytoalexin biosynthetic enzyme, and the accumulation of phytoalexins in relation to the induction of a hypersensitive response (HR) and cell necrosis in tobac- co (Nicotiana tabacum L.) were investigated. When tobacco leaves were inoculated with virulent or avirulent isolates of Ralstonia solanacearum, steady-state levels of mRNA complementary to cDNA of the sensitivity- related (sts) gene str319 were dramatically induced. This cDNA clone is greater than 90% homologous with a gene coding for 5-epi-aristolochene synthase (EAS), previously described as a branch-point enzyme regulat- ing the synthesis of capsidiol, the major sesquiterpenoid phytoalexin found in tobacco. Accumulation of EAS transcripts in leaves after inoculation with virulent and avirulent strains of R. solanacearum, or after treatment with necrotizing or non-necrotizing Elicitins was rapid but transient, and restricted to the site of infiltration. Two highly similar sesquiterpene cyclase activities, 5-epi- aristolochene synthase and a vetispiradiene synthase-like activity, were found in extracts of Elicitin-challenged and R. solanacearum-inoculated tobacco. Under all condi- tions tested, the induction of cyclase activity was closely correlated with induction of the cyclase mRNA level. In contrast, high levels of capsidiol were found only after treatment with the necrosis-inducing Elicitin cryptogein, or after infiltration with HR-inducing bacterial strains. Low levels of capsidiol did accumulate after application of capsicein, an Elicitin that induces little or no necrosis on tobacco, or after infection with a virulent bacterium. Hence, capsidiol accumulation, not 5-epi-aristolochene synthase gene expression or total sesquiterpene cyclase enzyme activity, appears to be a good marker for the HR of tobacco.

  • Characterization of border species among Pythiaceae: several Pythium isolates produce Elicitins, typical proteins from Phytophthora spp.
    Mycological Research, 1997
    Co-Authors: Franck Panabières, Michel Ponchet, Valérie Allasia, L. Cardin, Pierre Ricci
    Abstract:

    Elicitins, holoproteins which act as inducers of hypersensitivity on tobacco, were considered as a characteristic of Phytophthora. They are also produced, along with glycosylated isoforms, by three species belonging to the related genus Pythium, Py. vexans, Py. oedochilum and Py. marsipium, while other Pythium species do not possess such proteins. Various Elicitin-like sequences were determined, bringing novel features to the Elicitin family, such as an histidine residue and C-terminal extensions on the deduced peptide sequences. As the unique Elicitin content of these species supports a distinct location among Pythiaceae, we suggest the separation of vexans, Py. oedochilum and Py. marsipium from Pythium and consider them as linking species between Phytophthora and Pythium.