62 results on '"Sainsbury Laboratory"'
Search Results
2. Fortifying Plant Armor: CESA3 Enhances Arabidopsis thaliana 's Defense Against Bacterial Wilt Under Heat Stress.
- Author
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Singh J and Tiwari M
- Subjects
- Gene Expression Regulation, Plant, Stress, Physiological, Arabidopsis microbiology, Arabidopsis genetics, Arabidopsis immunology, Arabidopsis physiology, Arabidopsis Proteins genetics, Arabidopsis Proteins metabolism, Hot Temperature, Plant Diseases microbiology, Plant Diseases immunology
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2024
- Full Text
- View/download PDF
3. Burkholderia Tolerate Nature's Tearful Defense in the Allium Chemical Arms Race.
- Author
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Lovelace AH
- Subjects
- Plant Diseases microbiology, Allium, Burkholderia
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2024
- Full Text
- View/download PDF
4. Deciphering Molecular Orchestrations: XooClp Integrates Environmental Sensing and Virulence Regulation in Xanthomonas oryzae pv. oryzae .
- Author
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Sankari S and Lovelace AH
- Subjects
- Virulence, Oryza microbiology, Xanthomonas pathogenicity, Xanthomonas genetics, Xanthomonas physiology, Plant Diseases microbiology, Bacterial Proteins metabolism, Bacterial Proteins genetics, Gene Expression Regulation, Bacterial
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2024
- Full Text
- View/download PDF
5. Additive and Specific Effects of Elicitor Treatments on the Metabolic Profile of Arabidopsis thaliana .
- Author
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Cabre L, Jing L, Makechemu M, Heluin K, El Khamlichi S, Leprince J, Kiefer-Meyer MC, Pluchon S, Mollet JC, Zipfel C, and Nguema-Ona E
- Subjects
- Plant Immunity, Pathogen-Associated Molecular Pattern Molecules metabolism, Metabolome, Pseudomonas syringae physiology, Plant Diseases microbiology, Gene Expression Regulation, Plant, Arabidopsis microbiology, Chitosan pharmacology, Arabidopsis Proteins genetics, Arabidopsis Proteins metabolism
- Abstract
Several elicitors of plant defense have been identified and numerous efforts to use them in the field have been made. Exogenous elicitor treatments mimic the in planta activation of pattern-triggered immunity (PTI), which relies on the perception of pathogen-associated molecular patterns (PAMPs) such as bacterial flg22 or fungal chitins. Early transcriptional responses to distinct PAMPs are mostly overlapping, regardless of the elicitor being used. However, it remains poorly known if the same patterns are observed for metabolites and proteins produced later during PTI. In addition, little is known about the impact of a combination of elicitors on PTI and the level of induced resistance to pathogens. Here, we monitored Arabidopsis thaliana resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 ( Pto DC3000) following application of flg22 and chitosan elicitors, used individually or in combination. A slight, but not statistically significant increase in induced resistance was observed when the elicitors were applied together when compared with individual treatments. We investigated the effect of these treatments on the metabolome by using an untargeted analysis. We found that the combination of flg22 and chitosan impacted a higher number of metabolites and deregulated specific metabolic pathways compared with the elicitors individually. These results contribute to a better understanding of plant responses to elicitors, which might help better rationalize their use in the field. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license., Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2024
- Full Text
- View/download PDF
6. A Tale of Two Functions: How the Effector PsCRN108 Hijacks Plant Transcription Factors to Suppress Immunity.
- Author
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Lovelace AH
- Subjects
- Amino Acid Sequence, Plant Diseases, Plant Immunity genetics, Transcription Factors genetics, Plants genetics
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2024
- Full Text
- View/download PDF
7. Unveiling the Molecular Arsenal: Identification and Characterization of Sphaerulina musiva Effectors Targeting Populus Genotypes.
- Author
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Sankari S and Lovelace AH
- Subjects
- Disease Resistance genetics, Genotype, Plant Diseases genetics, Populus genetics, Ascomycota genetics
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
8. ROS, Moss, and a Rossmann Fold Protein: Identification of a Key Signaling Component for Plant Immunity.
- Author
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Lovelace AH
- Subjects
- Reactive Oxygen Species, Plant Immunity, Proteins, Signal Transduction
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
9. Sowing Symbiotic Success: Defining the Role of O-Antigen Polymerase in a Legume-Rhizobia Interaction.
- Author
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Tiwari M and Lovelace AH
- Subjects
- Symbiosis, Nitrogen Fixation, Root Nodules, Plant, Fabaceae, Rhizobium, Hexosyltransferases
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
10. Unraveling the Molecular Arms Race: Grapevine Fanleaf Virus Proteins as Suppressors of Plant Antiviral Silencing Pathways.
- Author
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Sankari S and Lovelace AH
- Subjects
- Plants, RNA Interference, Antiviral Agents, Plant Diseases, Nepovirus, Plant Viruses genetics
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
11. Unraveling the Function of FgNls1, a Fusarium graminearum Effector Critical for Full Virulence on Wheat.
- Author
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Tiwari M and Lovelace AH
- Subjects
- Virulence, Triticum, Fusarium
- Abstract
Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
12. FIRE Mimics a 14-3-3-Binding Motif to Promote Phytophthora palmivora Infection.
- Author
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Evangelisti E, Guyon A, Shenhav L, and Schornack S
- Subjects
- 14-3-3 Proteins, Plants, Plant Diseases, Phytophthora
- Abstract
The oomycete Phytophthora palmivora infects a wide range of tropical crops worldwide. Like other filamentous plant pathogens, it secretes effectors to colonize plant tissues. Here, we characterize FIRE, an RXLR effector that contains a canonical mode I 14-3-3 phospho-sensor-binding motif that is conserved in effectors of several Phytophthora species. FIRE is phosphorylated in planta and interacts with multiple 14-3-3 proteins. Binding is sensitive to the R18 14-3-3 inhibitor. FIRE promotes plant susceptibility and co-localizes with its target around haustoria. This work uncovers a new type of oomycete effector target mechanism. It demonstrates that substrate mimicry for 14-3-3 proteins is a cross-kingdom effector strategy used by both prokaryotic and eukaryotic plant pathogens to suppress host immunity. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license., Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
13. Playing with FIRE: How an RXLR Oomycete Effector Fuels Disease by Hijacking 14-3-3 Proteins.
- Author
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Tiwari M and Lovelace AH
- Subjects
- Amino Acid Motifs, Plants, Plant Diseases, 14-3-3 Proteins genetics, Phytophthora infestans
- Abstract
The plant pathogen Phytophthora palmivora causes rot disease in several monocots and dicots. The plant 14-3-3 proteins are targets of different types of effector molecules secreted by the pathogens. An RXLR-type effector FIRE (14-3-3 interacting RXLR effector) and its target 14-3-3 proteins that localize to haustoria have been identified, pointing to a potential site of interaction. The pathogen hijacks the host 14-3-3 proteins through FIRE-mediated interaction and lowers the immunity for disease progression. The effector FIRE and 14-3-3 interaction deciphered in this study could pave the way for genetic modification of plants with altered 14-3-3 protein for broad host resistance. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license., Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
14. An Improved Assembly of the Albugo candida Ac2V Genome Reveals the Expansion of the "CCG" Class of Effectors.
- Author
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Furzer OJ, Cevik V, Fairhead S, Bailey K, Redkar A, Schudoma C, MacLean D, Holub EB, and Jones JDG
- Subjects
- Candida genetics, Genome, Plant Diseases, Brassicaceae, Oomycetes genetics
- Abstract
Albugo candida is an obligate oomycete pathogen that infects many plants in the Brassicaceae family. We resequenced the genome of isolate Ac2V using PacBio long reads and constructed an assembly augmented by Illumina reads. The Ac2VPB genome assembly is 10% larger and more contiguous compared with a previous version. Our annotation of the new assembly, aided by RNA-sequencing information, revealed a 175% expansion (40 to 110) in the CHxC effector class, which we redefined as "CCG" based on motif analysis. This class of effectors consist of arrays of phylogenetically related paralogs residing in gene sparse regions, and shows signatures of positive selection and presence/absence polymorphism. This work provides a resource that allows the dissection of the genomic components underlying A. candida adaptation and, particularly, the role of CCG effectors in virulence and avirulence on different hosts.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
- Published
- 2022
- Full Text
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15. Lumi-Map, a Real-Time Luciferase Bioluminescence Screen of Mutants Combined with MutMap, Reveals Arabidopsis Genes Involved in PAMP-Triggered Immunity.
- Author
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Kato H, Onai K, Abe A, Shimizu M, Takagi H, Tateda C, Utsushi H, Singkarabanit-Ogawa S, Kitakura S, Ono E, Zipfel C, Takano Y, Ishiura M, and Terauchi R
- Subjects
- Gene Expression Regulation, Plant, Luciferases metabolism, Pathogen-Associated Molecular Pattern Molecules, Arabidopsis genetics, Arabidopsis immunology, Arabidopsis Proteins genetics, Arabidopsis Proteins metabolism, Genetic Testing methods, Mutation, Plant Immunity genetics
- Abstract
Plants recognize pathogen-associated molecular patterns (PAMPs) to activate PAMP-triggered immunity (PTI). However, our knowledge of PTI signaling remains limited. In this report, we introduce Lumi-Map, a high-throughput platform for identifying causative single-nucleotide polymorphisms (SNPs) for studying PTI signaling components. In Lumi-Map, a transgenic reporter plant line is produced that contains a firefly luciferase ( LUC ) gene driven by a defense gene promoter, which generates luminescence upon PAMP treatment. The line is mutagenized and the mutants with altered luminescence patterns are screened by a high-throughput real-time bioluminescence monitoring system. Selected mutants are subjected to MutMap analysis, a whole-genome sequencing-based method of rapid mutation identification, to identify the causative SNP responsible for the luminescence pattern change. We generated nine transgenic Arabidopsis reporter lines expressing the LUC gene fused to multiple promoter sequences of defense-related genes. These lines generate luminescence upon activation of FLAGELLIN-SENSING 2 (FLS2) by flg22, a PAMP derived from bacterial flagellin. We selected the WRKY29 -promoter reporter line to identify mutants in the signaling pathway downstream of FLS2 . After screening 24,000 ethylmethanesulfonate-induced mutants of the reporter line, we isolated 22 mutants with altered WRKY29 expression upon flg22 treatment (abbreviated as awf mutants). Although five flg22-insensitive awf mutants harbored mutations in FLS2 itself, Lumi-Map revealed three genes not previously associated with PTI. Lumi-Map has the potential to identify novel PAMPs and their receptors as well as signaling components downstream of the receptors.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
- Published
- 2020
- Full Text
- View/download PDF
16. What is the Molecular Basis of Nonhost Resistance?
- Author
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Panstruga R and Moscou MJ
- Subjects
- Host Specificity, Plants, Disease Resistance genetics, Plant Diseases, Plant Immunity
- Abstract
This article is part of the Top 10 Unanswered Questions in MPMI invited review series.Nonhost resistance is typically considered the ability of a plant species to repel all attempts of a pathogen species to colonize it and reproduce on it. Based on this common definition, nonhost resistance is presumed to be very durable and, thus, of great interest for its potential use in agriculture. Despite considerable research efforts, the molecular basis of this type of plant immunity remains nebulous. We here stress the fact that "nonhost resistance" is a phenomenological rather than a mechanistic concept that comprises more facets than typically considered. We further argue that nonhost resistance essentially relies on the very same genes and pathways as other types of plant immunity, of which some may act as bottlenecks for particular pathogens on a given plant species or under certain conditions. Thus, in our view, the frequently used term "nonhost genes" is misleading and should be avoided. Depending on the plant-pathogen combination, nonhost resistance may involve the recognition of pathogen effectors by host immune sensor proteins, which might give rise to host shifts or host range expansions due to evolutionary-conditioned gains and losses in respective armories. Thus, the extent of nonhost resistance also defines pathogen host ranges. In some instances, immune-related genes can be transferred across plant species to boost defense, resulting in augmented disease resistance. We discuss future routes for deepening our understanding of nonhost resistance and argue that the confusing term "nonhost resistance" should be used more cautiously in the light of a holistic view of plant immunity.
- Published
- 2020
- Full Text
- View/download PDF
17. Cloning of the Rice Xo1 Resistance Gene and Interaction of the Xo1 Protein with the Defense-Suppressing Xanthomonas Effector Tal2h.
- Author
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Read AC, Hutin M, Moscou MJ, Rinaldi FC, and Bogdanove AJ
- Subjects
- Cloning, Molecular, Humans, Plant Diseases microbiology, Disease Resistance genetics, Oryza genetics, Oryza microbiology, Plant Diseases genetics, Plant Proteins genetics, Xanthomonas pathogenicity
- Abstract
The Xo1 locus in the heirloom rice variety Carolina Gold Select confers resistance to bacterial leaf streak and bacterial blight, caused by Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae , respectively. Resistance is triggered by pathogen-delivered transcription activator-like effectors (TALEs) independent of their ability to activate transcription and is suppressed by truncated variants called truncTALEs, common among Asian strains. By transformation of the susceptible variety Nipponbare, we show that one of 14 nucleotide-binding, leucine-rich repeat (NLR) protein genes at the locus, with a zinc finger BED domain, is the Xo1 gene. Analyses of published transcriptomes revealed that the Xo1 -mediated response is more similar to those mediated by two other NLR resistance genes than it is to the response associated with TALE-specific transcriptional activation of the executor resistance gene Xa23 and that a truncTALE dampens or abolishes activation of defense-associated genes by Xo1 . In Nicotiana benthamiana leaves, fluorescently tagged Xo1 protein, like TALEs and truncTALEs, localized to the nucleus. And endogenous Xo1 specifically coimmunoprecipitated from rice leaves with a pathogen-delivered, epitope-tagged truncTALE. These observations suggest that suppression of Xo1-function by truncTALEs occurs through direct or indirect physical interaction. They further suggest that effector coimmunoprecipitation may be effective for identifying or characterizing other resistance genes.
- Published
- 2020
- Full Text
- View/download PDF
18. A Clone Resource of Magnaporthe oryzae Effectors That Share Sequence and Structural Similarities Across Host-Specific Lineages.
- Author
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Petit-Houdenot Y, Langner T, Harant A, Win J, and Kamoun S
- Subjects
- Oryza microbiology, Poaceae microbiology, Magnaporthe genetics, Magnaporthe pathogenicity, Plant Diseases microbiology
- Abstract
The blast fungus Magnaporthe oryzae (syn. Pyricularia oryzae ) is a destructive plant pathogen that can infect about 50 species of both wild and cultivated grasses, including important crops such as rice and wheat. M. oryzae is composed of genetically differentiated lineages that tend to infect specific host genera. To date, most studies of M. oryzae effectors have focused on the rice-infecting lineage. We describe a clone resource of 195 effectors of Magnaporthe species predicted from all the major host-specific lineages. These clones are freely available as Golden Gate-compatible entry plasmids. Our aim is to provide the community with an open source effector clone library to be used in a variety of functional studies. We hope that this resource will encourage studies of M. oryzae effectors on diverse host species.
- Published
- 2020
- Full Text
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19. The Genome of Peronospora belbahrii Reveals High Heterozygosity, a Low Number of Canonical Effectors, and TC-Rich Promoters.
- Author
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Thines M, Sharma R, Rodenburg SYA, Gogleva A, Judelson HS, Xia X, van den Hoogen J, Kitner M, Klein J, Neilen M, de Ridder D, Seidl MF, van den Ackerveken G, Govers F, Schornack S, and Studholme DJ
- Subjects
- Genomics, Plant Diseases microbiology, Promoter Regions, Genetic, Genome, Mitochondrial, Peronospora genetics
- Abstract
Along with Plasmopara destructor , Peronosopora belbahrii has arguably been the economically most important newly emerging downy mildew pathogen of the past two decades. Originating from Africa, it has started devastating basil production throughout the world, most likely due to the distribution of infested seed material. Here, we present the genome of this pathogen and results from comparisons of its genomic features to other oomycetes. The assembly of the nuclear genome was around 35.4 Mbp in length, with an N
50 scaffold length of around 248 kbp and an L50 scaffold count of 46. The circular mitochondrial genome consisted of around 40.1 kbp. From the repeat-masked genome, 9,049 protein-coding genes were predicted, out of which 335 were predicted to have extracellular functions, representing the smallest secretome so far found in peronosporalean oomycetes. About 16% of the genome consists of repetitive sequences, and, based on simple sequence repeat regions, we provide a set of microsatellites that could be used for population genetic studies of P. belbahrii . P. belbahrii has undergone a high degree of convergent evolution with other obligate parasitic pathogen groups, reflecting its obligate biotrophic lifestyle. Features of its secretome, signaling networks, and promoters are presented, and some patterns are hypothesized to reflect the high degree of host specificity in Peronospora species. In addition, we suggest the presence of additional virulence factors apart from classical effector classes that are promising candidates for future functional studies.- Published
- 2020
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20. The Zymoseptoria tritici ORFeome: A Functional Genomics Community Resource.
- Author
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Chaudhari Y, Cairns TC, Sidhu Y, Attah V, Thomas G, Csukai M, Talbot NJ, Studholme DJ, and Haynes K
- Subjects
- Triticum microbiology, Ascomycota genetics, Genome, Fungal genetics, Genomic Library, Genomics methods, Open Reading Frames genetics
- Abstract
Libraries of protein-encoding sequences can be generated by identification of open reading frames (ORFs) from a genome of choice that are then assembled into collections of plasmids termed ORFeome libraries. These represent powerful resources to facilitate functional genomic characterization of genes and their encoded products. Here, we report the generation of an ORFeome for Zymoseptoria tritici , which causes the most serious disease of wheat in temperate regions of the world. We screened the genome of strain IP0323 for high confidence gene models, identifying 4,075 candidates from 10,933 predicted genes. These were amplified from genomic DNA, were cloned into the Gateway entry vector pDONR207, and were sequenced, providing a total of 3,022 quality-controlled plasmids. The ORFeome includes genes predicted to encode effectors ( n = 410) and secondary metabolite biosynthetic proteins ( n = 171) in addition to genes residing at dispensable chromosomes ( n = 122) or those that are preferentially expressed during plant infection ( n = 527). The ORFeome plasmid library is compatible with our previously developed suite of Gateway destination vectors, which have various combinations of promoters, selection markers, and epitope tags. The Z. tritici ORFeome constitutes a powerful resource for functional genomics and offers unparalleled opportunities to understand the biology of Z. tritici .[Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
- Published
- 2019
- Full Text
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21. Widely Conserved Attenuation of Plant MAMP-Induced Calcium Influx by Bacteria Depends on Multiple Virulence Factors and May Involve Desensitization of Host Pattern Recognition Receptors.
- Author
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Lammertz M, Kuhn H, Pfeilmeier S, Malone J, Zipfel C, Kwaaitaal M, Lin NC, Kvitko BH, and Panstruga R
- Subjects
- Plant Diseases, Receptors, Pattern Recognition metabolism, Arabidopsis metabolism, Arabidopsis microbiology, Calcium metabolism, Host-Pathogen Interactions, Pseudomonas syringae physiology, Virulence Factors
- Abstract
Successful pathogens must efficiently defeat or delay host immune responses, including those triggered by release or exposure of microbe-associated molecular patterns (MAMPs). Knowledge of the molecular details leading to this phenomenon in genuine plant-pathogen interactions is still scarce. We took advantage of the well-established Arabidopsis thaliana - Pseudomonas syringae pv. tomato DC3000 pathosystem to explore the molecular prerequisites for the suppression of MAMP-triggered host defense by the bacterial invader. Using a transgenic Arabidopsis line expressing the calcium sensor apoaequorin, we discovered that strain DC3000 colonization results in a complete inhibition of MAMP-induced cytosolic calcium influx, a key event of immediate-early host immune signaling. A range of further plant-associated bacterial species is also able to prevent, either partially or fully, the MAMP-triggered cytosolic calcium pattern. Genetic analysis revealed that this suppressive effect partially relies on the bacterial type III secretion system (T3SS) but cannot be attributed to individual members of the currently known arsenal of strain DC3000 effector proteins. Although the phytotoxin coronatine and bacterial flagellin individually are dispensable for the effective inhibition of MAMP-induced calcium signatures, they contribute to the attenuation of calcium influx in the absence of the T3SS. Our findings suggest that the capacity to interfere with early plant immune responses is a widespread ability among plant-associated bacteria that, at least in strain DC3000, requires the combinatorial effect of multiple virulence determinants. This may also include the desensitization of host pattern recognition receptors by the prolonged exposure to MAMPs during bacterial pathogenesis.
- Published
- 2019
- Full Text
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22. The ELR-SOBIR1 Complex Functions as a Two-Component Receptor-Like Kinase to Mount Defense Against Phytophthora infestans.
- Author
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Domazakis E, Wouters D, Visser RGF, Kamoun S, Joosten MHAJ, and Vleeshouwers VGAA
- Subjects
- Cell Death, Gene Expression Regulation, Plant, Plant Diseases microbiology, Plants, Genetically Modified, Protein Domains, Nicotiana genetics, Nicotiana metabolism, Nicotiana microbiology, Phosphotransferases metabolism, Phytophthora infestans, Plant Proteins metabolism, Solanum metabolism, Solanum microbiology
- Abstract
The ELICITIN RESPONSE protein (ELR) from Solanum microdontum can recognize INF1 elicitin of Phytophthora infestans and trigger defense responses. ELR is a receptor-like protein (RLP) that lacks a cytoplasmic signaling domain and is anticipated to require interaction with a signaling-competent receptor-like kinase. SUPPRESSOR OF BIR1-1 (SOBIR1) has been proposed as a general interactor for RLPs involved in immunity and, as such, is a potential interactor for ELR. Here, we investigate whether SOBIR1 is required for response to INF1 and resistance to P. infestans and whether it associates with ELR. Our results show that virus-induced gene silencing of SOBIR1 in Nicotiana benthamiana leads to loss of INF1-triggered cell death and increased susceptibility to P. infestans. Using genetic complementation, we found that the kinase activity of SOBIR1 is required for INF1-triggered cell death. Coimmunoprecipitation experiments showed that ELR constitutively associates with potato SOBIR1 in planta, forming a bipartite receptor complex. Upon INF1 elicitation, this ELR-SOBIR1 complex recruits SERK3 (SOMATIC EMBRYOGENESIS RECEPTOR KINASE 3) leading to downstream signaling activation. Overall, our study shows that SOBIR1 is required for basal resistance to P. infestans and for INF1-triggered cell death and functions as an adaptor kinase for ELR.
- Published
- 2018
- Full Text
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23. The Rust Fungus Melampsora larici-populina Expresses a Conserved Genetic Program and Distinct Sets of Secreted Protein Genes During Infection of Its Two Host Plants, Larch and Poplar.
- Author
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Lorrain C, Marchal C, Hacquard S, Delaruelle C, Pétrowski J, Petre B, Hecker A, Frey P, and Duplessis S
- Subjects
- Fungal Proteins genetics, Host Specificity, Pharmacogenomic Variants, Plant Diseases microbiology, Basidiomycota physiology, Fungal Proteins metabolism, Gene Expression Regulation, Fungal physiology, Larix microbiology, Populus microbiology
- Abstract
Mechanisms required for broad-spectrum or specific host colonization of plant parasites are poorly understood. As a perfect illustration, heteroecious rust fungi require two alternate host plants to complete their life cycles. Melampsora larici-populina infects two taxonomically unrelated plants, larch, on which sexual reproduction is achieved, and poplar, on which clonal multiplication occurs, leading to severe epidemics in plantations. We applied deep RNA sequencing to three key developmental stages of M. larici-populina infection on larch: basidia, pycnia, and aecia, and we performed comparative transcriptomics of infection on poplar and larch hosts, using available expression data. Secreted protein was the only significantly overrepresented category among differentially expressed M. larici-populina genes between the basidial, the pycnial, and the aecial stages, highlighting their probable involvement in the infection process. Comparison of fungal transcriptomes in larch and poplar revealed a majority of rust genes were commonly expressed on the two hosts and a fraction exhibited host-specific expression. More particularly, gene families encoding small secreted proteins presented striking expression profiles that highlight probable candidate effectors specialized on each host. Our results bring valuable new information about the biological cycle of rust fungi and identify genes that may contribute to host specificity.
- Published
- 2018
- Full Text
- View/download PDF
24. Lessons in Effector and NLR Biology of Plant-Microbe Systems.
- Author
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Białas A, Zess EK, De la Concepcion JC, Franceschetti M, Pennington HG, Yoshida K, Upson JL, Chanclud E, Wu CH, Langner T, Maqbool A, Varden FA, Derevnina L, Belhaj K, Fujisaki K, Saitoh H, Terauchi R, Banfield MJ, and Kamoun S
- Subjects
- Amino Acid Sequence, Biological Evolution, Genetic Variation, NLR Proteins chemistry, NLR Proteins genetics, Plants immunology, Selection, Genetic, Host-Pathogen Interactions, NLR Proteins metabolism, Plants metabolism, Plants microbiology
- Abstract
A diversity of plant-associated organisms secrete effectors-proteins and metabolites that modulate plant physiology to favor host infection and colonization. However, effectors can also activate plant immune receptors, notably nucleotide-binding domain and leucine-rich repeat region (NLR)-containing proteins, enabling plants to fight off invading organisms. This interplay between effectors, their host targets, and the matching immune receptors is shaped by intricate molecular mechanisms and exceptionally dynamic coevolution. In this article, we focus on three effectors, AVR-Pik, AVR-Pia, and AVR-Pii, from the rice blast fungus Magnaporthe oryzae (syn. Pyricularia oryzae), and their corresponding rice NLR immune receptors, Pik, Pia, and Pii, to highlight general concepts of plant-microbe interactions. We draw 12 lessons in effector and NLR biology that have emerged from studying these three little effectors and are broadly applicable to other plant-microbe systems.
- Published
- 2018
- Full Text
- View/download PDF
25. Foundational and Translational Research Opportunities to Improve Plant Health.
- Author
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Michelmore R, Coaker G, Bart R, Beattie G, Bent A, Bruce T, Cameron D, Dangl J, Dinesh-Kumar S, Edwards R, Eves-van den Akker S, Gassmann W, Greenberg JT, Hanley-Bowdoin L, Harrison RJ, Harvey J, He P, Huffaker A, Hulbert S, Innes R, Jones JDG, Kaloshian I, Kamoun S, Katagiri F, Leach J, Ma W, McDowell J, Medford J, Meyers B, Nelson R, Oliver R, Qi Y, Saunders D, Shaw M, Smart C, Subudhi P, Torrance L, Tyler B, Valent B, and Walsh J
- Subjects
- Biotechnology methods, Climate Change, Crops, Agricultural microbiology, Crops, Agricultural parasitology, Humans, Plant Diseases microbiology, Plant Diseases parasitology, Agriculture methods, Crops, Agricultural growth & development, Food Supply, Translational Research, Biomedical methods
- Abstract
Reader Comments | Submit a Comment The white paper reports the deliberations of a workshop focused on biotic challenges to plant health held in Washington, D.C. in September 2016. Ensuring health of food plants is critical to maintaining the quality and productivity of crops and for sustenance of the rapidly growing human population. There is a close linkage between food security and societal stability; however, global food security is threatened by the vulnerability of our agricultural systems to numerous pests, pathogens, weeds, and environmental stresses. These threats are aggravated by climate change, the globalization of agriculture, and an over-reliance on nonsustainable inputs. New analytical and computational technologies are providing unprecedented resolution at a variety of molecular, cellular, organismal, and population scales for crop plants as well as pathogens, pests, beneficial microbes, and weeds. It is now possible to both characterize useful or deleterious variation as well as precisely manipulate it. Data-driven, informed decisions based on knowledge of the variation of biotic challenges and of natural and synthetic variation in crop plants will enable deployment of durable interventions throughout the world. These should be integral, dynamic components of agricultural strategies for sustainable agriculture.
- Published
- 2017
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26. Colonization of Barley by the Broad-Host Hemibiotrophic Pathogen Phytophthora palmivora Uncovers a Leaf Development-Dependent Involvement of Mlo.
- Author
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Le Fevre R, O'Boyle B, Moscou MJ, and Schornack S
- Subjects
- Mutation, Phytophthora classification, Plant Diseases microbiology, Plant Leaves growth & development, Plant Leaves metabolism, Plant Proteins genetics, Plant Roots microbiology, Gene Expression Regulation, Plant physiology, Hordeum, Phytophthora physiology, Plant Leaves microbiology, Plant Proteins metabolism
- Abstract
The discovery of barley Mlo demonstrated that filamentous pathogens rely on plant genes to achieve entry and lifecycle completion in barley leaves. While having a dramatic effect on foliar pathogens, it is unclear whether overlapping or distinct mechanisms affect filamentous pathogen infection of roots. To remove the bias connected with using different pathogens to understand colonization mechanisms in different tissues, we have utilized the aggressive hemibiotrophic oomycete pathogen Phytophthora palmivora. P. palmivora colonizes root as well as leaf tissues of barley (Hordeum vulgare). The infection is characterized by a transient biotrophy phase with formation of haustoria. Barley accessions varied in degree of susceptibility, with some accessions fully resistant to leaf infection. Notably, there was no overall correlation between degree of susceptibility in roots compared with leaves, suggesting that variation in different genes influences host susceptibility above and below ground. In addition, a developmental gradient influenced infection, with more extensive colonization observed in mature leaf sectors. The mlo5 mutation attenuates P. palmivora infection but only in young leaf tissues. The barley-P. palmivora interaction represents a simple system to identify and compare genetic components governing quantitative colonization in diverse barley tissue types.
- Published
- 2016
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27. Tomato I2 Immune Receptor Can Be Engineered to Confer Partial Resistance to the Oomycete Phytophthora infestans in Addition to the Fungus Fusarium oxysporum.
- Author
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Giannakopoulou A, Steele JF, Segretin ME, Bozkurt TO, Zhou J, Robatzek S, Banfield MJ, Pais M, and Kamoun S
- Subjects
- Amino Acid Sequence, Fusarium immunology, Solanum lycopersicum microbiology, Molecular Sequence Data, Phytophthora infestans immunology, Receptors, Immunologic chemistry, Fusarium pathogenicity, Solanum lycopersicum immunology, Phytophthora infestans pathogenicity, Receptors, Immunologic immunology
- Abstract
Plants and animals rely on immune receptors, known as nucleotide-binding domain and leucine-rich repeat (NLR)-containing proteins, to defend against invading pathogens and activate immune responses. How NLR receptors respond to pathogens is inadequately understood. We previously reported single-residue mutations that expand the response of the potato immune receptor R3a to AVR3a(EM), a stealthy effector from the late blight oomycete pathogen Phytophthora infestans. I2, another NLR that mediates resistance to the will-causing fungus Fusarium oxysporum f. sp. lycopersici, is the tomato ortholog of R3a. We transferred previously identified R3a mutations to I2 to assess the degree to which the resulting I2 mutants have an altered response. We discovered that wild-type I2 protein responds weakly to AVR3a. One mutant in the N-terminal coiled-coil domain, I2(I141N), appeared sensitized and displayed markedly increased response to AVR3a. Remarkably, I2(I141N) conferred partial resistance to P. infestans. Further, I2(I141N) has an expanded response spectrum to F. oxysporum f. sp. lycopersici effectors compared with the wild-type I2 protein. Our results suggest that synthetic immune receptors can be engineered to confer resistance to phylogenetically divergent pathogens and indicate that knowledge gathered for one NLR could be exploited to improve NLR from other plant species.
- Published
- 2015
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28. A Recent Expansion of the RXLR Effector Gene Avrblb2 Is Maintained in Global Populations of Phytophthora infestans Indicating Different Contributions to Virulence.
- Author
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Oliva RF, Cano LM, Raffaele S, Win J, Bozkurt TO, Belhaj K, Oh SK, Thines M, and Kamoun S
- Subjects
- Amino Acid Sequence, Conserved Sequence, Fungal Proteins metabolism, Genetic Variation, Host-Pathogen Interactions genetics, Molecular Sequence Data, Mutation, Phylogeny, Phytophthora genetics, Polymorphism, Genetic, Solanum tuberosum genetics, Solanum tuberosum microbiology, Virulence Factors genetics, Virulence Factors metabolism, Fungal Proteins genetics, Phytophthora infestans genetics, Phytophthora infestans pathogenicity
- Abstract
The introgression of disease resistance (R) genes encoding immunoreceptors with broad-spectrum recognition into cultivated potato appears to be the most promising approach to achieve sustainable management of late blight caused by the oomycete pathogen Phytophthora infestans. Rpi-blb2 from Solanum bulbocastanum shows great potential for use in agriculture based on preliminary potato disease trials. Rpi-blb2 confers immunity by recognizing the P. infestans avirulence effector protein AVRblb2 after it is translocated inside the plant cell. This effector belongs to the RXLR class of effectors and is under strong positive selection. Structure-function analyses revealed a key polymorphic amino acid (position 69) in AVRblb2 effector that is critical for activation of Rpi-blb2. In this study, we reconstructed the evolutionary history of the Avrblb2 gene family and further characterized its genetic structure in worldwide populations. Our data indicate that Avrblb2 evolved as a single-copy gene in a putative ancestral species of P. infestans and has recently expanded in the Phytophthora spp. that infect solanaceous hosts. As a consequence, at least four variants of AVRblb2 arose in P. infestans. One of these variants, with a Phe residue at position 69, evades recognition by the cognate resistance gene. Surprisingly, all Avrblb2 variants are maintained in pathogen populations. This suggests a potential benefit for the pathogen in preserving duplicated versions of AVRblb2, possibly because the variants may have different contributions to pathogen fitness in a diversified solanaceous host environment.
- Published
- 2015
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29. Candidate Effector Proteins of the Rust Pathogen Melampsora larici-populina Target Diverse Plant Cell Compartments.
- Author
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Petre B, Saunders DG, Sklenar J, Lorrain C, Win J, Duplessis S, and Kamoun S
- Subjects
- Basidiomycota genetics, Basidiomycota physiology, Fungal Proteins genetics, Gene Expression, Gene Expression Profiling, Genes, Reporter, Oligonucleotide Array Sequence Analysis, Plant Diseases microbiology, Plant Leaves microbiology, Plant Proteins genetics, Plant Proteins metabolism, Protein Transport, Recombinant Fusion Proteins, Nicotiana cytology, Transgenes, Fungal Proteins metabolism, Genome, Fungal genetics, Populus microbiology, Nicotiana microbiology
- Abstract
Rust fungi are devastating crop pathogens that deliver effector proteins into infected tissues to modulate plant functions and promote parasitic growth. The genome of the poplar leaf rust fungus Melampsora larici-populina revealed a large catalog of secreted proteins, some of which have been considered candidate effectors. Unraveling how these proteins function in host cells is a key to understanding pathogenicity mechanisms and developing resistant plants. In this study, we used an effectoromics pipeline to select, clone, and express 20 candidate effectors in Nicotiana benthamiana leaf cells to determine their subcellular localization and identify the plant proteins they interact with. Confocal microscopy revealed that six candidate effectors target the nucleus, nucleoli, chloroplasts, mitochondria, and discrete cellular bodies. We also used coimmunoprecipitation (coIP) and mass spectrometry to identify 606 N. benthamiana proteins that associate with the candidate effectors. Five candidate effectors specifically associated with a small set of plant proteins that may represent biologically relevant interactors. We confirmed the interaction between the candidate effector MLP124017 and TOPLESS-related protein 4 from poplar by in planta coIP. Altogether, our data enable us to validate effector proteins from M. larici-populina and reveal that these proteins may target multiple compartments and processes in plant cells. It also shows that N. benthamiana can be a powerful heterologous system to study effectors of obligate biotrophic pathogens.
- Published
- 2015
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30. 14-3-3 proteins in plant-pathogen interactions.
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Lozano-Durán R and Robatzek S
- Subjects
- 14-3-3 Proteins genetics, Models, Biological, Phosphorylation, Phylogeny, Plant Diseases microbiology, Plant Proteins genetics, Plant Proteins metabolism, Plants genetics, Plants immunology, Plants microbiology, 14-3-3 Proteins metabolism, Gene Expression Regulation, Plant, Host-Pathogen Interactions, Plant Diseases immunology, Plants metabolism, Signal Transduction
- Abstract
14-3-3 proteins define a eukaryotic-specific protein family with a general role in signal transduction. Primarily, 14-3-3 proteins act as phosphosensors, binding phosphorylated client proteins and modulating their functions. Since phosphorylation regulates a plethora of different physiological responses in plants, 14-3-3 proteins play roles in multiple signaling pathways, including those controlling metabolism, hormone signaling, cell division, and responses to abiotic and biotic stimuli. Increasing evidence supports a prominent role of 14-3-3 proteins in regulating plant immunity against pathogens at various levels. In this review, potential links between 14-3-3 function and the regulation of plant-pathogen interactions are discussed, with a special focus on the regulation of 14-3-3 proteins in response to pathogen perception, interactions between 14-3-3 proteins and defense-related proteins, and 14-3-3 proteins as targets of pathogen effectors.
- Published
- 2015
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31. In planta effector competition assays detect Hyaloperonospora arabidopsidis effectors that contribute to virulence and localize to different plant subcellular compartments.
- Author
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Badel JL, Piquerez SJ, Greenshields D, Rallapalli G, Fabro G, Ishaque N, and Jones JD
- Subjects
- Amino Acid Motifs, Antibiosis, Arabidopsis cytology, Arabidopsis immunology, Arabidopsis microbiology, Electrophoresis, Capillary, High-Throughput Nucleotide Sequencing, Host-Pathogen Interactions, Oomycetes pathogenicity, Plant Diseases microbiology, Plant Diseases parasitology, Plant Leaves cytology, Plant Leaves immunology, Plant Leaves microbiology, Plant Leaves parasitology, Protein Transport, Proteins genetics, Proteins metabolism, Pseudomonas syringae genetics, Pseudomonas syringae metabolism, Pseudomonas syringae pathogenicity, Recombinant Fusion Proteins, Sequence Analysis, DNA, Nicotiana cytology, Nicotiana immunology, Nicotiana metabolism, Nicotiana microbiology, Virulence genetics, Arabidopsis parasitology, Oomycetes genetics, Plant Diseases immunology, Pseudomonas syringae growth & development
- Abstract
The genome of the pathogenic oomycete Hyaloperonospora arabidopsidis is predicted to encode at least 134 high-confidence effectors (HaRxL) carrying the RxLR motif implicated in their translocation into plant cells. However, only four avirulence genes (ATR1, ATR13, ATR5, and ATR39) have been isolated. This indicates that identification of HaRxL effectors based on avirulence is low throughput. We aimed at rapidly identifying H. arabidopsidis effectors that contribute to virulence by developing methods to detect and quantify multiple candidates in bacterial mixed infections using either Illumina sequencing or capillary electrophoresis. In these assays, referred to here as in planta effector competition assays, we estimate the contribution to virulence of individual effectors by calculating the abundance of each HaRxL in the bacterial population recovered from leaves 3 days after inoculation relative to abundance in the initial mixed inoculum. We identified HaRxL that enhance Pseudomonas syringae pv. tomato DC3000 growth in some but not all Arabidopsis accessions. Further analysis showed that HaRxLL464, HaRxL75, HaRxL22, HaRxLL441, and HaRxL89 suppress pathogen-associated molecular pattern-triggered immunity (PTI) and localize to different subcellular compartments in Nicotiana benthamiana, providing evidence for a multilayered suppression of PTI by pathogenic oomycetes and molecular probes for the dissection of PTI.
- Published
- 2013
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32. Phosphoproteome analysis of Lotus japonicus roots reveals shared and distinct components of symbiosis and defense.
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Serna-Sanz A, Parniske M, and Peck SC
- Subjects
- Lotus genetics, Plant Proteins genetics, Plant Roots metabolism, Proteomics, Respiratory Burst, Gene Expression Regulation, Plant physiology, Lotus metabolism, Lotus microbiology, Plant Proteins metabolism, Plant Roots microbiology, Symbiosis physiology
- Abstract
Plant roots form an intracellular symbiosis with nitrogen-fixing bacteria while maintaining the capacity for defending themselves against bacterial pathogens. To investigate the molecular relationship between these opposing cellular responses, we compared changes in the root phosphoproteome of the legume Lotus japonicus occurring within minutes after perception of nodulation factor (NF), a symbiotic signaling molecule, to those elicited by flagellin peptide (flg22), a conserved pathogen-associated peptide motif present in flagellar protein of a wide range of bacteria. Phosphoproteins were visualized by autoradiography of two-dimensional polyacrylamide gels after in vivo labeling with 33P-orthophosphate. Comparisons of NF- and flg22-induced phosphoprotein patterns revealed signal-specific responses but also a surprisingly large overlap. Specificity of the responses was observed because the NF receptor kinases NFR1 and NFR5 were both required for NF- but not for flg22-mediated changes in the phosphoproteome. Moreover, NF did not stimulate an oxidative burst or activation of mitogen-activated protein kinases, two common markers for early defense responses that were induced by flg22. Inhibitor studies revealed that phosphorylation of at least some of the proteins in response to NF requires phospholipase D (PLD) whereas regulation of the flg22 phosphoproteome is PLD-independent. Although plant signal transduction during symbiosis and defense utilizes distinct components, phosphorylation of overlapping sets of proteins is achieved.
- Published
- 2011
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33. The major specificity-determining amino acids of the tomato Cf-9 disease resistance protein are at hypervariable solvent-exposed positions in the central leucine-rich repeats.
- Author
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Wulff BB, Heese A, Tomlinson-Buhot L, Jones DA, de la Peña M, and Jones JD
- Subjects
- Amino Acid Sequence, Amino Acids chemistry, Fungal Proteins genetics, Fungal Proteins physiology, Genes, Plant, Host-Pathogen Interactions genetics, Host-Pathogen Interactions physiology, Leucine-Rich Repeat Proteins, Solanum lycopersicum physiology, Membrane Glycoproteins physiology, Models, Molecular, Molecular Sequence Data, Mutagenesis, Site-Directed, Plant Diseases genetics, Plant Diseases microbiology, Plant Proteins physiology, Proteins chemistry, Proteins genetics, Proteins physiology, Recombinant Fusion Proteins chemistry, Recombinant Fusion Proteins genetics, Sequence Homology, Amino Acid, Solvents, Cladosporium pathogenicity, Solanum lycopersicum genetics, Solanum lycopersicum microbiology, Membrane Glycoproteins chemistry, Membrane Glycoproteins genetics, Plant Proteins chemistry, Plant Proteins genetics
- Abstract
The interaction between tomato and the leaf mold pathogen Cladosporium fulvum is controlled in a gene-for-gene manner by plant Cf genes that encode membrane-anchored extracytoplasmic leucine-rich repeat (LRR) glycoproteins, which confer recognition of their cognate fungal avirulence (Avr) proteins. Cf-9 and Cf-4 are two such proteins that are 91% identical yet recognize the sequence-unrelated fungal avirulence determinants Avr9 and Avr4, respectively. As shown previously, Cf-4 specificity is determined by three putative solvent-exposed residues in the central LRR and a deletion of two LRR relative to Cf-9. In this study, we focused on identifying the specificity determinants of Cf-9. We generated chimeras between Cf-9 and its close homologue Cf-9B and identified five amino acid residues that constitute major specificity determinants of Cf-9. Introduction of these residues into Cf-9B allowed recognition of Avr9. Consistent with a role in recognition specificity, the identified residues are putatively solvent exposed in the central LRR and occupy hypervariable positions in the global Cf alignment. One of the specificity residues is not found in any other known Cf protein, suggesting the importance of diversifying selection rather than sequence exchange between homologues. Interestingly, there is an overlap between the Cf-4 and Cf-9 specificity-determining residues, precluding a protein with dual specificity.
- Published
- 2009
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34. Rpi-vnt1.1, a Tm-2(2) homolog from Solanum venturii, confers resistance to potato late blight.
- Author
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Foster SJ, Park TH, Pel M, Brigneti G, Sliwka J, Jagger L, van der Vossen E, and Jones JD
- Subjects
- Amino Acid Sequence, Chromosome Mapping, Chromosomes, Plant genetics, Cloning, Molecular, DNA, Plant chemistry, DNA, Plant genetics, Host-Pathogen Interactions, Immunity, Innate genetics, Solanum lycopersicum genetics, Solanum lycopersicum microbiology, Molecular Sequence Data, Phytophthora infestans physiology, Plant Diseases microbiology, Plants, Genetically Modified microbiology, Sequence Analysis, DNA, Sequence Homology, Amino Acid, Solanum classification, Solanum microbiology, Solanum tuberosum genetics, Solanum tuberosum microbiology, Species Specificity, Genes, Plant genetics, Plant Diseases genetics, Plant Proteins genetics, Plants, Genetically Modified genetics, Solanum genetics
- Abstract
Despite the efforts of breeders and the extensive use of fungicide control measures, late blight still remains a major threat to potato cultivation worldwide. The introduction of genetic resistance into cultivated potato is considered a valuable method to achieve durable resistance to late blight. Here, we report the identification and cloning of Rpi-vnt1.1, a previously uncharacterized late-blight resistance gene from Solanum venturii. The gene was identified by a classical genetic and physical mapping approach and encodes a coiled-coil nucleotide-binding leucine-rich repeat protein with high similarity to Tm-2(2) from S. lycopersicum which confers resistance against Tomato mosaic virus. Transgenic potato and tomato plants carrying Rpi-vnt1.1 were shown to be resistant to Phytophthora infestans. Of 11 P. infestans isolates tested, only isolate EC1 from Ecuador was able to overcome Rpi-vnt1.1 and cause disease on the inoculated plants. Alleles of Rpi-vnt1.1 (Rpi-vnt1.2 and Rpi-vnt1.3) that differed by only a few nucleotides were found in other late-blight-resistant accessions of S. venturii. The late blight resistance gene Rpi-phu1 from S. phureja is shown here to be identical to Rpi-vnt1.1, suggesting either that this strong resistance gene has been maintained since a common ancestor, due to selection pressure for blight resistance, or that genetic exchange between S. venturii and S. phureja has occurred at some time.
- Published
- 2009
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35. Regulation of tomato Prf by Pto-like protein kinases.
- Author
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Mucyn TS, Wu AJ, Balmuth AL, Arasteh JM, and Rathjen JP
- Subjects
- Solanum lycopersicum genetics, Mutation, Plant Diseases microbiology, Plant Proteins genetics, Protein Serine-Threonine Kinases genetics, Pseudomonas syringae, Signal Transduction, Gene Expression Regulation, Plant, Solanum lycopersicum enzymology, Plant Proteins metabolism, Protein Serine-Threonine Kinases metabolism
- Abstract
Tomato Prf encodes a nucleotide-binding domain shared by Apaf-1, certain R proteins, and CED-4 fused to C-terminal leucine-rich repeats (NBARC-LRR) protein that is required for bacterial immunity to Pseudomonas syringae and sensitivity to the organophosphate fenthion. The signaling pathways involve two highly related protein kinases. Pto kinase mediates direct recognition of the bacterial effector proteins AvrPto or AvrPtoB. Fen kinase is required for fenthion sensitivity and recognition of bacterial effectors related to AvrPtoB. The role of Pto and its association with Prf has been characterized but Fen is poorly described. We show that, similar to Pto, Fen requires N-myristoylation and kinase activity for signaling and interacts with the N-terminal domain of Prf. Thus, the mechanisms of activation of Prf by the respective protein kinases are similar. Prf-Fen interaction is underlined by coregulatory mechanisms in which Prf negatively regulates Fen, most likely by controlling kinase activity. We further characterized negative regulation of Prf by Pto, and show that regulation is mediated by the previously described negative regulatory patch. Remarkably, the effectors released negative regulation of Prf in a manner dependent on Pto kinase activity. The data suggest a model in which Prf associates generally with Pto-like kinases in tightly regulated complexes, which are activated by effector-mediated disruption of negative regulation. Release of negative regulation may be a general feature of activation of NBARC-LRR proteins by cognate effectors.
- Published
- 2009
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36. The TIR domain of TIR-NB-LRR resistance proteins is a signaling domain involved in cell death induction.
- Author
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Swiderski MR, Birker D, and Jones JD
- Subjects
- Amino Acid Sequence, Amino Acid Substitution, Arabidopsis genetics, Arabidopsis metabolism, Cell Death, Gene Expression Regulation, Plant, Leucine-Rich Repeat Proteins, Molecular Sequence Data, Mutagenesis, Mutant Proteins metabolism, Mutation genetics, Plant Leaves cytology, Plant Leaves microbiology, Protein Structure, Tertiary, Seedlings cytology, Sequence Alignment, Nicotiana genetics, Nicotiana metabolism, Nicotiana microbiology, Arabidopsis cytology, Plant Proteins chemistry, Plant Proteins metabolism, Proteins chemistry, Proteins metabolism, Signal Transduction, Nicotiana cytology
- Abstract
In plants, the TIR (toll interleukin 1 receptor) domain is found almost exclusively in nucleotide-binding (NB) leucine-rich repeat resistance proteins and their truncated homologs, and has been proposed to play a signaling role during resistance responses mediated by TIR containing R proteins. Transient expression in Nicotiana benthamiana leaves of "TIR + 80", the RPS4 truncation without the NB-ARC domain, leads to EDS1-, SGT1-, and HSP90-dependent cell death. Transgenic Arabidopsis plants expressing the RPS4 TIR+80 from either dexamethasone or estradiol-inducible promoters display inducer-dependent cell death. Cell death is also elicited by transient expression of similarly truncated constructs from two other R proteins, RPP1A and At4g19530, but is not elicited by similar constructs representing RPP2A and RPP2B proteins. Site-directed mutagenesis of the RPS4 TIR domain identified many loss-of-function mutations but also revealed several gain-of function substitutions. Lack of cell death induction by the E160A substitution suggests that amino acids outside of the TIR domain contribute to cell death signaling in addition to the TIR domain itself. This is consistent with previous observations that the TIR domain itself is insufficient to induce cell death upon transient expression.
- Published
- 2009
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37. Functional conservation of wheat and rice Mlo orthologs in defense modulation to the powdery mildew fungus.
- Author
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Elliott C, Zhou F, Spielmeyer W, Panstruga R, and Schulze-Lefert P
- Subjects
- Amino Acid Sequence, Chromosome Mapping, Chromosomes, Plant genetics, DNA, Complementary chemistry, DNA, Complementary genetics, Gene Expression Regulation, Plant, Immunity, Innate genetics, Molecular Sequence Data, Mutation, Oryza microbiology, Phenotype, Plant Diseases microbiology, Sequence Alignment, Sequence Analysis, DNA, Sequence Homology, Amino Acid, Synteny, Triticum microbiology, Fungi growth & development, Oryza genetics, Plant Diseases genetics, Plant Proteins genetics, Triticum genetics
- Abstract
Homologs of barley Mlo are found in syntenic positions in all three genomes of hexaploid bread wheat, Triticum aestivum, and in rice, Oryza sativa. Candidate wheat orthologs, designated TaMlo-A1, TaMlo-B1, and TaMlo-D1, encode three distinct but highly related proteins that are 88% identical to barley MLO and appear to originate from the three diploid ancestral genomes of wheat. TaMlo-B1 and the rice ortholog, OsMlo2, are able to complement powdery mildew-resistant barley mlo mutants at the single-cell level. Overexpression of TaMlo-B1 or barley Mlo leads to super-susceptibility to the appropriate powdery mildew formae speciales in both wild-type barley and wheat. Surprisingly, overexpression of either Mlo or TaMlo-B1 also mediates enhanced fungal development to tested inappropriate formae speciales. These results underline a regulatory role for MLO and its wheat and rice orthologs in a basal defense mechanism that can interfere with forma specialis resistance to powdery mildews.
- Published
- 2002
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38. Induction of hydroxycinnamoyl-tyramine conjugates in pepper by Xanthomonas campestris, a plant defense response activated by hrp gene-dependent and hrp gene-independent mechanisms.
- Author
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Newman MA, von Roepenack-Lahaye E, Parr A, Daniels MJ, and Dow JM
- Subjects
- Anti-Bacterial Agents pharmacology, Capsicum metabolism, Coumaric Acids pharmacology, Fungal Proteins physiology, Genes, Fungal, Multigene Family, Phenols metabolism, Plant Diseases genetics, Plant Proteins genetics, Plant Proteins metabolism, Tyramine analogs & derivatives, Tyramine pharmacology, Tyrosine Decarboxylase metabolism, Xanthomonas campestris drug effects, Xanthomonas campestris genetics, Capsicum microbiology, Coumaric Acids metabolism, Fungal Proteins genetics, Plants, Medicinal, Tyramine biosynthesis, Xanthomonas campestris physiology
- Abstract
Inoculation of pepper leaves, Capsicum annuum cv. Early Calwonder ECW 10R, with strains of Xanthomonas campestris led to an accumulation of the phenolic conjugates feruloyltyramine (FT) and p-coumaroyltyramine (CT) 24 h postinoculation in nonhost- and gene-for-gene-determined incompatible interactions with X. campestris pv. campestris and X. campestris pv. vesicatoria, respectively. In contrast, neither compound was detected in compatible interactions with X. campestris pv. vesicatoria. The accumulation of FT and CT was preceded by an increase in the extractable activity of tyrosine decarboxylase as well as increases in the transcription of genes encoding phenylalanine ammonia-lyase and tyramine hydroxycinnamoyl transferase. No such changes were detected in compatible interactions. Very rapid accumulation of FT and CT occurred (4 h postinoculation) in pepper in response to a X. campestris pv. campestris mutant carrying a deletion of the hrp gene cluster. In contrast, hrp mutants of X. campestris pv. vesicatoria failed to elicit the production of FT and CT. These observations suggest the existence of hrp gene-dependent and -independent activation mechanisms of a defense response involving hydroxycinnamoyltyramines.
- Published
- 2001
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39. Expression of the gum operon directing xanthan biosynthesis in Xanthomonas campestris and its regulation in planta.
- Author
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Vojnov AA, Slater H, Daniels MJ, and Dow JM
- Subjects
- Bacterial Proteins physiology, Gene Expression Regulation, Bacterial, Genes, Regulator, Genes, Reporter, Genetic Complementation Test, Glucuronidase genetics, Mutagenesis, Pigmentation genetics, Plant Diseases genetics, Polysaccharides, Bacterial biosynthesis, Signal Transduction, Xanthomonas campestris pathogenicity, Bacterial Proteins genetics, Gene Expression Regulation, Plant, Operon, Polysaccharides, Bacterial genetics, Xanthomonas campestris genetics
- Abstract
The gum gene cluster of Xanthomonas campestris pv. campestris comprises 12 genes whose products are involved in the biosynthesis of the extracellular polysaccharide xanthan. These genes are expressed primarily as an operon from a promoter upstream of the first gene, gumB. Although the regulation of xanthan synthesis in vitro has been well studied, nothing is known of its regulation in planta. A reporter plasmid was constructed in which the promoter region of the gum operon was fused to gusA. In liquid cultures, the expression of the gumgusA reporter was correlated closely with the production of xanthan, although a low basal level of beta-glucuronidase activity was seen in the absence of added carbon sources when xanthan production was very low. The expression of the gumgusA fusion also was subject to positive regulation by rpfF, which is responsible for the synthesis of the diffusible signal factor (DSF). The expression of the gumgusA fusion in bacteria recovered from inoculated turnip leaves was maximal at the later phases of growth and was subject to regulation by rpfF. These results provide indirect support for the operation of the DSF regulatory system in bacteria in planta.
- Published
- 2001
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40. Definition of tissue-specific and general requirements for plant infection in a phytopathogenic fungus.
- Author
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Dufresne M and Osbourn AE
- Subjects
- Amino Acid Sequence, Magnaporthe pathogenicity, Mitogen-Activated Protein Kinases genetics, Mitogen-Activated Protein Kinases physiology, Molecular Sequence Data, Mutation, Plant Diseases microbiology, Plant Roots microbiology, Sequence Alignment, Signal Transduction, Fungal Proteins, Genes, Fungal, Magnaporthe genetics, Plant Diseases genetics, Plant Structures microbiology, Poaceae microbiology
- Abstract
Although plant diseases are usually characterized by the part of the plant that is affected (e.g., leaf spots, root rots, wilts), surprisingly little is known about the factors that condition the ability of pathogens to colonize different plant tissues. Here we demonstrate that the leaf blast pathogen Magnaporthe grisea also can infect plant roots, and we exploit this finding to distinguish tissue-specific and general requirements for plant infection. Tests of a M. grisea mutant collection identified some mutants that were defective specifically in infection of either leaves or roots, and others such as the map kinase mutant pmk1 that were generally defective in pathogenicity. Conservation of a functional PMK1-related MAP kinase in the root pathogen Gaeumannomyces graminis was also demonstrated. Exploitation of the ability of M. grisea to infect distinct plant tissues thus represents a powerful tool for the comprehensive dissection of genetic determinants of tissue specificity and global requirements for plant infection.
- Published
- 2001
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41. Effects of targeted replacement of the tomatinase gene on the interaction of Septoria lycopersici with tomato plants.
- Author
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Martin-Hernandez AM, Dufresne M, Hugouvieux V, Melton R, and Osbourn A
- Subjects
- Avena microbiology, Drug Resistance, Gene Deletion, Magnaporthe pathogenicity, Mitosporic Fungi genetics, Plant Leaves microbiology, Plant Roots microbiology, Tomatine metabolism, Tomatine toxicity, Glycoside Hydrolases genetics, Solanum lycopersicum microbiology, Solanum lycopersicum physiology, Mitosporic Fungi enzymology, Mitosporic Fungi pathogenicity
- Abstract
Many plants produce constitutive antifungal molecules belonging to the saponin family of secondary metabolites, which have been implicated in plant defense. Successful pathogens of these plants must presumably have some means of combating the chemical defenses of their hosts. In the oat root pathogen Gaeumannomyces graminis, the saponin-detoxifying enzyme avenacinase has been shown to be essential for pathogenicity. A number of other phytopathogenic fungi also produce saponin-degrading enzymes, although the significance of these for saponin resistance and pathogenicity has not yet been established. The tomato leaf spot pathogen Septoria lycopersici secretes the enzyme tomatinase, which degrades the tomato steroidal glycoalkaloid alpha-tomatine. Here we report the isolation and characterization of tomatinase-deficient mutants of S. lycopersici following targeted gene disruption. Tomatinase-minus mutants were more sensitive to alpha-tomatine than the wild-type strain. They could, however, still grow in the presence of 1 mM alpha-tomatine, suggesting that nondegradative mechanisms of tolerance are also important. There were no obvious effects of loss of tomatinase on macroscopic lesion formation on tomato leaves, but trypan blue staining of infected tissue during the early stages of infection revealed more dying mesophyll cells in leaves that had been inoculated with tomatinase-minus mutants. Expression of a defense-related basic beta-1,3 glucanase gene was also enhanced in these leaves. These differences in plant response may be associated with subtle differences in the growth of the wild-type and mutant strains during infection. Alternatively, tomatinase may be involved in suppression of plant defense mechanisms.
- Published
- 2000
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42. Stagonospora avenae secretes multiple enzymes that hydrolyze oat leaf saponins.
- Author
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Morrissey JP, Wubben JP, and Osbourn AE
- Subjects
- Amino Acid Sequence, Ascomycota genetics, Avena chemistry, Cloning, Molecular, Gene Expression, Genes, Fungal, Glycoside Hydrolases chemistry, Hydrolysis, Molecular Sequence Data, Mutation, Phenotype, Plant Leaves chemistry, Plant Leaves microbiology, Sequence Alignment, beta-Glucosidase chemistry, beta-Glucosidase genetics, beta-Glucosidase isolation & purification, Ascomycota enzymology, Avena microbiology, Glycoside Hydrolases metabolism, Saponins metabolism, beta-Glucosidase metabolism
- Abstract
The phytopathogenic fungus Stagonospora avenae is able to infect oat leaves despite the presence of avenacoside saponins in the leaf tissue. In response to pathogen attack, avenacosides are converted into 26-desglucoavenacosides (26-DGAs), which possess antifungal activity. These molecules are comprised of a steroidal backbone linked to a branched sugar chain consisting of one alpha-L-rhamnose and two (avenacoside A) or three (avenacoside B) beta-D-glucose residues. Isolates of the fungus that are pathogenic to oats are capable of sequential hydrolysis of the sugar residues from the 26-DGAs. Degradation is initiated by removal of the L-rhamnose, which abolishes antifungal activity. The D-glucose residues are then hydrolyzed by beta-glucosidase activity. A comprehensive analysis of saponin-hydrolyzing activities was undertaken, and it was established that S. avenae isolate WAC1293 secretes three enzymes, one alpha-rhamnosidase and two beta-glucosidases, that carry out this hydrolysis. The major beta-glucosidase was purified and the gene encoding the enzyme cloned. The protein is similar to saponin-hydrolyzing enzymes produced by three other phytopathogenic fungi, Gaeumannomyces graminis, Septoria lycopersici, and Botrytis cinerea, and is a family 3 beta-glucosidase. The gene encoding the beta-glucosidase is expressed during infection of oat leaves but is not essential for pathogenicity.
- Published
- 2000
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43. cDNA-AFLP display for the isolation of Peronospora parasitica genes expressed during infection in Arabidopsis thaliana.
- Author
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van der Biezen EA, Juwana H, Parker JE, and Jones JD
- Subjects
- Base Sequence, DNA Primers, DNA, Complementary, Gene Expression Regulation, Fungal, Gene Expression Regulation, Plant, Molecular Sequence Data, Arabidopsis microbiology, Genes, Fungal, Nucleic Acid Amplification Techniques, Oomycetes genetics
- Abstract
To identify genes from the obligatory biotrophic oomycete Peronospora parasitica that are expressed during infection in Arabidopsis thaliana we employed cDNA-amplified fragment length polymorphism (AFLP) display. cDNA-AFLP fragments from infected and non-infected leaves were separated in parallel by gel electrophoresis and displayed by autoradiography. Most differential gene fragments were derived from P. parasitica.
- Published
- 2000
- Full Text
- View/download PDF
44. Comparison of the hypersensitive response induced by the tomato Cf-4 and Cf-9 genes in Nicotiana spp.
- Author
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Thomas CM, Tang S, Hammond-Kosack K, and Jones JD
- Subjects
- Agrobacterium tumefaciens genetics, Agrobacterium tumefaciens metabolism, Blotting, Northern, Fungal Proteins metabolism, Solanum lycopersicum genetics, Membrane Glycoproteins metabolism, Plant Proteins metabolism, Plants, Genetically Modified genetics, Plants, Genetically Modified virology, Nicotiana virology, Membrane Glycoproteins genetics, Plant Proteins genetics, Plants, Toxic, Potexvirus pathogenicity, Nicotiana genetics
- Abstract
We have previously shown that tomato Cf-9 induces an Avr9-dependent hypersensitive response (HR) in Nicotiana tabacum and potato. We show here that Cf-4 also induces an Avr4-dependent HR in two tobacco species (N. tabacum and N. benthamiana). The HR induced by Cf-4 and Cf-9 was compared in stable tobacco transgenics by a seedling lethal assay and resistance to recombinant Potato virus X expressing Avr4 or Avr9. We also compared HR induction with Agrobacterium-mediated transient expression. The Cf-4/Avr4 combination induced a more rapid HR than Cf-9/Avr9. Sensitive assays for Cf-9 and Cf-4 function should prove useful for structure/function analyses of these resistance proteins in tobacco.
- Published
- 2000
- Full Text
- View/download PDF
45. Homologues of the Cf-9 disease resistance gene (Hcr9s) are present at multiple loci on the short arm of tomato chromosome 1.
- Author
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Parniske M, Wulff BB, Bonnema G, Thomas CM, Jones DA, and Jones JD
- Subjects
- Base Sequence, Conserved Sequence, DNA Primers, DNA Probes, Genetic Markers, Immunity, Innate genetics, Polymerase Chain Reaction, Polymorphism, Genetic, Chromosome Mapping, Solanum lycopersicum genetics, Membrane Glycoproteins genetics, Plant Proteins genetics
- Abstract
The tomato Cf-4 and Cf-9 genes map at a genetically complex locus on the short arm of chromosome 1 and confer resistance against Cladosporium fulvum through recognition of different pathogen-encoded avirulence determinants. Cf-4 and Cf-9 are members of a large gene family (Hcr9s, Homologues of Cladosporium fulvum resistance gene Cf-9), some of which encode additional distinct recognition specificities. A genetic analysis of the majority of Hcr9s suggests that their distribution is spatially restricted to the short arm of chromosome 1. Two loci of clustered Hcr9 genes have been analyzed physically that mapped distal (Northern Lights) and proximal (Southern Cross) to the Cf-4/9 locus (Milky Way). Sequence homologies between intergenic regions at Southern Cross and Milky Way indicate local Hcr9 duplication preceded cluster multiplication. The multiplication of clusters involved DNA flanking Hcr9 sequences as indicated by conserved lipoxygenase sequences at Southern Cross and Milky Way. The similar spatial distribution of Hcr9 clusters in different Lycopersicon spp. suggests Hcr9 cluster multiplication preceded speciation.
- Published
- 1999
- Full Text
- View/download PDF
46. A metalloprotease from Xanthomonas campestris that specifically degrades proline/hydroxyproline-rich glycoproteins of the plant extracellular matrix.
- Author
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Dow JM, Davies HA, and Daniels MJ
- Subjects
- Amino Acid Sequence, Brassica microbiology, Chromatography, Gel, Chromatography, High Pressure Liquid, Chromatography, Ion Exchange, Glycoproteins chemistry, Hydrolysis, Hydroxyproline metabolism, Metalloendopeptidases isolation & purification, Proline metabolism, Substrate Specificity, Brassica metabolism, Extracellular Matrix metabolism, Glycoproteins metabolism, Metalloendopeptidases metabolism, Xanthomonas campestris enzymology
- Abstract
Culture supernatants of Xanthomonas campestris pv. campestris contain an enzymic activity capable of degrading gp120, a proline-rich glycoprotein associated with the extracellular matrix of the vascular bundles in petioles of turnip (Brassica campestris). This activity did not reside in any of the three previously characterized proteases of X. campestris pv. campestris that were identified by their action against the model substrate beta-casein. The novel enzyme was purified by ion-exchange and size-exclusion high-performance liquid chromatography (HPLC). The enzyme, which has no activity against beta-casein, is active against some plant glycoproteins of the hydroxyproline-rich class such as extensin from potato and tomato and gpS-3, a glycoprotein induced in B. campestris petioles by wounding. Other hydroxyproline-rich glycoproteins, such as the solanaceous lectins, were not substrates however. Studies of the products released upon degradation of tomato extensin suggested that the degradative mechanism was proteolysis. Inhibitor studies suggested that the enzyme was a zinc-requiring metalloprotease. Extracellular matrix glycoproteins of the proline-rich and hydroxyproline-rich classes have been implicated in plant resistance to microbial attack, hence their degradation by X. campestris pv. campestris may have considerable significance for black rot pathogenesis.
- Published
- 1998
- Full Text
- View/download PDF
47. Entry of Xanthomonas campestris pv. campestris into hydathodes of Arabidopsis thaliana leaves: a system for studying early infection events in bacterial pathogenesis.
- Author
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Hugouvieux V, Barber CE, and Daniels MJ
- Subjects
- Mutation, Superoxide Dismutase metabolism, Xanthomonas campestris enzymology, Xanthomonas campestris genetics, Arabidopsis microbiology, Plant Diseases microbiology, Plant Leaves microbiology, Xanthomonas campestris pathogenicity
- Abstract
Xanthomonas campestris pv. campestris (Xcc) is a vascular pathogen of cruciferous plants that normally gains entry to plants via hydathodes. In order to study the basis of the preference for this protal of entry we have developed an Arabidopsis thaliana model with attached or detached leaves partially immersed in a bacterial suspension. Entry of bacteria into leaves, assessed by resistance to surface sterilization, could be detected after 1 h. Dissection of leaves and histochemical staining for beta-glucuronidase produced by the bacteria indicated that they were located in hydathodes. In contrast, similar experiments with the leaf-spotting pathogen X. campestris pv. armoraciae gave patterns of localized staining dispersed over the leaf area, indicative of entry through stomata. A survey of 41 A. thaliana accessions showed that they fell into three classes distinguishable by total numbers of Xcc that entered under standard conditions and by preference for hydathode colonization. Previously isolated Xcc mutants affected in pathogenicity were tested for hydathode colonization: an hrp mutant behaved indistinguishably from the wild type, and rpf regulatory mutants gave 10-fold reduced colonization, whereas with rfaX mutants with altered lipopolysaccharide, few if any viable bacteria were recoverable from hydathodes. This fact, together with the rapid induction of superoxide dismutase in the bacteria located in hydathodes, suggests that an early defense reaction is mounted in the hydathode.
- Published
- 1998
- Full Text
- View/download PDF
48. Heterologous expression of Septoria lycopersici tomatinase in Cladosporium fulvum: effects on compatible and incompatible interactions with tomato seedlings.
- Author
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Melton RE, Flegg LM, Brown JK, Oliver RP, Daniels MJ, and Osbourn AE
- Subjects
- Antifungal Agents pharmacology, Cladosporium drug effects, Cladosporium pathogenicity, Cotyledon, Mitosporic Fungi drug effects, Spores, Fungal, Cladosporium physiology, Glycoside Hydrolases biosynthesis, Solanum lycopersicum microbiology, Solanum lycopersicum physiology, Mitosporic Fungi physiology, Tomatine metabolism, Tomatine pharmacology
- Abstract
The anti-fungal, steroidal, glycoalkaloid saponin, alpha-tomatine, is present in uninfected tomato plants in substantial concentrations, and may contribute to the protection of tomato plants against attack by phytopathogenic fungi. In general, successful fungal pathogens of tomato are more resistant to alpha-tomatine in vitro than fungi that do not infect this plant. For a number of tomato pathogens, this resistance has been associated with the ability to detoxify alpha-tomatine through the action of enzymes known as tomatinases. In contrast, the biotrophic tomato pathogen Cladosporium fulvum is sensitive to alpha-tomatine and is unable to detoxify this saponin. This paper describes the effects of heterologous expression of the cDNA encoding tomatinase from the necrotroph Septoria lycopersici in two different physiological races of C. fulvum. Tomatinase-producing C. fulvum transformants showed increased sporulation on cotyledons of susceptible tomato lines. They also caused more extensive infection of seedlings of resistant tomato lines. Thus, alpha-tomatine may contribute to the ability of tomato to restrict the growth of C. fulvum in both compatible and incompatible interactions.
- Published
- 1998
- Full Text
- View/download PDF
49. The activity of lipid A and core components of bacterial lipopolysaccharides in the prevention of the hypersensitive response in pepper.
- Author
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Newman MA, Daniels MJ, and Dow JM
- Subjects
- Plant Leaves drug effects, Plant Leaves immunology, Vegetables immunology, Lipid A pharmacology, Lipopolysaccharides pharmacology, Vegetables drug effects, Xanthomonas campestris metabolism
- Abstract
Pre-treatment of leaves of pepper (Capsicum annuum) with lipopolysaccharide (LPS) preparations from enteric bacteria and Xanthomonas campestris could prevent the hypersensitive response caused by an avirulent X. campestris strain. By use of a range of deep-rough mutants, the minimal structure in Salmonella LPS responsible for the elicitation of this effect was determined to be lipid A attached to a disaccharide of 2-keto-3-deoxyoctulosonate; lipid A alone and the free core oligosaccharide from a Salmonella Ra mutant were not effective. For Xanthomonas, the core oligosaccharide alone had activity although lipid A was not effective. The results suggest that pepper cells can recognize different structures within bacterial LPS to trigger alterations in plant response to avirulent pathogens.
- Published
- 1997
- Full Text
- View/download PDF
50. Induction of extracellular matrix glycoproteins in Brassica petioles by wounding and in response to Xanthomonas campestris.
- Author
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Davies HA, Daniels MJ, and Dow JM
- Subjects
- Brassica microbiology, Extracellular Matrix Proteins immunology, Glycoproteins immunology, Mutation, Virulence genetics, Xanthomonas campestris genetics, Brassica metabolism, Extracellular Matrix Proteins biosynthesis, Glycoproteins biosynthesis, Xanthomonas campestris pathogenicity
- Abstract
A panel of monoclonal antibodies that recognize plant extracellular matrix glycoproteins previously implicated in plant-microbe interactions was used to study the effects of pathogen inoculation and wounding on glycoproteins in petioles of Brassica campestris. The panel of monoclonals comprised two sets: JIM11, JIM12, and JIM20 recognize epitopes carried on hydroxyproline-rich glycoproteins (HRGPs) (M. Smallwood, A. Beven, N. Donovan, S. J. Neitl, J. Peart, K. Roberts, and J. P. Knox, Plant J. 5:237-246, 1994); MAC204 and MAC265 recognize glycoproteins of the Rhizobium infection thread (K. A. VandenBosch, D. J. Bradley, S. Perotto, G. W. Butcher, and N. J. Brewin, EMBO J. 8:335-342, 1989). Wounding or inoculation of petioles with avirulent strains of pathovars of Xanthomonas campestris induced the synthesis of two new groups of antigens: gp160 ran as a smear on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with apparent molecular mass from 120 to 200 kDa and was recognized by JIM20 and MAC204; gpS remained in the stacking gel on SDS-PAGE and was recognized by JIM11, JIM20, and MAC204. The response to virulent strains of pathovars of X. campestris was either less pronounced or absent. gpS comprised several components that were resolved by cation-exchange chromatography. Some of these components were characterized as extensin-like HRGPs. The level of induction of the gpS group of antigens by virulent strains was not altered by mutation of a number of genes required for basic pathogenicity or by heat-killing the bacteria.
- Published
- 1997
- Full Text
- View/download PDF
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