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Sharma A, Iruegas-Bocardo F, Bibi S, Chen YC, Kim JG, Abrahamian P, Minsavage GV, Hurlbert JC, Vallad GE, Mudgett MB, Jones JB, Goss EM. Multiple Acquisitions of XopJ2 Effectors in Populations of Xanthomonas perforans. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024:MPMI05240048R. [PMID: 39102648 DOI: 10.1094/mpmi-05-24-0048-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/07/2024]
Abstract
Type III effectors (T3Es) are major determinants of Xanthomonas virulence and targets for resistance breeding. XopJ2 (synonym AvrBsT) is a highly conserved YopJ-family T3E acquired by X. perforans, the pathogen responsible for bacterial spot disease of tomato. In this study, we characterized a new variant (XopJ2b) of XopJ2, which is predicted to have a similar three-dimensional (3D) structure as the canonical XopJ2 (XopJ2a) despite sharing only 70% sequence identity. XopJ2b carries an acetyltransferase domain and the critical residues required for its activity, and the positions of these residues are predicted to be conserved in the 3D structure of the proteins. We demonstrated that XopJ2b is a functional T3E and triggers a hypersensitive response (HR) when translocated into pepper cells. Like XopJ2a, XopJ2b triggers HR in Arabidopsis that is suppressed by the deacetylase, SOBER1. We found xopJ2b in genome sequences of X. euvesicatoria, X. citri, X. guizotiae, and X. vasicola strains, suggesting widespread horizontal transfer. In X. perforans, xopJ2b was present in strains collected in North America, Africa, Asia, Australia, and Europe, whereas xopJ2a had a narrower geographic distribution. This study expands the Xanthomonas T3E repertoire, demonstrates functional conservation in T3E evolution, and further supports the importance of XopJ2 in X. perforans fitness on tomato. [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.
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Affiliation(s)
- Anuj Sharma
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
- Gulf Coast Research and Education Center, University of Florida, Gainesville, FL 32611, U.S.A
| | | | - Shaheen Bibi
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Yun-Chu Chen
- Department of Biology, Stanford University, Stanford, CA 94305, U.S.A
| | - Jung-Gun Kim
- Department of Biology, Stanford University, Stanford, CA 94305, U.S.A
| | - Peter Abrahamian
- Gulf Coast Research and Education Center, University of Florida, Gainesville, FL 32611, U.S.A
| | - Gerald V Minsavage
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Jason C Hurlbert
- Department of Chemistry, Physics, and Geology, Winthrop University, Rock Hill, SC 29733, U.S.A
| | - Gary E Vallad
- Gulf Coast Research and Education Center, University of Florida, Gainesville, FL 32611, U.S.A
| | - Mary B Mudgett
- Department of Biology, Stanford University, Stanford, CA 94305, U.S.A
| | - Jeffrey B Jones
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Erica M Goss
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, U.S.A
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Neves C, Ribeiro B, Amaro R, Expósito J, Grimplet J, Fortes AM. Network of GRAS transcription factors in plant development, fruit ripening and stress responses. HORTICULTURE RESEARCH 2023; 10:uhad220. [PMID: 38077496 PMCID: PMC10699852 DOI: 10.1093/hr/uhad220] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 10/20/2023] [Indexed: 06/23/2024]
Abstract
The plant-specific family of GRAS transcription factors has been wide implicated in the regulation of transcriptional reprogramming associated with a diversity of biological functions ranging from plant development processes to stress responses. Functional analyses of GRAS transcription factors supported by in silico structural and comparative analyses are emerging and clarifying the regulatory networks associated with their biological roles. In this review, a detailed analysis of GRAS proteins' structure and biochemical features as revealed by recent discoveries indicated how these characteristics may impact subcellular location, molecular mechanisms, and function. Nomenclature issues associated with GRAS classification into different subfamilies in diverse plant species even in the presence of robust genomic resources are discussed, in particular how it affects assumptions of biological function. Insights into the mechanisms driving evolution of this gene family and how genetic and epigenetic regulation of GRAS contributes to subfunctionalization are provided. Finally, this review debates challenges and future perspectives on the application of this complex but promising gene family for crop improvement to cope with challenges of environmental transition.
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Affiliation(s)
- Catarina Neves
- BioISI–Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa, Portugal
| | - Beatriz Ribeiro
- BioISI–Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa, Portugal
| | - Rute Amaro
- BioISI–Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa, Portugal
| | - Jesús Expósito
- BioISI–Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa, Portugal
| | - Jérôme Grimplet
- Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Departamento de Ciencia Vegetal, Gobierno de Aragón, Avda. Montañana 930, 50059 Zaragoza, Spain
- Instituto Agroalimentario de Aragón—IA2 (CITA-Universidad de Zaragoza), Calle Miguel Servet 177, 50013 Zaragoza, Spain
| | - Ana Margarida Fortes
- BioISI–Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisboa, Portugal
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Khan Y, Xiong Z, Zhang H, Liu S, Yaseen T, Hui T. Expression and roles of GRAS gene family in plant growth, signal transduction, biotic and abiotic stress resistance and symbiosis formation-a review. PLANT BIOLOGY (STUTTGART, GERMANY) 2022; 24:404-416. [PMID: 34854195 DOI: 10.1111/plb.13364] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/15/2021] [Indexed: 06/13/2023]
Abstract
The GRAS (derived from GAI, RGA and SCR) gene family consists of plant-specific genes, works as a transcriptional regulator and plays a key part in the regulation of plant growth and development. The past decade has witnessed significant progress in understanding and advances on GRAS transcription factors in various plants. A notable concern is to what extent the mechanisms found in plants, particularly crops, are shared by other species, and what other characteristics are dependent on GRAS transcription factor (TFS)-mediated gene expression. GRAS are involved in many processes that are intimately linked to plant growth regulation. However, GRAS also perform additional roles against environmental stresses, allowing plants to function more efficiently. GRAS increase plant growth and development by improving several physiological processes, such as phytohormone, biosynthetic and signalling pathways. Furthermore, the GRAS gene family plays an important role in response to abiotic stresses, e.g. photooxidative stress. Moreover, evidence shows the involvement of GRAS in arbuscule development during plant-mycorrhiza associations. In this review, the diverse roles of GRAS in plant systems are highlighted that could be useful in enhancing crop productivity through genetic modification, especially of crops. This is the first review to report the role and function of the GRAS gene family in plant systems. Furthermore, a large number of studies are reviewed, and several limitations and research gaps identified that must be addressed in future studies.
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Affiliation(s)
- Y Khan
- Key Laboratory of Plant Nutrition and Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resource and Environment, Northwest A&F University, Yangling, Shaanxi, China
| | - Z Xiong
- Key Laboratory of Plant Nutrition and Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resource and Environment, Northwest A&F University, Yangling, Shaanxi, China
| | - H Zhang
- Key Laboratory of Plant Nutrition and Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resource and Environment, Northwest A&F University, Yangling, Shaanxi, China
| | - S Liu
- Key Laboratory of Plant Nutrition and Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resource and Environment, Northwest A&F University, Yangling, Shaanxi, China
| | - T Yaseen
- Department of Botany, Bacha Khan University, Charsadda, Khyber Pakhtunkhwa, Pakistan
| | - T Hui
- Key Laboratory of Plant Nutrition and Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resource and Environment, Northwest A&F University, Yangling, Shaanxi, China
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Ramachandran P, J BJ, Maupin-Furlow JA, Uthandi S. Bacterial effectors mimicking ubiquitin-proteasome pathway tweak plant immunity. Microbiol Res 2021; 250:126810. [PMID: 34246833 DOI: 10.1016/j.micres.2021.126810] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 12/13/2022]
Abstract
Plant pathogenic Gram-negative bacteria evade the host plant immune system by secreting Type III (T3E) and Type IV effector (T4E) proteins into the plant cytoplasm. Mostly T3Es are secreted into the plant cells to establish pathogenicity by affecting the vital plant process viz. metabolic pathways, signal transduction and hormonal regulation. Ubiquitin-26S proteasome system (UPS) exists as one of the important pathways in plants to control plant immunity and various cellular processes by employing several enzymes and enzyme components. Pathogenic and non-pathogenic bacteria are found to secrete effectors into plants with structural and/or functional similarity to UPS pathway components like ubiquitin E3 ligases, F-box domains, cysteine proteases, inhibitor of host UPS or its components, etc. The bacterial effectors mimic UPS components and target plant resistance proteins for degradation by proteasomes, thereby taking control over the host cellular activities as a strategy to exert virulence. Thus, the bacterial effectors circumvent plant cellular pathways leading to infection and disease development. This review highlights known bacterial T3E and T4E proteins that function and interfere with the ubiquitination pathway to regulate the immune system of plants.
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Affiliation(s)
- Priyadharshini Ramachandran
- Biocatalysts Laboratory, Department of Agricultural Microbiology, Directorate of Natural Resource Management, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India
| | - Beslin Joshi J
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India
| | - Julie A Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA; Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Sivakumar Uthandi
- Biocatalysts Laboratory, Department of Agricultural Microbiology, Directorate of Natural Resource Management, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
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Rodríguez-Alvarez CI, López-Vidriero I, Franco-Zorrilla JM, Nombela G. Basal differences in the transcriptional profiles of tomato leaves associated with the presence/absence of the resistance gene Mi-1 and changes in these differences after infestation by the whitefly Bemisia tabaci. BULLETIN OF ENTOMOLOGICAL RESEARCH 2020; 110:463-479. [PMID: 31813394 DOI: 10.1017/s0007485319000828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The tomato Mi-1 gene mediates plant resistance to whitefly Bemisia tabaci, nematodes, and aphids. Other genes are also required for this resistance, and a model of interaction between the proteins encoded by these genes was proposed. Microarray analyses were used previously to identify genes involved in plant resistance to pests or pathogens, but scarcely in resistance to insects. In the present work, the GeneChip™ Tomato Genome Array (Affymetrix®) was used to compare the transcriptional profiles of Motelle (bearing Mi-1) and Moneymaker (lacking Mi-1) cultivars, both before and after B. tabaci infestation. Ten transcripts were expressed at least twofold in uninfested Motelle than in Moneymaker, while other eight were expressed half or less. After whitefly infestation, differences between cultivars increased to 14 transcripts expressed more in Motelle than in Moneymaker and 14 transcripts less expressed. Half of these transcripts showed no differential expression before infestation. These results show the baseline differences in the tomato transcriptomic profile associated with the presence or absence of the Mi-1 gene and provide us with valuable information on candidate genes to intervene in either compatible or incompatible tomato-whitefly interactions.
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Affiliation(s)
- Clara I Rodríguez-Alvarez
- Department of Plant Protection Institute for Agricultural Sciences (ICA), Spanish National Research Council (CSIC), Serrano 115 Dpdo., Madrid28006, Spain
| | - Irene López-Vidriero
- Genomics Unit, Centro Nacional de Biotecnología (CNB), Spanish National Research Council (CSIC), Darwin 3, Madrid28049, Spain
| | - José M Franco-Zorrilla
- Genomics Unit, Centro Nacional de Biotecnología (CNB), Spanish National Research Council (CSIC), Darwin 3, Madrid28049, Spain
| | - Gloria Nombela
- Department of Plant Protection Institute for Agricultural Sciences (ICA), Spanish National Research Council (CSIC), Serrano 115 Dpdo., Madrid28006, Spain
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Huang W, Xian Z, Kang X, Tang N, Li Z. Genome-wide identification, phylogeny and expression analysis of GRAS gene family in tomato. BMC PLANT BIOLOGY 2015; 15:209. [PMID: 26302743 PMCID: PMC4549011 DOI: 10.1186/s12870-015-0590-6] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 08/11/2015] [Indexed: 05/20/2023]
Abstract
BACKGROUND GRAS transcription factors usually act as integrators of multiple growth regulatory and environmental signals, including axillary shoot meristem formation, root radial pattering, phytohormones, light signaling, and abiotic/biotic stress. However, little is known about this gene family in tomato (Solanum lycopersicum), the most important model plant for crop species with fleshy fruits. RESULTS In this study, 53 GRAS genes were identified and renamed based on tomato whole-genome sequence and their respective chromosome distribution except 19 members were kept as their already existed name. Multiple sequence alignment showed typical GRAS domain in these proteins. Phylogenetic analysis of GRAS proteins from tomato, Arabidopsis, Populus, P.mume, and Rice revealed that SlGRAS proteins could be divided into at least 13 subfamilies. SlGRAS24 and SlGRAS40 were identified as target genes of miR171 using5'-RACE (Rapid amplification of cDNA ends). qRT-PCR analysis revealed tissue-/organ- and development stage-specific expression patterns of SlGRAS genes. Moreover, their expression patterns in response to different hormone and abiotic stress treatments were also investigated. CONCLUSIONS This study provides the first comprehensive analysis of GRAS gene family in the tomato genome. The data will undoubtedly be useful for better understanding the potential functions of GRAS genes, and their possible roles in mediating hormone cross-talk and abiotic stress in tomato as well as in some other relative species.
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Affiliation(s)
- Wei Huang
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing, 400044, People's Republic China.
| | - Zhiqiang Xian
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing, 400044, People's Republic China.
| | - Xia Kang
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing, 400044, People's Republic China.
| | - Ning Tang
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing, 400044, People's Republic China.
| | - Zhengguo Li
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing, 400044, People's Republic China.
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Stork W, Kim JG, Mudgett MB. Functional Analysis of Plant Defense Suppression and Activation by the Xanthomonas Core Type III Effector XopX. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:180-94. [PMID: 25338145 PMCID: PMC4293322 DOI: 10.1094/mpmi-09-14-0263-r] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Many phytopathogenic type III secretion effector proteins (T3Es) have been shown to target and suppress plant immune signaling but perturbation of the plant immune system by T3Es can also elicit a plant response. XopX is a "core" Xanthomonas T3E that contributes to growth and symptom development during Xanthomonas euvesicatoria infection of tomato but its functional role is undefined. We tested the effect of XopX on several aspects of plant immune signaling. XopX promoted ethylene production and plant cell death (PCD) during X. euvesicatoria infection of susceptible tomato and in transient expression assays in Nicotiana benthamiana, which is consistent with its requirement for the development of X. euvesicatoria-induced disease symptoms. Additionally, although XopX suppressed flagellin-induced reactive oxygen species, it promoted the accumulation of pattern-triggered immunity (PTI) gene transcripts. Surprisingly, XopX coexpression with other PCD elicitors resulted in delayed PCD, suggesting antagonism between XopX-dependent PCD and other PCD pathways. However, we found no evidence that XopX contributed to the suppression of effector-triggered immunity during X. euvesicatoria-tomato interactions, suggesting that XopX's primary virulence role is to modulate PTI. These results highlight the dual role of a core Xanthomonas T3E in simultaneously suppressing and activating plant defense responses.
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Üstün S, Bartetzko V, Börnke F. The Xanthomonas effector XopJ triggers a conditional hypersensitive response upon treatment of N. benthamiana leaves with salicylic acid. FRONTIERS IN PLANT SCIENCE 2015; 6:599. [PMID: 26284106 PMCID: PMC4522559 DOI: 10.3389/fpls.2015.00599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/20/2015] [Indexed: 05/09/2023]
Abstract
XopJ is a Xanthomonas type III effector protein that promotes bacterial virulence on susceptible pepper plants through the inhibition of the host cell proteasome and a resultant suppression of salicylic acid (SA) - dependent defense responses. We show here that Nicotiana benthamiana leaves transiently expressing XopJ display hypersensitive response (HR) -like symptoms when exogenously treated with SA. This apparent avirulence function of XopJ was further dependent on effector myristoylation as well as on an intact catalytic triad, suggesting a requirement of its enzymatic activity for HR-like symptom elicitation. The ability of XopJ to cause a HR-like symptom development upon SA treatment was lost upon silencing of SGT1 and NDR1, respectively, but was independent of EDS1 silencing, suggesting that XopJ is recognized by an R protein of the CC-NBS-LRR class. Furthermore, silencing of NPR1 abolished the elicitation of HR-like symptoms in XopJ expressing leaves after SA application. Measurement of the proteasome activity indicated that proteasome inhibition by XopJ was alleviated in the presence of SA, an effect that was not observed in NPR1 silenced plants. Our results suggest that XopJ - triggered HR-like symptoms are closely related to the virulence function of the effector and that XopJ follows a two-signal model in order to elicit a response in the non-host plant N. benthamiana.
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Affiliation(s)
- Suayib Üstün
- Plant Health, Plant Metabolism Group, Leibniz-Institute of Vegetable and Ornamental Crops, GroßbeerenGermany
| | - Verena Bartetzko
- Division of Biochemistry, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, ErlangenGermany
| | - Frederik Börnke
- Plant Health, Plant Metabolism Group, Leibniz-Institute of Vegetable and Ornamental Crops, GroßbeerenGermany
- Division of Biochemistry, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, ErlangenGermany
- Institute of Biochemistry and Biology, University of PotsdamPotsdam, Germany
- *Correspondence: Frederik Börnke, Plant Health, Plant Metabolism Group, Leibniz-Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, 14979 Großbeeren, Germany,
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New insights into the role of the small ubiquitin-like modifier (SUMO) in plants. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 300:161-209. [PMID: 23273862 DOI: 10.1016/b978-0-12-405210-9.00005-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Small ubiquitin-like modifier (SUMO) is a small (∼12kDa) protein that occurs in all eukaryotes and participates in the reversible posttranslational modification of target cellular proteins. The three-dimensional structure of SUMO and ubiquitin (Ub) are superimposable although there is very little similarity in their primary amino acid sequences. In all organisms, conjugation and deconjugation of Ub and SUMO proceed by the same reactions while using pathway-specific enzymes. SUMO conjugation in plants is a part of the controls governing important biological processes such as growth, development, flowering, environmental (abiotic) stress responses, and response to pathogen infection. Most of the evidence for this comes from genetic analyses. Recent efforts to dissect the function of sumoylation have focused on uncovering targets of SUMO conjugation by using either a yeast two-hybrid screen employing components of the SUMO cycle as bait or by using affinity purification of SUMO-conjugated proteins followed by identification of these proteins by mass spectrometry. This chapter reviews the current knowledge regarding sumoylation in plants, with special focus on the model plant Arabidopsis thaliana.
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Sinha DK, Nagaraju J, Tomar A, Bentur JS, Nair S. Pyrosequencing-based transcriptome analysis of the asian rice gall midge reveals differential response during compatible and incompatible interaction. Int J Mol Sci 2012; 13:13079-103. [PMID: 23202939 PMCID: PMC3497313 DOI: 10.3390/ijms131013079] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 09/14/2012] [Accepted: 09/27/2012] [Indexed: 01/21/2023] Open
Abstract
The Asian rice gall midge (Orseolia oryzae) is a major pest responsible for immense loss in rice productivity. Currently, very little knowledge exists with regard to this insect at the molecular level. The present study was initiated with the aim of developing molecular resources as well as identifying alterations at the transcriptome level in the gall midge maggots that are in a compatible (SH) or in an incompatible interaction (RH) with their rice host. Roche 454 pyrosequencing strategy was used to develop both transcriptomics and genomics resources that led to the identification of 79,028 and 85,395 EST sequences from gall midge biotype 4 (GMB4) maggots feeding on a susceptible and resistant rice variety, TN1 (SH) and Suraksha (RH), respectively. Comparative transcriptome analysis of the maggots in SH and RH revealed over-representation of transcripts from proteolysis and protein phosphorylation in maggots from RH. In contrast, over-representation of transcripts for translation, regulation of transcription and transcripts involved in electron transport chain were observed in maggots from SH. This investigation, besides unveiling various mechanisms underlying insect-plant interactions, will also lead to a better understanding of strategies adopted by insects in general, and the Asian rice gall midge in particular, to overcome host defense.
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Affiliation(s)
- Deepak Kumar Sinha
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India; E-Mail:
| | - Javaregowda Nagaraju
- Laboratory of Molecular Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500001, India; E-Mail:
| | - Archana Tomar
- Laboratory of Molecular Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500001, India; E-Mail:
| | | | - Suresh Nair
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India; E-Mail:
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Schulze S, Kay S, Büttner D, Egler M, Eschen-Lippold L, Hause G, Krüger A, Lee J, Müller O, Scheel D, Szczesny R, Thieme F, Bonas U. Analysis of new type III effectors from Xanthomonas uncovers XopB and XopS as suppressors of plant immunity. THE NEW PHYTOLOGIST 2012; 195:894-911. [PMID: 22738163 DOI: 10.1111/j.1469-8137.2012.04210.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The pathogenicity of the Gram-negative plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv) is dependent on type III effectors (T3Es) that are injected into plant cells by a type III secretion system and interfere with cellular processes to the benefit of the pathogen. In this study, we analyzed eight T3Es from Xcv strain 85-10, six of which were newly identified effectors. Genetic studies and protoplast expression assays revealed that XopB and XopS contribute to disease symptoms and bacterial growth, and suppress pathogen-associated molecular pattern (PAMP)-triggered plant defense gene expression. In addition, XopB inhibits cell death reactions induced by different T3Es, thus suppressing defense responses related to both PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI). XopB localizes to the Golgi apparatus and cytoplasm of the plant cell and interferes with eukaryotic vesicle trafficking. Interestingly, a XopB point mutant derivative was defective in the suppression of ETI-related responses, but still interfered with vesicle trafficking and was only slightly affected with regard to the suppression of defense gene induction. This suggests that XopB-mediated suppression of PTI and ETI is dependent on different mechanisms that can be functionally separated.
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Affiliation(s)
- Sebastian Schulze
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
| | - Sabine Kay
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
| | - Daniela Büttner
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
| | - Monique Egler
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
| | | | - Gerd Hause
- Biozentrum, Martin-Luther-University Halle-Wittenberg, Weinbergweg 22, D-06120 Halle (Saale), Germany
| | - Antje Krüger
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
| | - Justin Lee
- Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle (Saale), Germany
| | - Oliver Müller
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
| | - Dierk Scheel
- Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle (Saale), Germany
| | - Robert Szczesny
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
| | - Frank Thieme
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
| | - Ulla Bonas
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
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Rivas S, Genin S. A plethora of virulence strategies hidden behind nuclear targeting of microbial effectors. FRONTIERS IN PLANT SCIENCE 2011; 2:104. [PMID: 22639625 PMCID: PMC3355726 DOI: 10.3389/fpls.2011.00104] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 12/09/2011] [Indexed: 05/24/2023]
Abstract
Plant immune responses depend on the ability to couple rapid recognition of the invading microbe to an efficient response. During evolution, plant pathogens have acquired the ability to deliver effector molecules inside host cells in order to manipulate cellular and molecular processes and establish pathogenicity. Following translocation into plant cells, microbial effectors may be addressed to different subcellular compartments. Intriguingly, a significant number of effector proteins from different pathogenic microorganisms, including viruses, oomycetes, fungi, nematodes, and bacteria, is targeted to the nucleus of host cells. In agreement with this observation, increasing evidence highlights the crucial role played by nuclear dynamics, and nucleocytoplasmic protein trafficking during a great variety of analyzed plant-pathogen interactions. Once in the nucleus, effector proteins are able to manipulate host transcription or directly subvert essential host components to promote virulence. Along these lines, it has been suggested that some effectors may affect histone packing and, thereby, chromatin configuration. In addition, microbial effectors may either directly activate transcription or target host transcription factors to alter their regular molecular functions. Alternatively, nuclear translocation of effectors may affect subcellular localization of their cognate resistance proteins in a process that is essential for resistance protein-mediated plant immunity. Here, we review recent progress in our field on the identification of microbial effectors that are targeted to the nucleus of host plant cells. In addition, we discuss different virulence strategies deployed by microbes, which have been uncovered through examination of the mechanisms that guide nuclear localization of effector proteins.
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Affiliation(s)
- Susana Rivas
- Institut National de la Recherche Agronomique, Laboratoire des Interactions Plantes-MicroorganismesUMR 441, Castanet-Tolosan, France
- Centre National de la Recherche Scientifique, Laboratoire des Interactions Plantes-MicroorganismesUMR 2594, Castanet-Tolosan, France
| | - Stéphane Genin
- Institut National de la Recherche Agronomique, Laboratoire des Interactions Plantes-MicroorganismesUMR 441, Castanet-Tolosan, France
- Centre National de la Recherche Scientifique, Laboratoire des Interactions Plantes-MicroorganismesUMR 2594, Castanet-Tolosan, France
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Lewis JD, Lee A, Ma W, Zhou H, Guttman DS, Desveaux D. The YopJ superfamily in plant-associated bacteria. MOLECULAR PLANT PATHOLOGY 2011; 12:928-37. [PMID: 21726386 PMCID: PMC6640427 DOI: 10.1111/j.1364-3703.2011.00719.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Bacterial pathogens employ the type III secretion system to secrete and translocate effector proteins into their hosts. The primary function of these effector proteins is believed to be the suppression of host defence responses or innate immunity. However, some effector proteins may be recognized by the host and consequently trigger a targeted immune response. The YopJ/HopZ/AvrRxv family of bacterial effector proteins is a widely distributed and evolutionarily diverse family, found in both animal and plant pathogens, as well as plant symbionts. How can an effector family effectively promote the virulence of pathogens on hosts from two separate kingdoms? Our understanding of the evolutionary relationships among the YopJ superfamily members provides an excellent opportunity to address this question and to investigate the functions and virulence strategies of a diverse type III effector family in animal and plant hosts. In this work, we briefly review the literature on YopJ, the archetypal member from Yersinia pestis, and discuss members of the superfamily in species of Pseudomonas, Xanthomonas, Ralstonia and Rhizobium. We review the molecular and cellular functions, if known, of the YopJ homologues in plants, and highlight the diversity of responses in different plant species, with a particular focus on the Pseudomonas syringae HopZ family. The YopJ superfamily provides an excellent foundation for the study of effector diversification in the context of wide-ranging, co-evolutionary interactions.
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Affiliation(s)
- Jennifer D Lewis
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
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Zhou H, Lin J, Johnson A, Morgan RL, Zhong W, Ma W. Pseudomonas syringae type III effector HopZ1 targets a host enzyme to suppress isoflavone biosynthesis and promote infection in soybean. Cell Host Microbe 2011; 9:177-186. [PMID: 21402357 DOI: 10.1016/j.chom.2011.02.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 12/19/2010] [Accepted: 01/28/2011] [Indexed: 11/22/2022]
Abstract
Type III secreted effectors (T3SEs), such as Pseudomonas syringae HopZ1, are essential bacterial virulence proteins injected into the host cytosol to facilitate infection. However, few direct targets of T3SEs are known. Investigating the target(s) of HopZ1 in soybean, a natural P. syringae host, we find that HopZ1 physically interacts with the isoflavone biosynthesis enzyme, 2-hydroxyisoflavanone dehydratase (GmHID1). P. syringae infection induces gmhid1 expression and production of daidzein, a major soybean isoflavone. Silencing gmhid1 increases susceptibility to P. syringae infection, supporting a role for GmHID1 in innate immunity. P. syringae expressing active but not the catalytic mutant of HopZ1 inhibits daidzein induction and promotes bacterial multiplication in soybean. HopZ1-enhanced P. syringae multiplication is at least partially dependent on GmHID1. Thus, GmHID1 is a virulence target of HopZ1 to promote P. syringae infection of soybean. This work highlights the isoflavonoid biosynthesis pathway as an antibacterial defense mechanism and a direct T3SE target.
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Affiliation(s)
- Huanbin Zhou
- Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA 92521, USA; Center for Plant Cell Biology, University of California, Riverside, Riverside, CA 92521, USA; Institute for Integrative Genomic Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Jian Lin
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
| | - Aimee Johnson
- Center for Plant Cell Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Robyn L Morgan
- Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA 92521, USA; Center for Plant Cell Biology, University of California, Riverside, Riverside, CA 92521, USA; Institute for Integrative Genomic Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Wenwan Zhong
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, CA 92521, USA; Department of Chemistry, University of California, Riverside, Riverside, CA 92521, USA
| | - Wenbo Ma
- Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA 92521, USA; Center for Plant Cell Biology, University of California, Riverside, Riverside, CA 92521, USA; Institute for Integrative Genomic Biology, University of California, Riverside, Riverside, CA 92521, USA.
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16
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Melech-Bonfil S, Sessa G. Tomato MAPKKKε is a positive regulator of cell-death signaling networks associated with plant immunity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:379-91. [PMID: 21049563 DOI: 10.1111/j.1365-313x.2010.04333.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Mitogen-activated protein (MAP) kinase cascades are fundamental components of the signaling pathways associated with plant immunity. Despite the large number of MAP kinase kinase kinases (MAPKKK) encoded in the plant genome, only very few of them have an assigned function. Here, we identified MAPKKK gene of tomato (Solanum lycopersicum), SIMAPKKKε, which is required for hypersensitive response cell death and disease resistance against Gram-negative bacterial pathogens. Silencing of SIMAPKKKε compromised tomato resistance to Xanthomonas campestris and Pseudomonas syringae strains, resulting in the appearance of disease symptoms and enhanced bacterial growth. In addition, silencing of NbMAPKKKε in Nicotiana benthamiana plants significantly inhibited the cell death triggered by expression of different R gene/effector gene pairs. Conversely, overexpression of either the full-length SIMAPKKKε gene or its kinase domain in N. benthamiana leaves caused pathogen-independent activation of cell death that required an intact kinase catalytic domain. Moreover, by suppressing the expression of various MAPKK and MAPK genes and overexpressing the SIMAPKKKε kinase domain, we identified a signaling cascade acting downstream of SIMAPKKKε that includes MEK2, WIPK and SIPK. Additional epistasis experiments revealed that SIPKK functions as a negative regulator of SIMAPKKKε-mediated cell death. Our results provide evidence that SIMAPKKKε is a signaling molecule that positively regulates cell death networks associated with plant immunity.
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Affiliation(s)
- Shiri Melech-Bonfil
- Department of Molecular Biology and Ecology of Plants, Tel-Aviv University, 69978 Tel-Aviv, Israel
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17
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Szczesny R, Büttner D, Escolar L, Schulze S, Seiferth A, Bonas U. Suppression of the AvrBs1-specific hypersensitive response by the YopJ effector homolog AvrBsT from Xanthomonas depends on a SNF1-related kinase. THE NEW PHYTOLOGIST 2010; 187:1058-1074. [PMID: 20609114 DOI: 10.1111/j.1469-8137.2010.03346.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
*Pathogenicity of the Gram-negative plant pathogen Xanthomonas campestris pv. vesicatoria (Xcv) depends on a type III secretion system that translocates a cocktail of > 25 type III effector proteins into the plant cell. *In this study, we identified the effector AvrBsT as a suppressor of specific plant defense. AvrBsT belongs to the YopJ/AvrRxv protein family, members of which are predicted to act as proteases and/or acetyltransferases. *AvrBsT suppresses the hypersensitive response (HR) that is elicited by the effector protein AvrBs1 from Xcv in resistant pepper plants. HR suppression occurs inside the plant cell and depends on a conserved predicted catalytic residue of AvrBsT. Yeast two-hybrid based analyses identified plant interaction partners of AvrBs1 and AvrBsT, including a putative regulator of sugar metabolism, SNF1-related kinase 1 (SnRK1), as interactor of AvrBsT. Intriguingly, gene silencing experiments revealed that SnRK1 is required for the induction of the AvrBs1-specific HR. *We therefore speculate that SnRK1 is involved in the AvrBsT-mediated suppression of the AvrBs1-specific HR.
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Affiliation(s)
- Robert Szczesny
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Daniela Büttner
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Lucia Escolar
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Sebastian Schulze
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Anja Seiferth
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Ulla Bonas
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
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18
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Lewis JD, Wu R, Guttman DS, Desveaux D. Allele-specific virulence attenuation of the Pseudomonas syringae HopZ1a type III effector via the Arabidopsis ZAR1 resistance protein. PLoS Genet 2010; 6:e1000894. [PMID: 20368970 PMCID: PMC2848558 DOI: 10.1371/journal.pgen.1000894] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 03/03/2010] [Indexed: 11/19/2022] Open
Abstract
Plant resistance (R) proteins provide a robust surveillance system to defend against potential pathogens. Despite their importance in plant innate immunity, relatively few of the ∼170 R proteins in Arabidopsis have well-characterized resistance specificity. In order to identify the R protein responsible for recognition of the Pseudomonas syringae type III secreted effector (T3SE) HopZ1a, we assembled an Arabidopsis R gene T–DNA Insertion Collection (ARTIC) from publicly available Arabidopsis thaliana insertion lines and screened it for plants lacking HopZ1a-induced immunity. This reverse genetic screen revealed that the Arabidopsis R protein HOPZ-ACTIVATED RESISTANCE 1 (ZAR1; At3g50950) is required for recognition of HopZ1a in Arabidopsis. ZAR1 belongs to the coiled-coil (CC) class of nucleotide binding site and leucine-rich repeat (NBS–LRR) containing R proteins; however, the ZAR1 CC domain phylogenetically clusters in a clade distinct from other related Arabidopsis R proteins. ZAR1–mediated immunity is independent of several genes required by other R protein signaling pathways, including NDR1 and RAR1, suggesting that ZAR1 possesses distinct signaling requirements. The closely-related T3SE protein, HopZ1b, is still recognized by zar1 Arabidopsis plants indicating that Arabidopsis has evolved at least two independent R proteins to recognize the HopZ T3SE family. Also, in Arabidopsis zar1 plants HopZ1a promotes P. syringae growth indicative of an ancestral virulence function for this T3SE prior to the evolution of recognition by the host resistance protein ZAR1. Our results demonstrate that the Arabidopsis resistance protein ZAR1 confers allele-specific recognition and virulence attenuation of the Pseudomonas syringae T3SE protein HopZ1a. Pseudomonas syringae is a model bacterial pathogen that can infect a broad range of plant species, including important crop plants, as well as the model plant Arabidopsis thaliana. P. syringae employs a specialized syringe-like structure called the type III secretion system to inject virulence proteins termed “effectors” directly into the cells of its plant host. In response, plants have evolved a surveillance system to recognize the presence of type III secreted effector (T3SE) proteins as a trigger for immunity. The sentinels of this surveillance system are termed resistance (R) proteins. Here we identify a new resistance protein, ZAR1, which recognizes the T3SE HopZ1a from P. syringae. HopZ1a is part of the important YopJ superfamily of T3SEs whose archetypical member, YopJ, is found in the causal agent of the bubonic plague, Yersinia pestis. We show that ZAR1–mediated immunity is independent of known Arabidopsis resistance-related genes suggesting that ZAR1 possesses novel signaling requirements. Interestingly, in Arabidopsis plants lacking ZAR1, HopZ1a enhances the virulence of P. syringae indicating that ZAR1 has evolved to recognize and attenuate an ancestral HopZ1a virulence function.
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Affiliation(s)
- Jennifer D. Lewis
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Ronald Wu
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - David S. Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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19
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Morgan RL, Zhou H, Lehto E, Nguyen N, Bains A, Wang X, Ma W. Catalytic domain of the diversified Pseudomonas syringae type III effector HopZ1 determines the allelic specificity in plant hosts. Mol Microbiol 2010; 76:437-55. [PMID: 20233307 DOI: 10.1111/j.1365-2958.2010.07107.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The type III secretion systems (T3SS) and secreted effectors (T3SEs) are essential virulence factors in Gram-negative bacteria. During the arms race, plants have evolved resistance (R) genes to detect specific T3SEs and activate defence responses. However, this immunity can be efficiently defeated by the pathogens through effector evolution. HopZ1 of the plant pathogen Pseudomonas syringae is a member of the widely distributed YopJ T3SE family. Three alleles are known to be present in P. syringae, with HopZ1a most resembling the ancestral allelic form. In this study, molecular mechanisms underlying the sequence diversification-enabled HopZ1 allelic specificity is investigated. Using domain shuffling experiments, we present evidence showing that a central domain upstream of the conserved catalytic cysteine residue determines HopZ1 recognition specificity. Random and targeted mutagenesis identified three amino acids involved in HopZ1 allelic specificity. Particularly, the exchange of cysteine141 in HopZ1a with lysine137 at the corresponding position in HopZ1b abolished HopZ1a recognition in soybean. This position is under strong positive selection, suggesting that the cysteine/lysine mutation might be a key step driving the evolution of HopZ1. Our data support a model in which sequence diversification imposed by the plant R gene-associated immunity has driven HopZ1 evolution by allowing allele-specific substrate-binding.
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Affiliation(s)
- Robyn L Morgan
- Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
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20
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Panthee DR, Chen F. Genomics of fungal disease resistance in tomato. Curr Genomics 2010; 11:30-9. [PMID: 20808521 PMCID: PMC2851114 DOI: 10.2174/138920210790217927] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 06/19/2009] [Accepted: 06/19/2009] [Indexed: 11/26/2022] Open
Abstract
Tomato (Solanum lycopersicum) is an important vegetable crop worldwide. Often times, its production is hindered by fungal diseases. Important fungal diseases limiting tomato production are late blight, caused by Phytophthora infestans, early blight, caused by Alternaria solanii, and septoria leaf spot, caused by Septoria lycopersici, fusarium wilt caused by Fusarium oxysporium fsp. oxysporium, and verticilium wilt caused by Verticilium dahlea. The Phytophthora infestans is the same fungus that caused the devastating loss of potato in Europe in 1845. A similar magnitude of crop loss in tomato has not occurred but Phytophthora infestans has caused the complete loss of tomato crops around the world on a small scale. Several attempts have been made through conventional breeding and the molecular biological approaches to understand the biology of host-pathogen interaction so that the disease can be managed and crop loss prevented. In this review, we present a comprehensive analysis of information produced by molecular genetic and genomic experiments on host-pathogen interactions of late blight, early blight, septoria leaf spot, verticilim wilt and fusarium wilt in tomato. Furthermore, approaches adopted to manage these diseases in tomato including genetic transformation are presented. Attempts made to link molecular markers with putative genes and their use in crop improvement are discussed.
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Affiliation(s)
- Dilip R. Panthee
- Department of Horticultural Science, North Carolina State University, Mountain Horticultural Crops Research and Extension Center, 455 Research Dr., Mills River, NC 28759, USA
| | - Feng Chen
- Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA
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Abstract
Plant pathogenic bacteria of the genus Xanthomonas cause a variety of diseases in economically important monocotyledonous and dicotyledonous crop plants worldwide. Successful infection and bacterial multiplication in the host tissue often depend on the virulence factors secreted including adhesins, polysaccharides, LPS and degradative enzymes. One of the key pathogenicity factors is the type III secretion system, which injects effector proteins into the host cell cytosol to manipulate plant cellular processes such as basal defense to the benefit of the pathogen. The coordinated expression of bacterial virulence factors is orchestrated by quorum-sensing pathways, multiple two-component systems and transcriptional regulators such as Clp, Zur, FhrR, HrpX and HpaR. Furthermore, virulence gene expression is post-transcriptionally controlled by the RNA-binding protein RsmA. In this review, we summarize the current knowledge on the infection strategies and regulatory networks controlling secreted virulence factors from Xanthomonas species.
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Affiliation(s)
- Daniela Büttner
- Genetics Department, Institute of Biology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany.
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22
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Robb J, Castroverde CD, Shittu HO, Nazar RN. Patterns of defence gene expression in the tomato– Verticilliuminteraction. BOTANY 2009. [PMID: 0 DOI: 10.1139/b09-056] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In a tomato plant infected by Verticillium dahliae , race 1, compatibility or incompatibility appears to be determined in the stem, but little is known about the genes that either regulate or effect critical cellular events. In the present study, microarray and RT-PCR analyses were used to assess changes in tomato mRNA populations during both interactions. Initially, a commercially available DNA chip was used to screen gene expression at a single critical time point after inoculation of resistant and susceptible plants. From the results, the most-affected genes were selected to develop a tomato Verticillium response (TVR) DNA chip for detailed analyses of gene expression for 15 d after inoculation. Taken together, over half of the genes on the TVR array exhibited one of three distinct patterns of change, one reflecting a resistant phenotype and two being consistent with a susceptible phenotype. Of particular interest was a cluster of strongly expressed genes belonging to groups 2 and 3 that appeared to be co-ordinately down regulated in infected resistant plants relative to susceptible. Many of these genes encode pathogenesis related (PR) proteins. The data demonstrate that even though complex, the biological system can be standardized sufficiently to allow the reproducible analysis of gene expression in a whole plant system and provide patterns of transcriptional variation that can be used to assess the significance of specific genes in pathogenesis and resistance.
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Affiliation(s)
- Jane Robb
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | | | - Hakeem O. Shittu
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Ross N. Nazar
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
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23
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Shittu HO, Castroverde DCM, Nazar RN, Robb J. Plant-endophyte interplay protects tomato against a virulent Verticillium. PLANTA 2009; 229:415-26. [PMID: 0 DOI: 10.1007/s00425-008-0840-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 10/10/2008] [Indexed: 05/23/2023]
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24
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Y4lO of Rhizobium sp. strain NGR234 is a symbiotic determinant required for symbiosome differentiation. J Bacteriol 2008; 191:735-46. [PMID: 19060155 DOI: 10.1128/jb.01404-08] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Type 3 (T3) effector proteins, secreted by nitrogen-fixing rhizobia with a bacterial T3 secretion system, affect the nodulation of certain host legumes. The open reading frame y4lO of Rhizobium sp. strain NGR234 encodes a protein with sequence similarities to T3 effectors from pathogenic bacteria (the YopJ effector family). Transcription studies showed that the promoter activity of y4lO depended on the transcriptional activator TtsI. Recombinant Y4lO protein expressed in Escherichia coli did not acetylate two representative mitogen-activated protein kinase kinases (human MKK6 and MKK1 from Medicago truncatula), indicating that YopJ-like proteins differ with respect to their substrate specificities. The y4lO gene was mutated in NGR234 (strain NGROmegay4lO) and in NGR Omega nopL, a mutant that does not produce the T3 effector NopL (strain NGR Omega nopLOmegay4lO). When used as inoculants, the symbiotic properties of the mutants differed. Tephrosia vogelii, Phaseolus vulgaris cv. Yudou No. 1, and Vigna unguiculata cv. Sui Qing Dou Jiao formed pink effective nodules with NGR234 and NGR Omega nopL Omega y4lO. Nodules induced by NGR Omega y4lO were first pink but rapidly turned greenish (ineffective nodules), indicating premature senescence. An ultrastructural analysis of the nodules induced by NGR Omega y4lO revealed abnormal formation of enlarged infection droplets in ineffective nodules, whereas symbiosomes harboring a single bacteroid were frequently observed in effective nodules induced by NGR234 or NGR Omega nopL Omega y4lO. It is concluded that Y4lO is a symbiotic determinant involved in the differentiation of symbiosomes. Y4lO mitigated senescence-inducing effects caused by the T3 effector NopL, suggesting synergistic effects for Y4lO and NopL in nitrogen-fixing nodules.
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25
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Bhattarai KK, Xie QG, Mantelin S, Bishnoi U, Girke T, Navarre DA, Kaloshian I. Tomato susceptibility to root-knot nematodes requires an intact jasmonic acid signaling pathway. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:1205-14. [PMID: 18700825 DOI: 10.1094/mpmi-21-9-1205] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Responses of resistant (Mi-1/Mi-1) and susceptible (mi-1/ mi-1) tomato (Solanum lycopersicum) to root-knot nematodes (RKNs; Meloidogyne spp.) infection were monitored using cDNA microarrays, and the roles of salicylic acid (SA) and jasmonic acid (JA) defense signaling were evaluated in these interactions. Array analysis was used to compare transcript profiles in incompatible and compatible interactions of tomato roots 24 h after RKN infestation. The jai1 and def1 tomato mutant, altered in JA signaling, and tomato transgenic line NahG, altered in SA signaling, in the presence or absence of the RKN resistance gene Mi-1, were evaluated. The array analysis identified 1,497 and 750 genes differentially regulated in the incompatible and compatible interactions, respectively. Of the differentially regulated genes, 37% were specific to the incompatible interactions. NahG affected neither Mi-1 resistance nor basal defenses to RKNs. However, jai1 reduced tomato susceptibility to RKNs while not affecting Mi-1 resistance. In contrast, the def1 mutant did not affect RKN susceptibility. These results indicate that JA-dependent signaling does not play a role in Mi-1-mediated defense; however, an intact JA signaling pathway is required for tomato susceptibility to RKNs. In addition, low levels of SA might be sufficient for basal and Mi-1 resistance to RKNs.
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Affiliation(s)
- Kishor K Bhattarai
- Department of Nematology, Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA
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26
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Lewis JD, Abada W, Ma W, Guttman DS, Desveaux D. The HopZ family of Pseudomonas syringae type III effectors require myristoylation for virulence and avirulence functions in Arabidopsis thaliana. J Bacteriol 2008; 190:2880-91. [PMID: 18263728 PMCID: PMC2293245 DOI: 10.1128/jb.01702-07] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Accepted: 01/28/2008] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas syringae utilizes the type III secretion system to translocate effector proteins into plant cells, where they can contribute to the pathogen's ability to infect and cause disease. Recognition of these effectors by resistance proteins induces defense responses that typically include a programmed cell death reaction called the hypersensitive response. The YopJ/HopZ family of type III effector proteins is a common family of effector proteins found in animal- and plant-pathogenic bacteria. The HopZ family in P. syringae includes HopZ1a(PsyA2), HopZ1b(PgyUnB647), HopZ1c(PmaE54326), HopZ2(Ppi895A) and HopZ3(PsyB728a). HopZ1a is predicted to be most similar to the ancestral hopZ allele and causes a hypersensitive response in multiple plant species, including Arabidopsis thaliana. Therefore, it has been proposed that host defense responses have driven the diversification of this effector family. In this study, we further characterized the hypersensitive response induced by HopZ1a and demonstrated that it is not dependent on known resistance genes. Further, we identified a novel virulence function for HopZ2 that requires the catalytic cysteine demonstrated to be required for protease activity. Sequence analysis of the HopZ family revealed the presence of a predicted myristoylation sequence in all members except HopZ3. We demonstrated that the myristoylation site is required for membrane localization of this effector family and contributes to the virulence and avirulence activities of HopZ2 and HopZ1a, respectively. This paper provides insight into the selective pressures driving virulence protein evolution by describing a detailed functional characterization of the diverse HopZ family of type III effectors with the model plant Arabidopsis.
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Affiliation(s)
- Jennifer D Lewis
- Department of Cell & Systems Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario M5S 3B2, Canada
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Whalen M, Richter T, Zakhareyvich K, Yoshikawa M, Al-Azzeh D, Adefioye A, Spicer G, Mendoza LL, Morales CQ, Klassen V, Perez-Baron G, Toebe CS, Tzovolous A, Gerstman E, Evans E, Thompson C, Lopez M, Ronald PC. Identification of a host 14-3-3 Protein that Interacts with Xanthomonas effector AvrRxv. PHYSIOLOGICAL AND MOLECULAR PLANT PATHOLOGY 2008; 72:46-55. [PMID: 21796232 PMCID: PMC3142867 DOI: 10.1016/j.pmpp.2008.05.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
AvrRxv is a member of a family of pathogen effectors present in pathogens of both plant and mammalian species. Xanthomonas campestris pv. vesicatoria strains carrying AvrRxv induce a hypersensitive response (HR) in the tomato cultivar Hawaii 7998. Using a yeast two-hybrid screen, we identified a 14-3-3 protein from tomato that interacts with AvrRxv called AvrRxv Interactor 1 (ARI1). The interaction was confirmed in vitro with affinity chromatography. Using mutagenesis, we identified a 14-3-3-binding domain in AvrRxv and demonstrated that a mutant in that domain showed concomitant loss of interaction with ARI1 and HR-inducing activity in tomato. These results demonstrate that the AvrRxv bacterial effector recruits 14-3-3 proteins for its function within host cells. AvrRxv homologues YopP and YopJ from Yersinia do not have AvrRxv-specific HR-inducing activity when delivered into tomato host cells by Agrobacterium. Although YopP itself cannot induce HR, its C-terminal domain containing the catalytic residues can replace that of AvrRxv in an AvrRxv-YopP chimera for HR-inducing activity. Phylogenetic analysis indicates that the sequences encoding the C-termini of family members are evolving independently from those encoding the N-termini. Our results support a model in which there are three functional domains in proteins of the family, translocation, interaction, and catalytic.
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Affiliation(s)
- Maureen Whalen
- Crop Improvement and Utilization Unit, Western Regional Research Center, ARS USDA, 800 Buchanan Street, Albany, CA 94710, US
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
- Corresponding author. Crop Improvement and Utilization Unit, Western Regional Research Center, ARS USDA, 800 Buchanan Street, Albany, CA 94710, USA. Tel.: +1 510 559 5950; fax: + 1 510 559 5818. (M.C. Whalen), (P.C. Ronald)
| | - Todd Richter
- Department of Plant Pathology, University of California at Davis, One Shields Ave, Davis CA 95616, USA
| | - Kseniya Zakhareyvich
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Masayasu Yoshikawa
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Dana Al-Azzeh
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Adeshola Adefioye
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Greg Spicer
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Laura L. Mendoza
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Christine Q. Morales
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Vicki Klassen
- Department of Biology, City College of San Francisco, 50 Phelan Avenue, San Francisco, CA 94112, USA
| | - Gina Perez-Baron
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Carole S. Toebe
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
- Department of Biology, City College of San Francisco, 50 Phelan Avenue, San Francisco, CA 94112, USA
| | - Ageliki Tzovolous
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Emily Gerstman
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Erika Evans
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Cheryl Thompson
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Mary Lopez
- Biology Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Pamela C. Ronald
- Department of Plant Pathology, University of California at Davis, One Shields Ave, Davis CA 95616, USA
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Göhre V, Robatzek S. Breaking the barriers: microbial effector molecules subvert plant immunity. ANNUAL REVIEW OF PHYTOPATHOLOGY 2008; 46:189-215. [PMID: 18422429 DOI: 10.1146/annurev.phyto.46.120407.110050] [Citation(s) in RCA: 220] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Adaptation to specialized environments allows microorganisms to inhabit an enormous variety of ecological niches. Growth inside plant tissues is a niche offering a constant nutrient supply, but to access this niche, plant defense mechanisms ranging from passive barriers to induced defense reactions have to be overcome. Pathogens have to break several, if not all, of these barriers. For this purpose, they secrete effector molecules into plant cells to interfere with individual defense responses. Plant defense is organized in multiple layers, and therefore the action of effectors likely follows this same order, leading to a hierarchy in effector orchestration. In this review we summarize the latest findings regarding the level at which effectors manipulate plant immunity. Particular attention is given to those effectors whose mechanism of action is known. Additionally, we compare methods to identify and characterize effector molecules.
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Affiliation(s)
- Vera Göhre
- Max-Planck Institute for Plant Breeding Research, 50829 Cologne, Germany.
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Robb J, Lee B, Nazar RN. Gene suppression in a tolerant tomato-vascular pathogen interaction. PLANTA 2007; 226:299-309. [PMID: 17308929 DOI: 10.1007/s00425-007-0482-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Accepted: 01/19/2007] [Indexed: 05/14/2023]
Abstract
A plant can respond to the threat of a pathogen through resistance defenses or through tolerance. Resistance has been widely studied in many host pathogen systems but little is known about genetic changes which underlie a tolerant interaction. A recently developed model system for a tolerant tomato (Lycopersicon esculentum Mill) interaction with a fungal wilt pathogen, Verticillium dahliae Kleb, is examined with respect to changes in gene expression and compared to a susceptible infection. The results indicate that genetic changes can be dramatically different and some genes that are strongly elevated in the susceptible interaction are actually down-regulated in tolerance. Similar levels of fungal DNA and an up-regulation of many pathogenesis related genes indicate that in both types of interaction the presence of fungus is clearly recognized by the plant but other changes correlate with the absence of symptoms in the tolerant interaction. For example, a gene encoding a known 14-3-3 regulatory protein and a number of genes normally affected by this protein are down-regulated. Furthermore, genes which may contribute to foliar necrosis and cell death in the susceptible interaction also appear to be suppressed in the tolerant interaction, raising the possibility that the wilt symptoms, chlorosis and necrosis which are observed in the susceptible interaction, are actually programmed to further limit the growth of the fungal pathogen, and protect the general tomato population.
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Affiliation(s)
- Jane Robb
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
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Balaji V, Gibly A, Debbie P, Sessa G. Transcriptional analysis of the tomato resistance response triggered by recognition of the Xanthomonas type III effector AvrXv3. Funct Integr Genomics 2007; 7:305-16. [PMID: 17582538 DOI: 10.1007/s10142-007-0050-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2007] [Revised: 05/08/2007] [Accepted: 05/14/2007] [Indexed: 12/31/2022]
Abstract
The type III effector AvrXv3 from Xanthomonas campestris pv. vesicatoria (Xcv) elicits a resistance response in the tomato line Hawaii 7981. To test whether similar genes participate in responses triggered by recognition of different avirulence proteins, we examined the effect of AvrXv3 expression on the plant transcriptome as compared to that of other avirulence proteins. By microarray analysis we monitored expression of approximately 8,600 tomato genes upon inoculation with isogenic Xcv strains differing only by the avrXv3 gene. Changes in transcript levels of 139 genes were observed within 8 h, and a massive shift in expression of 1,294 genes was detected at 12 h. Recognition of AvrXv3 modulated a large number of genes encoding transcription factors and signaling components. In addition, genes involved in defense and stress responses, lipid metabolism, protein degradation, and secondary metabolism were mainly up-regulated. Conversely, genes related to photosynthesis and protein synthesis were generally down-regulated. Many novel genes encoding proteins of unknown function were also identified. A comparison between AvrXv3-modulated genes and those differentially expressed in tomato plants recognizing other bacterial effectors revealed partial overlap and similar distribution in functional classes. The identification of tomato genes modulated by AvrXv3 expression paves the way for dissecting defense networks activated by recognition of this effector in resistant plants.
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Affiliation(s)
- Vasudevan Balaji
- Department of Plant Sciences, Tel-Aviv University, 69978, Tel-Aviv, Israel.
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Cunnac S, Wilson A, Nuwer J, Kirik A, Baranage G, Mudgett MB. A conserved carboxylesterase is a SUPPRESSOR OF AVRBST-ELICITED RESISTANCE in Arabidopsis. THE PLANT CELL 2007; 19:688-705. [PMID: 17293566 PMCID: PMC1867326 DOI: 10.1105/tpc.106.048710] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
AvrBsT is a type III effector from Xanthomonas campestris pv vesicatoria that is translocated into plant cells during infection. AvrBsT is predicted to encode a Cys protease that targets intracellular host proteins. To dissect AvrBsT function and recognition in Arabidopsis thaliana, 71 ecotypes were screened to identify lines that elicit an AvrBsT-dependent hypersensitive response (HR) after Xanthomonas campestris pv campestris (Xcc) infection. The HR was observed only in the Pi-0 ecotype infected with Xcc strain 8004 expressing AvrBsT. To create a robust pathosystem to study AvrBsT immunity in Arabidopsis, the foliar pathogen Pseudomonas syringae pv tomato (Pst) strain DC3000 was engineered to translocate AvrBsT into Arabidopsis by the Pseudomonas type III secretion (T3S) system. Pi-0 leaves infected with Pst DC3000 expressing a Pst T3S signal fused to AvrBsT-HA (AvrBsTHYB-HA) elicited HR and limited pathogen growth, confirming that the HR leads to defense. Resistance in Pi-0 is caused by a recessive mutation predicted to inactivate a carboxylesterase known to hydrolyze lysophospholipids and acylated proteins in eukaryotes. Transgenic Pi-0 plants expressing the wild-type Columbia allele are susceptible to Pst DC3000 AvrBsTHYB-HA infection. Furthermore, wild-type recombinant protein cleaves synthetic p-nitrophenyl ester substrates in vitro. These data indicate that the carboxylesterase inhibits AvrBsT-triggered phenotypes in Arabidopsis. Here, we present the cloning and characterization of the SUPPRESSOR OF AVRBST-ELICITED RESISTANCE1.
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Affiliation(s)
- Sébastien Cunnac
- Department of Biological Sciences, Stanford University, Stanford, California 94305, USA
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Wise RP, Moscou MJ, Bogdanove AJ, Whitham SA. Transcript profiling in host-pathogen interactions. ANNUAL REVIEW OF PHYTOPATHOLOGY 2007; 45:329-69. [PMID: 17480183 DOI: 10.1146/annurev.phyto.45.011107.143944] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Using genomic technologies, it is now possible to address research hypotheses in the context of entire developmental or biochemical pathways, gene networks, and chromosomal location of relevant genes and their inferred evolutionary history. Through a range of platforms, researchers can survey an entire transcriptome under a variety of experimental and field conditions. Interpretation of such data has led to new insights and revealed previously undescribed phenomena. In the area of plant-pathogen interactions, transcript profiling has provided unparalleled perception into the mechanisms underlying gene-for-gene resistance and basal defense, host vs nonhost resistance, biotrophy vs necrotrophy, and pathogenicity of vascular vs nonvascular pathogens, among many others. In this way, genomic technologies have facilitated a system-wide approach to unifying themes and unique features in the interactions of hosts and pathogens.
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Affiliation(s)
- Roger P Wise
- Corn Insects and Crop Genetics Research, USDA-ARS, Iowa State University, Ames, Iowa 50011-1020, USA.
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Mayrose M, Ekengren SK, Melech-Bonfil S, Martin GB, Sessa G. A novel link between tomato GRAS genes, plant disease resistance and mechanical stress response. MOLECULAR PLANT PATHOLOGY 2006; 7:593-604. [PMID: 20507472 DOI: 10.1111/j.1364-3703.2006.00364.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
SUMMARY Members of the GRAS family of transcriptional regulators have been implicated in the control of plant growth and development, and in the interaction of plants with symbiotic bacteria. Here we examine the complexity of the GRAS gene family in tomato (Solanum lycopersicum) and investigate its role in disease resistance and mechanical stress. A large number of tomato ESTs corresponding to GRAS transcripts were retrieved from the public database and assembled in 17 contigs of putative genes. Expression analysis of these genes by real-time RT-PCR revealed that six SlGRAS transcripts accumulate during the onset of disease resistance to Pseudomonas syringae pv. tomato. Further analysis of two selected family members showed that their transcripts preferentially accumulate in tomato plants in response to different avirulent bacteria or to the fungal elicitor EIX, and their expression kinetics correlate with the appearance of the hypersensitive response. In addition, transcript levels of eight SlGRAS genes, including all the Pseudomonas-inducible family members, increased in response to mechanical stress much earlier than upon pathogen attack. Accumulation of SlGRAS transcripts following mechanical stress was in part dependent on the signalling molecule jasmonic acid. Remarkably, suppression of SlGRAS6 gene expression by virus-induced gene silencing impaired tomato resistance to P. syringae pv. tomato. These results support a function for GRAS transcriptional regulators in the plant response to biotic and abiotic stress.
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Affiliation(s)
- Maya Mayrose
- Department of Plant Sciences, Tel Aviv University, 69978 Tel Aviv, Israel
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Gürlebeck D, Thieme F, Bonas U. Type III effector proteins from the plant pathogen Xanthomonas and their role in the interaction with the host plant. JOURNAL OF PLANT PHYSIOLOGY 2006; 163:233-55. [PMID: 16386329 DOI: 10.1016/j.jplph.2005.11.011] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2005] [Accepted: 11/15/2005] [Indexed: 05/05/2023]
Abstract
Pathogenicity of Xanthomonas campestris pathovar (pv.) vesicatoria and most other Gram-negative bacterial plant pathogens largely depends on a type III secretion (TTS) system which is encoded by hypersensitive response and pathogenicity (hrp) genes. These genes are induced in the plant and are essential for the bacterium to be virulent in susceptible hosts and for the induction of the hypersensitive response (HR) in resistant host and non-host plants. The TTS machinery secretes proteins into the extracellular milieu and effector proteins into the plant cell cytosol. In the plant, the effectors presumably interfere with cellular processes to the benefit of the pathogen or have an avirulence activity that betrays the bacterium to the plant surveillance system. Type III effectors were identified by their avirulence activity, co-regulation with the TTS system and homology to known effectors. A number of effector proteins are members of families, e.g., the AvrBs3 family in Xanthomonas. AvrBs3 localizes to the nucleus of the plant cell where it modulates plant gene expression. Another family that is also present in Xanthomonas is the YopJ/AvrRxv family. The latter proteins appear to act as SUMO cysteine proteases in the host. Here, we will present an overview about the regulation of the TTS system and its substrates and discuss the function of the AvrRxv and AvrBs3 family members in more detail.
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Affiliation(s)
- Doreen Gürlebeck
- Institute of Genetics, Martin-Luther University Halle-Wittenberg, Weinbergweg 10, 06120 Halle, Germany.
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