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Tendiuk N, Diakonova A, Petrova O, Mukhametzyanov T, Makshakova O, Gorshkov V. Svx Peptidases of Phytopathogenic Pectolytic Bacteria: Structural, Catalytic and Phytoimmune Properties. Int J Mol Sci 2024; 25:756. [PMID: 38255830 PMCID: PMC10815107 DOI: 10.3390/ijms25020756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 12/31/2023] [Accepted: 01/02/2024] [Indexed: 01/24/2024] Open
Abstract
Svx proteins are virulence factors secreted by phytopathogenic bacteria of the Pectobacterium genus into the host plant cell wall. Svx-encoding genes are present in almost all species of the soft rot Pectobacteriaceae (Pectobacterium and Dickeya genera). The Svx of P. atrosepticum (Pba) has been shown to be a gluzincin metallopeptidase that presumably targets plant extensins, proteins that contribute to plant cell wall rigidity and participate in cell signaling. However, the particular "output" of the Pba Svx action in terms of plant-pathogen interactions and plant immune responses remained unknown. The Svx proteins are largely unexplored in Dickeya species, even though some of them have genes encoding two Svx homologs. Therefore, our study aims to compare the structural and catalytic properties of the Svx proteins of Pba and D. solani (Dso) and to test the phytoimmune properties of these proteins. Two assayed Dso Svx proteins, similar to Pba Svx, were gluzincin metallopeptidases with conservative tertiary structures. The two domains of the Svx proteins form electronegative clefts where the active centers of the peptidase domains are located. All three assayed Svx proteins possessed phytoimmunosuppressory properties and induced ethylene-mediated plant susceptible responses that play a decisive role in Pba-caused disease.
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Affiliation(s)
- Natalia Tendiuk
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (N.T.); (A.D.); (O.P.); (O.M.)
| | - Anastasiya Diakonova
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (N.T.); (A.D.); (O.P.); (O.M.)
| | - Olga Petrova
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (N.T.); (A.D.); (O.P.); (O.M.)
| | - Timur Mukhametzyanov
- Department of Physical Chemistry, Kazan Federal University, 420008 Kazan, Russia;
| | - Olga Makshakova
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (N.T.); (A.D.); (O.P.); (O.M.)
| | - Vladimir Gorshkov
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (N.T.); (A.D.); (O.P.); (O.M.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
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2
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Wein P, Dornblut K, Herkersdorf S, Krüger T, Molloy EM, Brakhage AA, Hoffmeister D, Hertweck C. Bacterial secretion systems contribute to rapid tissue decay in button mushroom soft rot disease. mBio 2023; 14:e0078723. [PMID: 37486262 PMCID: PMC10470514 DOI: 10.1128/mbio.00787-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 06/08/2023] [Indexed: 07/25/2023] Open
Abstract
The soft rot pathogen Janthinobacterium agaricidamnosum causes devastating damage to button mushrooms (Agaricus bisporus), one of the most cultivated and commercially relevant mushrooms. We previously discovered that this pathogen releases the membrane-disrupting lipopeptide jagaricin. This bacterial toxin, however, could not solely explain the rapid decay of mushroom fruiting bodies, indicating that J. agaricidamnosum implements a more sophisticated infection strategy. In this study, we show that secretion systems play a crucial role in soft rot disease. By mining the genome of J. agaricidamnosum, we identified gene clusters encoding a type I (T1SS), a type II (T2SS), a type III (T3SS), and two type VI secretion systems (T6SSs). We targeted the T2SS and T3SS for gene inactivation studies, and subsequent bioassays implicated both in soft rot disease. Furthermore, through a combination of comparative secretome analysis and activity-guided fractionation, we identified a number of secreted lytic enzymes responsible for mushroom damage. Our findings regarding the contribution of secretion systems to the disease process expand the current knowledge of bacterial soft rot pathogens and represent a significant stride toward identifying targets for their disarmament with secretion system inhibitors. IMPORTANCE The button mushroom (Agaricus bisporus) is the most popular edible mushroom in the Western world. However, mushroom crops can fall victim to serious bacterial diseases that are a major threat to the mushroom industry, among them being soft rot disease caused by Janthinobacterium agaricidamnosum. Here, we show that the rapid dissolution of mushroom fruiting bodies after bacterial invasion is due to degradative enzymes and putative effector proteins secreted via the type II secretion system (T2SS) and the type III secretion system (T3SS), respectively. The ability to degrade mushroom tissue is significantly attenuated in secretion-deficient mutants, which establishes that secretion systems are key factors in mushroom soft rot disease. This insight is of both ecological and agricultural relevance by shedding light on the disease processes behind a pathogenic bacterial-fungal interaction which, in turn, serves as a starting point for the development of secretion system inhibitors to control disease progression.
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Affiliation(s)
- Philipp Wein
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Katharina Dornblut
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Sebastian Herkersdorf
- Department of Pharmaceutical Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Friedrich Schiller University Jena, Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
| | - Thomas Krüger
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Evelyn M. Molloy
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Axel A. Brakhage
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Dirk Hoffmeister
- Department of Pharmaceutical Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Friedrich Schiller University Jena, Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
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3
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Yu S, Kang J, Chung EH, Lee Y. Disruption of the metC Gene Affects Methionine Biosynthesis in Pectobacterium carotovorum subsp. carotovorum Pcc21 and Reduces Soft-Rot Disease. THE PLANT PATHOLOGY JOURNAL 2023; 39:62-74. [PMID: 36760050 PMCID: PMC9929172 DOI: 10.5423/ppj.oa.09.2022.0135] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 06/18/2023]
Abstract
Plant pathogenic Pectobacterium species cause severe soft rot/blackleg diseases in many economically important crops worldwide. Pectobacterium utilizes plant cell wall degrading enzymes (PCWDEs) as the main virulence determinants for its pathogenicity. In this study, we screened a random mutant, M29 is a transposon insertion mutation in the metC gene encoding cystathionine β-lyase that catalyzes cystathionine to homocysteine at the penultimate step in methionine biosynthesis. M29 became a methionine auxotroph and resulted in growth defects in methionine-limited conditions. Impaired growth was restored with exogenous methionine or homocysteine rather than cystathionine. The mutant exhibited reduced soft rot symptoms in Chinese cabbages and potato tubers, maintaining activities of PCWDEs and swimming motility. The mutant was unable to proliferate in both Chinese cabbages and potato tubers. The reduced virulence was partially restored by a complemented strain or 100 µM of methionine, whereas it was fully restored by the extremely high concentration (1 mM). Our transcriptomic analysis showed that genes involved in methionine biosynthesis or transporter were downregulated in the mutant. Our results demonstrate that MetC is important for methionine biosynthesis and transporter and influences its virulence through Pcc21 multiplication in plant hosts.
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Affiliation(s)
- Seonmi Yu
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
| | - Jihee Kang
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
| | - Eui-Hwan Chung
- Department of Plant Biotechnology, Korea University, Seoul 02841,
Korea
| | - Yunho Lee
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
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4
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Host plant physiological transformation and microbial population heterogeneity as important determinants of the Soft Rot Pectobacteriaceae-plant interactions. Semin Cell Dev Biol 2023; 148-149:33-41. [PMID: 36621443 DOI: 10.1016/j.semcdb.2023.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 01/04/2023] [Accepted: 01/04/2023] [Indexed: 01/07/2023]
Abstract
Pectobacterium and Dickeya species belonging to the Soft Rot Pectobacteriaceae (SRP) are one of the most devastating phytopathogens. They degrade plant tissues by producing an arsenal of plant cell wall degrading enzymes. However, SRP-plant interactions are not restricted to the production of these "brute force" weapons. Additionally, these bacteria apply stealth behavior related to (1) manipulation of the host plant via induction of susceptible responses and (2) formation of heterogeneous populations with functionally specialized cells. Our review aims to summarize current knowledge on SRP-induced plant susceptible responses and on the heterogeneity of SRP populations. The review shows that SRP are capable of adjusting the host's hormonal balance, inducing host-mediated plant cell wall modification, promoting iron assimilation by the host, stimulating the accumulation of reactive oxygen species and host cell death, and activating the synthesis of secondary metabolites that are ineffective in limiting disease progression. By this means, SRP facilitate host plant susceptibility. During host colonization, SRP populations produce various functionally specialized cells adapted for enhanced virulence, increased resistance, motility, vegetative growth, or colonization of the vascular system. This enables SRP to perform self-contradictory tasks, which benefits a population's overall fitness in various environments, including host plants. Such stealthy tactical actions facilitate plant-SRP interactions and disease progression.
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Hadizadeh I, Peivastegan B, Wang J, Sipari N, Nielsen KL, Pirhonen M. Gene expression and phytohormone levels in the asymptomatic and symptomatic phases of infection in potato tubers inoculated with Dickeya solani. PLoS One 2022; 17:e0273481. [PMID: 36037153 PMCID: PMC9423618 DOI: 10.1371/journal.pone.0273481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 08/10/2022] [Indexed: 11/28/2022] Open
Abstract
Dickeya solani is a soft rot bacterium with high virulence. In potato, D. solani, like the other potato-infecting soft rot bacteria, causes rotting and wilting of the stems and rotting of tubers in the field and in storage. Latent, asymptomatic infections of potato tubers are common in harvested tubers, and if the storage conditions are not optimal, the latent infection turns into active rotting. We characterized potato gene expression in artificially inoculated tubers in nonsymptomatic, early infections 1 and 24 hours post-inoculation (hpi) and compared the results to the response in symptomatic tuber tissue 1 week (168 hpi) later with RNA-Seq. In the beginning of the infection, potato tubers expressed genes involved in the detection of the bacterium through pathogen-associated molecular patterns (PAMPs), which induced genes involved in PAMPs-triggered immunity, resistance, production of pathogenesis-related proteins, ROS, secondary metabolites and salicylic acid (SA) and jasmonic acid (JA) biosynthesis and signaling genes. In the symptomatic tuber tissue one week later, the PAMPs-triggered gene expression was downregulated, whereas primary metabolism was affected, most likely leading to free sugars fueling plant defense but possibly also aiding the growth of the pathogen. In the symptomatic tubers, pectic enzymes and cell wall-based defenses were activated. Measurement of hormone production revealed increased SA concentration and almost no JA in the asymptomatic tubers at the beginning of the infection and high level of JA and reduced SA in the symptomatic tubers one week later. These findings suggest that potato tubers rely on different defense strategies in the different phases of D. solani infection even when the infection takes place in fully susceptible plants incubated in conditions leading to rotting. These results support the idea that D. solani is a biotroph rather than a true necrotroph.
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Affiliation(s)
- Iman Hadizadeh
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
| | - Bahram Peivastegan
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
| | - Jinhui Wang
- College of Plant Protection, Hebei Agricultural University, Hebei, China
| | - Nina Sipari
- Viikki Metabolomics Unit, Faculty of Biological and Environmental sciences, University of Helsinki, Helsinki, Finland
| | | | - Minna Pirhonen
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
- * E-mail:
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Structure-Functional Characteristics of the Svx Protein—The Virulence Factor of the Phytopathogenic Bacterium Pectobacterium atrosepticum. Int J Mol Sci 2022; 23:ijms23136914. [PMID: 35805920 PMCID: PMC9266454 DOI: 10.3390/ijms23136914] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 11/17/2022] Open
Abstract
The Svx proteins are virulence factors of phytopathogenic bacteria of the Pectobacterium genus. The specific functions of these proteins are unknown. Here we show that most of the phytopathogenic species of Pectobacterium, Dickeya, and Xanthomonas genera have genes encoding Svx proteins, as well as some plant-non-associated species of different bacterial genera. As such, the Svx-like proteins of phytopathogenic species form a distinct clade, pointing to the directed evolution of these proteins to provide effective interactions with plants. To get a better insight into the structure and functions of the Svx proteins, we analyzed the Svx of Pectobacterium atrosepticum (Pba)—an extracellular virulence factor secreted into the host plant cell wall (PCW). Using in silico analyses and by obtaining and analyzing the recombinant Pba Svx and its mutant forms, we showed that this protein was a gluzincin metallopeptidase. The 3D structure model of the Pba Svx was built and benchmarked against the experimental overall secondary structure content. Structure-based substrate specificity analysis using molecular docking revealed that the Pba Svx substrate-binding pocket might accept α-glycosylated proteins represented in the PCW by extensins—proteins that strengthen the PCW. Thus, these results elucidate the way in which the Pba Svx may contribute to the Pba virulence.
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Zhou J, Hu M, Hu A, Li C, Ren X, Tao M, Xue Y, Chen S, Tang C, Xu Y, Zhang L, Zhou X. Isolation and Genome Analysis of Pectobacterium colocasium sp. nov. and Pectobacterium aroidearum, Two New Pathogens of Taro. FRONTIERS IN PLANT SCIENCE 2022; 13:852750. [PMID: 35557713 PMCID: PMC9088014 DOI: 10.3389/fpls.2022.852750] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 03/28/2022] [Indexed: 06/15/2023]
Abstract
Bacterial soft rot is one of the most destructive diseases of taro (Colocasia esculenta) worldwide. In recent years, frequent outbreaks of soft rot disease have seriously affected taro production and became a major constraint to the development of taro planting in China. However, little is known about the causal agents of this disease, and the only reported pathogens are two Dickeya species and P. carotovorum. In this study, we report taro soft rot caused by two novel Pectobacterium strains, LJ1 and LJ2, isolated from taro corms in Ruyuan County, Shaoguan City, Guangdong Province, China. We showed that LJ1 and LJ2 fulfill Koch's postulates for taro soft rot. The two pathogens can infect taro both individually and simultaneously, and neither synergistic nor antagonistic interaction was observed between the two pathogens. Genome sequencing of the two strains indicated that LJ1 represents a novel species of the genus Pectobacterium, for which the name "Pectobacterium colocasium sp. nov." is proposed, while LJ2 belongs to Pectobacterium aroidearum. Pan-genome analysis revealed multiple pathogenicity-related differences between LJ1, LJ2, and other Pectobacterium species, including unique virulence factors, variation in the copy number and organization of Type III, IV, and VI secretion systems, and differential production of plant cell wall degrading enzymes. This study identifies two new soft rot Pectobacteriaceae (SRP) pathogens causing taro soft rot in China, reports a new case of co-infection of plant pathogens, and provides valuable resources for further investigation of the pathogenic mechanisms of SRP.
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Affiliation(s)
- Jianuan Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Ming Hu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Anqun Hu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Chuhao Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Xinyue Ren
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Min Tao
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Yang Xue
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Shanshan Chen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Chongzhi Tang
- Guangdong Tianhe Agricultural Means of Production Co., Ltd., Guangzhou, China
| | - Yiwu Xu
- Guangdong Tianhe Agricultural Means of Production Co., Ltd., Guangzhou, China
- Qingyuan Agricultural Science and Technology Service Co., Ltd., Qingyuan, China
| | - Lianhui Zhang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Xiaofan Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
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Gorshkov V, Parfirova O, Petrova O, Gogoleva N, Kovtunov E, Vorob’ev V, Gogolev Y. The Knockout of Enterobactin-Related Gene in Pectobacterium atrosepticum Results in Reduced Stress Resistance and Virulence towards the Primed Plants. Int J Mol Sci 2021; 22:ijms22179594. [PMID: 34502502 PMCID: PMC8431002 DOI: 10.3390/ijms22179594] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/31/2021] [Accepted: 09/02/2021] [Indexed: 11/16/2022] Open
Abstract
Siderophores produced by microorganisms to scavenge iron from the environment have been shown to contribute to virulence and/or stress resistance of some plant pathogenic bacteria. Phytopathogenic bacteria of Pectobacterium genus possess genes for the synthesis of siderophore enterobactin, which role in plant-pathogen interactions has not been elucidated. In the present study we characterized the phenotype of the mutant strain of Pba deficient for the enterobactin-biosynthetic gene entA. We showed that enterobactin may be considered as a conditionally beneficial virulence factor of Pba. The entA knockout did not reduce Pba virulence on non-primed plants; however, salicylic acid-primed plants were more resistant to ΔentA mutant than to the wild type Pba. The reduced virulence of ΔentA mutant towards the primed plants is likely explained by its compromised resistance to oxidative stress.
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Affiliation(s)
- Vladimir Gorshkov
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (O.P.); (O.P.); (N.G.); (E.K.); (V.V.); (Y.G.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
- Correspondence:
| | - Olga Parfirova
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (O.P.); (O.P.); (N.G.); (E.K.); (V.V.); (Y.G.)
| | - Olga Petrova
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (O.P.); (O.P.); (N.G.); (E.K.); (V.V.); (Y.G.)
| | - Natalia Gogoleva
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (O.P.); (O.P.); (N.G.); (E.K.); (V.V.); (Y.G.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Evgeny Kovtunov
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (O.P.); (O.P.); (N.G.); (E.K.); (V.V.); (Y.G.)
| | - Vladimir Vorob’ev
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (O.P.); (O.P.); (N.G.); (E.K.); (V.V.); (Y.G.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Yuri Gogolev
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia; (O.P.); (O.P.); (N.G.); (E.K.); (V.V.); (Y.G.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
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Wang H, Wang Y, Humphris S, Nie W, Zhang P, Wright F, Campbell E, Hu B, Fan J, Toth I. Pectobacterium atrosepticum KDPG aldolase, Eda, participates in the Entner-Doudoroff pathway and independently inhibits expression of virulence determinants. MOLECULAR PLANT PATHOLOGY 2021; 22:271-283. [PMID: 33301200 PMCID: PMC7814964 DOI: 10.1111/mpp.13025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/04/2020] [Accepted: 11/04/2020] [Indexed: 05/22/2023]
Abstract
Pectobacterium carotovorum has an incomplete Entner-Doudoroff (ED) pathway, including enzyme 2-keto-3-deoxy-6-phosphogluconate aldolase (Eda) but lacking phosphogluconate dehydratase (Edd), while P. atrosepticum (Pba) has a complete pathway. To understand the role of the ED pathway in Pectobacterium infection, mutants of these two key enzymes, Δeda and Δedd, were constructed in Pba SCRI1039. Δeda exhibited significant decreased virulence on potato tubers and colonization in planta and was greatly attenuated in pectinase activity and the ability to use pectin breakdown products, including polygalacturonic acid (PGA) and galacturonic acid. These reduced phenotypes were restored following complementation with an external vector expressing eda. Quantitative reverse transcription PCR analysis revealed that expression of the pectinase genes pelA, pelC, pehN, pelW, and pmeB in Δeda cultured in pyruvate, with or without PGA, was significantly reduced compared to the wild type, while genes for virulence regulators (kdgR, hexR, hexA, and rsmA) remained unchanged. However, Δedd showed similar phenotypes to the wild type. To our knowledge, this is the first demonstration that disruption of eda has a feedback effect on inhibiting pectin degradation and that Eda is involved in building the arsenal of pectinases needed during infection by Pectobacterium.
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Affiliation(s)
- Huan Wang
- Department of Plant PathologyNanjing Agricultural UniversityNanjingChina
- Cell and Molecular ScienceJames Hutton InstituteDundeeUK
- Institute of Agricultural Science of Taihu Lake DistrictSuzhouChina
| | - Yujie Wang
- Department of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Sonia Humphris
- Cell and Molecular ScienceJames Hutton InstituteDundeeUK
| | - Weihua Nie
- Department of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Pengfei Zhang
- Department of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Frank Wright
- Bioinformatics and StatisticsJames Hutton InstituteDundeeUK
| | - Emma Campbell
- Cell and Molecular ScienceJames Hutton InstituteDundeeUK
| | - Baishi Hu
- Department of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Jiaqin Fan
- Department of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Ian Toth
- Cell and Molecular ScienceJames Hutton InstituteDundeeUK
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10
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Tsers I, Gorshkov V, Gogoleva N, Parfirova O, Petrova O, Gogolev Y. Plant Soft Rot Development and Regulation from the Viewpoint of Transcriptomic Profiling. PLANTS 2020; 9:plants9091176. [PMID: 32927917 PMCID: PMC7570247 DOI: 10.3390/plants9091176] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/05/2020] [Accepted: 09/07/2020] [Indexed: 02/07/2023]
Abstract
Soft rot caused by Pectobacterium species is a devastating plant disease poorly characterized in terms of host plant responses. In this study, changes in the transcriptome of tobacco plants after infection with Pectobacterium atrosepticum (Pba) were analyzed using RNA-Seq. To draw a comprehensive and nontrivially itemized picture of physiological events in Pba-infected plants and to reveal novel potential molecular "players" in plant-Pba interactions, an original functional gene classification was performed. The classifications present in various databases were merged, enriched by "missed" genes, and divided into subcategories. Particular changes in plant cell wall-related processes, perturbations in hormonal and other regulatory systems, and alterations in primary, secondary, and redox metabolism were elucidated in terms of gene expression. Special attention was paid to the prediction of transcription factors (TFs) involved in the disease's development. Herewith, gene expression was analyzed within the predicted TF regulons assembled at the whole-genome level based on the presence of particular cis-regulatory elements (CREs) in gene promoters. Several TFs, whose regulons were enriched by differentially expressed genes, were considered to be potential master regulators of Pba-induced plant responses. Differential regulation of genes belonging to a particular multigene family and encoding cognate proteins was explained by the presence/absence of the particular CRE in gene promoters.
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Affiliation(s)
- Ivan Tsers
- Laboratory of plant infectious diseases, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, 420111 Kazan, Russia;
| | - Vladimir Gorshkov
- Laboratory of plant infectious diseases, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, 420111 Kazan, Russia;
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, 420111 Kazan, Russia; (N.G.); (O.P.); (O.P.); (Y.G.)
- Correspondence:
| | - Natalia Gogoleva
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, 420111 Kazan, Russia; (N.G.); (O.P.); (O.P.); (Y.G.)
| | - Olga Parfirova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, 420111 Kazan, Russia; (N.G.); (O.P.); (O.P.); (Y.G.)
| | - Olga Petrova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, 420111 Kazan, Russia; (N.G.); (O.P.); (O.P.); (Y.G.)
| | - Yuri Gogolev
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, 420111 Kazan, Russia; (N.G.); (O.P.); (O.P.); (Y.G.)
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Horizontally Acquired Quorum-Sensing Regulators Recruited by the PhoP Regulatory Network Expand the Host Adaptation Repertoire in the Phytopathogen Pectobacterium brasiliense. mSystems 2020; 5:5/1/e00650-19. [PMID: 31992632 PMCID: PMC6989131 DOI: 10.1128/msystems.00650-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In this study, we examine the impact of transcriptional network rearrangements driven by horizontal gene acquisition in PhoP and SlyA regulons using as a case study a phytopathosystem comprised of potato tubers and the soft-rot pathogen Pectobacterium brasiliense 1692 (Pb1692). Genome simulations and statistical analyses uncovered the tendency of PhoP and SlyA networks to mobilize lineage-specific traits predicted as horizontal gene transfer at late infection, highlighting the prominence of regulatory network rearrangements in this stage of infection. The evidence further supports the circumscription of two horizontally acquired quorum-sensing regulators (carR and expR1) by the PhoP network. By recruiting carR and expR1, the PhoP network also impacts certain host adaptation- and bacterial competition-related systems, seemingly in a quorum sensing-dependent manner, such as the type VI secretion system, carbapenem biosynthesis, and plant cell wall-degrading enzymes (PCWDE) like cellulases and pectate lyases. Conversely, polygalacturonases and the type III secretion system (T3SS) exhibit a transcriptional pattern that suggests quorum-sensing-independent regulation by the PhoP network. This includes an uncharacterized novel phage-related gene family within the T3SS gene cluster that has been recently acquired by two Pectobacterium species. The evidence further suggests a PhoP-dependent regulation of carbapenem- and PCWDE-encoding genes based on the synthesized products' optimum pH. The PhoP network also controls slyA expression in planta, which seems to impact carbohydrate metabolism regulation, especially at early infection, when 76.2% of the SlyA-regulated genes from that category also require PhoP to achieve normal expression levels.IMPORTANCE Exchanging genetic material through horizontal transfer is a critical mechanism that drives bacteria to efficiently adapt to host defenses. In this report, we demonstrate that a specific plant-pathogenic species (from the Pectobacterium genus) successfully integrated a population density-based behavior system (quorum sensing) acquired through horizontal transfer into a resident stress-response gene regulatory network controlled by the PhoP protein. Evidence found here underscores that subsets of bacterial weaponry critical for colonization, typically known to respond to quorum sensing, are also controlled by PhoP. Some of these traits include different types of enzymes that can efficiently break down plant cell walls depending on the environmental acidity level. Thus, we hypothesize that PhoP's ability to elicit regulatory responses based on acidity and nutrient availability fluctuations has strongly impacted the fixation of its regulatory connection with quorum sensing. In addition, another global gene regulator, known as SlyA, was found under the PhoP regulatory network. The SlyA regulator controls a series of carbohydrate metabolism-related traits, which also seem to be regulated by PhoP. By centralizing quorum sensing and slyA under PhoP scrutiny, Pectobacterium cells added an advantageous layer of control over those two networks that potentially enhances colonization efficiency.
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Santamaría-Hernando S, Senovilla M, González-Mula A, Martínez-García PM, Nebreda S, Rodríguez-Palenzuela P, López-Solanilla E, Rodríguez-Herva JJ. The Pseudomonas syringae pv. tomato DC3000 PSPTO_0820 multidrug transporter is involved in resistance to plant antimicrobials and bacterial survival during tomato plant infection. PLoS One 2019; 14:e0218815. [PMID: 31237890 PMCID: PMC6592562 DOI: 10.1371/journal.pone.0218815] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 06/10/2019] [Indexed: 01/25/2023] Open
Abstract
Multidrug resistance efflux pumps protect bacterial cells against a wide spectrum of antimicrobial compounds. PSPTO_0820 is a predicted multidrug transporter from the phytopathogenic bacterium Pseudomonas syringae pv. tomato DC3000. Orthologs of this protein are conserved within many Pseudomonas species that interact with plants. To study the potential role of PSPTO_0820 in plant-bacteria interaction, a mutant in this gene was isolated and characterized. In addition, with the aim to find the outer membrane channel for this efflux system, a mutant in PSPTO_4977, a TolC-like gene, was also analyzed. Both mutants were more susceptible to trans-cinnamic and chlorogenic acids and to the flavonoid (+)-catechin, when added to the culture medium. The expression level of both genes increased in the presence of (+)-catechin and, in the case of PSPTO_0820, also in response to trans-cinnamic acid. PSPTO_0820 and PSPTO_4977 mutants were unable to colonize tomato at high population levels. This work evidences the involvement of these two proteins in the resistance to plant antimicrobials, supporting also the importance of chlorogenic acid, trans-cinnamic acid, and (+)-catechin in the tomato plant defense response against P. syringae pv. tomato DC3000 infection.
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Affiliation(s)
- Saray Santamaría-Hernando
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Marta Senovilla
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Almudena González-Mula
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Pedro Manuel Martínez-García
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Sandra Nebreda
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Pablo Rodríguez-Palenzuela
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Emilia López-Solanilla
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - José Juan Rodríguez-Herva
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
- * E-mail:
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Li L, Yuan L, Shi Y, Xie X, Chai A, Wang Q, Li B. Comparative genomic analysis of Pectobacterium carotovorum subsp. brasiliense SX309 provides novel insights into its genetic and phenotypic features. BMC Genomics 2019; 20:486. [PMID: 31195968 PMCID: PMC6567464 DOI: 10.1186/s12864-019-5831-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 05/23/2019] [Indexed: 12/20/2022] Open
Abstract
Background Pectobacterium carotovorum subsp. brasiliense is a broad host range bacterial pathogen, which causes blackleg of potatoes and bacterial soft rot of vegetables worldwide. Production of plant cell wall degrading enzymes is usually critical for Pectobacterium infection. However, other virulence factors and the mechanisms of genetic adaptation still need to be studied in detail. Results In this study, the complete genome of P. carotovorum subsp. brasiliense strain SX309 isolated from cucumber was compared with eight other pathogenic bacteria belonging to the Pectobacterium genus, which were isolated from various host plants. Genome comparison revealed that most virulence genes are highly conserved in the Pectobacterium strains, especially for the key virulence determinants involved in the biosynthesis of extracellular enzymes and others including the type II and III secretion systems, quorum sensing system, flagellar and chemotactic genes. Nevertheless, some variable regions of the T6SS and the CRISP-Cas immune system are unique for P. carotovorum subsp. brasiliense. Conclusions The extensive comparative genomics analysis revealed highly conserved virulence genes in the Pectobacterium strains. However, several variable regions of type VI secretion system and two subtype Cas mechanism-Cas immune systems possibly contribute to the process of Pectobacterium infection and adaptive immunity. Electronic supplementary material The online version of this article (10.1186/s12864-019-5831-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lei Li
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Lifang Yuan
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.,Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Yanxia Shi
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Xuewen Xie
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Ali Chai
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Qi Wang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Baoju Li
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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Draft Genome Sequence of Pectobacterium carotovorum subsp. carotovorum ATCC 39048, a Carbapenem-Producing Phytopathogen. Microbiol Resour Announc 2018; 7:MRA00825-18. [PMID: 30533884 PMCID: PMC6256451 DOI: 10.1128/mra.00825-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 07/01/2018] [Indexed: 11/20/2022] Open
Abstract
Pectobacterium carotovorum subsp. carotovorum ATCC 39048 was originally isolated in the 1980s and studied because it produced the β-lactam antibiotic 1-carbapen-2-em-3-carboxylic acid. Pectobacterium carotovorum subsp. carotovorum ATCC 39048 was originally isolated in the 1980s and studied because it produced the β-lactam antibiotic 1-carbapen-2-em-3-carboxylic acid. The draft genome for this strain was 4,637,928 bp with a G+C content of 51.98%. The genome contained the carbapenem biosynthetic cluster, genes encoding plant virulence determinants, and a single metallo-β-lactamase.
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15
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Li X, Ma Y, Liang S, Tian Y, Yin S, Xie S, Xie H. Comparative genomics of 84 Pectobacterium genomes reveals the variations related to a pathogenic lifestyle. BMC Genomics 2018; 19:889. [PMID: 30526490 PMCID: PMC6286560 DOI: 10.1186/s12864-018-5269-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 11/19/2018] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Pectobacterium spp. are necrotrophic bacterial plant pathogens of the family Pectobacteriaceae, responsible for a wide spectrum of diseases of important crops and ornamental plants including soft rot, blackleg, and stem wilt. P. carotovorum is a genetically heterogeneous species consisting of three valid subspecies, P. carotovorum subsp. brasiliense (Pcb), P. carotovorum subsp. carotovorum (Pcc), and P. carotovorum subsp. odoriferum (Pco). RESULTS Thirty-two P. carotovorum strains had their whole genomes sequenced, including the first complete genome of Pco and another circular genome of Pcb, as well as the high-coverage genome sequences for 30 additional strains covering Pcc, Pcb, and Pco. In combination with 52 other publicly available genome sequences, the comparative genomics study of P. carotovorum and other four closely related species P. polaris, P. parmentieri, P. atrosepticum, and Candidatus P. maceratum was conducted focusing on CRISPR-Cas defense systems and pathogenicity determinants. Our analysis identified two CRISPR-Cas types (I-F and I-E) in Pectobacterium, as well as another I-C type in Dickeya that is not found in Pectobacterium. The core pathogenicity factors (e.g., plant cell wall-degrading enzymes) were highly conserved, whereas some factors (e.g., flagellin, siderophores, polysaccharides, protein secretion systems, and regulatory factors) were varied among these species and/or subspecies. Notably, a novel type of T6SS as well as the sorbitol metabolizing srl operon was identified to be specific to Pco in Pectobacterium. CONCLUSIONS This study not only advances the available knowledge about the genetic differentiation of individual subspecies of P. carotovorum, but also delineates the general genetic features of P. carotovorum by comparison with its four closely related species, thereby substantially enriching the extent of information now available for functional genomic investigations about Pectobacterium.
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Affiliation(s)
- Xiaoying Li
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097 People’s Republic of China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing, 100097 People’s Republic of China
| | - Yali Ma
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097 People’s Republic of China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing, 100097 People’s Republic of China
| | - Shuqing Liang
- Health Time Gene Institute, Shenzhen, Guangdong 518000 People’s Republic of China
| | - Yu Tian
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097 People’s Republic of China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing, 100097 People’s Republic of China
| | - Sanjun Yin
- Health Time Gene Institute, Shenzhen, Guangdong 518000 People’s Republic of China
| | - Sisi Xie
- Health Time Gene Institute, Shenzhen, Guangdong 518000 People’s Republic of China
| | - Hua Xie
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097 People’s Republic of China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing, 100097 People’s Republic of China
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16
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Mesarich CH, Rees-George J, Gardner PP, Ghomi FA, Gerth ML, Andersen MT, Rikkerink EHA, Fineran PC, Templeton MD. Transposon insertion libraries for the characterization of mutants from the kiwifruit pathogen Pseudomonas syringae pv. actinidiae. PLoS One 2017; 12:e0172790. [PMID: 28249011 PMCID: PMC5332098 DOI: 10.1371/journal.pone.0172790] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 02/09/2017] [Indexed: 01/15/2023] Open
Abstract
Pseudomonas syringae pv. actinidiae (Psa), the causal agent of kiwifruit canker, is one of the most devastating plant diseases of recent times. We have generated two mini-Tn5-based random insertion libraries of Psa ICMP 18884. The first, a 'phenotype of interest' (POI) library, consists of 10,368 independent mutants gridded into 96-well plates. By replica plating onto selective media, the POI library was successfully screened for auxotrophic and motility mutants. Lipopolysaccharide (LPS) biosynthesis mutants with 'Fuzzy-Spreader'-like morphologies were also identified through a visual screen. The second, a 'mutant of interest' (MOI) library, comprises around 96,000 independent mutants, also stored in 96-well plates, with approximately 200 individuals per well. The MOI library was sequenced on the Illumina MiSeq platform using Transposon-Directed Insertion site Sequencing (TraDIS) to map insertion sites onto the Psa genome. A grid-based PCR method was developed to recover individual mutants, and using this strategy, the MOI library was successfully screened for a putative LPS mutant not identified in the visual screen. The Psa chromosome and plasmid had 24,031 and 1,236 independent insertion events respectively, giving insertion frequencies of 3.65 and 16.6 per kb respectively. These data suggest that the MOI library is near saturation, with the theoretical probability of finding an insert in any one chromosomal gene estimated to be 97.5%. However, only 47% of chromosomal genes had insertions. This surprisingly low rate cannot be solely explained by the lack of insertions in essential genes, which would be expected to be around 5%. Strikingly, many accessory genes, including most of those encoding type III effectors, lacked insertions. In contrast, 94% of genes on the Psa plasmid had insertions, including for example, the type III effector HopAU1. These results suggest that some chromosomal sites are rendered inaccessible to transposon insertion, either by DNA-binding proteins or by the architecture of the nucleoid.
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Affiliation(s)
- Carl H. Mesarich
- Bioprotection Portfolio, The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
- Laboratory of Molecular Plant Pathology, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
- Bio-Protection Research Centre, New Zealand
| | - Jonathan Rees-George
- Bioprotection Portfolio, The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
| | - Paul P. Gardner
- Bio-Protection Research Centre, New Zealand
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Fatemeh Ashari Ghomi
- Bio-Protection Research Centre, New Zealand
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Monica L. Gerth
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Mark T. Andersen
- Bioprotection Portfolio, The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
| | - Erik H. A. Rikkerink
- Bioprotection Portfolio, The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
| | - Peter C. Fineran
- Bio-Protection Research Centre, New Zealand
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Matthew D. Templeton
- Bioprotection Portfolio, The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
- Bio-Protection Research Centre, New Zealand
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Jin L, Ham JH, Hage R, Zhao W, Soto-Hernández J, Lee SY, Paek SM, Kim MG, Boone C, Coplin DL, Mackey D. Direct and Indirect Targeting of PP2A by Conserved Bacterial Type-III Effector Proteins. PLoS Pathog 2016; 12:e1005609. [PMID: 27191168 PMCID: PMC4871590 DOI: 10.1371/journal.ppat.1005609] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 04/12/2016] [Indexed: 11/19/2022] Open
Abstract
Bacterial AvrE-family Type-III effector proteins (T3Es) contribute significantly to the virulence of plant-pathogenic species of Pseudomonas, Pantoea, Ralstonia, Erwinia, Dickeya and Pectobacterium, with hosts ranging from monocots to dicots. However, the mode of action of AvrE-family T3Es remains enigmatic, due in large part to their toxicity when expressed in plant or yeast cells. To search for targets of WtsE, an AvrE-family T3E from the maize pathogen Pantoea stewartii subsp. stewartii, we employed a yeast-two-hybrid screen with non-lethal fragments of WtsE and a synthetic genetic array with full-length WtsE. Together these screens indicate that WtsE targets maize protein phosphatase 2A (PP2A) heterotrimeric enzyme complexes via direct interaction with B' regulatory subunits. AvrE1, another AvrE-family T3E from Pseudomonas syringae pv. tomato strain DC3000 (Pto DC3000), associates with specific PP2A B' subunit proteins from its susceptible host Arabidopsis that are homologous to the maize B' subunits shown to interact with WtsE. Additionally, AvrE1 was observed to associate with the WtsE-interacting maize proteins, indicating that PP2A B' subunits are likely conserved targets of AvrE-family T3Es. Notably, the ability of AvrE1 to promote bacterial growth and/or suppress callose deposition was compromised in Arabidopsis plants with mutations of PP2A genes. Also, chemical inhibition of PP2A activity blocked the virulence activity of both WtsE and AvrE1 in planta. The function of HopM1, a Pto DC3000 T3E that is functionally redundant to AvrE1, was also impaired in specific PP2A mutant lines, although no direct interaction with B' subunits was observed. These results indicate that sub-component specific PP2A complexes are targeted by bacterial T3Es, including direct targeting by members of the widely conserved AvrE-family.
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Affiliation(s)
- Lin Jin
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Jong Hyun Ham
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
- Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America
| | - Rosemary Hage
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Wanying Zhao
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Jaricelis Soto-Hernández
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Sang Yeol Lee
- Division of Applied Life Science (BK21Plus), PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Seung-Mann Paek
- College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Min Gab Kim
- College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Charles Boone
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - David L. Coplin
- Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America
| | - David Mackey
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
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Degrave A, Siamer S, Boureau T, Barny MA. The AvrE superfamily: ancestral type III effectors involved in suppression of pathogen-associated molecular pattern-triggered immunity. MOLECULAR PLANT PATHOLOGY 2015; 16:899-905. [PMID: 25640649 PMCID: PMC6638435 DOI: 10.1111/mpp.12237] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The AvrE superfamily of type III effectors (T3Es) is widespread among type III-dependent phytobacteria and plays a crucial role during bacterial pathogenesis. Members of the AvrE superfamily are vertically inherited core effectors, indicating an ancestral acquisition of these effectors in bacterial plant pathogens. AvrE-T3Es contribute significantly to virulence by suppressing pathogen-associated molecular pattern (PAMP)-triggered immunity. They inhibit salicylic acid-mediated plant defences, interfere with vesicular trafficking and promote bacterial growth in planta. AvrE-T3Es elicit cell death in both host and non-host plants independent of any known plant resistance protein, suggesting an original interaction with the plant immune system. Recent studies in yeast have indicated that they activate protein phosphatase 2A and inhibit serine palmitoyl transferase, the first enzyme of the sphingolipid biosynthesis pathway. In this review, we describe the current picture that has emerged from studies of the different members of this fascinating large family.
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Affiliation(s)
- Alexandre Degrave
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), 49045, Angers, France
- UMR1345, IRHS, Institut National de la Recherche Agronomique (INRA), 49071, Beaucouzé, France
| | - Sabrina Siamer
- Focal Area Infection Biology, Biozentrum, University of Basel, CH-4056, Basel, Switzerland
| | - Tristan Boureau
- UMR1345, IRHS, Institut National de la Recherche Agronomique (INRA), 49071, Beaucouzé, France
- UMR1345, IRHS, Université d'Angers, SFR 4207 QUASAV, PRES l'UNAM, 49045, Angers, France
| | - Marie-Anne Barny
- UMR1392, INRA, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât á 7ème Etage Case 237, 7 Quai St.-Bernard, 75252, Paris, France
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Vanga BR, Ramakrishnan P, Butler RC, Toth IK, Ronson CW, Jacobs JME, Pitman AR. Mobilization of horizontally acquired island 2 is induced in planta in the phytopathogen Pectobacterium atrosepticum SCRI1043 and involves the putative relaxase ECA0613 and quorum sensing. Environ Microbiol 2015; 17:4730-44. [PMID: 26271942 DOI: 10.1111/1462-2920.13024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 08/11/2015] [Accepted: 08/12/2015] [Indexed: 01/30/2023]
Abstract
Integrative and conjugative elements (ICEs) contribute to the rapid evolution of bacterial pathogens via horizontal gene transfer of virulence determinants. ICEs have common mechanisms for transmission, yet the cues triggering this process under natural environmental or physiological conditions are largely unknown. In this study, mobilization of the putative ICE horizontally acquired island 2 (HAI2), present in the chromosome of the phytopathogen Pectobacterium atrosepticum SCRI1043, was examined during infection of the host plant potato. Under these conditions, mobilization of HAI2 increased markedly compared with in vitro cultures. In planta-induced mobilization of HAI2 was regulated by quorum sensing and involved the putative ICE-encoded relaxase ECA0613. Disruption of ECA0613 also reduced transcription of genes involved in production of coronafacic acid (Cfa), the major virulence factor harboured on HAI2, whereas their expression was unaffected in the quorum-sensing (expI) mutant. Thus, suppression of cfa gene expression was not regulated by the mobilization of the ICE per se, but was due directly to inactivation of the relaxase. The identification of genetic factors associated solely with in planta mobilization of an ICE demonstrates that this process is highly adapted to the natural environment of the bacterial host and can influence the expression of virulence determinants.
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Affiliation(s)
- Bhanupratap R Vanga
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, 8140, New Zealand.,Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Pavithra Ramakrishnan
- Bioprotection Research Centre, Lincoln University, PO Box 84, Canterbury, 7647, New Zealand
| | - Ruth C Butler
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, 8140, New Zealand
| | - Ian K Toth
- James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Clive W Ronson
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Jeanne M E Jacobs
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, 8140, New Zealand.,Bioprotection Research Centre, Lincoln University, PO Box 84, Canterbury, 7647, New Zealand
| | - Andrew R Pitman
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, 8140, New Zealand.,Bioprotection Research Centre, Lincoln University, PO Box 84, Canterbury, 7647, New Zealand
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Siamer S, Guillas I, Shimobayashi M, Kunz C, Hall MN, Barny MA. Expression of the bacterial type III effector DspA/E in Saccharomyces cerevisiae down-regulates the sphingolipid biosynthetic pathway leading to growth arrest. J Biol Chem 2014; 289:18466-77. [PMID: 24828506 DOI: 10.1074/jbc.m114.562769] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Erwinia amylovora, the bacterium responsible for fire blight, relies on a type III secretion system and a single injected effector, DspA/E, to induce disease in host plants. DspA/E belongs to the widespread AvrE family of type III effectors that suppress plant defense responses and promote bacterial growth following infection. Ectopic expression of DspA/E in plant or in Saccharomyces cerevisiae is toxic, indicating that DspA/E likely targets a cellular process conserved between yeast and plant. To unravel the mode of action of DspA/E, we screened the Euroscarf S. cerevisiae library for mutants resistant to DspA/E-induced growth arrest. The most resistant mutants (Δsur4, Δfen1, Δipt1, Δskn1, Δcsg1, Δcsg2, Δorm1, and Δorm2) were impaired in the sphingolipid biosynthetic pathway. Exogenously supplied sphingolipid precursors such as the long chain bases (LCBs) phytosphingosine and dihydrosphingosine also suppressed the DspA/E-induced yeast growth defect. Expression of DspA/E in yeast down-regulated LCB biosynthesis and induced a rapid decrease in LCB levels, indicating that serine palmitoyltransferase (SPT), the first and rate-limiting enzyme of the sphingolipid biosynthetic pathway, was repressed. SPT down-regulation was mediated by dephosphorylation and activation of Orm proteins that negatively regulate SPT. A Δcdc55 mutation affecting Cdc55-PP2A protein phosphatase activity prevented Orm dephosphorylation and suppressed DspA/E-induced growth arrest.
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Affiliation(s)
- Sabrina Siamer
- From the Institut National de la Recherche Agronomique UMR1392, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât A 7ème Etage Case 237, 7 Quai St.-Bernard, 75252 Paris, France, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Isabelle Guillas
- Sorbonne Universités, UMR1166, Institut National de la Santé et de la recherche médicale-UPMC, Pitié-Salpétrière University Hospital, F75013, Paris, France
| | | | - Caroline Kunz
- Sorbonne Universités, UPMC University Paris 06, UFR 927, F-75005 Paris, France, and Muséum National d'Histoire Naturelle, UMR7245, Molécules de Communication et Adaptation des Micro-organismes, F-75005 Paris, France
| | - Michael N Hall
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Marie-Anne Barny
- From the Institut National de la Recherche Agronomique UMR1392, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât A 7ème Etage Case 237, 7 Quai St.-Bernard, 75252 Paris, France,
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21
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Siamer S, Gaubert S, Boureau T, Brisset MN, Barny MA. Mutational analysis of a predicted double β-propeller domain of the DspA/E effector of Erwinia amylovora. FEMS Microbiol Lett 2013; 342:54-61. [PMID: 23421848 DOI: 10.1111/1574-6968.12108] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 02/07/2013] [Accepted: 02/18/2013] [Indexed: 12/11/2022] Open
Abstract
The bacterium Erwinia amylovora causes fire blight, an invasive disease that threatens apple trees, pear trees and other plants of the Rosaceae family. Erwinia amylovora pathogenicity relies on a type III secretion system and on a single effector DspA/E. This effector belongs to the widespread AvrE family of effectors whose biological function is unknown. In this manuscript, we performed a bioinformatic analysis of DspA/E- and AvrE-related effectors. Motif search identified nuclear localization signals, peroxisome targeting signals, endoplasmic reticulum membrane retention signals and leucine zipper motifs, but none of these motifs were present in all the AvrE-related effectors analysed. Protein threading analysis, however, predicted a conserved double β-propeller domain in the N-terminal part of all the analysed effector sequences. We then performed a random pentapeptide mutagenesis of DspA/E, which led to the characterization of 13 new altered proteins with a five amino acids insertion. Eight harboured the insertion inside the predicted β-propeller domain and six of these eight insertions impaired DspA/E stability or function. Conversely, the two remaining insertions generated proteins that were functional and abundantly secreted in the supernatant suggesting that these two insertions stabilized the protein.
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22
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Davidsson PR, Kariola T, Niemi O, Palva ET. Pathogenicity of and plant immunity to soft rot pectobacteria. FRONTIERS IN PLANT SCIENCE 2013; 4:191. [PMID: 23781227 PMCID: PMC3678301 DOI: 10.3389/fpls.2013.00191] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/23/2013] [Indexed: 05/20/2023]
Abstract
Soft rot pectobacteria are broad host range enterobacterial pathogens that cause disease on a variety of plant species including the major crop potato. Pectobacteria are aggressive necrotrophs that harbor a large arsenal of plant cell wall-degrading enzymes as their primary virulence determinants. These enzymes together with additional virulence factors are employed to macerate the host tissue and promote host cell death to provide nutrients for the pathogens. In contrast to (hemi)biotrophs such as Pseudomonas, type III secretion systems (T3SS) and T3 effectors do not appear central to pathogenesis of pectobacteria. Indeed, recent genomic analysis of several Pectobacterium species including the emerging pathogen Pectobacterium wasabiae has shown that many strains lack the entire T3SS as well as the T3 effectors. Instead, this analysis has indicated the presence of novel virulence determinants. Resistance to broad host range pectobacteria is complex and does not appear to involve single resistance genes. Instead, activation of plant innate immunity systems including both SA (salicylic acid) and JA (jasmonic acid)/ET (ethylene)-mediated defenses appears to play a central role in attenuation of Pectobacterium virulence. These defenses are triggered by detection of pathogen-associated molecular patterns (PAMPs) or recognition of modified-self such as damage-associated molecular patterns (DAMPs) and result in enhancement of basal immunity (PAMP/DAMP-triggered immunity or pattern-triggered immunity, PTI). In particular plant cell wall fragments released by the action of the degradative enzymes secreted by pectobacteria are major players in enhanced immunity toward these pathogens. Most notably bacterial pectin-degrading enzymes release oligogalacturonide (OG) fragments recognized as DAMPs activating innate immune responses. Recent progress in understanding OG recognition and signaling allows novel genetic screens for OG-insensitive mutants and will provide new insights into plant defense strategies against necrotrophs such as pectobacteria.
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Affiliation(s)
| | - Tarja Kariola
- Division of Genetics, Department of Biosciences, University of HelsinkiHelsinki, Finland
| | - Outi Niemi
- Division of Genetics, Department of Biosciences, University of HelsinkiHelsinki, Finland
| | - E. T. Palva
- Division of Genetics, Department of Biosciences, University of HelsinkiHelsinki, Finland
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23
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Cubitt MF, Hedley PE, Williamson NR, Morris JA, Campbell E, Toth IK, Salmond GPC. A metabolic regulator modulates virulence and quorum sensing signal production in Pectobacterium atrosepticum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:356-366. [PMID: 23113713 DOI: 10.1094/mpmi-09-12-0210-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Plant cell wall-degrading enzymes (PCWDE) are key virulence determinants in the pathogenesis of the potato pathogen Pectobacterium atrosepticum. In this study, we report the impact on virulence of a transposon insertion mutation in the metJ gene that codes for the repressor of the methionine biosynthesis regulon. In a mutant strain defective for the small regulatory RNA rsmB, PCWDE are not produced and virulence in potato tubers is almost totally abolished. However, when the metJ gene is disrupted in this background, the rsmB(-) phenotype is suppressed and virulence and PCWDE production are restored. Additionally, when metJ is disrupted, production of the quorum-sensing signal, N-(3-oxohexanoyl)-homoserine lactone, is increased. The metJ mutant strains showed pleiotropic transcriptional impacts affecting approximately a quarter of the genome. Genes involved in methionine biosynthesis were most highly upregulated but many virulence-associated transcripts were also upregulated. This is the first report of the impact of the MetJ repressor on virulence in bacteria.
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Affiliation(s)
- Marion F Cubitt
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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24
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Nykyri J, Niemi O, Koskinen P, Nokso-Koivisto J, Pasanen M, Broberg M, Plyusnin I, Törönen P, Holm L, Pirhonen M, Palva ET. Revised phylogeny and novel horizontally acquired virulence determinants of the model soft rot phytopathogen Pectobacterium wasabiae SCC3193. PLoS Pathog 2012; 8:e1003013. [PMID: 23133391 PMCID: PMC3486870 DOI: 10.1371/journal.ppat.1003013] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 09/18/2012] [Indexed: 11/19/2022] Open
Abstract
Soft rot disease is economically one of the most devastating bacterial diseases affecting plants worldwide. In this study, we present novel insights into the phylogeny and virulence of the soft rot model Pectobacterium sp. SCC3193, which was isolated from a diseased potato stem in Finland in the early 1980s. Genomic approaches, including proteome and genome comparisons of all sequenced soft rot bacteria, revealed that SCC3193, previously included in the species Pectobacterium carotovorum, can now be more accurately classified as Pectobacterium wasabiae. Together with the recently revised phylogeny of a few P. carotovorum strains and an increasing number of studies on P. wasabiae, our work indicates that P. wasabiae has been unnoticed but present in potato fields worldwide. A combination of genomic approaches and in planta experiments identified features that separate SCC3193 and other P. wasabiae strains from the rest of soft rot bacteria, such as the absence of a type III secretion system that contributes to virulence of other soft rot species. Experimentally established virulence determinants include the putative transcriptional regulator SirB, two partially redundant type VI secretion systems and two horizontally acquired clusters (Vic1 and Vic2), which contain predicted virulence genes. Genome comparison also revealed other interesting traits that may be related to life in planta or other specific environmental conditions. These traits include a predicted benzoic acid/salicylic acid carboxyl methyltransferase of eukaryotic origin. The novelties found in this work indicate that soft rot bacteria have a reservoir of unknown traits that may be utilized in the poorly understood latent stage in planta. The genomic approaches and the comparison of the model strain SCC3193 to other sequenced Pectobacterium strains, including the type strain of P. wasabiae, provides a solid basis for further investigation of the virulence, distribution and phylogeny of soft rot bacteria and, potentially, other bacteria as well.
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Affiliation(s)
- Johanna Nykyri
- Department of Agricultural Sciences, Plant Pathology, University of Helsinki, Helsinki, Finland
| | - Outi Niemi
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
| | - Patrik Koskinen
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
| | | | - Miia Pasanen
- Department of Agricultural Sciences, Plant Pathology, University of Helsinki, Helsinki, Finland
| | - Martin Broberg
- Department of Agricultural Sciences, Plant Pathology, University of Helsinki, Helsinki, Finland
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
| | - Ilja Plyusnin
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Petri Törönen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Liisa Holm
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Minna Pirhonen
- Department of Agricultural Sciences, Plant Pathology, University of Helsinki, Helsinki, Finland
| | - E. Tapio Palva
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
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25
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Karki HS, Barphagha IK, Ham JH. A conserved two-component regulatory system, PidS/PidR, globally regulates pigmentation and virulence-related phenotypes of Burkholderia glumae. MOLECULAR PLANT PATHOLOGY 2012; 13:785-94. [PMID: 22364153 PMCID: PMC6638751 DOI: 10.1111/j.1364-3703.2012.00787.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Burkholderia glumae is a rice pathogenic bacterium that causes bacterial panicle blight. Some strains of this pathogen produce dark brown pigments when grown on casamino-acid peptone glucose (CPG) agar medium. A pigment-positive and highly virulent strain of B. glumae, 411gr-6, was randomly mutagenized with mini-Tn5gus, and the resulting mini-Tn5gus derivatives showing altered pigmentation phenotypes were screened on CPG agar plates to identify the genetic elements governing the pigmentation of B. glumae. In this study, a novel two-component regulatory system (TCRS) composed of the PidS sensor histidine kinase and the PidR response regulator was identified as an essential regulatory factor for pigmentation. Notably, the PidS/PidR TCRS was also required for the elicitation of the hypersensitive response on tobacco leaves, indicating the dependence of the hypersensitive response and pathogenicity (Hrp) type III secretion system of B. glumae on this regulatory factor. In addition, B. glumae mutants defective in the PidS/PidR TCRS showed less production of the phytotoxin, toxoflavin, and less virulence on rice panicles and onion bulbs relative to the parental strain, 411gr-6. The presence of highly homologous PidS and PidR orthologues in other Burkholderia species suggests that PidS/PidR-family TCRSs may exert the same or similar functions in different Burkholderia species, including both plant and animal pathogens.
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Affiliation(s)
- Hari Sharan Karki
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA
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26
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Vanga BR, Butler RC, Toth IK, Ronson CW, Pitman AR. Inactivation of PbTopo IIIβ causes hyper-excision of the Pathogenicity Island HAI2 resulting in reduced virulence of Pectobacterium atrosepticum. Mol Microbiol 2012; 84:648-63. [PMID: 22524709 DOI: 10.1111/j.1365-2958.2012.08050.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Topoisomerase III enzymes are present only in a limited set of bacteria and their physiological role remains unclear. Here, we show that PbTopo IIIβ, a homologue of topoisomerase III encoded on the chromosome of Pectobacterium atrosepticum strain SCRI1043 (Pba SCRI1043), is involved in excision of HAI2, a discrete ~100 kb region, from the Pba SCRI1043 chromosome. HAI2 is a Pathogenicity Island (PAI) that encodes coronafacic acid (Cfa), a major virulence determinant required for infection of potato. PAIs are horizontally acquired genetic elements that in some instances are able to excise from the chromosome of their host cell to form a circular episome prior to transfer to a recipient bacterium. We demonstrate excision of HAI2 from the chromosome, a process that is independent of growth phase and that results in the production of a circular intermediate. Inactivation of PbTopo IIIβ causes a 10(3) - to 10(4) -fold increase in excision, leading to reduced fitness in vitro and a decrease in the virulence of Pba SCRI1043 on potato. These results suggest that PbTopo IIIβ is required for stable maintenance of HAI2 in the chromosome of Pba SCRI1043 and may control as yet unidentified genes involved in viability and virulence of Pba SCRI1043 on potato.
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Affiliation(s)
- Bhanupratap R Vanga
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 4704, Christchurch, New Zealand
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27
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Rio-Alvarez I, Rodríguez-Herva JJ, Cuartas-Lanza R, Toth I, Pritchard L, Rodríguez-Palenzuela P, López-Solanilla E. Genome-wide analysis of the response of Dickeya dadantii 3937 to plant antimicrobial peptides. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:523-533. [PMID: 22204647 DOI: 10.1094/mpmi-09-11-0247] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Antimicrobial peptides constitute an important factor in the defense of plants against pathogens, and bacterial resistance to these peptides have previously been shown to be an important virulence factor in Dickeya dadantii, the causal agent of soft-rot disease of vegetables. In order to understand the bacterial response to antimicrobial peptides, a transcriptional microarray analysis was performed upon treatment with sub-lethal concentration of thionins, a widespread plant peptide. In all, 36 genes were found to be overexpressed, and were classified according to their deduced function as i) transcriptional regulators, ii) transport, and iii) modification of the bacterial membrane. One gene encoding a uricase was found to be repressed. The majority of these genes are known to be under the control of the PhoP/PhoQ system. Five genes representing the different functions induced were selected for further analysis. The results obtained indicate that the presence of antimicrobial peptides induces a complex response which includes peptide-specific elements and general stress-response elements contributing differentially to the virulence in different hosts.
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Affiliation(s)
- Isabel Rio-Alvarez
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
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28
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McNally RR, Toth IK, Cock PJA, Pritchard L, Hedley PE, Morris JA, Zhao Y, Sundin GW. Genetic characterization of the HrpL regulon of the fire blight pathogen Erwinia amylovora reveals novel virulence factors. MOLECULAR PLANT PATHOLOGY 2012; 13:160-73. [PMID: 21831138 PMCID: PMC6638853 DOI: 10.1111/j.1364-3703.2011.00738.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The bacterial pathogen Erwinia amylovora is the causal agent of fire blight, an economically significant disease of apple and pear. Disease initiation by E. amylovora requires the translocation of effector proteins into host cells via the hypersensitive response and pathogenicity (hrp) type III secretion system (T3SS). The alternative sigma factor HrpL positively regulates the transcription of structural and translocated components of the T3SS via hrp promoter elements. To characterize genome-wide HrpL-dependent gene expression in E. amylovora Ea1189, wild-type and Ea1189ΔhrpL strains were cultured in hrp-inducing minimal medium, and total RNA was compared using a custom microarray designed to represent the annotated genes of E. amylovora ATCC 49946. The results revealed 24 genes differentially regulated in Ea1189ΔhrpL relative to Ea1189 with fold-change expression ratios greater than 1.5; of these, 19 genes exhibited decreased transcript abundance and five genes showed increased transcript abundance relative to Ea1189. To expand our understanding of the HrpL regulon and to elucidate direct versus indirect HrpL-mediated effects on gene expression, the genome of E. amylovora ATCC 49946 was examined in silico using a hidden Markov model assembled from known Erwinia spp. hrp promoters. This technique identified 15 putative type III novel hrp promoters, seven of which were validated with quantitative polymerase chain reaction based on expression analyses. It was found that HrpL-regulated genes encode all known components of the hrp T3SS, as well as five putative type III effectors. Eight genes displayed apparent indirect HrpL regulation, suggesting that the HrpL regulon is connected to downstream signalling networks. The construction of deletion mutants of three novel HrpL-regulated genes resulted in the identification of additional virulence factors as well as mutants displaying abnormal motility and biofilm phenotypes.
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Affiliation(s)
- R Ryan McNally
- Department of Plant Pathology, Michigan State University, East Lansing, MI 48824, USA
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29
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Charkowski A, Blanco C, Condemine G, Expert D, Franza T, Hayes C, Hugouvieux-Cotte-Pattat N, López Solanilla E, Low D, Moleleki L, Pirhonen M, Pitman A, Perna N, Reverchon S, Rodríguez Palenzuela P, San Francisco M, Toth I, Tsuyumu S, van der Waals J, van der Wolf J, Van Gijsegem F, Yang CH, Yedidia I. The role of secretion systems and small molecules in soft-rot Enterobacteriaceae pathogenicity. ANNUAL REVIEW OF PHYTOPATHOLOGY 2012; 50:425-49. [PMID: 22702350 DOI: 10.1146/annurev-phyto-081211-173013] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Soft-rot Enterobacteriaceae (SRE), which belong to the genera Pectobacterium and Dickeya, consist mainly of broad host-range pathogens that cause wilt, rot, and blackleg diseases on a wide range of plants. They are found in plants, insects, soil, and water in agricultural regions worldwide. SRE encode all six known protein secretion systems present in gram-negative bacteria, and these systems are involved in attacking host plants and competing bacteria. They also produce and detect multiple types of small molecules to coordinate pathogenesis, modify the plant environment, attack competing microbes, and perhaps to attract insect vectors. This review integrates new information about the role protein secretion and detection and production of ions and small molecules play in soft-rot pathogenicity.
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Affiliation(s)
- Amy Charkowski
- Department of Plant Pathology, University of Wisconsin, Madison, Wisconsin 53706, USA.
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30
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Siamer S, Patrit O, Fagard M, Belgareh-Touzé N, Barny MA. Expressing the Erwinia amylovora type III effector DspA/E in the yeast Saccharomyces cerevisiae strongly alters cellular trafficking. FEBS Open Bio 2011; 1:23-8. [PMID: 23650572 PMCID: PMC3642059 DOI: 10.1016/j.fob.2011.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/02/2011] [Accepted: 11/03/2011] [Indexed: 11/18/2022] Open
Abstract
Erwinia amylovora is responsible for fire blight, a necrotic disease of apples and pears. E. amylovora relies on a type III secretion system (T3SS) to induce disease on host plants. DspA/E belongs to the AvrE family of type III effector. Effectors of the AvrE family are injected via the T3SS in plant cell and are important to promote bacterial growth following infection and to suppress plant defense responses. Their mode of action in the plant cells is unknown. Here we study the physiological effects induced by dspA/E expression in the yeast Saccharomyces cerevisiae. Expression of dspA/E in the yeast inhibits cell growth. This growth inhibition is associated with perturbations of the actin cytoskeleton and endocytosis.
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Affiliation(s)
- Sabrina Siamer
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Oriane Patrit
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Mathilde Fagard
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Naïma Belgareh-Touzé
- FRE 3354 CNRS/UPMC, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Marie-Anne Barny
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- Corresponding author at: AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France. Fax: +33 1 44 08 16 98.
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31
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Pérez-Mendoza D, Coulthurst SJ, Humphris S, Campbell E, Welch M, Toth IK, Salmond GPC. A multi-repeat adhesin of the phytopathogen, Pectobacterium atrosepticum, is secreted by a Type I pathway and is subject to complex regulation involving a non-canonical diguanylate cyclase. Mol Microbiol 2011; 82:719-33. [PMID: 21992096 DOI: 10.1111/j.1365-2958.2011.07849.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cyclic diguanylate (c-di-GMP) is a second messenger controlling many important bacterial processes. The phytopathogen Pectobacterium atrosepticum SCRI1043 (Pba1043) possesses a Type I secretion system (T1SS) essential for the secretion of a proteinaceous multi-repeat adhesin (MRP) required for binding to the host plant. The genes encoding the MRP and the T1SS are tightly linked to genes encoding several putative c-di-GMP regulatory components. We show that c-di-GMP regulates secreted MRP levels in Pba1043 through the action of two genes encoding predicted diguanylate cyclase (DGC) and phosphodiesterase proteins (ECA3270 and ECA3271). Phenotypic analyses and quantification of c-di-GMP levels demonstrated that ECA3270 and ECA3271 regulate secreted MRP levels by increasing and decreasing, respectively, the intracellular levels of c-di-GMP. Moreover, ECA3270 represents the first active DGC reported to have an alternative active-site motif from the 'canonical' GG[D/E]EF. ECA3270 has an A-site motif of SGDEF and analysis of single amino acid replacements demonstrated that the first position of this motif can tolerate functional substitution. Serine in position one of the A-site is also observed in many other DGCs. Finally, another T1SS-linked regulator (ECA3265) also plays an important role in regulating secreted MRP, with an altered localization of MRP observed in an ECA3265 mutant background. Mutants defective in these three T1SS-linked regulators exhibit a reduction in root binding and virulence, confirming that this complex, finely tuned regulation system is crucial in the interaction with host plants.
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32
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Kim HS, Thammarat P, Lommel SA, Hogan CS, Charkowski AO. Pectobacterium carotovorum elicits plant cell death with DspE/F but the P. carotovorum DspE does not suppress callose or induce expression of plant genes early in plant-microbe interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:773-86. [PMID: 21469936 DOI: 10.1094/mpmi-06-10-0143] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The broad-host-range bacterial soft rot pathogen Pectobacterium carotovorum causes a DspE/F-dependent plant cell death on Nicotiana benthamiana within 24 h postinoculation (hpi) followed by leaf maceration within 48 hpi. P. carotovorum strains with mutations in type III secretion system (T3SS) regulatory and structural genes, including the dspE/F operon, did not cause hypersensitive response (HR)-like cell death and or leaf maceration. A strain with a mutation in the type II secretion system caused HR-like plant cell death but no maceration. P. carotovorum was unable to impede callose deposition in N. benthamiana leaves, suggesting that P. carotovorum does not suppress this basal immunity function. Within 24 hpi, there was callose deposition along leaf veins and examination showed that the pathogen cells were localized along the veins. To further examine HR-like plant cell death induced by P. carotovorum, gene expression profiles in N. benthamiana leaves inoculated with wild-type and mutant P. carotovorum and Pseudomonas syringae strains were compared. The N. benthamiana gene expression profile of leaves infiltrated with Pectobacterium carotovorum was similar to leaves infiltrated with a Pseudomonas syringae T3SS mutant. These data support a model where Pectobacterium carotovorum uses the T3SS to induce plant cell death in order to promote leaf maceration rather than to suppress plant immunity.
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Affiliation(s)
- Hye-Sook Kim
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
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Marquez-Villavicencio MDP, Groves RL, Charkowski AO. Soft Rot Disease Severity Is Affected by Potato Physiology and Pectobacterium taxa. PLANT DISEASE 2011; 95:232-241. [PMID: 30743537 DOI: 10.1094/pdis-07-10-0526] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Pectobacterium species cause disease worldwide in many crop and ornamental plants, including potato. A new Pectobacterium subspecies, P. carotovorum subsp. brasiliensis was recently described in Brazil and later found in the United States, Israel, and South Africa. Its virulence traits and host range remain unknown. A comparison of three taxa commonly found on potato showed that both P. carotovorum subsp. carotovorum and subsp. brasiliensis are more aggressive in causing tuber and stem soft rot than P. atrosepticum. Also, despite bacterial growth inhibition in vitro of P. carotovorum subsp. carotovorum and P. atrosepticum strains by P. carotovorum subsp. brasiliensis, this new subspecies and P. carotovorum subsp. carotovorum are able to co-colonize in the same infected tissue. Both subspecies were motile in lesions. Pathogenesis assays showed that host ranges of all three overlap, but are not identical. The host ranges of individual strains of P. carotovorum subsp. carotovorum and subsp. brasiliensis are limited, whereas P. atrosepticum can macerate many plant species in addition to potato. There was high variability in virulence assays with potato tuber; thus physiological factors were investigated. Tuber size, maturity, and field location had significant effects on susceptibility to soft rot, with larger, more mature tubers being more susceptible.
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Yang S, Peng Q, Zhang Q, Zou L, Li Y, Robert C, Pritchard L, Liu H, Hovey R, Wang Q, Birch P, Toth IK, Yang CH. Genome-wide identification of HrpL-regulated genes in the necrotrophic phytopathogen Dickeya dadantii 3937. PLoS One 2010; 5:e13472. [PMID: 20976052 PMCID: PMC2957411 DOI: 10.1371/journal.pone.0013472] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Accepted: 09/30/2010] [Indexed: 12/26/2022] Open
Abstract
Background Dickeya dadantii is a necrotrophic pathogen causing disease in many plants. Previous studies have demonstrated that the type III secretion system (T3SS) of D. dadantii is required for full virulence. HrpL is an alternative sigma factor that binds to the hrp box promoter sequence of T3SS genes to up-regulate their expression. Methodology/Principal Findings To explore the inventory of HrpL-regulated genes of D. dadantii 3937 (3937), transcriptome profiles of wild-type 3937 and a hrpL mutant grown in a T3SS-inducing medium were examined. Using a cut-off value of 1.5, significant differential expression was observed in sixty-three genes, which are involved in various cellular functions such as type III secretion, chemotaxis, metabolism, regulation, and stress response. A hidden Markov model (HMM) was used to predict candidate hrp box binding sites in the intergenic regions of 3937, including the promoter regions of HrpL-regulated genes identified in the microarray assay. In contrast to biotrophic phytopathgens such as Pseudomonas syringae, among the HrpL up-regulated genes in 3937 only those within the T3SS were found to contain a hrp box sequence. Moreover, direct binding of purified HrpL protein to the hrp box was demonstrated for hrp box-containing DNA fragments of hrpA and hrpN using the electrophoretic mobility shift assay (EMSA). In this study, a putative T3SS effector DspA/E was also identified as a HrpL-upregulated gene, and shown to be translocated into plant cells in a T3SS-dependent manner. Conclusion/Significances We provide the genome-wide study of HrpL-regulated genes in a necrotrophic phytopathogen (D. dadantii 3937) through a combination of transcriptomics and bioinformatics, which led to identification of several effectors. Our study indicates the extent of differences for T3SS effector protein inventory requirements between necrotrophic and biotrophic pathogens, and may allow the development of different strategies for disease control for these different groups of pathogens.
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Affiliation(s)
- Shihui Yang
- Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Quan Peng
- Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Qiu Zhang
- Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Lifang Zou
- Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Yan Li
- Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Plant Pathology, China Agricultural University, Beijing, China
| | - Christelle Robert
- Plant Pathology, Scottish Crop Research Institute, Invergowrie, Dundee, United Kingdom
| | - Leighton Pritchard
- Plant Pathology, Scottish Crop Research Institute, Invergowrie, Dundee, United Kingdom
| | - Hui Liu
- Plant Pathology, Scottish Crop Research Institute, Invergowrie, Dundee, United Kingdom
| | - Raymond Hovey
- Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Qi Wang
- Department of Plant Pathology, China Agricultural University, Beijing, China
| | - Paul Birch
- Plant Pathology, Scottish Crop Research Institute, Invergowrie, Dundee, United Kingdom
| | - Ian K. Toth
- Plant Pathology, Scottish Crop Research Institute, Invergowrie, Dundee, United Kingdom
- * E-mail: (CHY); (IKT)
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, United States of America
- * E-mail: (CHY); (IKT)
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Terta M, Kettani-Halabi M, Ibenyassine K, Tran D, Meimoun P, M'hand RA, El-Maarouf-Bouteau H, Val F, Ennaji MM, Bouteau F. Arabidopsis thaliana cells: a model to evaluate the virulence of Pectobacterium carotovorum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:139-43. [PMID: 20064057 DOI: 10.1094/mpmi-23-2-0139] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Pectobacterium carotovorum are economically important plant pathogens that cause plant soft rot. These enterobacteria display high diversity world-wide. Their pathogenesis depends on production and secretion of virulence factors such as plant cell wall-degrading enzymes, type III effectors, a necrosis-inducing protein, and a secreted virulence factor from Xanthomonas spp., which are tightly regulated by quorum sensing. Pectobacterium carotovorum also present pathogen-associated molecular patterns that could participate in their pathogenicity. In this study, by using suspension cells of Arabidopsis thaliana, we correlate plant cell death and pectate lyase activities during coinfection with different P. carotovorum strains. When comparing soft rot symptoms induced on potato slices with pectate lyase activities and plant cell death observed during coculture with Arabidopsis thaliana cells, the order of strain virulence was found to be the same. Therefore, Arabidopsis thaliana cells could be an alternative tool to evaluate rapidly and efficiently the virulence of different P. carotovorum strains.
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Affiliation(s)
- Meriam Terta
- LEM-EA3514-Universite Paris Diderot-Paris 7, 2 place Jussieu, 75251 Paris cedex 05, France
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Schneider DJ, Collmer A. Studying plant-pathogen interactions in the genomics era: beyond molecular Koch's postulates to systems biology. ANNUAL REVIEW OF PHYTOPATHOLOGY 2010; 48:457-479. [PMID: 20687834 DOI: 10.1146/annurev-phyto-073009-114411] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Molecular factors enabling microbial pathogens to cause plant diseases have been sought with increasing efficacy over three research eras that successively introduced the tools of disease physiology, single-gene molecular genetics, and genomics. From this work emerged a unified model of the interactions of biotrophic and hemibiotrophic pathogens, which posits that successful pathogens typically defeat two levels of plant defense by translocating cytoplasmic effectors that suppress the first defense (surface arrayed against microbial signatures) while evading the second defense (internally arrayed against effectors). As is predicted from this model and confirmed by sequence pattern-driven discovery of large repertoires of cytoplasmic effectors in the genomes of many pathogens, the coevolution of (hemi)biotrophic pathogens and their hosts has generated pathosystems featuring extreme complexity and apparent robustness. These findings highlight the need for a fourth research era of systems biology in which virulence factors are studied as pathosystem components, and pathosystems are studied for their emergent properties.
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Affiliation(s)
- David J Schneider
- U.S. Department of Agriculture, Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, New York 14853, USA.
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37
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Pritchard L, Liu H, Booth C, Douglas E, François P, Schrenzel J, Hedley PE, Birch PRJ, Toth IK. Microarray comparative genomic hybridisation analysis incorporating genomic organisation, and application to enterobacterial plant pathogens. PLoS Comput Biol 2009; 5:e1000473. [PMID: 19696881 PMCID: PMC2718846 DOI: 10.1371/journal.pcbi.1000473] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 07/16/2009] [Indexed: 11/18/2022] Open
Abstract
Microarray comparative genomic hybridisation (aCGH) provides an estimate of the relative abundance of genomic DNA (gDNA) taken from comparator and reference organisms by hybridisation to a microarray containing probes that represent sequences from the reference organism. The experimental method is used in a number of biological applications, including the detection of human chromosomal aberrations, and in comparative genomic analysis of bacterial strains, but optimisation of the analysis is desirable in each problem domain.We present a method for analysis of bacterial aCGH data that encodes spatial information from the reference genome in a hidden Markov model. This technique is the first such method to be validated in comparisons of sequenced bacteria that diverge at the strain and at the genus level: Pectobacterium atrosepticum SCRI1043 (Pba1043) and Dickeya dadantii 3937 (Dda3937); and Lactococcus lactis subsp. lactis IL1403 and L. lactis subsp. cremoris MG1363. In all cases our method is found to outperform common and widely used aCGH analysis methods that do not incorporate spatial information. This analysis is applied to comparisons between commercially important plant pathogenic soft-rotting enterobacteria (SRE) Pba1043, P. atrosepticum SCRI1039, P. carotovorum 193, and Dda3937.Our analysis indicates that it should not be assumed that hybridisation strength is a reliable proxy for sequence identity in aCGH experiments, and robustly extends the applicability of aCGH to bacterial comparisons at the genus level. Our results in the SRE further provide evidence for a dynamic, plastic 'accessory' genome, revealing major genomic islands encoding gene products that provide insight into, and may play a direct role in determining, variation amongst the SRE in terms of their environmental survival, host range and aetiology, such as phytotoxin synthesis, multidrug resistance, and nitrogen fixation.
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Affiliation(s)
- Leighton Pritchard
- Plant Pathology Programme, SCRI, Dundee, Scotland, United Kingdom
- * E-mail: (LP); (IKT)
| | - Hui Liu
- Plant Pathology Programme, SCRI, Dundee, Scotland, United Kingdom
| | - Clare Booth
- Genetics Programme, SCRI, Dundee, Scotland, United Kingdom
| | - Emma Douglas
- Plant Pathology Programme, SCRI, Dundee, Scotland, United Kingdom
| | - Patrice François
- Genomic Research Laboratory, Infectious Diseases Service, Geneva University Hospitals and the University of Geneva, Geneva, Switzerland
| | - Jacques Schrenzel
- Genomic Research Laboratory, Infectious Diseases Service, Geneva University Hospitals and the University of Geneva, Geneva, Switzerland
| | | | - Paul R. J. Birch
- Plant Pathology Programme, SCRI, Dundee, Scotland, United Kingdom
- Division of Plant Science, College of Life Sciences, University of Dundee at SCRI, Dundee, Scotland, United Kingdom
| | - Ian K. Toth
- Plant Pathology Programme, SCRI, Dundee, Scotland, United Kingdom
- * E-mail: (LP); (IKT)
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38
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Ham JH, Majerczak DR, Nomura K, Mecey C, Uribe F, He SY, Mackey D, Coplin DL. Multiple activities of the plant pathogen type III effector proteins WtsE and AvrE require WxxxE motifs. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:703-12. [PMID: 19445595 PMCID: PMC2748107 DOI: 10.1094/mpmi-22-6-0703] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The broadly conserved AvrE-family of type III effectors from gram-negative plant-pathogenic bacteria includes important virulence factors, yet little is known about the mechanisms by which these effectors function inside plant cells to promote disease. We have identified two conserved motifs in AvrE-family effectors: a WxxxE motif and a putative C-terminal endoplasmic reticulum membrane retention/retrieval signal (ERMRS). The WxxxE and ERMRS motifs are both required for the virulence activities of WtsE and AvrE, which are major virulence factors of the corn pathogen Pantoea stewartii subsp. stewartii and the tomato or Arabidopsis pathogen Pseudomonas syringae pv. tomato, respectively. The WxxxE and the predicted ERMRS motifs are also required for other biological activities of WtsE, including elicitation of the hypersensitive response in nonhost plants and suppression of defense responses in Arabidopsis. A family of type III effectors from mammalian bacterial pathogens requires WxxxE and subcellular targeting motifs for virulence functions that involve their ability to mimic activated G-proteins. The conservation of related motifs and their necessity for the function of type III effectors from plant pathogens indicates that disturbing host pathways by mimicking activated host G-proteins may be a virulence mechanism employed by plant pathogens as well.
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Affiliation(s)
- Jong Hyun Ham
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, 43210
- Department of Plant Pathology, The Ohio State University, Columbus, OH, 43210
| | - Doris R. Majerczak
- Department of Plant Pathology, The Ohio State University, Columbus, OH, 43210
| | - Kinya Nomura
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824
| | - Christy Mecey
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824
| | - Francisco Uribe
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824
| | - Sheng-Yang He
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824
| | - David Mackey
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, 43210
| | - David L. Coplin
- Department of Plant Pathology, The Ohio State University, Columbus, OH, 43210
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39
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Phylogeny and virulence of naturally occurring type III secretion system-deficient Pectobacterium strains. Appl Environ Microbiol 2009; 75:4539-49. [PMID: 19411432 DOI: 10.1128/aem.01336-08] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pectobacterium species are enterobacterial plant-pathogenic bacteria that cause soft rot disease in diverse plant species. Previous epidemiological studies of Pectobacterium species have suffered from an inability to identify most isolates to the species or subspecies level. We used three previously described DNA-based methods, 16S-23S intergenic transcribed spacer PCR-restriction fragment length polymorphism analysis, multilocus sequence analysis (MLSA), and pulsed-field gel electrophoresis, to examine isolates from diseased stems and tubers and found that MLSA provided the most reliable classification of isolates. We found that strains belonging to at least two Pectobacterium clades were present in each field examined, although representatives of only three of five Pectobacterium clades were isolated. Hypersensitive response and DNA hybridization assays revealed that strains of both Pectobacterium carotovorum and Pectobacterium wasabiae lack a type III secretion system (T3SS). Two of the T3SS-deficient strains assayed lack genes adjacent to the T3SS gene cluster, suggesting that multiple deletions occurred in Pectobacterium strains in this locus, and all strains appear to have only six rRNA operons instead of the seven operons typically found in Pectobacterium strains. The virulence of most of the T3SS-deficient strains was similar to that of T3SS-encoding strains in stems and tubers.
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40
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Glasner JD, Marquez-Villavicencio M, Kim HS, Jahn CE, Ma B, Biehl BS, Rissman AI, Mole B, Yi X, Yang CH, Dangl JL, Grant SR, Perna NT, Charkowski AO. Niche-specificity and the variable fraction of the Pectobacterium pan-genome. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:1549-1560. [PMID: 18986251 DOI: 10.1094/mpmi-21-12-1549] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We compare genome sequences of three closely related soft-rot pathogens that vary in host range and geographical distribution to identify genetic differences that could account for lifestyle differences. The isolates compared, Pectobacterium atrosepticum SCRI1043, P. carotovorum WPP14, and P. brasiliensis 1692, represent diverse lineages of the genus. P. carotovorum and P. brasiliensis genome contigs, generated by 454 pyrosequencing ordered by reference to the previously published complete circular chromosome of P. atrosepticum genome and each other, account for 96% of the predicted genome size. Orthologous proteins encoded by P. carotovorum and P. brasiliensis are approximately 95% identical to each other and 92% identical to P. atrosepticum. Multiple alignment using Mauve identified a core genome of 3.9 Mb conserved among these Pectobacterium spp. Each core genome is interrupted at many points by species-specific insertions or deletions (indels) that account for approximately 0.9 to 1.1 Mb. We demonstrate that the presence of a hrpK-like type III secretion system-dependent effector protein in P. carotovorum and P. brasiliensis and its absence from P. atrosepticum is insufficient to explain variability in their response to infection in a plant. Additional genes that vary among these species include those encoding peptide toxin production, enzyme production, secretion proteins, and antibiotic production, as well as differences in more general aspects of gene regulation and metabolism that may be relevant to pathogenicity.
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Affiliation(s)
- J D Glasner
- Genome Center of Wisconsin, Madison, WI, USA.
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41
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Degrave A, Fagard M, Perino C, Brisset MN, Gaubert S, Laroche S, Patrit O, Barny MA. Erwinia amylovora type three-secreted proteins trigger cell death and defense responses in Arabidopsis thaliana. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:1076-1086. [PMID: 18616404 DOI: 10.1094/mpmi-21-8-1076] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Erwinia amylovora is the bacterium responsible for fire blight, a necrotic disease affecting plants of the rosaceous family. E. amylovora pathogenicity requires a functional type three secretion system (T3SS). We show here that E. amylovora triggers a T3SS-dependent cell death on Arabidopsis thaliana. The plants respond by inducing T3SS-dependent defense responses, including salicylic acid (SA)-independent callose deposition, activation of the SA defense pathway, reactive oxygen species (ROS) accumulation, and part of the jasmonic acid/ethylene defense pathway. Several of these reactions are similar to what is observed in host plants. We show that the cell death triggered by E. amylovora on A. thaliana could not be simply explained by the recognition of AvrRpt2 ea by the resistance gene product RPS2. We then analyzed the role of type three-secreted proteins (T3SPs) DspA/E, HrpN, and HrpW in the induction of cell death and defense reactions in A. thaliana following infection with the corresponding E. amylovora mutant strains. HrpN and DspA/E were found to play an important role in the induction of cell death, activation of defense pathways, and ROS accumulation. None of the T3SPs tested played a major role in the induction of SA-independent callose deposition. The relative importance of T3SPs in A. thaliana is correlated with their relative importance in the disease process on host plants, indicating that A. thaliana can be used as a model to study their role.
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Affiliation(s)
- A Degrave
- 1Laboratoire des Interactions Plantes Pathogènes UMR 217 INRA/AgroParisTech/UPMC Paris VI, 16 rue Claude Bernard 75005 Paris, France
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42
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Liu H, Coulthurst SJ, Pritchard L, Hedley PE, Ravensdale M, Humphris S, Burr T, Takle G, Brurberg MB, Birch PRJ, Salmond GPC, Toth IK. Quorum sensing coordinates brute force and stealth modes of infection in the plant pathogen Pectobacterium atrosepticum. PLoS Pathog 2008; 4:e1000093. [PMID: 18566662 PMCID: PMC2413422 DOI: 10.1371/journal.ppat.1000093] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 05/20/2008] [Indexed: 01/11/2023] Open
Abstract
Quorum sensing (QS) in vitro controls production of plant cell wall degrading enzymes (PCWDEs) and other virulence factors in the soft rotting enterobacterial plant pathogen Pectobacterium atrosepticum (Pba). Here, we demonstrate the genome-wide regulatory role of QS in vivo during the Pba-potato interaction, using a Pba-specific microarray. We show that 26% of the Pba genome exhibited differential transcription in a QS (expI-) mutant, compared to the wild-type, suggesting that QS may make a greater contribution to pathogenesis than previously thought. We identify novel components of the QS regulon, including the Type I and II secretion systems, which are involved in the secretion of PCWDEs; a novel Type VI secretion system (T6SS) and its predicted substrates Hcp and VgrG; more than 70 known or putative regulators, some of which have been demonstrated to control pathogenesis and, remarkably, the Type III secretion system and associated effector proteins, and coronafacoyl-amide conjugates, both of which play roles in the manipulation of plant defences. We show that the T6SS and a novel potential regulator, VirS, are required for full virulence in Pba, and propose a model placing QS at the apex of a regulatory hierarchy controlling the later stages of disease progression in Pba. Our findings indicate that QS is a master regulator of phytopathogenesis, controlling multiple other regulators that, in turn, co-ordinately regulate genes associated with manipulation of host defences in concert with the destructive arsenal of PCWDEs that manifest the soft rot disease phenotype.
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Affiliation(s)
- Hui Liu
- Plant Pathology Programme, SCRI, Invergowrie, Dundee, United Kingdom
| | - Sarah J. Coulthurst
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Peter E. Hedley
- Plant Pathology Programme, SCRI, Invergowrie, Dundee, United Kingdom
| | | | - Sonia Humphris
- Plant Pathology Programme, SCRI, Invergowrie, Dundee, United Kingdom
| | - Tom Burr
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Gunnhild Takle
- Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Ås, Norway
| | - May-Bente Brurberg
- Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Ås, Norway
| | - Paul R. J. Birch
- Plant Pathology Programme, SCRI, Invergowrie, Dundee, United Kingdom
| | | | - Ian K. Toth
- Plant Pathology Programme, SCRI, Invergowrie, Dundee, United Kingdom
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43
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Coulthurst SJ, Lilley KS, Hedley PE, Liu H, Toth IK, Salmond GPC. DsbA plays a critical and multifaceted role in the production of secreted virulence factors by the phytopathogen Erwinia carotovora subsp. atroseptica. J Biol Chem 2008; 283:23739-53. [PMID: 18562317 DOI: 10.1074/jbc.m801829200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Erwinia carotovora subsp. atroseptica is an enterobacterial phytopathogen causing economically significant soft rot disease. Pathogenesis is mediated by multiple secreted virulence factors, many of which are secreted by the type II (Out) secretion system. DsbA catalyzes the introduction of disulfide bonds into periplasmic and secreted proteins. In this study, the extracellular proteome (secretome) of wild type E. carotovora subsp. atroseptica SCRI1043, and dsbA and out mutants, was analyzed by spectral counting mass spectrometry. This revealed that dsbA inactivation had a huge impact on the secretome and identified diverse DsbA- and Out-dependent secreted proteins, representing known, predicted, and novel candidate virulence factors. Further characterization of the dsbA mutant showed that secreted enzyme activities, motility, production of the quorum-sensing signal, and virulence were absent or substantially reduced. The impact of DsbA on secreted virulence factor production was mediated at multiple levels, including impacting on the Out secretion system and the virulence gene regulatory network. Transcriptome analyses revealed that the abundance of a broad, but defined, set of transcripts, including many virulence factors, was altered in the dsbA mutant, identifying a new virulence regulon responsive to extracytoplasmic conditions. In conclusion, DsbA plays a crucial, multifaceted role in the pathogenesis of E. carotovora subsp. atroseptica.
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Affiliation(s)
- Sarah J Coulthurst
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
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Reboutier D, Bouteau F. Harpins and ion channels modulations: Many ways to die. PLANT SIGNALING & BEHAVIOR 2008; 3:314-6. [PMID: 19841656 PMCID: PMC2634268 DOI: 10.4161/psb.3.5.5304] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 11/15/2007] [Indexed: 05/24/2023]
Abstract
Harpins are type three secretion system (TTSS) effectors. While few harpins are thought to be translocators of TTSS effectors through the host plasma membrane during plant/bacteria interactions, functions of many harpins remain for the moment mysterious. We recently showed that the HrpW(ea) harpin from Erwinia amylovora, at subnamolar concentration, was able to decrease defense responses triggered by another harpin from this bacteria, HrpN(ea). This antagonism could be the result of opposed anion channels modulations triggered by HrpW(ea) and HrpN(ea). At upper concentrations HrpW(ea) alone, or in combination with HrpN(ea), was able to induce cell death. This form of cell death involves strong ion channel activation and shares similarity with apoptosis volume decrease (AVD), a form of programmed cell death well described in animal cells. All these results suggest different ways for harpins to trigger cell death and highlight the role of ion channels during cell death processes.
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Affiliation(s)
- David Reboutier
- LEM; EA 3514; Université Paris Diderot; Case 7069; Paris, France
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Whisson SC, Boevink PC, Moleleki L, Avrova AO, Morales JG, Gilroy EM, Armstrong MR, Grouffaud S, van West P, Chapman S, Hein I, Toth IK, Pritchard L, Birch PRJ. A translocation signal for delivery of oomycete effector proteins into host plant cells. Nature 2007; 450:115-8. [PMID: 17914356 DOI: 10.1038/nature06203] [Citation(s) in RCA: 495] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Accepted: 08/24/2007] [Indexed: 12/26/2022]
Abstract
Bacterial, oomycete and fungal plant pathogens establish disease by translocation of effector proteins into host cells, where they may directly manipulate host innate immunity. In bacteria, translocation is through the type III secretion system, but analogous processes for effector delivery are uncharacterized in fungi and oomycetes. Here we report functional analyses of two motifs, RXLR and EER, present in translocated oomycete effectors. We use the Phytophthora infestans RXLR-EER-containing protein Avr3a as a reporter for translocation because it triggers RXLR-EER-independent hypersensitive cell death following recognition within plant cells that contain the R3a resistance protein. We show that Avr3a, with or without RXLR-EER motifs, is secreted from P. infestans biotrophic structures called haustoria, demonstrating that these motifs are not required for targeting to haustoria or for secretion. However, following replacement of Avr3a RXLR-EER motifs with alanine residues, singly or in combination, or with residues KMIK-DDK--representing a change that conserves physicochemical properties of the protein--P. infestans fails to deliver Avr3a or an Avr3a-GUS fusion protein into plant cells, demonstrating that these motifs are required for translocation. We show that RXLR-EER-encoding genes are transcriptionally upregulated during infection. Bioinformatic analysis identifies 425 potential genes encoding secreted RXLR-EER class proteins in the P. infestans genome. Identification of this class of proteins provides unparalleled opportunities to determine how oomycetes manipulate hosts to establish infection.
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Affiliation(s)
- Stephen C Whisson
- Plant Pathology Programme, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK.
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Wang J, Gardiol N, Burr T, Salmond GPC, Welch M. RelA-dependent (p)ppGpp production controls exoenzyme synthesis in Erwinia carotovora subsp. atroseptica. J Bacteriol 2007; 189:7643-52. [PMID: 17766416 PMCID: PMC2168740 DOI: 10.1128/jb.00920-07] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 08/22/2007] [Indexed: 11/20/2022] Open
Abstract
In this report, we investigate the link between nutrient limitation, RelA-mediated (p)ppGpp production, and virulence in the phytopathogen Erwinia carotovora subsp. atroseptica. A relA null mutant (JWC7) was constructed by allelic exchange, and we confirmed that, unlike the wild-type progenitor, this mutant did not produce elevated levels of (p)ppGpp upon nutrient downshift. However, (p)ppGpp production could be restored in strain JWC7 during nutrient limitation by supplying relA in trans. During growth on exoenzyme-inducing minimal medium, the relA mutant showed a diminution in secreted pectate lyase and protease activities and a severe defect in motility. The relA mutant was also impaired in its ability to cause rot in potato tubers. In the presence of serine hydroxamate (a competitive inhibitor of seryl tRNA synthase and a potent inducer of the stringent response in wild-type E. carotovora subsp. atroseptica), exoenzyme production was essentially abolished in JWC7 but could be restored in the presence of plasmid-borne relA. The inhibition of exoenzyme production in JWC7 caused by serine hydroxamate could not be overcome by addition of the quorum-sensing signal molecule, N-3-oxohexanoyl-l-homoserine lactone. Quantitative reverse transcription-PCR analysis of selected RNA species confirmed that the effects of relA on secreted pectate lyase activity and motility could be attributed to a reduction in transcription of the corresponding genes. We conclude that nutrient limitation is a potent environmental cue that triggers (p)ppGpp-dependent exoenzyme production in E. carotovora subsp. atroseptica. Furthermore, our data suggest that nutrient limitation [or rather, (p)ppGpp accumulation] is a prerequisite for effective quorum-sensing-dependent activation of exoenzyme production.
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Affiliation(s)
- Jinhong Wang
- Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge CB2 1QW, United Kingdom
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47
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Mattinen L, Nissinen R, Riipi T, Kalkkinen N, Pirhonen M. Host-extract induced changes in the secretome of the plant pathogenic bacterium
Pectobacterium atrosepticum. Proteomics 2007; 7:3527-37. [PMID: 17726675 DOI: 10.1002/pmic.200600759] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Pectobacterium atrosepticum is a Gram-negative plant pathogenic bacterium that causes rotting in potato stems and tubers. The secreted proteins of this pathogen were analyzed with proteomics from culture supernatant of cells grown in minimal medium supplemented with host extracts. More than 40 proteins were identified, among them known virulence determinants, such as pectic enzymes, metalloprotease, and virulence protein Svx, along with flagella proteins, GroEL and cyclophilin-type chaperones and several hypothetical proteins or proteins with unknown function. Some of the identified proteins may be involved in utilization of nutrients or transport of minerals. Northern and real-time RT-PCR analyses suggested that most of the proteins upregulated by plant extract were transcriptionally regulated. Among the identified proteins were VgrG and four homologs of hemolysin-coregulated proteins (Hcps). A mutant strain lacking one of the hcp genes was not affected in virulence, while a bacterial strain overexpressing the same gene was shown to have increased virulence, which suggests that these proteins may be new virulence determinants of P. atrosepticum. Comparison of the secretomes of wild type cells and hrcC mutant defective in Type III secretion suggested that the production of the identified proteins was independent of functional Type III secretion system.
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Affiliation(s)
- Laura Mattinen
- Department of Applied Biology, University of Helsinki, Finland
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48
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Barnard AM, Bowden SD, Burr T, Coulthurst SJ, Monson RE, Salmond GP. Quorum sensing, virulence and secondary metabolite production in plant soft-rotting bacteria. Philos Trans R Soc Lond B Biol Sci 2007; 362:1165-83. [PMID: 17360277 PMCID: PMC2435580 DOI: 10.1098/rstb.2007.2042] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Quorum sensing describes the ability of bacteria to sense their population density and respond by modulating gene expression. In the plant soft-rotting bacteria, such as Erwinia, an arsenal of plant cell wall-degrading enzymes is produced in a cell density-dependent manner, which causes maceration of plant tissue. However, quorum sensing is central not only to controlling the production of such destructive enzymes, but also to the control of a number of other virulence determinants and secondary metabolites. Erwinia synthesizes both N-acylhomoserine lactone (AHL) and autoinducer-2 types of quorum sensing signal, which both play a role in regulating gene expression in the phytopathogen. We review the models for AHL-based regulation of carbapenem antibiotic production in Erwinia. We also discuss the importance of quorum sensing in the production and secretion of virulence determinants by Erwinia, and its interplay with other regulatory systems.
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Affiliation(s)
| | | | | | | | | | - George P.C Salmond
- Department of Biochemistry, University of CambridgeTennis Court Road, Cambridge CB2 1QW, UK
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49
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Reboutier D, Frankart C, Briand J, Biligui B, Laroche S, Rona JP, Barny MA, Bouteau F. The HrpN(ea) harpin from Erwinia amylovora triggers differential responses on the nonhost Arabidopsis thaliana cells and on the host apple cells. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:94-100. [PMID: 17249426 DOI: 10.1094/mpmi-20-0094] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Erwinia amylovora is a gram-negative necrogenic bacterium causing fire blight of the Maloideae subfamily of Rosaceae such as apple and pear. It provokes progressive necrosis in aerial parts of susceptible host plants (compatible interaction) and a hypersensitive reaction (HR) when infiltrated in nonhost plants (incompatible interaction). The HrpN(ea) harpin is a type three secretion system effector secreted by E. amylovora. This protein is involved in pathogenicity and HR-eliciting capacity of E. amylovora. In the present study, we showed that, in nonhost Arabidopsis thaliana cells, purified HrpN(ea) induces cell death and H2O2 production, two nonhost resistance responses, but failed to induce such responses in host MM106 apple cells. Moreover, HrpN(ea) induced an increase in anion current in host MM106 apple cells, at the opposite of the decrease of anion current previously shown to be necessary to induce cell death in nonhost A. thaliana cells. These results suggest that HrpN(ea) induced different signaling pathways, which could account for early induced compatible or incompatible interaction development.
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Affiliation(s)
- David Reboutier
- LEM, EA 3514, Université Paris 7, Case 7069, 2 place Jussieu, 75251 Paris 5, France
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Ham JH, Majerczak DR, Arroyo-Rodriguez AS, Mackey DM, Coplin DL. WtsE, an AvrE-family effector protein from Pantoea stewartii subsp. stewartii, causes disease-associated cell death in corn and requires a chaperone protein for stability. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2006; 19:1092-102. [PMID: 17022173 DOI: 10.1094/mpmi-19-1092] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The pathogenicity of Pantoea stewartii subsp. stewartii to sweet corn and maize requires a Hrp type III secretion system. In this study, we genetically and functionally characterized a disease-specific (Dsp) effector locus, composed of wtsE and wtsF, that is adjacent to the hrp gene cluster. WtsE, a member of the AvrE family of effector proteins, was essential for pathogenesis on corn and was complemented by DspA/E from Erwinia amylovora. An intact C-terminus of WtsE, which contained a putative endoplasmic reticulum membrane retention signal, was important for function of WtsE. Delivery of WtsE into sweet corn leaves by an Escherichia coli strain carrying the hrp cluster of Erwinia chrysanthemi caused water-soaking and necrosis. WtsE-induced cell death was not inhibited by cycloheximide treatment, unlike the hypersensitive response caused by a known Avr protein, AvrRxol. WtsF, the putative chaperone of WtsE, was not required for secretion of WtsE from P. stewartii, and the virulence of wtsF mutants was reduced only at low inoculum concentrations. However, WtsF was required for full accumulation of WtsE within the bacteria at low temperatures. In contrast, WtsF was needed for efficient delivery of WtsE from E. coli via the Erwinia chrysanthemi Hrp system.
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Affiliation(s)
- Jong Hyun Ham
- Department of Plant Pathology, The Ohio State University, Columbus 43210-1087, USA
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