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Liu K, Shi L, Luo H, Zhang K, Liu J, Qiu S, Li X, He S, Liu Z. Ralstonia solanacearum effector RipAK suppresses homodimerization of the host transcription factor ERF098 to enhance susceptibility and the sensitivity of pepper plants to dehydration. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:121-144. [PMID: 37738430 DOI: 10.1111/tpj.16479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 08/03/2023] [Accepted: 08/25/2023] [Indexed: 09/24/2023]
Abstract
Plants have evolved a sophisticated immune system to defend against invasion by pathogens. In response, pathogens deploy copious effectors to evade the immune responses. However, the molecular mechanisms used by pathogen effectors to suppress plant immunity remain unclear. Herein, we report that an effector secreted by Ralstonia solanacearum, RipAK, modulates the transcriptional activity of the ethylene-responsive factor ERF098 to suppress immunity and dehydration tolerance, which causes bacterial wilt in pepper (Capsicum annuum L.) plants. Silencing ERF098 enhances the resistance of pepper plants to R. solanacearum infection not only by inhibiting the host colonization of R. solanacearum but also by increasing the immunity and tolerance of pepper plants to dehydration and including the closure of stomata to reduce the loss of water in an abscisic acid signal-dependent manner. In contrast, the ectopic expression of ERF098 in Nicotiana benthamiana enhances wilt disease. We also show that RipAK targets and inhibits the ERF098 homodimerization to repress the expression of salicylic acid-dependent PR1 and dehydration tolerance-related OSR1 and OSM1 by cis-elements in their promoters. Taken together, our study reveals a regulatory mechanism used by the R. solanacearum effector RipAK to increase virulence by specifically inhibiting the homodimerization of ERF098 and reprogramming the transcription of PR1, OSR1, and OSM1 to boost susceptibility and dehydration sensitivity. Thus, our study sheds light on a previously unidentified strategy by which a pathogen simultaneously suppresses plant immunity and tolerance to dehydration by secreting an effector to interfere with the activity of a transcription factor and manipulate plant transcriptional programs.
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Affiliation(s)
- Kaisheng Liu
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Lanping Shi
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Hongli Luo
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Kan Zhang
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Jianxin Liu
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Shanshan Qiu
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xia Li
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Shuilin He
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Zhiqin Liu
- Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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Vailleau F, Genin S. Ralstonia solanacearum: An Arsenal of Virulence Strategies and Prospects for Resistance. ANNUAL REVIEW OF PHYTOPATHOLOGY 2023; 61:25-47. [PMID: 37506349 DOI: 10.1146/annurev-phyto-021622-104551] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
The group of strains constituting the Ralstonia solanacearum species complex (RSSC) is a prominent model for the study of plant-pathogenic bacteria because of its impact on agriculture, owing to its wide host range, worldwide distribution, and long persistence in the environment. RSSC strains have led to numerous studies aimed at deciphering the molecular bases of virulence, and many biological functions and mechanisms have been described to contribute to host infection and pathogenesis. In this review, we put into perspective recent advances in our understanding of virulence in RSSC strains, both in terms of the inventory of functions that participate in this process and their evolutionary dynamics. We also present the different strategies that have been developed to combat these pathogenic strains through biological control, antimicrobial agents, plant genetics, or microbiota engineering.
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Affiliation(s)
- Fabienne Vailleau
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France; ,
| | - Stéphane Genin
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France; ,
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Baroukh C, Cottret L, Pires E, Peyraud R, Guidot A, Genin S. Insights into the metabolic specificities of pathogenic strains from the Ralstonia solanacearum species complex. mSystems 2023; 8:e0008323. [PMID: 37341493 PMCID: PMC10470067 DOI: 10.1128/msystems.00083-23] [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: 01/25/2023] [Accepted: 04/14/2023] [Indexed: 06/22/2023] Open
Abstract
All the strains grouped under the species Ralstonia solanacearum represent a species complex responsible for many diseases on agricultural crops throughout the world. The strains have different lifestyles and host range. Here, we investigated whether specific metabolic pathways contribute to strain diversification. To this end, we carried out systematic comparisons on 11 strains representing the diversity of the species complex. We reconstructed the metabolic network of each strain from its genome sequence and looked for the metabolic pathways differentiating the different reconstructed networks and, by extension, the different strains. Finally, we conducted an experimental validation by determining the metabolic profile of each strain with the Biolog technology. Results revealed that the metabolism is conserved between strains, with a core metabolism composed of 82% of the pan-reactome. The three species composing the species complex could be distinguished according to the presence/absence of some metabolic pathways, in particular, one involving salicylic acid degradation. Phenotypic assays revealed that the trophic preferences on organic acids and several amino acids such as glutamine, glutamate, aspartate, and asparagine are conserved between strains. Finally, we generated mutants lacking the quorum-sensing-dependent regulator PhcA in four diverse strains, and we showed that the phcA-dependent trade-off between growth and production of virulence factors is conserved across the R. solanacearum species complex. IMPORTANCE Ralstonia solanacearum is one of the most important threats to plant health worldwide, causing disease on a very large range of agricultural crops such as tomato or potato. Behind the R. solanacearum name are hundreds of strains with different host range and lifestyle, classified into three species. Studying the differences between strains allows to better apprehend the biology of the pathogens and the specificity of some strains. None of the published genomic comparative studies have focused on the metabolism of the strains so far. We developed a new bioinformatic pipeline to build high-quality metabolic networks and used a combination of metabolic modeling and high-throughput phenotypic Biolog microplates to look for the metabolic differences between 11 strains across the three species. Our study revealed that genes encoding enzymes are overall conserved, with few variations between strains. However, more variations were observed when considering substrate usage. These variations probably result from regulation rather than the presence or absence of enzymes in the genome.
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Affiliation(s)
- Caroline Baroukh
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Ludovic Cottret
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Emma Pires
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Rémi Peyraud
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Alice Guidot
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Stéphane Genin
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
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Plant-Pathogenic Ralstonia Phylotypes Evolved Divergent Respiratory Strategies and Behaviors To Thrive in Xylem. mBio 2023; 14:e0318822. [PMID: 36744950 PMCID: PMC9973335 DOI: 10.1128/mbio.03188-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bacterial pathogens in the Ralstonia solanacearum species complex (RSSC) infect the water-transporting xylem vessels of plants, causing bacterial wilt disease. Strains in RSSC phylotypes I and III can reduce nitrate to dinitrogen via complete denitrification. The four-step denitrification pathway enables bacteria to use inorganic nitrogen species as terminal electron acceptors, supporting their growth in oxygen-limited environments such as biofilms or plant xylem. Reduction of nitrate, nitrite, and nitric oxide all contribute to the virulence of a model phylotype I strain. However, little is known about the physiological role of the last denitrification step, the reduction of nitrous oxide to dinitrogen by NosZ. We found that phylotypes I and III need NosZ for full virulence. However, strains in phylotypes II and IV are highly virulent despite lacking NosZ. The ability to respire by reducing nitrate to nitrous oxide does not greatly enhance the growth of phylotype II and IV strains. These partial denitrifying strains reach high cell densities during plant infection and cause typical wilt disease. However, unlike phylotype I and III strains, partial denitrifiers cannot grow well under anaerobic conditions or form thick biofilms in culture or in tomato xylem vessels. Furthermore, aerotaxis assays show that strains from different phylotypes have different oxygen and nitrate preferences. Together, these results indicate that the RSSC contains two subgroups that occupy the same habitat but have evolved divergent energy metabolism strategies to exploit distinct metabolic niches in the xylem. IMPORTANCE Plant-pathogenic Ralstonia spp. are a heterogeneous globally distributed group of bacteria that colonize plant xylem vessels. Ralstonia cells multiply rapidly in plants and obstruct water transport, causing fatal wilting and serious economic losses of many key food security crops. The virulence of these pathogens depends on their ability to grow to high cell densities in the low-oxygen xylem environment. Plant-pathogenic Ralstonia can use denitrifying respiration to generate ATP. The last denitrification step, nitrous oxide reduction by NosZ, contributes to energy production and virulence for only one of the three phytopathogenic Ralstonia species. These complete denitrifiers form thicker biofilms in culture and in tomato xylem, suggesting they are better adapted to hypoxic niches. Strains with partial denitrification physiology form less biofilm and are more often planktonic. They are nonetheless highly virulent. Thus, these closely related bacteria have adapted their core metabolic functions to exploit distinct microniches in the same habitat.
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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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Yu G, Derkacheva M, Rufian JS, Brillada C, Kowarschik K, Jiang S, Derbyshire P, Ma M, DeFalco TA, Morcillo RJL, Stransfeld L, Wei Y, Zhou J, Menke FLH, Trujillo M, Zipfel C, Macho AP. The Arabidopsis E3 ubiquitin ligase PUB4 regulates BIK1 and is targeted by a bacterial type-III effector. EMBO J 2022; 41:e107257. [PMID: 36314733 PMCID: PMC9713774 DOI: 10.15252/embj.2020107257] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 09/26/2022] [Accepted: 10/07/2022] [Indexed: 12/03/2022] Open
Abstract
Plant immunity is tightly controlled by a complex and dynamic regulatory network, which ensures optimal activation upon detection of potential pathogens. Accordingly, each component of this network is a potential target for manipulation by pathogens. Here, we report that RipAC, a type III-secreted effector from the bacterial pathogen Ralstonia solanacearum, targets the plant E3 ubiquitin ligase PUB4 to inhibit pattern-triggered immunity (PTI). PUB4 plays a positive role in PTI by regulating the homeostasis of the central immune kinase BIK1. Before PAMP perception, PUB4 promotes the degradation of non-activated BIK1, while after PAMP perception, PUB4 contributes to the accumulation of activated BIK1. RipAC leads to BIK1 degradation, which correlates with its PTI-inhibitory activity. RipAC causes a reduction in pathogen-associated molecular pattern (PAMP)-induced PUB4 accumulation and phosphorylation. Our results shed light on the role played by PUB4 in immune regulation, and illustrate an indirect targeting of the immune signalling hub BIK1 by a bacterial effector.
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Affiliation(s)
- Gang Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Maria Derkacheva
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Present address:
The Earlham InstituteNorwich Research ParkNorwichUK
| | - Jose S Rufian
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Carla Brillada
- Faculty of Biology, Institute of Biology IIAlbert‐Ludwigs‐University FreiburgFreiburgGermany
| | | | - Shushu Jiang
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Present address:
Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell ScienceChinese Academy of SciencesShanghaiChina
| | - Paul Derbyshire
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | - Miaomiao Ma
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
| | - Thomas A DeFalco
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Rafael J L Morcillo
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Lena Stransfeld
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Yali Wei
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Jian‐Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
| | - Frank L H Menke
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | - Marco Trujillo
- Faculty of Biology, Institute of Biology IIAlbert‐Ludwigs‐University FreiburgFreiburgGermany
- Leibniz Institute for Plant BiochemistryHalle (Saale)Germany
| | - Cyril Zipfel
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Alberto P Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
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Song S, Sun X, Guo Q, Cui B, Zhu Y, Li X, Zhou J, Zhang LH, Deng Y. An anthranilic acid-responsive transcriptional regulator controls the physiology and pathogenicity of Ralstonia solanacearum. PLoS Pathog 2022; 18:e1010562. [PMID: 35617422 PMCID: PMC9176790 DOI: 10.1371/journal.ppat.1010562] [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: 12/09/2021] [Revised: 06/08/2022] [Accepted: 04/29/2022] [Indexed: 11/25/2022] Open
Abstract
Quorum sensing (QS) is widely employed by bacterial cells to control gene expression in a cell density-dependent manner. A previous study revealed that anthranilic acid from Ralstonia solanacearum plays a vital role in regulating the physiology and pathogenicity of R. solanacearum. We reported here that anthranilic acid controls the important biological functions and virulence of R. solanacearum through the receptor protein RaaR, which contains helix-turn-helix (HTH) and LysR substrate binding (LysR_substrate) domains. RaaR regulates the same processes as anthranilic acid, and both are present in various bacterial species. In addition, anthranilic acid-deficient mutant phenotypes were rescued by in trans expression of RaaR. Intriguingly, we found that anthranilic acid binds to the LysR_substrate domain of RaaR with high affinity, induces allosteric conformational changes, and then enhances the binding of RaaR to the promoter DNA regions of target genes. These findings indicate that the components of the anthranilic acid signaling system are distinguished from those of the typical QS systems. Together, our work presents a unique and widely conserved signaling system that might be an important new type of cell-to-cell communication system in bacteria. Bacterial wilt caused by Ralstonia solanacearum is one of the most widespread, harmful and destructive plant diseases in the world. Our previous study showed that the pathogenic bacterium R. solanacearum uses anthranilic acid to regulate the important biological functions, virulence and the production of quorum sensing signals. Here, we show that RaaR, a transcriptional regulator from R. solanacearum, was first identified to regulate the same phenotypes as anthranilic acid. Anthranilic acid binds to the LysR_substrate domain of RaaR and enhances the regulatory activity of RaaR to control the target gene expression, including the QS signal synthase encoding genes, phcB and solI. Both the anthranilic acid synthase TrpEG and the response regulator RaaR are present in diverse bacteria, suggesting that the anthranilic acid-type signaling system is widespread. Together, our work describes a system where a pathogen uses a single protein to control the bacterial physiology and pathogenesis by responding to anthranilic acid.
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Affiliation(s)
- Shihao Song
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou, China
| | - Xiuyun Sun
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Quan Guo
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Binbin Cui
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Yu Zhu
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Xia Li
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Jianuan Zhou
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou, China
| | - Lian-Hui Zhang
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou, China
| | - Yinyue Deng
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
- * E-mail:
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Ferreira EGC, Gomes DF, Delai CV, Barreiros MAB, Grange L, Rodrigues EP, Henning LMM, Barcellos FG, Hungria M. Revealing potential functions of hypothetical proteins induced by genistein in the symbiosis island of Bradyrhizobium japonicum commercial strain SEMIA 5079 (= CPAC 15). BMC Microbiol 2022; 22:122. [PMID: 35513812 PMCID: PMC9069715 DOI: 10.1186/s12866-022-02527-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 04/11/2022] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Bradyrhizobium japonicum strain SEMIA 5079 (= CPAC 15) is a nitrogen-fixing symbiont of soybean broadly used in commercial inoculants in Brazil. Its genome has about 50% of hypothetical (HP) protein-coding genes, many in the symbiosis island, raising questions about their putative role on the biological nitrogen fixation (BNF) process. This study aimed to infer functional roles to 15 HP genes localized in the symbiosis island of SEMIA 5079, and to analyze their expression in the presence of a nod-gene inducer. RESULTS A workflow of bioinformatics tools/databases was established and allowed the functional annotation of the HP genes. Most were enzymes, including transferases in the biosynthetic pathways of cobalamin, amino acids and secondary metabolites that may help in saprophytic ability and stress tolerance, and hydrolases, that may be important for competitiveness, plant infection, and stress tolerance. Putative roles for other enzymes and transporters identified are discussed. Some HP proteins were specific to the genus Bradyrhizobium, others to specific host legumes, and the analysis of orthologues helped to predict roles in BNF. CONCLUSIONS All 15 HP genes were induced by genistein and high induction was confirmed in five of them, suggesting major roles in the BNF process.
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Affiliation(s)
- Everton Geraldo Capote Ferreira
- Londrina State University (UEL), Celso Garcia Cid Road (PR 445), km 380, CEP 86057-970 Londrina, PR Brazil
- Embrapa Soja, Rodovia Carlos João Strass, C.P. 231, CEP 86001-970 Londrina, PR Brazil
| | | | - Caroline Vanzzo Delai
- Federal University of Paraná (UFPR), Estrada dos Pioneiros 2153, CEP 85950-000 Palotina, PR Brazil
| | | | - Luciana Grange
- Federal University of Paraná (UFPR), Estrada dos Pioneiros 2153, CEP 85950-000 Palotina, PR Brazil
| | - Elisete Pains Rodrigues
- Londrina State University (UEL), Celso Garcia Cid Road (PR 445), km 380, CEP 86057-970 Londrina, PR Brazil
| | | | - Fernando Gomes Barcellos
- Londrina State University (UEL), Celso Garcia Cid Road (PR 445), km 380, CEP 86057-970 Londrina, PR Brazil
| | - Mariangela Hungria
- Londrina State University (UEL), Celso Garcia Cid Road (PR 445), km 380, CEP 86057-970 Londrina, PR Brazil
- Embrapa Soja, Rodovia Carlos João Strass, C.P. 231, CEP 86001-970 Londrina, PR Brazil
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Baroukh C, Zemouri M, Genin S. Trophic preferences of the pathogen Ralstonia solanacearum and consequences on its growth in xylem sap. Microbiologyopen 2022; 11:e1240. [PMID: 35212480 PMCID: PMC8770891 DOI: 10.1002/mbo3.1240] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/16/2021] [Indexed: 11/16/2022] Open
Abstract
Ralstonia solanacearum is one of the most destructive pathogens worldwide. In the last 30 years, the molecular mechanisms at the origin of R. solanacearum pathogenicity have been studied in depth. However, the nutrition status of the pathogen once inside the plant has been poorly investigated. Yet, the pathogen needs substrates to sustain a fast-enough growth, maintain its virulence and subvert the host immunity. This study aimed to explore in-depth the xylem environment where the pathogen is abundant, and its trophic preferences. First, we determined the composition of tomato xylem sap, where fast multiplication of the pathogen occurs. Then, kinetic growth on single and mixtures of carbon sources in relation to this environment was performed to fully quantify growth. Finally, we calculated the concentration of available metabolites in the xylem sap flux to assess how much it can support bacterial growth in planta. Overall, the study underlines the adaptation of R. solanacearum to the xylem environment and the fact that the pathogen assimilates several substrates at the same time in media composed of several carbon sources. It also provides metrics on key physiological parameters governing the growth of this major pathogen, which will be instrumental in the future to better understand its metabolic behavior during infection.
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Affiliation(s)
| | - Meriem Zemouri
- LIPMEINRACNRSUniversité de ToulouseCastanet‐TolosanFrance
| | - Stéphane Genin
- LIPMEINRACNRSUniversité de ToulouseCastanet‐TolosanFrance
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10
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Wei Y, Zhang Y, Meng J, Wang Y, Zhong C, Ma H. Transcriptome and metabolome profiling in naturally infested Casuarina equisetifolia clones by Ralstonia solanacearum. Genomics 2021; 113:1906-1918. [PMID: 33771635 DOI: 10.1016/j.ygeno.2021.03.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 03/06/2021] [Accepted: 03/21/2021] [Indexed: 12/01/2022]
Abstract
Casuarina equisetifolia is an important pioneer tree and suffers from bacterial wilt caused by Ralstonia solanacearum. We collected resistant (R) and susceptible (S) C. equisetifolia clones naturally infected by R. solanacearum and compared their transcriptome and metabolome with a clone (CK) from a non-infested forest, in order to study their response and resistance to bacterial wilt. We identified 18 flavonoids differentially accumulated among the three clonal groups as potential selection biomarkers against R. solanacearum. Flavonoid synthesis-related genes were up-regulated in the resistant clones, probably enhancing accumulation of flavonoids and boosting resistance against bacterial wilt. The down-regulation of auxin/indoleacetic acid-related genes and up-regulation of brassinosteroid, salicylic acid and jasmonic acid-related differentially expressed genes in the R vs CK and R vs S clonal groups may have triggered defense signals and increased expression of defense-related genes against R. solanacearum. Overall, this study provides an important insight into pathogen-response and resistance to bacterial wilt in C. equisetifolia.
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Affiliation(s)
- Yongcheng Wei
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong, Guangzhou 510520, China.
| | - Yong Zhang
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong, Guangzhou 510520, China.
| | - Jingxiang Meng
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong, Guangzhou 510520, China.
| | - Yujiao Wang
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong, Guangzhou 510520, China.
| | - Chonglu Zhong
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong, Guangzhou 510520, China.
| | - Haibin Ma
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong, Guangzhou 510520, China.
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Xian L, Yu G, Wei Y, Rufian JS, Li Y, Zhuang H, Xue H, Morcillo RJL, Macho AP. A Bacterial Effector Protein Hijacks Plant Metabolism to Support Pathogen Nutrition. Cell Host Microbe 2020; 28:548-557.e7. [PMID: 32735848 DOI: 10.1016/j.chom.2020.07.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 04/23/2020] [Accepted: 06/30/2020] [Indexed: 01/01/2023]
Abstract
Many bacterial plant pathogens employ a type III secretion system to inject effector proteins within plant cells to suppress plant immunity. Whether and how effector proteins also co-opt plant metabolism to support extensive bacterial replication remains an open question. Here, we show that Ralstonia solanacearum, the causal agent of bacterial wilt disease, secretes the effector protein RipI, which interacts with plant glutamate decarboxylases (GADs) to alter plant metabolism and support bacterial growth. GADs are activated by calmodulin and catalyze the biosynthesis of gamma-aminobutyric acid (GABA), an important signaling molecule in plants and animals. RipI promotes the interaction of GADs with calmodulin, enhancing the production of GABA. R. solanacearum is able to replicate efficiently using GABA as a nutrient, and both RipI and plant GABA contribute to a successful infection. This work reveals a pathogenic strategy to hijack plant metabolism for the biosynthesis of nutrients that support microbial growth during plant colonization.
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Affiliation(s)
- Liu Xian
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gang Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Yali Wei
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jose S Rufian
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Yansha Li
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Haiyan Zhuang
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Hao Xue
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rafael J L Morcillo
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Alberto P Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China.
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12
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Yu G, Xian L, Xue H, Yu W, Rufian JS, Sang Y, Morcillo RJL, Wang Y, Macho AP. A bacterial effector protein prevents MAPK-mediated phosphorylation of SGT1 to suppress plant immunity. PLoS Pathog 2020; 16:e1008933. [PMID: 32976518 PMCID: PMC7540872 DOI: 10.1371/journal.ppat.1008933] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 10/07/2020] [Accepted: 08/27/2020] [Indexed: 11/23/2022] Open
Abstract
Nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins function as sensors that perceive pathogen molecules and activate immunity. In plants, the accumulation and activation of NLRs is regulated by SUPPRESSOR OF G2 ALLELE OF skp1 (SGT1). In this work, we found that an effector protein named RipAC, secreted by the plant pathogen Ralstonia solanacearum, associates with SGT1 to suppress NLR-mediated SGT1-dependent immune responses, including those triggered by another R. solanacearum effector, RipE1. RipAC does not affect the accumulation of SGT1 or NLRs, or their interaction. However, RipAC inhibits the interaction between SGT1 and MAP kinases, and the phosphorylation of a MAPK target motif in the C-terminal domain of SGT1. Such phosphorylation is enhanced upon activation of immune signaling and contributes to the activation of immune responses mediated by the NLR RPS2. Additionally, SGT1 phosphorylation contributes to resistance against R. solanacearum. Our results shed light onto the mechanism of activation of NLR-mediated immunity, and suggest a positive feedback loop between MAPK activation and SGT1-dependent NLR activation.
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Affiliation(s)
- Gang Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Liu Xian
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hao Xue
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wenjia Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jose S. Rufian
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yuying Sang
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Rafael J. L. Morcillo
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yaru Wang
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Alberto P. Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
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13
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Shen F, Yin W, Song S, Zhang Z, Ye P, Zhang Y, Zhou J, He F, Li P, Deng Y. Ralstonia solanacearum promotes pathogenicity by utilizing l-glutamic acid from host plants. MOLECULAR PLANT PATHOLOGY 2020; 21:1099-1110. [PMID: 32599676 PMCID: PMC7368120 DOI: 10.1111/mpp.12963] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 05/20/2020] [Indexed: 05/22/2023]
Abstract
Ralstonia solanacearum is an important bacterial pathogen that can infect a broad range of plants worldwide. A previous study showed that R. solanacearum could respond to exogenous organic acids or amino acids to modulate cell motility. However, it was unclear whether R. solanacearum uses these compounds to control infection. In this study, we found that R. solanacearum GMI1000 uses host plant metabolites to enhance the biosynthesis of virulence factors. We demonstrated that l-glutamic acid from host plants is the key active component associated with increased extracellular polysaccharide production, cellulase activity, swimming motility, and biofilm formation in R. solanacearum GMI1000. In addition, l-glutamic acid also promoted colonization of R. solanacearum cells in the roots and stems of tomato plants and accelerated disease incidence. Furthermore, genetic screening and biochemical analysis suggested that RS01577, a hybrid sensor histidine kinase/response regulator, is involved in l-glutamic acid signalling in R. solanacearum. Mutations in RS01577 and exogenous addition of l-glutamic acid to the GMI1000 wild-type strain had overlapping effects on both the transcriptome and biological functions of R. solanacearum, including on motility, biofilm formation, and virulence. Thus, our results have established a new interaction mechanism between R. solanacearum and host plants that highlights the complexity of the virulence regulation mechanism and may provide new insight into disease control.
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Affiliation(s)
- Fangfang Shen
- College of AgricultureSouth China Agricultural UniversityGuangzhouChina
| | - Wenfang Yin
- College of AgricultureSouth China Agricultural UniversityGuangzhouChina
| | - Shihao Song
- College of AgricultureSouth China Agricultural UniversityGuangzhouChina
| | - Zhihan Zhang
- College of AgricultureSouth China Agricultural UniversityGuangzhouChina
| | - Peiyi Ye
- College of AgricultureSouth China Agricultural UniversityGuangzhouChina
| | - Yong Zhang
- College of Resources and EnvironmentSouthwest UniversityChongqingChina
| | - Jianuan Zhou
- College of AgricultureSouth China Agricultural UniversityGuangzhouChina
| | - Fei He
- College of AgricultureSouth China Agricultural UniversityGuangzhouChina
| | - Peng Li
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan ProvinceCollege of Life SciencesHainan Normal UniversityHaikouChina
| | - Yinyue Deng
- School of Pharmaceutical Sciences (Shenzhen)Sun Yat‐sen UniversityGuangzhouChina
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Abstract
Xylella fastidiosa is one of the most important threats to plant health worldwide, causing disease in the Americas on a range of agricultural crops and trees, and recently associated with a critical epidemic affecting olive trees in Europe. A main challenge for the detection of the pathogen and the development of physiological studies is its fastidious growth, as the generation time can vary from 10 to 100 h for some strains. This physiological peculiarity is shared with several human pathogens and is poorly understood. We performed an analysis of the metabolic capabilities of X. fastidiosa through a genome-scale metabolic model of the bacterium. This model was reconstructed and manually curated using experiments and bibliographical evidence. Our study revealed that fastidious growth most probably results from different metabolic specificities such as the absence of highly efficient enzymes or a global inefficiency in virulence factor production. These results support the idea that the fragility of the metabolic network may have been shaped during evolution to lead to the self-limiting behavior of X. fastidiosa. High proliferation rate and robustness are vital characteristics of bacterial pathogens that successfully colonize their hosts. The observation of drastically slow growth in some pathogens is thus paradoxical and remains unexplained. In this study, we sought to understand the slow (fastidious) growth of the plant pathogen Xylella fastidiosa. Using genome-scale metabolic network reconstruction, modeling, and experimental validation, we explored its metabolic capabilities. Despite genome reduction and slow growth, the pathogen’s metabolic network is complete but strikingly minimalist and lacking in robustness. Most alternative reactions were missing, especially those favoring fast growth, and were replaced by less efficient paths. We also found that the production of some virulence factors imposes a heavy burden on growth. Interestingly, some specific determinants of fastidious growth were also found in other slow-growing pathogens, enriching the view that these metabolic peculiarities are a pathogenicity strategy to remain at a low population level. IMPORTANCEXylella fastidiosa is one of the most important threats to plant health worldwide, causing disease in the Americas on a range of agricultural crops and trees, and recently associated with a critical epidemic affecting olive trees in Europe. A main challenge for the detection of the pathogen and the development of physiological studies is its fastidious growth, as the generation time can vary from 10 to 100 h for some strains. This physiological peculiarity is shared with several human pathogens and is poorly understood. We performed an analysis of the metabolic capabilities of X. fastidiosa through a genome-scale metabolic model of the bacterium. This model was reconstructed and manually curated using experiments and bibliographical evidence. Our study revealed that fastidious growth most probably results from different metabolic specificities such as the absence of highly efficient enzymes or a global inefficiency in virulence factor production. These results support the idea that the fragility of the metabolic network may have been shaped during evolution to lead to the self-limiting behavior of X. fastidiosa.
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The Entner-Doudoroff and Nonoxidative Pentose Phosphate Pathways Bypass Glycolysis and the Oxidative Pentose Phosphate Pathway in Ralstonia solanacearum. mSystems 2020; 5:5/2/e00091-20. [PMID: 32156794 PMCID: PMC7065512 DOI: 10.1128/msystems.00091-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Understanding the metabolic versatility of Ralstonia solanacearum is important, as it regulates the trade-off between virulence and metabolism (1, 2) in a wide range of plant hosts. Due to a lack of clear evidence until this work, several published research papers reported on the potential roles of glycolysis and the oxidative pentose phosphate pathway (OxPPP) in R. solanacearum (3, 4). This work provided evidence from 13C stable isotope feeding and genome annotation-based comparative metabolic network analysis that the Entner-Doudoroff pathway and non-OxPPP bypass glycolysis and OxPPP during the oxidation of glucose, a component of the host xylem pool that serves as a potential carbon source (5). The outcomes help better define the central carbon metabolic network of R. solanacearum that can be integrated with 13C metabolic flux analysis as well as flux balance analysis studies for defining the metabolic phenotypes. The study highlights the need to critically examine phytopathogens whose metabolism is poorly understood. In Ralstonia solanacearum, a devastating phytopathogen whose metabolism is poorly understood, we observed that the Entner-Doudoroff (ED) pathway and nonoxidative pentose phosphate pathway (non-OxPPP) bypass glycolysis and OxPPP under glucose oxidation. Evidence derived from 13C stable isotope feeding and genome annotation-based comparative metabolic network analysis supported the observations. Comparative metabolic network analysis derived from the currently available 53 annotated R. solanacearum strains, including a recently reported strain (F1C1), representing the four phylotypes, confirmed the lack of key genes coding for phosphofructokinase (pfk-1) and phosphogluconate dehydrogenase (gnd) enzymes that are relevant for glycolysis and OxPPP, respectively. R. solanacearum F1C1 cells fed with [13C]glucose (99% [1-13C]glucose or 99% [1,2-13C]glucose or 40% [13C6]glucose) followed by gas chromatography-mass spectrometry (GC-MS)-based labeling analysis of fragments from amino acids, glycerol, and ribose provided clear evidence that rather than glycolysis and the OxPPP, the ED pathway and non-OxPPP are the main routes sustaining metabolism in R. solanacearum. The 13C incorporation in the mass ions of alanine (m/z 260 and m/z 232), valine (m/z 288 and m/z 260), glycine (m/z 218), serine (m/z 390 and m/z 362), histidine (m/z 440 and m/z 412), tyrosine (m/z 466 and m/z 438), phenylalanine (m/z 336 and m/z 308), glycerol (m/z 377), and ribose (m/z 160) mapped the pathways supporting the observations. The outcomes help better define the central carbon metabolic network of R. solanacearum that can be integrated with 13C metabolic flux analysis as well as flux balance analysis studies for defining the metabolic phenotypes. IMPORTANCE Understanding the metabolic versatility of Ralstonia solanacearum is important, as it regulates the trade-off between virulence and metabolism (1, 2) in a wide range of plant hosts. Due to a lack of clear evidence until this work, several published research papers reported on the potential roles of glycolysis and the oxidative pentose phosphate pathway (OxPPP) in R. solanacearum (3, 4). This work provided evidence from 13C stable isotope feeding and genome annotation-based comparative metabolic network analysis that the Entner-Doudoroff pathway and non-OxPPP bypass glycolysis and OxPPP during the oxidation of glucose, a component of the host xylem pool that serves as a potential carbon source (5). The outcomes help better define the central carbon metabolic network of R. solanacearum that can be integrated with 13C metabolic flux analysis as well as flux balance analysis studies for defining the metabolic phenotypes. The study highlights the need to critically examine phytopathogens whose metabolism is poorly understood.
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Abstract
S. enterica is a major foodborne pathogen, which can be transmitted via several distinct routes from animals and environmental sources to human hosts. Multiple subspecies and serotypes of S. enterica exhibit considerable differences in virulence, host specificity, and colonization. This study provides detailed insights into the dynamics of recombination and its contributions to S. enterica subspecies evolution. Widespread recombination within the species means that new adaptations arising in one lineage can be rapidly transferred to another lineage. We therefore predict that recombination has been an important factor in the emergence of several major disease-causing strains from diverse genomic backgrounds and their ability to adapt to disparate environments. Salmonella is responsible for many nontyphoidal foodborne infections and enteric (typhoid) fever in humans. Of the two Salmonella species, Salmonella enterica is highly diverse and includes 10 known subspecies and approximately 2,600 serotypes. Understanding the evolutionary processes that generate the tremendous diversity in Salmonella is important in reducing and controlling the incidence of disease outbreaks and the emergence of virulent strains. In this study, we aim to elucidate the impact of homologous recombination in the diversification of S. enterica subspecies. Using a data set of previously published 926 Salmonella genomes representing the 10 S. enterica subspecies and Salmonella bongori, we calculated a genus-wide pan-genome composed of 84,041 genes and the S. enterica pan-genome of 81,371 genes. The size of the accessory genomes varies between 12,429 genes in S. enterica subsp. arizonae (subsp. IIIa) to 33,257 genes in S. enterica subsp. enterica (subsp. I). A total of 12,136 genes in the Salmonella pan-genome show evidence of recombination, representing 14.44% of the pan-genome. We identified genomic hot spots of recombination that include genes associated with flagellin and the synthesis of methionine and thiamine pyrophosphate, which are known to influence host adaptation and virulence. Last, we uncovered within-species heterogeneity in rates of recombination and preferential genetic exchange between certain donor and recipient strains. Frequent but biased recombination within a bacterial species may suggest that lineages vary in their response to environmental selection pressure. Certain lineages, such as the more uncommon non-enterica subspecies (non-S. enterica subsp. enterica), may also act as a major reservoir of genetic diversity for the wider population. IMPORTANCES. enterica is a major foodborne pathogen, which can be transmitted via several distinct routes from animals and environmental sources to human hosts. Multiple subspecies and serotypes of S. enterica exhibit considerable differences in virulence, host specificity, and colonization. This study provides detailed insights into the dynamics of recombination and its contributions to S. enterica subspecies evolution. Widespread recombination within the species means that new adaptations arising in one lineage can be rapidly transferred to another lineage. We therefore predict that recombination has been an important factor in the emergence of several major disease-causing strains from diverse genomic backgrounds and their ability to adapt to disparate environments.
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Metabolomic Profiling of the Host Response of Tomato ( Solanum lycopersicum) Following Infection by Ralstonia solanacearum. Int J Mol Sci 2019; 20:ijms20163945. [PMID: 31416118 PMCID: PMC6720392 DOI: 10.3390/ijms20163945] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 08/07/2019] [Accepted: 08/08/2019] [Indexed: 12/16/2022] Open
Abstract
Tomato (Solanum lycopersicum) is an important dietary source of bioactive phytochemicals and active breeding programs constantly produce new cultivars possessing superior and desirable traits. The phytopathogenic Ralstonia solanacearum, the causal agent of bacterial wilt, is a highly destructive bacterial disease with a high economic impact on tomato production. This study followed an untargeted metabolomic approach involving four tomato cultivars and aimed at the identification of secondary metabolites involved in plant defense after infection with R. solanacearum. Liquid chromatography coupled to mass spectrometry (LC-MS) in combination with multivariate data analysis and chemometric modelling were utilized for the identification of discriminant secondary metabolites. The total of 81 statistically selected features were annotated belonging to the metabolite classes of amino acids, organic acids, fatty acids, various derivatives of cinnamic acid and benzoic acids, flavonoids and steroidal glycoalkaloids. The results indicate that the phenylpropanoid pathway, represented by flavonoids and hydroxycinnamic acids, is of prime importance in the tomato defense response. The hydroxycinnamic acids esters of quinic acid, hexoses and glucaric acids were identified as signatory biomarkers, as well as the hydroxycinnamic acid amides to polyamines and tyramine. Interestingly, the rapid and differential accumulation of putrescine, dopamine, and tyramine derivatives, along with the presence of a newly documented metabolite, feruloyl serotonin, were documented in the infected plants. Metabolite concentration variability in the different cultivar tissues point to cultivar-specific variation in the speed and manner of resource redistribution between the host tissues. These metabolic phenotypes provide insights into the differential metabolic signatures underlying the defense metabolism of the four cultivars, defining their defensive capabilities to R. solanacearum.
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Zhang JL, Wang D, Liang YW, Zhong WY, Ming ZH, Tang DJ, Tang JL. The Gram-negative phytopathogen Xanthomonas campestris pv. campestris employs a 5'UTR as a feedback controller to regulate methionine biosynthesis. MICROBIOLOGY-SGM 2018; 164:1146-1155. [PMID: 30024369 PMCID: PMC6230763 DOI: 10.1099/mic.0.000690] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The synthesis of methionine is critical for most bacteria. It is known that cellular methionine has a feedback effect on the expression of met genes involved in de novo methionine biosynthesis. Previous studies revealed that Gram-negative bacteria control met gene expression at the transcriptional level by regulator proteins, while most Gram-positive bacteria regulate met genes at post-transcriptional level by RNA regulators (riboregulators) located in the 5′UTR of met genes. However, despite its importance, the methionine biosynthesis pathway in the Gram-negative Xanthomonas genus that includes many important plant pathogens is completely uncharacterized. Here, we address this issue using the crucifer black rot pathogen Xanthomonas campestris pv. campestris (Xcc), a model bacterium in microbe–plant interaction studies. The work identified an operon (met) involved in de novo methionine biosynthesis in Xcc. Disruption of the operon resulted in defective growth in methionine-limited media and in planta. Western blot analysis revealed that the expression of the operon is dependent on methionine levels. Further molecular analyses demonstrated that the 5′UTR, but not the promoter of the operon, is involved in feedback regulation on operon expression in response to methionine availability, providing an example of a Gram-negative bacterium utilizing a 5′UTR region to control the expression of the genes involved in methionine biosynthesis.
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Affiliation(s)
- Jian-Ling Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Dan Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Yu-Wei Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Wan-Ying Zhong
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Zhen-Hua Ming
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Dong-Jie Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
- *Correspondence: Dong-Jie Tang,
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
- Ji-Liang Tang,
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Wei Y, Caceres‐Moreno C, Jimenez‐Gongora T, Wang K, Sang Y, Lozano‐Duran R, Macho AP. The Ralstonia solanacearum csp22 peptide, but not flagellin-derived peptides, is perceived by plants from the Solanaceae family. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1349-1362. [PMID: 29265643 PMCID: PMC5999195 DOI: 10.1111/pbi.12874] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/10/2017] [Accepted: 12/12/2017] [Indexed: 05/20/2023]
Abstract
Ralstonia solanacearum, the causal agent of bacterial wilt disease, is considered one of the most destructive bacterial pathogens due to its lethality, unusually wide host range, persistence and broad geographical distribution. In spite of the extensive research on plant immunity over the last years, the perception of molecular patterns from R. solanacearum that activate immunity in plants is still poorly understood, which hinders the development of strategies to generate resistance against bacterial wilt disease. The perception of a conserved peptide of bacterial flagellin, flg22, is regarded as paradigm of plant perception of invading bacteria; however, no elicitor activity has been detected for R. solanacearum flg22. Recent reports have shown that other epitopes from flagellin are able to elicit immune responses in specific species from the Solanaceae family, yet our results show that these plants do not perceive any epitope from R. solanacearum flagellin. Searching for elicitor peptides from R. solanacearum, we found several protein sequences similar to the consensus of the elicitor peptide csp22, reported to elicit immunity in specific Solanaceae plants. A R. solanacearum csp22 peptide (csp22Rsol ) was indeed able to trigger immune responses in Nicotiana benthamiana and tomato, but not in Arabidopsis thaliana. Additionally, csp22Rsol treatment conferred increased resistance to R. solanacearum in tomato. Transgenic A. thaliana plants expressing the tomato csp22 receptor (SlCORE) gained the ability to respond to csp22Rsol and became more resistant to R. solanacearum infection. Our results shed light on the mechanisms for perception of R. solanacearum by plants, paving the way for improving current approaches to generate resistance against R. solanacearum.
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Affiliation(s)
- Yali Wei
- Shanghai Center for Plant Stress BiologyCAS Center for Excellence in Molecular Plant SciencesShanghai Institutes of Biological SciencesChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Carlos Caceres‐Moreno
- Shanghai Center for Plant Stress BiologyCAS Center for Excellence in Molecular Plant SciencesShanghai Institutes of Biological SciencesChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Tamara Jimenez‐Gongora
- Shanghai Center for Plant Stress BiologyCAS Center for Excellence in Molecular Plant SciencesShanghai Institutes of Biological SciencesChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Keke Wang
- Shanghai Center for Plant Stress BiologyCAS Center for Excellence in Molecular Plant SciencesShanghai Institutes of Biological SciencesChinese Academy of SciencesShanghaiChina
| | - Yuying Sang
- Shanghai Center for Plant Stress BiologyCAS Center for Excellence in Molecular Plant SciencesShanghai Institutes of Biological SciencesChinese Academy of SciencesShanghaiChina
| | - Rosa Lozano‐Duran
- Shanghai Center for Plant Stress BiologyCAS Center for Excellence in Molecular Plant SciencesShanghai Institutes of Biological SciencesChinese Academy of SciencesShanghaiChina
| | - Alberto P. Macho
- Shanghai Center for Plant Stress BiologyCAS Center for Excellence in Molecular Plant SciencesShanghai Institutes of Biological SciencesChinese Academy of SciencesShanghaiChina
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20
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Lowe-Power TM, Khokhani D, Allen C. How Ralstonia solanacearum Exploits and Thrives in the Flowing Plant Xylem Environment. Trends Microbiol 2018; 26:929-942. [PMID: 29941188 DOI: 10.1016/j.tim.2018.06.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/24/2018] [Accepted: 06/04/2018] [Indexed: 10/28/2022]
Abstract
The plant wilt pathogen Ralstonia solanacearum thrives in the water-transporting xylem vessels of its host plants. Xylem is a relatively nutrient-poor, high-flow environment but R. solanacearum succeeds there by tuning its own metabolism and altering xylem sap biochemistry. Flow influences many traits that the bacterium requires for pathogenesis. Most notably, a quorum sensing system mediates the pathogen's major transition from a rapidly dividing early phase that voraciously consumes diverse food sources and avidly adheres to plant surfaces to a slower-growing late phase that can use fewer nutrients but produces virulence factors and disperses effectively. This review discusses recent findings about R. solanacearum pathogenesis in the context of its flowing in planta niche, with emphasis on R. solanacearum metabolism in plants.
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Affiliation(s)
- Tiffany M Lowe-Power
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA; Current address: Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Devanshi Khokhani
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA; Current address: Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Control of primary metabolism by a virulence regulatory network promotes robustness in a plant pathogen. Nat Commun 2018; 9:418. [PMID: 29379078 PMCID: PMC5788922 DOI: 10.1038/s41467-017-02660-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 12/17/2017] [Indexed: 11/09/2022] Open
Abstract
Robustness is a key system-level property of living organisms to maintain their functions while tolerating perturbations. We investigate here how a regulatory network controlling multiple virulence factors impacts phenotypic robustness of a bacterial plant pathogen. We reconstruct a cell-scale model of Ralstonia solanacearum connecting a genome-scale metabolic network, a virulence macromolecule network, and a virulence regulatory network, which includes 63 regulatory components. We develop in silico methods to quantify phenotypic robustness under a broad set of conditions in high-throughput simulation analyses. This approach reveals that the virulence regulatory network exerts a control of the primary metabolism to promote robustness upon infection. The virulence regulatory network plugs into the primary metabolism mainly through the control of genes likely acquired via horizontal gene transfer, which results in a functional overlay with ancestral genes. These results support the view that robustness may be a selected trait that promotes pathogenic fitness upon infection.
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Preston GM. Profiling the extended phenotype of plant pathogens: Challenges in Bacterial Molecular Plant Pathology. MOLECULAR PLANT PATHOLOGY 2017; 18:443-456. [PMID: 28026146 PMCID: PMC6638297 DOI: 10.1111/mpp.12530] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 12/20/2016] [Accepted: 12/21/2016] [Indexed: 05/18/2023]
Abstract
One of the most fundamental questions in plant pathology is what determines whether a pathogen grows within a plant? This question is frequently studied in terms of the role of elicitors and pathogenicity factors in the triggering or overcoming of host defences. However, this focus fails to address the basic question of how the environment in host tissues acts to support or restrict pathogen growth. Efforts to understand this aspect of host-pathogen interactions are commonly confounded by several issues, including the complexity of the plant environment, the artificial nature of many experimental infection systems and the fact that the physiological properties of a pathogen growing in association with a plant can be very different from the properties of the pathogen in culture. It is also important to recognize that the phenotype and evolution of pathogen and host are inextricably linked through their interactions, such that the environment experienced by a pathogen within a host, and its phenotype within the host, is a product of both its interaction with its host and its evolutionary history, including its co-evolution with host plants. As the phenotypic properties of a pathogen within a host cannot be defined in isolation from the host, it may be appropriate to think of pathogens as having an 'extended phenotype' that is the product of their genotype, host interactions and population structure within the host environment. This article reflects on the challenge of defining and studying this extended phenotype, in relation to the questions posed below, and considers how knowledge of the phenotype of pathogens in the host environment could be used to improve disease control. What determines whether a pathogen grows within a plant? What aspects of pathogen biology should be considered in describing the extended phenotype of a pathogen within a host? How can we study the extended phenotype in ways that provide insights into the phenotypic properties of pathogens during natural infections?
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Affiliation(s)
- Gail M. Preston
- Department of Plant SciencesUniversity of OxfordSouth Parks RoadOxfordOX1 3RBUK
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Puigvert M, Guarischi-Sousa R, Zuluaga P, Coll NS, Macho AP, Setubal JC, Valls M. Transcriptomes of Ralstonia solanacearum during Root Colonization of Solanum commersonii. FRONTIERS IN PLANT SCIENCE 2017; 8:370. [PMID: 28373879 PMCID: PMC5357869 DOI: 10.3389/fpls.2017.00370] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/02/2017] [Indexed: 05/03/2023]
Abstract
Bacterial wilt of potatoes-also called brown rot-is a devastating disease caused by the vascular pathogen Ralstonia solanacearum that leads to significant yield loss. As in other plant-pathogen interactions, the first contacts established between the bacterium and the plant largely condition the disease outcome. Here, we studied the transcriptome of R. solanacearum UY031 early after infection in two accessions of the wild potato Solanum commersonii showing contrasting resistance to bacterial wilt. Total RNAs obtained from asymptomatic infected roots were deep sequenced and for 4,609 out of the 4,778 annotated genes in strain UY031 were recovered. Only 2 genes were differentially-expressed between the resistant and the susceptible plant accessions, suggesting that the bacterial component plays a minor role in the establishment of disease. On the contrary, 422 genes were differentially expressed (DE) in planta compared to growth on a synthetic rich medium. Only 73 of these genes had been previously identified as DE in a transcriptome of R. solanacearum extracted from infected tomato xylem vessels. Virulence determinants such as the Type Three Secretion System (T3SS) and its effector proteins, motility structures, and reactive oxygen species (ROS) detoxifying enzymes were induced during infection of S. commersonii. On the contrary, metabolic activities were mostly repressed during early root colonization, with the notable exception of nitrogen metabolism, sulfate reduction and phosphate uptake. Several of the R. solanacearum genes identified as significantly up-regulated during infection had not been previously described as virulence factors. This is the first report describing the R. solanacearum transcriptome directly obtained from infected tissue and also the first to analyze bacterial gene expression in the roots, where plant infection takes place. We also demonstrate that the bacterial transcriptome in planta can be studied when pathogen numbers are low by sequencing transcripts from infected tissue avoiding prokaryotic RNA enrichment.
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Affiliation(s)
- Marina Puigvert
- Department of Genetics, University of BarcelonaBarcelona, Spain
- Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain
| | | | - Paola Zuluaga
- Department of Genetics, University of BarcelonaBarcelona, Spain
- Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain
| | - Núria S. Coll
- Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain
| | - Alberto P. Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences (CAS)Shanghai, China
| | - João C. Setubal
- Department of Biochemistry, University of São PauloSão Paulo, Brazil
| | - Marc Valls
- Department of Genetics, University of BarcelonaBarcelona, Spain
- Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain
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Wang K, Remigi P, Anisimova M, Lonjon F, Kars I, Kajava A, Li CH, Cheng CP, Vailleau F, Genin S, Peeters N. Functional assignment to positively selected sites in the core type III effector RipG7 from Ralstonia solanacearum. MOLECULAR PLANT PATHOLOGY 2016; 17:553-64. [PMID: 26300048 PMCID: PMC6638336 DOI: 10.1111/mpp.12302] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The soil-borne pathogen Ralstonia solanacearum causes bacterial wilt in a broad range of plants. The main virulence determinants of R. solanacearum are the type III secretion system (T3SS) and its associated type III effectors (T3Es), translocated into the host cells. Of the conserved T3Es among R. solanacearum strains, the Fbox protein RipG7 is required for R. solanacearum pathogenesis on Medicago truncatula. In this work, we describe the natural ripG7 variability existing in the R. solanacearum species complex. We show that eight representative ripG7 orthologues have different contributions to pathogenicity on M. truncatula: only ripG7 from Asian or African strains can complement the absence of ripG7 in GMI1000 (Asian reference strain). Nonetheless, RipG7 proteins from American and Indonesian strains can still interact with M. truncatula SKP1-like/MSKa protein, essential for the function of RipG7 in virulence. This indicates that the absence of complementation is most likely a result of the variability in the leucine-rich repeat (LRR) domain of RipG7. We identified 11 sites under positive selection in the LRR domains of RipG7. By studying the functional impact of these 11 sites, we show the contribution of five positively selected sites for the function of RipG7CMR15 in M. truncatula colonization. This work reveals the genetic and functional variation of the essential core T3E RipG7 from R. solanacearum. This analysis is the first of its kind on an essential disease-controlling T3E, and sheds light on the co-evolutionary arms race between the bacterium and its hosts.
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Affiliation(s)
- Keke Wang
- INRA, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR441, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
- CNRS, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR2594, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
| | - Philippe Remigi
- INRA, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR441, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
- CNRS, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR2594, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
| | - Maria Anisimova
- Institute of Applied Simulations, School of Life Sciences and Facility Management, Zürich University of Applied Sciences, Gruenalstrasse 14, 8820, Wädesnwil, Switzerland
| | - Fabien Lonjon
- INRA, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR441, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
- CNRS, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR2594, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
| | - Ilona Kars
- INRA, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR441, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
- CNRS, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR2594, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
| | - Andrey Kajava
- Centre de Recherche de Biochimie Macromoléculaire, CNRS, UMR5237, 1919 Route de Mende, 34000, Montpellier, France
| | - Chien-Hui Li
- Institute of Plant Biology, National Taiwan University, Taipei, 11529, Taiwan, R.O.C
| | - Chiu-Ping Cheng
- Institute of Plant Biology, National Taiwan University, Taipei, 11529, Taiwan, R.O.C
| | - Fabienne Vailleau
- INRA, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR441, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
- CNRS, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR2594, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
- Université de Toulouse, INP, ENSAT, 18 Chemin de Borde Rouge, Castanet-Tolosan, 31326, France
| | - Stéphane Genin
- INRA, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR441, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
- CNRS, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR2594, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
| | - Nemo Peeters
- INRA, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR441, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
- CNRS, Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR2594, CS52627 Chemin de Borde Rouge, 31326, Castanet-Tolosan, France
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Kumar JS, Umesha S, Prasad KS, Niranjana P. Detection of Quorum Sensing Molecules and Biofilm Formation in Ralstonia solanacearum. Curr Microbiol 2015; 72:297-305. [PMID: 26620535 DOI: 10.1007/s00284-015-0953-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 10/21/2015] [Indexed: 01/25/2023]
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Ray SK, Kumar R, Peeters N, Boucher C, Genin S. rpoN1, but not rpoN2, is required for twitching motility, natural competence, growth on nitrate, and virulence of Ralstonia solanacearum. Front Microbiol 2015; 6:229. [PMID: 25852679 PMCID: PMC4371752 DOI: 10.3389/fmicb.2015.00229] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 03/08/2015] [Indexed: 12/30/2022] Open
Abstract
The plant pathogen Ralstonia solanacearum has two genes encoding for the sigma factor σ(54): rpoN1, located in the chromosome and rpoN2, located in a distinct "megaplasmid" replicon. In this study, individual mutants as well as a double mutant of rpoN were created in R. solanacearum strain GMI1000 in order to determine the extent of functional overlap between these two genes. By virulence assay we observed that rpoN1 is required for virulence whereas rpoN2 is not. In addition rpoN1 controls other important functions such twitching motility, natural transformation and growth on nitrate, unlike rpoN2. The rpoN1 and rpoN2 genes have different expression pattern, the expression of rpoN1 being constitutive whereas rpoN2 expression is induced in minimal medium and in the presence of plant cells. Moreover, the expression of rpoN2 is dependent upon rpoN1. Our work therefore reveals that the two rpoN genes are not functionally redundant in R. solanacearum. A list of potential σ(54) targets was identified in the R. solanacearum genome and suggests that multiple traits are under the control of these regulators. Based on these findings, we provide a model describing the functional connection between RpoN1 and the PehR pathogenicity regulator and their dual role in the control of several R. solanacearum virulence determinants.
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Affiliation(s)
- Suvendra K Ray
- Department of Molecular Biology and Biotechnology, Tezpur University Tezpur, India
| | - Rahul Kumar
- Department of Molecular Biology and Biotechnology, Tezpur University Tezpur, India
| | - Nemo Peeters
- Laboratoire des Interactions Plantes-Microorganismes, INRA, UMR 441 Castanet-Tolosan, France ; Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique, UMR 2594 Castanet-Tolosan, France
| | - Christian Boucher
- Laboratoire des Interactions Plantes-Microorganismes, INRA, UMR 441 Castanet-Tolosan, France ; Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique, UMR 2594 Castanet-Tolosan, France
| | - Stephane Genin
- Laboratoire des Interactions Plantes-Microorganismes, INRA, UMR 441 Castanet-Tolosan, France ; Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique, UMR 2594 Castanet-Tolosan, France
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A Ralstonia solanacearum type III effector directs the production of the plant signal metabolite trehalose-6-phosphate. mBio 2014; 5:mBio.02065-14. [PMID: 25538193 PMCID: PMC4278537 DOI: 10.1128/mbio.02065-14] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The plant pathogen Ralstonia solanacearum possesses two genes encoding a trehalose-6-phosphate synthase (TPS), an enzyme of the trehalose biosynthetic pathway. One of these genes, named ripTPS, was found to encode a protein with an additional N-terminal domain which directs its translocation into host plant cells through the type 3 secretion system. RipTPS is a conserved effector in the R. solanacearum species complex, and homologues were also detected in other bacterial plant pathogens. Functional analysis of RipTPS demonstrated that this type 3 effector synthesizes trehalose-6-phosphate and identified residues essential for this enzymatic activity. Although trehalose-6-phosphate is a key signal molecule in plants that regulates sugar status and carbon assimilation, the disruption of ripTPS did not alter the virulence of R. solanacearum on plants. However, heterologous expression assays showed that this effector specifically elicits a hypersensitive-like response on tobacco that is independent of its enzymatic activity and is triggered by the C-terminal half of the protein. Recognition of this effector by the plant immune system is suggestive of a role during the infectious process. Ralstonia solanacearum, the causal agent of bacterial wilt disease, infects more than two hundred plant species, including economically important crops. The type III secretion system plays a major role in the pathogenicity of this bacterium, and approximately 70 effector proteins have been shown to be translocated into host plant cells. This study provides the first description of a type III effector endowed with a trehalose-6-phosphate synthase enzymatic activity and illustrates a new mechanism by which the bacteria may manipulate the plant metabolism upon infection. In recent years, trehalose-6-phosphate has emerged as an essential signal molecule in plants, connecting plant metabolism and development. The finding that a bacterial pathogen could induce the production of trehalose-6-phosphate in plant cells further highlights the importance of this metabolite in multiple aspects of the molecular physiology of plants.
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Helliwell KE, Scaife MA, Sasso S, Araujo APU, Purton S, Smith AG. Unraveling vitamin B12-responsive gene regulation in algae. PLANT PHYSIOLOGY 2014; 165:388-97. [PMID: 24627342 PMCID: PMC4012597 DOI: 10.1104/pp.113.234369] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Photosynthetic microalgae play a vital role in primary productivity and biogeochemical cycling in both marine and freshwater systems across the globe. However, the growth of these cosmopolitan organisms depends on the bioavailability of nutrients such as vitamins. Approximately one-half of all microalgal species requires vitamin B12 as a growth supplement. The major determinant of algal B12 requirements is defined by the isoform of methionine synthase possessed by an alga, such that the presence of the B12-independent methionine synthase (METE) enables growth without this vitamin. Moreover, the widespread but phylogenetically unrelated distribution of B12 auxotrophy across the algal lineages suggests that the METE gene has been lost multiple times in evolution. Given that METE expression is repressed by the presence of B12, prolonged repression by a reliable source of the vitamin could lead to the accumulation of mutations and eventually gene loss. Here, we probe METE gene regulation by B12 and methionine/folate cycle metabolites in both marine and freshwater microalgal species. In addition, we identify a B12-responsive element of Chlamydomonas reinhardtii METE using a reporter gene approach. We show that complete repression of the reporter occurs via a region spanning -574 to -90 bp upstream of the METE start codon. A proteomics study reveals that two other genes (S-Adenosylhomocysteine hydrolase and Serine hydroxymethyltransferase2) involved in the methionine-folate cycle are also repressed by B12 in C. reinhardtii. The strong repressible nature and high sensitivity of the B12-responsive element has promising biotechnological applications as a cost-effective regulatory gene expression tool.
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Peeters N, Guidot A, Vailleau F, Valls M. Ralstonia solanacearum, a widespread bacterial plant pathogen in the post-genomic era. MOLECULAR PLANT PATHOLOGY 2013; 14:651-62. [PMID: 23718203 PMCID: PMC6638647 DOI: 10.1111/mpp.12038] [Citation(s) in RCA: 194] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
UNLABELLED Ralstonia solanacearum is a soil-borne bacterium causing the widespread disease known as bacterial wilt. Ralstonia solanacearum is also the causal agent of Moko disease of banana and brown rot of potato. Since the last R. solanacearum pathogen profile was published 10 years ago, studies concerning this plant pathogen have taken a genomic and post-genomic direction. This was pioneered by the first sequenced and annotated genome for a major plant bacterial pathogen and followed by many more genomes in subsequent years. All molecular features studied now have a genomic flavour. In the future, this will help in connecting the classical field of pathology and diversity studies with the gene content of specific strains. In this review, we summarize the recent research on this bacterial pathogen, including strain classification, host range, pathogenicity determinants, regulation of virulence genes, type III effector repertoire, effector-triggered immunity, plant signalling in response to R. solanacearum, as well as a review of different new pathosystems. TAXONOMY Bacteria; Proteobacteria; β subdivision; Ralstonia group; genus Ralstonia. DISEASE SYMPTOMS Ralstonia solanacearum is the agent of bacterial wilt of plants, characterized by a sudden wilt of the whole plant. Typically, stem cross-sections will ooze a slimy bacterial exudate. In the case of Moko disease of banana and brown rot of potato, there is also visible bacterial colonization of banana fruit and potato tuber. DISEASE CONTROL As a soil-borne pathogen, infected fields can rarely be reused, even after rotation with nonhost plants. The disease is controlled by the use of resistant and tolerant plant cultivars. The prevention of spread of the disease has been achieved, in some instances, by the application of strict prophylactic sanitation practices. USEFUL WEBSITES Stock centre: International Centre for Microbial Resources-French Collection for Plant-associated Bacteria CIRM-CFBP, IRHS UMR 1345 INRA-ACO-UA, 42 rue Georges Morel, 49070 Beaucouzé Cedex, France, http://www.angers-nantes.inra.fr/cfbp/. Ralstonia Genome browser: https://iant.toulouse.inra.fr/R.solanacearum. GMI1000 insertion mutant library: https://iant.toulouse.inra.fr/R.solanacearumGMI1000/GenomicResources. MaGe Genome Browser: https://www.genoscope.cns.fr/agc/microscope/mage/viewer.php?
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Affiliation(s)
- Nemo Peeters
- INRA UMR441 Laboratoire des Interactions Plantes Micro-organismes (LIPM), 24 chemin de Borde Rouge-Auzeville CS 52627, 31326, Castanet Tolosan Cedex, France
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