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Li P, Bez C, Zhang Y, Deng Y, Venturi V. N-acyl homoserine lactone cell-cell diffusible signalling in the Ralstonia solanacearum species complex. MOLECULAR PLANT PATHOLOGY 2024; 25:e13467. [PMID: 39099210 PMCID: PMC11298618 DOI: 10.1111/mpp.13467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 04/29/2024] [Accepted: 04/29/2024] [Indexed: 08/06/2024]
Abstract
Ralstonia solanacearum species complex (RSSC) includes soilborne bacterial plant pathogens with worldwide distribution and wide host ranges. Virulence factors are regulated via four hierarchically organized cell-cell contact independent quorum-sensing (QS) signalling systems: the Phc, which uses as signals (R)-methyl 3-hydroxypalmitate [(R)-3-OH PAME] or (R)-methyl 3-hydroxymyristate [(R)-3-OH MAME], the N-acyl homoserine lactone (AHL)-dependent RasI/R and SolI/R systems, and the recently identified anthranilic acid-dependent system. The unique Phc QS system has been extensively studied; however, the role of the two AHL QS systems has only recently been addressed. In this microreview, we present and discuss current data of the SolI/R and RasI/R QS systems in the RSSC. We also present the distribution and frequency of these AHL QS systems in the RSSC, discuss possible ecological roles and evolutive implications. The complex QS hierarchical networks emphasizes the crucial role of cell-cell signalling in the virulence of the RSSC.
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Affiliation(s)
- Peng Li
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life SciencesHainan Normal UniversityHaikouChina
- International Centre for Genetic Engineering and BiotechnologyTriesteItaly
| | - Cristina Bez
- International Centre for Genetic Engineering and BiotechnologyTriesteItaly
| | - Yong Zhang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River BasinSouthwest UniversityChongqingChina
| | - Yinyue Deng
- School of Pharmaceutical Sciences (Shenzhen)Shenzhen Campus of Sun Yat‐sen University, Sun Yatsen UniversityShenzhenChina
| | - Vittorio Venturi
- International Centre for Genetic Engineering and BiotechnologyTriesteItaly
- African Genome Center, University Mohammed VI Polytechnic (UM6P)Ben GuerirMorocco
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Meshram S, Adhikari TB. Microbiome-Mediated Strategies to Manage Major Soil-Borne Diseases of Tomato. PLANTS (BASEL, SWITZERLAND) 2024; 13:364. [PMID: 38337897 PMCID: PMC10856849 DOI: 10.3390/plants13030364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 01/23/2024] [Accepted: 01/23/2024] [Indexed: 02/12/2024]
Abstract
The tomato (Solanum lycopersicum L.) is consumed globally as a fresh vegetable due to its high nutritional value and antioxidant properties. However, soil-borne diseases can severely limit tomato production. These diseases, such as bacterial wilt (BW), Fusarium wilt (FW), Verticillium wilt (VW), and root-knot nematodes (RKN), can significantly reduce the yield and quality of tomatoes. Using agrochemicals to combat these diseases can lead to chemical residues, pesticide resistance, and environmental pollution. Unfortunately, resistant varieties are not yet available. Therefore, we must find alternative strategies to protect tomatoes from these soil-borne diseases. One of the most promising solutions is harnessing microbial communities that can suppress disease and promote plant growth and immunity. Recent omics technologies and next-generation sequencing advances can help us develop microbiome-based strategies to mitigate tomato soil-borne diseases. This review emphasizes the importance of interdisciplinary approaches to understanding the utilization of beneficial microbiomes to mitigate soil-borne diseases and improve crop productivity.
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Affiliation(s)
- Shweta Meshram
- Department of Plant Pathology, Lovely Professional University, Phagwara 144402, India;
| | - Tika B. Adhikari
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
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Liu Q, Li C, Zhang X, Ding M, Liao X, Yan J, Hu M, Yang L, Wang X, Liao L, Li P, Zhou X. PhcX Is a LqsR-family response regulator that contributes to Ralstonia solanacearum virulence and regulates multiple virulence factors. mBio 2023; 14:e0202823. [PMID: 37787568 PMCID: PMC10653808 DOI: 10.1128/mbio.02028-23] [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: 08/02/2023] [Accepted: 08/15/2023] [Indexed: 10/04/2023] Open
Abstract
IMPORTANCE The bacterial wilt caused by the soil-borne phytopathogen Ralstonia solanacearum is one of the most destructive crop diseases. To achieve a successful infection, R. solanacearum has evolved an intricate regulatory network to orchestrate the expression of an arsenal of virulence factors and fine-tune the allocation of energy. However, despite the wealth of knowledge gained in the past decades, many players and connections are still missing from the network. The importance of our study lies in the identification of PhcX, a novel conserved global regulator with critical roles in modulating the virulence and metabolism of R. solanacearum. PhcX affects many well-characterized regulators and exhibits contrasting modes of regulation from the central regulator PhcA on a variety of virulence-associated traits and genes. Our findings add a valuable piece to the puzzle of how the pathogen regulates its proliferation and infection, which is critical for understanding its pathogenesis and developing disease control strategies.
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Affiliation(s)
- Qingmei Liu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Chuhao Li
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Xiaohan Zhang
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Mengfan Ding
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Xinyue Liao
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Jinli Yan
- School of Agricultural Science, Xichang University, Xichang, China
| | - Ming Hu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Leilei Yang
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Xiaoqing Wang
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Lisheng Liao
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Peng Li
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Hainan Provincial Key Laboratory for Tropical Plant and Animal Ecology, College of Life Sciences, Hainan Normal University, Haikou, China
| | - Xiaofan Zhou
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
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Dominelli N, Regaiolo A, Willy L, Heermann R. Interkingdom Signaling of the Insect Pathogen Photorhabdus luminescens with Plants Via the LuxR solo SdiA. Microorganisms 2023; 11:microorganisms11040890. [PMID: 37110313 PMCID: PMC10143992 DOI: 10.3390/microorganisms11040890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 03/31/2023] Open
Abstract
In bacteria, group-coordinated behavior such as biofilm formation or virulence are often mediated via cell–cell communication, a process referred to as quorum sensing (QS). The canonical QS system of Gram-negative bacteria uses N-acyl homoserine lactones (AHLs) as communication molecules, which are produced by LuxI-type synthases and sensed by cognate LuxR-type receptors. These receptors act as transcriptional regulators controlling the expression of specific genes. Some bacteria harbor LuxR-type receptors lacking a cognate LuxI-type synthases, designated as LuxR solos. Among many other LuxR solos, the entomopathogenic enteric bacterium Photorhabdus luminescens harbors a SdiA-like LuxR solo containing an AHL signal-binding domain, for which a respective signal molecule and target genes have not been identified yet. Here we performed SPR analysis to demonstrate that SdiA acts as a bidirectional regulator of transcription, tightly controlling its own expression and the adjacent PluDJC_01670 (aidA) gene in P. luminescens, a gene supposed to be involved in the colonization of eukaryotes. Via qPCR we could further determine that in sdiA deletion mutant strains, aidA is upregulated, indicating that SdiA negatively affects expression of aidA. Furthermore, the ΔsdiA deletion mutant exhibited differences in biofilm formation and motility compared with the wild-type. Finally, using nanoDSF analysis we could identify putative binding ability of SdiA towards diverse AHLs, but also to plant-derived signals, modulating the DNA-binding capacity of SdiA, suggesting that this LuxR solo acts as an important player in interkingdom signaling between P. luminescens and plants.
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Cell Density-Regulated Adhesins Contribute to Early Disease Development and Adhesion in Ralstonia solanacearum. Appl Environ Microbiol 2023; 89:e0156522. [PMID: 36688670 PMCID: PMC9973027 DOI: 10.1128/aem.01565-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Adhesins (adhesive proteins) help bacteria stick to and colonize diverse surfaces and often contribute to virulence. The genome of the bacterial wilt pathogen Ralstonia solanacearum (Rs) encodes dozens of putative adhesins, some of which are upregulated during plant pathogenesis. Little is known about the role of these proteins in bacterial wilt disease. During tomato colonization, three putative Rs adhesin genes were upregulated in a ΔphcA quorum-sensing mutant that cannot respond to high cell densities: radA (Ralstonia adhesin A), rcpA (Ralstonia collagen-like protein A), and rcpB. Based on this differential gene expression, we hypothesized that adhesins repressed by PhcA contribute to early disease stages when Rs experiences a low cell density. During root colonization, Rs upregulated rcpA and rcpB, but not radA, relative to bacteria in the stem at mid-disease. Root attachment assays and confocal microscopy with ΔrcpA/B and ΔradA revealed that all three adhesins help Rs attach to tomato seedling roots. Biofilm assays on abiotic surfaces found that Rs does not require RadA, RcpA, or RcpB for interbacterial attachment (cohesion), but these proteins are essential for anchoring aggregates to a surface (adhesion). However, Rs did not require the adhesins for later disease stages in planta, including colonization of the root endosphere and stems. Interestingly, all three adhesins were essential for full competitive fitness in planta. Together, these infection stage-specific assays identified three proteins that contribute to adhesion and the critical first host-pathogen interaction in bacterial wilt disease. IMPORTANCE Every microbe must balance its need to attach to surfaces with the biological imperative to move and spread. The high-impact plant-pathogenic bacterium Ralstonia solanacearum can stick to biotic and abiotic substrates, presumably using some of the dozens of putative adhesins encoded in its genome. We confirmed the functions and identified the biological roles of multiple afimbrial adhesins. By assaying the competitive fitness and the success of adhesin mutants in three different plant compartments, we identified the specific disease stages and host tissues where three previously cryptic adhesins contribute to success in plants. Combined with tissue-specific regulatory data, this work indicates that R. solanacearum deploys distinct adhesins that help it succeed at different stages of plant pathogenesis.
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Kumar S, Ahmad K, Behera SK, Nagrale DT, Chaurasia A, Yadav MK, Murmu S, Jha Y, Rajawat MVS, Malviya D, Singh UB, Shankar R, Tripathy M, Singh HV. Biocomputational Assessment of Natural Compounds as a Potent Inhibitor to Quorum Sensors in Ralstonia solanacearum. Molecules 2022; 27:molecules27093034. [PMID: 35566383 PMCID: PMC9102662 DOI: 10.3390/molecules27093034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 04/24/2022] [Accepted: 05/02/2022] [Indexed: 11/16/2022] Open
Abstract
Ralstonia solanacearum is among the most damaging bacterial phytopathogens with a wide number of hosts and a broad geographic distribution worldwide. The pathway of phenotype conversion (Phc) is operated by quorum-sensing signals and modulated through the (R)-methyl 3-hydroxypalmitate (3-OH PAME) in R. solanacearum. However, the molecular structures of the Phc pathway components are not yet established, and the structural consequences of 3-OH PAME on quorum sensing are not well studied. In this study, 3D structures of quorum-sensing proteins of the Phc pathway (PhcA and PhcR) were computationally modeled, followed by the virtual screening of the natural compounds library against the predicted active site residues of PhcA and PhcR proteins that could be employed in limiting signaling through 3-OH PAME. Two of the best scoring common ligands ZINC000014762512 and ZINC000011865192 for PhcA and PhcR were further analyzed utilizing orbital energies such as HOMO and LUMO, followed by molecular dynamics simulations of the complexes for 100 ns to determine the ligands binding stability. The findings indicate that ZINC000014762512 and ZINC000011865192 may be capable of inhibiting both PhcA and PhcR. We believe that, after further validation, these compounds may have the potential to disrupt bacterial quorum sensing and thus control this devastating phytopathogenic bacterial pathogen.
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Affiliation(s)
- Sunil Kumar
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau 275103, India; (K.A.); (M.V.S.R.); (D.M.); (U.B.S.)
- ICAR-Indian Agricultural Statistics Research Institute, New Delhi 110012, India;
- Correspondence: (S.K.); (H.V.S.)
| | - Khurshid Ahmad
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau 275103, India; (K.A.); (M.V.S.R.); (D.M.); (U.B.S.)
| | - Santosh Kumar Behera
- National Institute of Pharmaceutical Education and Research, Ahmedabad 382355, India;
| | - Dipak T. Nagrale
- ICAR-Central Institute for Cotton Research, Nagpur 440010, India;
| | - Anurag Chaurasia
- ICAR-Indian Institute of Vegetable Research, Varanasi 221305, India;
| | - Manoj Kumar Yadav
- Department of Bioinformatics, SRM University, Sonepat 131029, India;
| | - Sneha Murmu
- ICAR-Indian Agricultural Statistics Research Institute, New Delhi 110012, India;
| | - Yachana Jha
- N. V. Patel College of Pure and Applied Sciences, S.P. University, Anand 388315, India;
| | - Mahendra Vikram Singh Rajawat
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau 275103, India; (K.A.); (M.V.S.R.); (D.M.); (U.B.S.)
| | - Deepti Malviya
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau 275103, India; (K.A.); (M.V.S.R.); (D.M.); (U.B.S.)
| | - Udai B. Singh
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau 275103, India; (K.A.); (M.V.S.R.); (D.M.); (U.B.S.)
| | - Raja Shankar
- ICAR-IIHR, Hessaraghatta Lake Post, Bengaluru 560089, India;
| | - Minaketan Tripathy
- Department of Pharmacy, Sitaram Kashyap College of Pharmacy, Rahod 495556, India;
| | - Harsh Vardhan Singh
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau 275103, India; (K.A.); (M.V.S.R.); (D.M.); (U.B.S.)
- Correspondence: (S.K.); (H.V.S.)
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Du H, Yang J, Chen B, Zhang X, Xu X, Wen C, Geng S. Dual RNA-seq Reveals the Global Transcriptome Dynamics of Ralstonia solanacearum and Pepper ( Capsicum annuum) Hypocotyls During Bacterial Wilt Pathogenesis. PHYTOPATHOLOGY 2022; 112:630-642. [PMID: 34346759 DOI: 10.1094/phyto-01-21-0032-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Bacterial wilt, caused by Ralstonia solanacearum, is a serious disease in pepper. However, the interaction between the pathogen and pepper remains largely unknown. This study aimed to gain insights into determinants of pepper susceptibility and R. solanacearum pathogenesis. We assembled the complete genome of R. solanacearum strain Rs-SY1 and identified 5,106 predicted genes, including 84 type III effectors (T3E). RNA-seq was used to identify differentially expressed genes (DEGs) in susceptible pepper CM334 at 1 and 5 days postinoculation (dpi) with R. solanacearum. Dual RNA-seq was used to simultaneously capture transcriptome changes in the host and pathogen at 3 and 7 dpi. A total of 1,400, 3,335, 2,878, and 4,484 DEGs of pepper (PDEGs) were identified in the CM334 hypocotyls at 1, 3, 5, and 7 dpi, respectively. Functional enrichment of the PDEGs suggests that inducing ethylene production, suppression of photosynthesis, downregulation of polysaccharide metabolism, and weakening of cell wall defenses may contribute to successful infection by R. solanacearum. When comparing in planta and nutrient agar growth of the R. solanacearum, 218 and 1,042 DEGs of R. solanacearum (RDEGs) were detected at 3 and 7 dpi, respectively. Additional analysis of the RDEGs suggested that enhanced starch and sucrose metabolism, and upregulation of virulence factors may promote R. solanacearum colonization. Strikingly, 26 R. solanacearum genes were found to have similar DEG patterns during a variety of host-R. solanacearum interactions. This study provides a foundation for a better understanding of the transcriptional changes during pepper-R. solanacearum interactions and will aid in the discovery of potential susceptibility and virulence factors.
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Affiliation(s)
- Heshan Du
- Beijing Vegetable Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
- National Engineering Research Center for Vegetables, Beijing 100097, China
- Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing 100097, China
| | - Jingjing Yang
- Beijing Vegetable Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
- National Engineering Research Center for Vegetables, Beijing 100097, China
- Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing 100097, China
| | - Bin Chen
- Beijing Vegetable Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
- National Engineering Research Center for Vegetables, Beijing 100097, China
- Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing 100097, China
| | - Xiaofen Zhang
- Beijing Vegetable Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
- National Engineering Research Center for Vegetables, Beijing 100097, China
- Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing 100097, China
| | - Xiulan Xu
- Beijing Vegetable Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
- National Engineering Research Center for Vegetables, Beijing 100097, China
- Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing 100097, China
| | - Changlong Wen
- Beijing Vegetable Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
- National Engineering Research Center for Vegetables, Beijing 100097, China
- Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing 100097, China
| | - Sansheng Geng
- Beijing Vegetable Research Center, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
- National Engineering Research Center for Vegetables, Beijing 100097, China
- Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing 100097, China
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Schachterle JK, Huang Q. Implication of the Type III Effector RipS1 in the Cool-Virulence of Ralstonia solanacearum Strain UW551. FRONTIERS IN PLANT SCIENCE 2021; 12:705717. [PMID: 34367225 PMCID: PMC8339923 DOI: 10.3389/fpls.2021.705717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Members of the Ralstonia solanacearum species complex cause a variety of wilting diseases across a wide range of hosts by colonizing and blocking xylem vessels. Of great concern are race 3 biovar 2 strains of R. solanacearum capable of causing brown rot of potato at cool temperatures, which are select agents in the United States. To gain a better understanding of cool-virulence mechanisms, we generated libraries of transposon mutants in the cool-virulent R. solanacearum strain UW551 and screened 10,000 mutants using our seedling assay for significantly reduced virulence at 20°C. We found several mutants that exhibited reduced virulence at 28 and 20°C and also mutants that were only affected at the cooler temperature. One mutant of the latter chosen for further study had the transposon inserted in an intergenic region between a type III secretion system effector gene ripS1 and a major facilitator superfamily (MFS) protein gene. Gene expression analysis showed that expression of ripS1 was altered by the transposon insertion, but not the MFS protein gene. An independent mutant with this insertion upstream of ripS1 was generated and used to confirm virulence and gene expression phenotypes. The effector, RipS1, has unknown function and is part of a family of effectors belonging to the largest known type III effectors. The functional connection between RipS1 and cool-virulence of R. solanacearum UW551 suggests that RipS1 (and/or its upstream promoter element) may serve as a potential target for development of cool-virulence-specific diagnostic tools to differentiate the highly regulated cool-virulent strains from non-cool-virulent strains of R. solanacearum. Our results provide important information for continued work toward a better understanding of cool-virulence of R. solanacearum and development of proper control strategies to combat this important plant pathogen.
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Affiliation(s)
| | - Qi Huang
- Floral and Nursery Plants Research Unit, United States National Arboretum, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD, United States
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A high-throughput virulence screening method for the Ralstonia solanacearum species complex. J Microbiol Methods 2021; 187:106270. [PMID: 34144052 DOI: 10.1016/j.mimet.2021.106270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/07/2021] [Accepted: 06/10/2021] [Indexed: 11/24/2022]
Abstract
Ralstonia solanacearum species complex strains are the causative agents for wilting diseases of many plants, including the economically important brown rot of potato. We developed a high-throughput virulence screen that is implemented in 96-well microtiter plates using seedlings grown in soft water agar to save space, effort, and resources. Nicotiana glutinosa was determined to be the most effective host for this assay, and we confirmed bacterial growth and systemic spread in inoculated seedlings. In our assay, N. glutinosa seeds were sown quickly and easily on top of individual water agar wells of a 96-well plate by pipetting out desired number of seeds in an aqueous suspension. They were inoculated on the same day by first touching a bacterial colony with an autoclaved toothpick and then stabbing the toothpick into the center of the water agar well. Such inoculation method resulted in inocula above a threshold of 2 × 104 CFU per well achieving consistent virulence results and enabling reduction of inoculum preparation efforts to facilitate high-throughput screening. Our assay is suitable for forward genetic screening of a large number of strains, isolates or mutants for disease symptoms under both cool (20 °C) and warm (28 °C) temperature conditions before detailed studies can be narrowed down to a manageable number of desired candidates. Our virulence screen method provides a valuable tool for future work in understanding genetics of virulence of Rssc, especially cool virulence of the highly regulated race 3 biovar 2 group of R. solanacearum, leading toward development of effective control strategies.
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de Pedro-Jové R, Puigvert M, Sebastià P, Macho AP, Monteiro JS, Coll NS, Setúbal JC, Valls M. Dynamic expression of Ralstonia solanacearum virulence factors and metabolism-controlling genes during plant infection. BMC Genomics 2021; 22:170. [PMID: 33750302 PMCID: PMC7941725 DOI: 10.1186/s12864-021-07457-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 02/19/2021] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Ralstonia solanacearum is the causal agent of bacterial wilt, a devastating plant disease responsible for serious economic losses especially on potato, tomato, and other solanaceous plant species in temperate countries. In R. solanacearum, gene expression analysis has been key to unravel many virulence determinants as well as their regulatory networks. However, most of these assays have been performed using either bacteria grown in minimal medium or in planta, after symptom onset, which occurs at late stages of colonization. Thus, little is known about the genetic program that coordinates virulence gene expression and metabolic adaptation along the different stages of plant infection by R. solanacearum. RESULTS We performed an RNA-sequencing analysis of the transcriptome of bacteria recovered from potato apoplast and from the xylem of asymptomatic or wilted potato plants, which correspond to three different conditions (Apoplast, Early and Late xylem). Our results show dynamic expression of metabolism-controlling genes and virulence factors during parasitic growth inside the plant. Flagellar motility genes were especially up-regulated in the apoplast and twitching motility genes showed a more sustained expression in planta regardless of the condition. Xylem-induced genes included virulence genes, such as the type III secretion system (T3SS) and most of its related effectors and nitrogen utilisation genes. The upstream regulators of the T3SS were exclusively up-regulated in the apoplast, preceding the induction of their downstream targets. Finally, a large subset of genes involved in central metabolism was exclusively down-regulated in the xylem at late infection stages. CONCLUSIONS This is the first report describing R. solanacearum dynamic transcriptional changes within the plant during infection. Our data define four main genetic programmes that define gene pathogen physiology during plant colonisation. The described expression of virulence genes, which might reflect bacterial states in different infection stages, provides key information on the R. solanacearum potato infection process.
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Affiliation(s)
- R de Pedro-Jové
- Department of Genetics, University of Barcelona, Barcelona, Catalonia, Spain
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - M Puigvert
- Department of Genetics, University of Barcelona, Barcelona, Catalonia, Spain
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - P Sebastià
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - A P Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 201602, China
| | - J S Monteiro
- Departamento de Bioquímica, Universidade de São Paulo, São Paulo, Brazil
| | - N S Coll
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - J C Setúbal
- Departamento de Bioquímica, Universidade de São Paulo, São Paulo, Brazil
| | - M Valls
- Department of Genetics, University of Barcelona, Barcelona, Catalonia, Spain.
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain.
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Zarattini M, Farjad M, Launay A, Cannella D, Soulié MC, Bernacchia G, Fagard M. Every cloud has a silver lining: how abiotic stresses affect gene expression in plant-pathogen interactions. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:1020-1033. [PMID: 33188434 PMCID: PMC7904152 DOI: 10.1093/jxb/eraa531] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 11/10/2020] [Indexed: 05/03/2023]
Abstract
Current environmental and climate changes are having a pronounced influence on the outcome of plant-pathogen interactions, further highlighting the fact that abiotic stresses strongly affect biotic interactions at various levels. For instance, physiological parameters such as plant architecture and tissue organization together with primary and specialized metabolism are affected by environmental constraints, and these combine to make an individual plant either a more or less suitable host for a given pathogen. In addition, abiotic stresses can affect the timely expression of plant defense and pathogen virulence. Indeed, several studies have shown that variations in temperature, and in water and mineral nutrient availability affect the expression of plant defense genes. The expression of virulence genes, known to be crucial for disease outbreak, is also affected by environmental conditions, potentially modifying existing pathosystems and paving the way for emerging pathogens. In this review, we summarize our current knowledge on the impact of abiotic stress on biotic interactions at the transcriptional level in both the plant and the pathogen side of the interaction. We also perform a metadata analysis of four different combinations of abiotic and biotic stresses, which identifies 197 common modulated genes with strong enrichment in Gene Ontology terms related to defense . We also describe the multistress-specific responses of selected defense-related genes.
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Affiliation(s)
- Marco Zarattini
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
- PhotoBioCatalysis Unit – Crop Production and Biostimulation Lab (CPBL), Interfaculty School of Bioengineers, Université Libre de Bruxelles (ULB), CP150, Avenue F.D. Roosevelt 50, Brussels, Belgium
| | - Mahsa Farjad
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Alban Launay
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - David Cannella
- PhotoBioCatalysis Unit – Crop Production and Biostimulation Lab (CPBL), Interfaculty School of Bioengineers, Université Libre de Bruxelles (ULB), CP150, Avenue F.D. Roosevelt 50, Brussels, Belgium
| | - Marie-Christine Soulié
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
- Sorbonne Universités, UPMC Univ. Paris 06, UFR 927, 4 place Jussieu, Paris, France
| | - Giovanni Bernacchia
- Department of Life Sciences and Biotechnology, University of Ferrara, Via Borsari 46, Ferrara, Italy
| | - Mathilde Fagard
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
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12
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Quorum Sensing Regulation in Phytopathogenic Bacteria. Microorganisms 2021; 9:microorganisms9020239. [PMID: 33498890 PMCID: PMC7912708 DOI: 10.3390/microorganisms9020239] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 11/17/2022] Open
Abstract
Quorum sensing is a type of chemical communication by which bacterial populations control expression of their genes in a coordinated manner. This regulatory mechanism is commonly used by pathogens to control the expression of genes encoding virulence factors and that of genes involved in the bacterial adaptation to variations in environmental conditions. In phytopathogenic bacteria, several mechanisms of quorum sensing have been characterized. In this review, we describe the different quorum sensing systems present in phytopathogenic bacteria, such as those using the signal molecules named N-acyl-homoserine lactone (AHL), diffusible signal factor (DSF), and the unknown signal molecule of the virulence factor modulating (VFM) system. We focus on studies performed on phytopathogenic bacteria of major importance, including Pseudomonas, Ralstonia, Agrobacterium, Xanthomonas, Erwinia, Xylella,Dickeya, and Pectobacterium spp. For each system, we present the mechanism of regulation, the functions targeted by the quorum sensing system, and the mechanisms by which quorum sensing is regulated.
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13
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Roman-Reyna V, Truchon A, Sharma P, Hand FP, Mazloom R, Vinatzer BA, Jacobs JM, Allen C. Genome Resource: Ralstonia solanacearum Phylotype II Sequevar 1 (Race 3 Biovar 2) Strain UW848 From the 2020 U.S. Geranium Introduction. PLANT DISEASE 2021; 105:207-208. [PMID: 33175669 DOI: 10.1094/pdis-06-20-1269-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ralstonia solanacearum phylotype II sequevar 1 (RsII-1, formerly race 3 biovar 2) causes tomato bacterial wilt, potato brown rot, and Southern wilt of geranium. Strains in RsII-1 cause wilting in potato and tomato at cooler temperatures than tropical lowland R. solanacearum strains. Although periodically introduced, RsII-1 has not established in the United States. This pathogen is of quarantine concern and listed as a Federal Select Agent. We report a rapidly sequenced (<2 days) draft genome of UW848, a RsII-1 isolate introduced to the United States in geranium cuttings in spring 2020. UW848 belongs to the near-clonal cluster of RsII-1 global pandemic strains.
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Affiliation(s)
- Veronica Roman-Reyna
- Department of Plant Pathology, The Ohio State University, Columbus, OH
- Infectious Disease Institute, The Ohio State University, Columbus, OH
| | - Alicia Truchon
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI
| | - Parul Sharma
- Department of Computer Science, Virginia Tech, Blacksburg, VA
| | | | - Reza Mazloom
- Department of Computer Science, Virginia Tech, Blacksburg, VA
| | - Boris A Vinatzer
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA
| | - Jonathan M Jacobs
- Department of Plant Pathology, The Ohio State University, Columbus, OH
- Infectious Disease Institute, The Ohio State University, Columbus, OH
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI
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14
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Rivera AJ, Tyx RE, Keong LM, Stanfill SB, Watson CH. Microbial communities and gene contributions in smokeless tobacco products. Appl Microbiol Biotechnol 2020; 104:10613-10629. [PMID: 33180172 PMCID: PMC7849185 DOI: 10.1007/s00253-020-10999-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 10/29/2020] [Accepted: 11/03/2020] [Indexed: 02/05/2023]
Abstract
Smokeless tobacco products (STP) contain bacteria, mold, and fungi due to exposure from surrounding environments and tobacco processing. This has been a cause for concern since the presence of microorganisms has been linked to the formation of highly carcinogenic tobacco-specific nitrosamines. These communities have also been reported to produce toxins and other pro-inflammatory molecules that can cause mouth lesions and elicit inflammatory responses in STP users. Moreover, microbial species in these products could transfer to the mouth and gastrointestinal tract, potentially altering the established respective microbiotas of the consumer. Here, we present the first metagenomic analysis of select smokeless tobacco products, specifically US domestic moist and dry snuff. Bacterial, eukaryotic, and viral species were found in all tobacco products where 68% of the total species was comprised of Bacteria with 3 dominant phyla but also included 32% Eukarya and 1% share abundance for Archaea and Viruses. Furthermore, 693,318 genes were found to be present and included nitrate and nitrite reduction and transport enzymes, antibiotic resistance genes associated with resistance to vancomycin, β-lactamases, their derivatives, and other antibiotics, as well as genes encoding multi-drug transporters and efflux pumps. Additional analyses showed the presence of endo- and exotoxin genes in addition to other molecules associated with inflammatory responses. Our results present a novel aspect of the smokeless tobacco microbiome and provide a better understanding of these products' microbiology. KEY POINTS: • The findings presented will help understand microbial contributions to overall STP chemistries. • Gene function categorization reveals harmful constituents outside canonical forms. • Pathway genes for TSNA precursor activity may occur at early stages of production. • Bacteria in STPs carry antibiotic resistance genes and gene transfer mechanisms.
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Affiliation(s)
- A J Rivera
- Division of Laboratory Sciences, Centers for Disease Control and Prevention, 4770 Buford Highway, NE MS 110-03, Atlanta, GA, 30341-3717, USA.
| | - R E Tyx
- Division of Laboratory Sciences, Centers for Disease Control and Prevention, 4770 Buford Highway, NE MS 110-03, Atlanta, GA, 30341-3717, USA
| | - L M Keong
- Battelle Analytical Services, Atlanta, GA, USA
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - S B Stanfill
- Division of Laboratory Sciences, Centers for Disease Control and Prevention, 4770 Buford Highway, NE MS 110-03, Atlanta, GA, 30341-3717, USA
| | - C H Watson
- Division of Laboratory Sciences, Centers for Disease Control and Prevention, 4770 Buford Highway, NE MS 110-03, Atlanta, GA, 30341-3717, USA
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15
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Paudel S, Dobhal S, Alvarez AM, Arif M. Taxonomy and Phylogenetic Research on Ralstonia solanacearum Species Complex: A Complex Pathogen with Extraordinary Economic Consequences. Pathogens 2020; 9:E886. [PMID: 33113847 PMCID: PMC7694096 DOI: 10.3390/pathogens9110886] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/15/2020] [Accepted: 10/15/2020] [Indexed: 01/22/2023] Open
Abstract
The bacterial wilt pathogen, first known as Bacillus solanacearum, has undergone numerous taxonomic changes since its first description in 1896. The history and significance of this pathogen is covered in this review with an emphasis on the advances in technology that were used to support each reclassification that finally led to the current separation of Ralstonia solanacearum into three genomic species. Frequent name changes occurred as methodology transitioned from phenotypic, biochemical, and molecular studies, to genomics and functional genomics. The diversity, wide host range, and geographical distribution of the bacterial wilt pathogen resulted in its division into three species as genomic analyses elucidated phylogenetic relationships among strains. Current advances in phylogenetics and functional genomics now open new avenues for research into epidemiology and control of the devastating bacterial wilt disease.
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Affiliation(s)
| | | | - Anne M. Alvarez
- Department of Plant and Environmental Protection Sciences, University of Hawaii at Manoa, Honolulu, HI 96822, USA; (S.P.); (S.D.)
| | - Mohammad Arif
- Department of Plant and Environmental Protection Sciences, University of Hawaii at Manoa, Honolulu, HI 96822, USA; (S.P.); (S.D.)
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16
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In Silico and In Vitro Analyses of Glucosamine and Indole Acetaldehyde Inhibit Pathogenic Regulator Gene phcA of Ralstonia solanacearum, a Causative Agent of Bacterial Wilt of Tomato. Appl Biochem Biotechnol 2020; 192:230-242. [DOI: 10.1007/s12010-020-03328-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 04/23/2020] [Indexed: 10/24/2022]
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17
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Fan J, Ma L, Zhao C, Yan J, Che S, Zhou Z, Wang H, Yang L, Hu B. Transcriptome of Pectobacterium carotovorum subsp. carotovorum PccS1 infected in calla plants in vivo highlights a spatiotemporal expression pattern of genes related to virulence, adaptation, and host response. MOLECULAR PLANT PATHOLOGY 2020; 21:871-891. [PMID: 32267092 PMCID: PMC7214478 DOI: 10.1111/mpp.12936] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 02/14/2020] [Accepted: 02/29/2020] [Indexed: 06/11/2023]
Abstract
Bacterial pathogens from the genus Pectobacterium cause soft rot in various plants, and result in important economic losses worldwide. We understand much about how these pathogens digest their hosts and protect themselves against plant defences, as well as some regulatory networks in these processes. However, the spatiotemporal expression of genome-wide infection of Pectobacterium remains unclear, although researchers analysed this in some phytopathogens. In the present work, comparing the transcriptome profiles from cellular infection with growth in minimal and rich media, RNA-Seq analyses revealed that the differentially expressed genes (log2 -fold ratio ≥ 1.0) in the cells of Pectobacterium carotovorum subsp. carotovorum PccS1 recovered at a series of time points after inoculation in the host in vivo covered approximately 50% of genes in the genome. Based on the dynamic expression changes in infection, the significantly differentially expressed genes (log2 -fold ratio ≥ 2.0) were classified into five types, and the main expression pattern of the genes for carbohydrate metabolism underlying the processes of infection was identified. The results are helpful to our understanding of the inducement of host plant and environmental adaption of Pectobacterium. In addition, our results demonstrate that maceration caused by PccS1 is due to the depression of callose deposition in the plant for resistance by the pathogenesis-related genes and the superlytic ability of pectinolytic enzymes produced in PccS1, rather than the promotion of plant cell death elicited by the T3SS of bacteria as described in previous work.
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Affiliation(s)
- Jiaqin Fan
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Lin Ma
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Chendi Zhao
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Jingyuan Yan
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Shu Che
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Zhaowei Zhou
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Huan Wang
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Liuke Yang
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Baishi Hu
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
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18
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Hayashi K, Senuma W, Kai K, Kiba A, Ohnishi K, Hikichi Y. Major exopolysaccharide, EPS I, is associated with the feedback loop in the quorum sensing of Ralstonia solanacearum strain OE1-1. MOLECULAR PLANT PATHOLOGY 2019; 20:1740-1747. [PMID: 31560834 PMCID: PMC6859485 DOI: 10.1111/mpp.12870] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The Gram-negative soil-borne bacterium Ralstonia solanacearum first infects roots of host plants and then invades xylem vessels. In xylem vessels, the bacteria grow vigorously and produce exopolysaccharides (EPSs) to cause a wilt symptom on host plants. The EPSs are thus the main virulence factors of R. solanacearum. The strain OE1-1 of R. solanacearum produces methyl 3-hydroxymyristate as a quorum-sensing (QS) signal, and senses this QS signal, activating QS. The QS-activated LysR-type transcriptional regulator PhcA induces the production of virulence-related metabolites including ralfuranone and the major EPS, EPS I. To elucidate the function of EPS I, the transcriptomes of R. solanacearum strains were analysed using RNA sequencing technology. The expression of 97.2% of the positively QS-regulated genes was down-regulated in the epsB-deleted mutant ΔepsB, which lost its EPS I productivity. Furthermore, expression of 98.0% of the negatively QS-regulated genes was up-regulated in ΔepsB. The deficiency to produce EPS I led to a significantly suppressed ralfuranone productivity and significantly enhanced swimming motility, which are suppressed by QS, but did not affect the expression levels of phcA and phcB, which encode a methyltransferase required for methyl 3-hydroxymyristate production. Overall, QS-dependently produced EPS I may be associated with the feedback loop of QS.
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Affiliation(s)
- Kazusa Hayashi
- Faculty of Agriculture and Marine ScienceKochi UniversityNankokuKochi783‐8502Japan
- Present address:
Kochi Prefectural Agriculture Research CenterNankokuKochi783‐0023Japan
| | - Wakana Senuma
- Faculty of Agriculture and Marine ScienceKochi UniversityNankokuKochi783‐8502Japan
| | - Kenji Kai
- Graduate School of Life and Environmental SciencesOsaka Prefecture UniversitySakaiOsaka599‐8531Japan
| | - Akinori Kiba
- Faculty of Agriculture and Marine ScienceKochi UniversityNankokuKochi783‐8502Japan
| | - Kouhei Ohnishi
- Faculty of Agriculture and Marine ScienceKochi UniversityNankokuKochi783‐8502Japan
| | - Yasufumi Hikichi
- Faculty of Agriculture and Marine ScienceKochi UniversityNankokuKochi783‐8502Japan
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Ferro P, Vaz-Moreira I, Manaia CM. Betaproteobacteria are predominant in drinking water: are there reasons for concern? Crit Rev Microbiol 2019; 45:649-667. [PMID: 31686572 DOI: 10.1080/1040841x.2019.1680602] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Betaproteobacteria include some of the most abundant and ubiquitous bacterial genera that can be found in drinking water, including mineral water. The combination of physiology and ecology traits place some Betaproteobacteria in the list of potential, yet sometimes neglected, opportunistic pathogens that can be transmitted by water or aqueous solutions. Indeed, some drinking water Betaproteobacteria with intrinsic and sometimes acquired antibiotic resistance, harbouring virulence factors and often found in biofilm structures, can persist after water disinfection and reach the consumer. This literature review summarises and discusses the current knowledge about the occurrence and implications of Betaproteobacteria in drinking water. Although the sparse knowledge on the ecology and physiology of Betaproteobacteria thriving in tap or bottled natural mineral/spring drinking water (DW) is an evidence of this review, it is demonstrated that DW holds a high diversity of Betaproteobacteria, whose presence may not be innocuous. Frequently belonging to genera also found in humans, DW Betaproteobacteria are ubiquitous in different habitats, have the potential to resist antibiotics either due to intrinsic or acquired mechanisms, and hold different virulence factors. The combination of these factors places DW Betaproteobacteria in the list of candidates of emerging opportunistic pathogens. Improved bacterial identification of clinical isolates associated with opportunistic infections and additional genomic and physiological studies may contribute to elucidate the potential impact of these bacteria.
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Affiliation(s)
- Pompeyo Ferro
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Porto, Portugal
| | - Ivone Vaz-Moreira
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Porto, Portugal
| | - Célia M Manaia
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Porto, Portugal
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20
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Hayashi K, Kai K, Mori Y, Ishikawa S, Ujita Y, Ohnishi K, Kiba A, Hikichi Y. Contribution of a lectin, LecM, to the quorum sensing signalling pathway of Ralstonia solanacearum strain OE1-1. MOLECULAR PLANT PATHOLOGY 2019; 20:334-345. [PMID: 30312504 PMCID: PMC6637872 DOI: 10.1111/mpp.12757] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The soil-borne bacterium Ralstonia solanacearum invades the roots and colonizes the intercellular spaces and then the xylem. The expression of lecM, encoding a lectin LecM, is induced by an OmpR family response regulator HrpG in R. solanacearum strain OE1-1. LecM contributes to the attachment of strain OE1-1 to the host cells of intercellular spaces. OE1-1 produces methyl 3-hydroxymyristate (3-OH MAME) through a methyltransferase (PhcB) and extracellularly secretes the chemical as a quorum sensing (QS) signal, which activates QS. The expression of lecM is also induced by the PhcA virulence regulator functioning through QS, and the resulting LecM is implicated in the QS-dependent production of major exopolysaccharide EPS I and the aggregation of OE1-1 cells. To investigate the function of LecM in QS, we analysed the transcriptome of R. solanacearum strains generated by RNA sequencing technology. In the lecM mutant, the expression of positively QS-regulated genes and negatively QS-regulated genes was down-regulated (by >90%) and up-regulated (by ~60%), respectively. However, phcB and phcA in the lecM mutant were expressed at levels similar to those in strain OE1-1. The lecM mutant produced significantly less ralfuranone and exhibited a significantly greater swimming motility, which were positively and negatively regulated by QS, respectively. In addition, the extracellular 3-OH MAME content of the lecM mutant was significantly lower than that of OE1-1. The application of 3-OH MAME more strongly increased EPS I production in the phcB-deleted mutant and strain OE1-1 than in the lecM mutant. Thus, the QS-dependent production of LecM contributes to the QS signalling pathway.
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Affiliation(s)
- Kazusa Hayashi
- Laboratory of Plant Pathology and BiotechnologyKochi UniversityNankokuKochi783‐8502Japan
| | - Kenji Kai
- Graduate School of Life and Environmental SciencesOsaka Prefecture UniversitySakaiOsaka599‐8531Japan
| | - Yuka Mori
- Laboratory of Plant Pathology and BiotechnologyKochi UniversityNankokuKochi783‐8502Japan
| | - Shiho Ishikawa
- Laboratory of Plant Pathology and BiotechnologyKochi UniversityNankokuKochi783‐8502Japan
| | - Yumeto Ujita
- Graduate School of Life and Environmental SciencesOsaka Prefecture UniversitySakaiOsaka599‐8531Japan
| | - Kouhei Ohnishi
- Research Institute of Molecular Genetics, Kochi UniversityNankokuKochi783‐8502Japan
| | - Akinori Kiba
- Laboratory of Plant Pathology and BiotechnologyKochi UniversityNankokuKochi783‐8502Japan
| | - Yasufumi Hikichi
- Laboratory of Plant Pathology and BiotechnologyKochi UniversityNankokuKochi783‐8502Japan
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21
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Stulberg MJ, Cai X, Ahmad AA, Huang Q. Identification of a DNA region associated with the cool virulence of Ralstonia solancearum strain UW551 and its utilization for specific detection of the bacterium's race 3 biovar 2 strains. PLoS One 2018; 13:e0207280. [PMID: 30427920 PMCID: PMC6235357 DOI: 10.1371/journal.pone.0207280] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 10/28/2018] [Indexed: 11/19/2022] Open
Abstract
The cool virulent Ralstonia solanacearum race 3 biovar 2 (r3b2) strains cause destructive brown rot of potato. They are quarantined pathogens in Europe and Canada and select agent pathogens in the United States. We previously identified r3b2 (sequevars 1 and 2)-unique fragments that clustered into 32 regions in the genome of R. solanacearum. In this study, we targeted five of those regions for mutagenesis in order to determine whether they are involved in cool temperature-related biological functions for diagnostic purpose. Knockout mutants of four regions produced no changes to the biology of the r3b2 strain UW551. The mutation of region 13, which is 3,407 bp in size, resulted in significantly reduced twitching motility, attachment to the roots of tomato seedlings, and virulence under cool temperature conditions (18-24°C), although no significant difference was found under warm temperature conditions (24-30°C) as compared to the wild type strain. As a result, we designed primer pair Rs-CV-F and Rs-CV-R to target the region 13 for specific detection of r3b2 strains of R. solanacearum. Our assay specifically detected all the 34 r3b2 strains and none of the 56 non-r3b2 strains of R. solanacearum, nor any other five plant- or soil-associated bacteria including Enterobacter cloacae, Pseudomonas syringae pv. syringae, Xanthomonas campestris pv. campestris, X. citri, and R. pickettii. Unexpectedly, in silico analysis predicted that a recently deposited non-sequevar 1 or 2 Brazilian R. solanacearum strain RS489 would be recognized by our assay and by previously published r3b2-specific assays, although the cool-virulent status of this strain is unclear. Our PCR assay is the first to target a DNA region associated with cool-virulence that makes r3b2 strains highly regulated pathogens for specific detection of this important group of R. solanacearum.
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Affiliation(s)
- Michael J. Stulberg
- Floral and Nursery Plants Research Unit, U. S. National Arboretum, U. S. Dept. of Agriculture-Agricultural Research Service, Beltsville, MD, United States of America
| | - Xueqing Cai
- Floral and Nursery Plants Research Unit, U. S. National Arboretum, U. S. Dept. of Agriculture-Agricultural Research Service, Beltsville, MD, United States of America
| | - Abdelmonim Ali Ahmad
- Floral and Nursery Plants Research Unit, U. S. National Arboretum, U. S. Dept. of Agriculture-Agricultural Research Service, Beltsville, MD, United States of America
- Department of Plant Pathology, Faculty of Agriculture, Minia University, El-minia, Egypt
| | - Qi Huang
- Floral and Nursery Plants Research Unit, U. S. National Arboretum, U. S. Dept. of Agriculture-Agricultural Research Service, Beltsville, MD, United States of America
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22
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Kwak MJ, Kong HG, Choi K, Kwon SK, Song JY, Lee J, Lee PA, Choi SY, Seo M, Lee HJ, Jung EJ, Park H, Roy N, Kim H, Lee MM, Rubin EM, Lee SW, Kim JF. Rhizosphere microbiome structure alters to enable wilt resistance in tomato. Nat Biotechnol 2018; 36:nbt.4232. [PMID: 30295674 DOI: 10.1038/nbt.4232] [Citation(s) in RCA: 329] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 08/01/2018] [Indexed: 11/09/2022]
Abstract
Tomato variety Hawaii 7996 is resistant to the soil-borne pathogen Ralstonia solanacearum, whereas the Moneymaker variety is susceptible to the pathogen. To evaluate whether plant-associated microorganisms have a role in disease resistance, we analyzed the rhizosphere microbiomes of both varieties in a mesocosm experiment. Microbiome structures differed between the two cultivars. Transplantation of rhizosphere microbiota from resistant plants suppressed disease symptoms in susceptible plants. Comparative analyses of rhizosphere metagenomes from resistant and susceptible plants enabled the identification and assembly of a flavobacterial genome that was far more abundant in the resistant plant rhizosphere microbiome than in that of the susceptible plant. We cultivated this flavobacterium, named TRM1, and found that it could suppress R. solanacearum-disease development in a susceptible plant in pot experiments. Our findings reveal a role for native microbiota in protecting plants from microbial pathogens, and our approach charts a path toward the development of probiotics to ameliorate plant diseases.
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Affiliation(s)
- Min-Jung Kwak
- Department of Systems Biology, Division of Life Sciences, and Institute for Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Hyun Gi Kong
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Kihyuck Choi
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Soon-Kyeong Kwon
- Department of Systems Biology, Division of Life Sciences, and Institute for Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Ju Yeon Song
- Department of Systems Biology, Division of Life Sciences, and Institute for Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Jidam Lee
- Department of Systems Biology, Division of Life Sciences, and Institute for Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Pyeong An Lee
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Soo Yeon Choi
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | | | - Hyoung Ju Lee
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Eun Joo Jung
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Hyein Park
- Department of Systems Biology, Division of Life Sciences, and Institute for Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Nazish Roy
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Heebal Kim
- C&K Genomics, Seoul, Republic of Korea
- Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Myeong Min Lee
- Department of Systems Biology, Division of Life Sciences, and Institute for Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Edward M Rubin
- Department of Energy Joint Genome Institute (DOE JGI) and Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Seon-Woo Lee
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Jihyun F Kim
- Department of Systems Biology, Division of Life Sciences, and Institute for Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
- Strategic Initiative for Microbiomes in Agriculture and Food (iMAF), Yonsei University, Seoul, Republic of Korea
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23
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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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24
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Mori Y, Hosoi Y, Ishikawa S, Hayashi K, Asai Y, Ohnishi H, Shimatani M, Inoue K, Ikeda K, Nakayashiki H, Nishimura Y, Ohnishi K, Kiba A, Kai K, Hikichi Y. Ralfuranones contribute to mushroom-type biofilm formation by Ralstonia solanacearum strain OE1-1. MOLECULAR PLANT PATHOLOGY 2018; 19:975-985. [PMID: 28722830 PMCID: PMC6638155 DOI: 10.1111/mpp.12583] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 07/04/2017] [Accepted: 07/15/2017] [Indexed: 06/01/2023]
Abstract
After invasion into intercellular spaces of tomato plants, the soil-borne, plant-pathogenic Ralstonia solanacearum strain OE1-1 forms mushroom-shaped biofilms (mushroom-type biofilms, mBFs) on tomato cells, leading to its virulence. The strain OE1-1 produces aryl-furanone secondary metabolites, ralfuranones (A, B, J, K and L), dependent on the quorum sensing (QS) system, with methyl 3-hydroxymyristate (3-OH MAME) synthesized by PhcB as a QS signal. Ralfuranones are associated with the feedback loop of the QS system. A ralfuranone productivity-deficient mutant (ΔralA) exhibited significantly reduced growth in intercellular spaces compared with strain OE1-1, losing its virulence. To analyse the function of ralfuranones in mBF formation by OE1-1 cells, we observed cell aggregates of R. solanacearum strains statically incubated in tomato apoplast fluids on filters under a scanning electron microscope. The ΔralA strain formed significantly fewer microcolonies and mBFs than strain OE1-1. Supplementation of ralfuranones A, B, J and K, but not L, significantly enhanced the development of mBF formation by ΔralA. Furthermore, a phcB- and ralA-deleted mutant (ΔphcB/ralA) exhibited less formation of mBFs than OE1-1, although a QS-deficient, phcB-deleted mutant formed mBFs similar to OE1-1. Supplementation with 3-OH MAME significantly reduced the formation of mBFs by ΔphcB/ralA. The application of each ralfuranone significantly increased the formation of mBFs by ΔphcB/ralA supplied with 3-OH MAME. Together, our findings indicate that ralfuranones are implicated not only in the development of mBFs by strain OE1-1, but also in the suppression of QS-mediated negative regulation of mBF formation.
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Affiliation(s)
- Yuka Mori
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Yuki Hosoi
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Shiho Ishikawa
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Kazusa Hayashi
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Yu Asai
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Hideyuki Ohnishi
- Graduate School of Life and Environmental SciencesOsaka Prefecture UniversitySakaiOsaka599‐8531Japan
| | - Mika Shimatani
- Graduate School of Life and Environmental SciencesOsaka Prefecture UniversitySakaiOsaka599‐8531Japan
| | - Kanako Inoue
- Research Center for Ultra‐High Voltage Electron MicroscopyOsaka University, MihogaokaIbarakiOsaka567‐0047Japan
| | - Kenichi Ikeda
- Graduate School of Agricultural ScienceKobe UniversityNada‐ku, KobeHyogo657‐8501Japan
| | - Hitoshi Nakayashiki
- Graduate School of Agricultural ScienceKobe UniversityNada‐ku, KobeHyogo657‐8501Japan
| | - Yasuyo Nishimura
- Laboratory of Horticultural ScienceKochi University, NankokuKochi783‐8502Japan
| | - Kouhei Ohnishi
- Research Institute of Molecular GeneticsKochi University, NankokuKochi783‐8502Japan
| | - Akinori Kiba
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Kenji Kai
- Graduate School of Life and Environmental SciencesOsaka Prefecture UniversitySakaiOsaka599‐8531Japan
| | - Yasufumi Hikichi
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
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25
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Mori Y, Ishikawa S, Ohnishi H, Shimatani M, Morikawa Y, Hayashi K, Ohnishi K, Kiba A, Kai K, Hikichi Y. Involvement of ralfuranones in the quorum sensing signalling pathway and virulence of Ralstonia solanacearum strain OE1-1. MOLECULAR PLANT PATHOLOGY 2018; 19:454-463. [PMID: 28116815 PMCID: PMC6638173 DOI: 10.1111/mpp.12537] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 01/05/2017] [Accepted: 01/10/2017] [Indexed: 05/02/2023]
Abstract
The soil-borne, plant-pathogenic Ralstonia solanacearum strain OE1-1 produces and secretes methyl 3-hydroxymyristate (3-OH MAME) as a quorum sensing (QS) signal, which contributes to its virulence. A global virulence regulator, PhcA, functioning through the QS system, positively regulates the expression of ralA, which encodes furanone synthase, to produce aryl-furanone secondary metabolites, ralfuranones. A ralfuranone-deficient mutant (ΔralA) is weakly virulent when directly inoculated into tomato xylem vessels. To investigate the functions of ralfuranones, we analysed R. solanacearum transcriptome data generated by RNA sequencing technology. ΔralA expressed phcB, which is associated with 3-OH MAME production, and phcA at levels similar to those in strain OE1-1. In addition, ΔralA exhibited down-regulated expression of more than 90% of the QS positively regulated genes, and up-regulated expression of more than 75% of the QS negatively regulated genes. These results suggest that ralfuranones affect the QS feedback loop. Ralfuranone supplementation restored the ability of ΔralA cells to aggregate. In addition, ralfuranones A and B restored the swimming motility of ΔralA to wild-type levels. However, the application of exogenous ralfuranones did not affect the production of the major exopolysaccharide, EPS I, in ΔralA. Quantitative real-time polymerase chain reaction assays revealed that the deletion of ralA results in the down-regulated expression of vsrAD and vsrBC, which encode a sensor kinase and a response regulator, respectively, in the two-component regulatory systems that influence EPS I production. The application of ralfuranone B restored the expression of these two genes. Overall, our findings indicate that integrated signalling via ralfuranones influences the QS and virulence of R. solanacearum.
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Affiliation(s)
- Yuka Mori
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Shiho Ishikawa
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Hideyuki Ohnishi
- Graduate School of Life and Environmental SciencesOsaka Prefecture University, SakaiOsaka599‐8531Japan
| | - Mika Shimatani
- Graduate School of Life and Environmental SciencesOsaka Prefecture University, SakaiOsaka599‐8531Japan
| | - Yukino Morikawa
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Kazusa Hayashi
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Kouhei Ohnishi
- Research Institute of Molecular GeneticsKochi University, NankokuKochi783‐8502Japan
| | - Akinori Kiba
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
| | - Kenji Kai
- Graduate School of Life and Environmental SciencesOsaka Prefecture University, SakaiOsaka599‐8531Japan
| | - Yasufumi Hikichi
- Laboratory of Plant Pathology and BiotechnologyKochi University, NankokuKochi783‐8502Japan
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26
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Hayes MM, MacIntyre AM, Allen C. Complete Genome Sequences of the Plant Pathogens Ralstonia solanacearum Type Strain K60 and R. solanacearum Race 3 Biovar 2 Strain UW551. GENOME ANNOUNCEMENTS 2017; 5:e01088-17. [PMID: 28983002 PMCID: PMC5629059 DOI: 10.1128/genomea.01088-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 09/01/2017] [Indexed: 11/20/2022]
Abstract
Ralstonia solanacearum is a globally distributed plant pathogen that causes bacterial wilt diseases of many crop hosts, threatening both sustenance farming and industrial agriculture. Here, we present closed genome sequences for the R. solanacearum type strain, K60, and the cool-tolerant potato brown rot strain R. solanacearum UW551, a highly regulated U.S. select agent pathogen.
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Affiliation(s)
- Madeline M Hayes
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - April M MacIntyre
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
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27
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Bocsanczy AM, Huguet-Tapia JC, Norman DJ. Comparative Genomics of Ralstonia solanacearum Identifies Candidate Genes Associated with Cool Virulence. FRONTIERS IN PLANT SCIENCE 2017; 8:1565. [PMID: 28955357 PMCID: PMC5601409 DOI: 10.3389/fpls.2017.01565] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/28/2017] [Indexed: 06/01/2023]
Abstract
Strains of the Ralstonia solanacearum species complex in the phylotype IIB group are capable of causing Bacterial Wilt disease in potato and tomato at temperatures lower than 24°C. The capability of these strains to survive and to incite infection at temperatures colder than their normally tropical boundaries represents a threat to United States agriculture in temperate regions. In this work, we used a comparative genomics approach to identify orthologous genes linked to the lower temperature virulence phenotype. Six R. solanacearum cool virulent (CV) strains were compared to six strains non-pathogenic at low temperature (NPLT). CV strains can cause Bacterial Wilt symptoms at temperatures below 24°C, while NPLT cannot. Four R. solanacearum strains were sequenced for this work in order to complete the comparison. An orthologous genes comparison identified 44 genes present only in CV strains and 19 genes present only in NPLT strains. Gene annotation revealed a high percentage of genes compared with whole genomes in the transcriptional regulator and transport categories. A single nucleotide polymorphism (SNP) analysis identified 265 genes containing conserved non-synonymous SNPs in CV strains. Ten genes in the pathogenicity category were identified in this group. Comparisons of type 3 secretion system, type 6 secretion system (T6SS) clusters, and associated effectors did not indicate a correlation with the CV phenotype except for one T6SS VGR effector potentially associated with the CV phenotype. This is the first R. solanacearum genomic comparative analysis of multiple strains with different temperature related virulence. The candidate genes identified by this comparison are potential factors involved in virulence at low temperatures that need to be investigated. The high percentage of transcriptional regulators among the genes present only in CV strains supports the hypothesis that temperature dependent regulation of virulence genes explains the differential virulence phenotype at low temperatures. This comparison contributes to find new possible connections of temperature dependent virulence to the previously described complex regulatory system involving quorum-sensing, phenotype conversion (phcA), acyl-HSL production and responses to SA. It also added novel candidate T6SS effectors and useful detailed information about the T6SS in R. solanacearum.
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Affiliation(s)
- Ana M. Bocsanczy
- Mid-Florida Research and Education Center, Department of Plant Pathology, University of Florida, ApopkaFL, United States
| | - Jose C. Huguet-Tapia
- Department of Plant Pathology, University of Florida, GainesvilleFL, United States
| | - David J. Norman
- Mid-Florida Research and Education Center, Department of Plant Pathology, University of Florida, ApopkaFL, United States
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28
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Hikichi Y, Mori Y, Ishikawa S, Hayashi K, Ohnishi K, Kiba A, Kai K. Regulation Involved in Colonization of Intercellular Spaces of Host Plants in Ralstonia solanacearum. FRONTIERS IN PLANT SCIENCE 2017; 8:967. [PMID: 28642776 PMCID: PMC5462968 DOI: 10.3389/fpls.2017.00967] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/23/2017] [Indexed: 05/25/2023]
Abstract
A soil-borne bacterium Ralstonia solanacearum invading plant roots first colonizes the intercellular spaces of the root, and eventually enters xylem vessels, where it replicates at high levels leading to wilting symptoms. After invasion into intercellular spaces, R. solanacearum strain OE1-1 attaches to host cells and expression of the hrp genes encoding components of the type III secretion system (T3SS). OE1-1 then constructs T3SS and secrets effectors into host cells, inducing expression of the host gene encoding phosphatidic acid phosphatase. This leads to suppressing plant innate immunity. Then, OE1-1 grows on host cells, inducing quorum sensing (QS). The QS contributes to regulation of OE1-1 colonization of intercellular spaces including mushroom-type biofilm formation on host cells, leading to its virulence. R. solanacearum strains AW1 and K60 produce methyl 3-hydroxypalmitate (3-OH PAME) as a QS signal. The methyltransferase PhcB synthesizes 3-OH PAME. When 3-OH PAME reaches a threshold level, it increases the ability of the histidine kinase PhcS to phosphorylate the response regulator PhcR. This results in elevated levels of functional PhcA, the global virulence regulator. On the other hand, strains OE1-1 and GMI1000 produce methyl 3-hydroxymyristate (3-OH MAME) as a QS signal. Among R. solanacearum strains, the deduced PhcB and PhcS amino acid sequences are related to the production of QS signals. R. solanacearum produces aryl-furanone secondary metabolites, ralfuranones, which are extracellularly secreted and required for its virulence, dependent on the QS. Interestingly, ralfuranones affect the QS feedback loop. Taken together, integrated signaling via ralfuranones influences the QS, contributing to pathogen virulence.
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Affiliation(s)
- Yasufumi Hikichi
- Laboratory of Plant Pathology and Biotechnology, Kochi UniversityKochi, Japan
| | - Yuka Mori
- Laboratory of Plant Pathology and Biotechnology, Kochi UniversityKochi, Japan
| | - Shiho Ishikawa
- Laboratory of Plant Pathology and Biotechnology, Kochi UniversityKochi, Japan
| | - Kazusa Hayashi
- Laboratory of Plant Pathology and Biotechnology, Kochi UniversityKochi, Japan
| | - Kouhei Ohnishi
- Research Institute of Molecular Genetics, Kochi UniversityKochi, Japan
| | - Akinori Kiba
- Laboratory of Plant Pathology and Biotechnology, Kochi UniversityKochi, Japan
| | - Kenji Kai
- Graduate School of Life and Environmental Sciences, Osaka Prefecture UniversityOsaka, Japan
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29
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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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30
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Leonard S, Hommais F, Nasser W, Reverchon S. Plant-phytopathogen interactions: bacterial responses to environmental and plant stimuli. Environ Microbiol 2017; 19:1689-1716. [DOI: 10.1111/1462-2920.13611] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 11/09/2016] [Accepted: 11/16/2016] [Indexed: 01/06/2023]
Affiliation(s)
- Simon Leonard
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - Florence Hommais
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - William Nasser
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - Sylvie Reverchon
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
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31
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Schandry N. A Practical Guide to Visualization and Statistical Analysis of R. solanacearum Infection Data Using R. FRONTIERS IN PLANT SCIENCE 2017; 8:623. [PMID: 28484483 PMCID: PMC5401893 DOI: 10.3389/fpls.2017.00623] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 04/06/2017] [Indexed: 05/11/2023]
Abstract
This paper describes and summarizes approaches for visualization and statistical analysis using data from Ralstonia solanacearum infection experiments based on methods and concepts that are broadly applicable. Members of the R. solanacearum species complex cause bacterial wilt disease. Bacterial wilt is a lethal plant disease and has been studied for over 100 years. During this time various methods to quantify disease and different ways to analyze the generated data have been employed. Here, I aim to provide a general background on three distinct and commonly used measures of disease: the area under the disease progression curve, longitudinal recordings of disease severity and host survival. I will discuss how one can proceed with visualization, statistical analysis, and interpretation using different datasets while revisiting the general concepts of statistical analysis. Datasets and R code to perform all analyses discussed here are included in the supplement.
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32
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Jacques MA, Arlat M, Boulanger A, Boureau T, Carrère S, Cesbron S, Chen NWG, Cociancich S, Darrasse A, Denancé N, Fischer-Le Saux M, Gagnevin L, Koebnik R, Lauber E, Noël LD, Pieretti I, Portier P, Pruvost O, Rieux A, Robène I, Royer M, Szurek B, Verdier V, Vernière C. Using Ecology, Physiology, and Genomics to Understand Host Specificity in Xanthomonas. ANNUAL REVIEW OF PHYTOPATHOLOGY 2016; 54:163-87. [PMID: 27296145 DOI: 10.1146/annurev-phyto-080615-100147] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
How pathogens coevolve with and adapt to their hosts are critical to understanding how host jumps and/or acquisition of novel traits can lead to new disease emergences. The Xanthomonas genus includes Gram-negative plant-pathogenic bacteria that collectively infect a broad range of crops and wild plant species. However, individual Xanthomonas strains usually cause disease on only a few plant species and are highly adapted to their hosts, making them pertinent models to study host specificity. This review summarizes our current understanding of the molecular basis of host specificity in the Xanthomonas genus, with a particular focus on the ecology, physiology, and pathogenicity of the bacterium. Despite our limited understanding of the basis of host specificity, type III effectors, microbe-associated molecular patterns, lipopolysaccharides, transcriptional regulators, and chemotactic sensors emerge as key determinants for shaping host specificity.
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Affiliation(s)
- Marie-Agnès Jacques
- INRA, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), F-49071 Beaucouzé, France; , , , , ,
| | - Matthieu Arlat
- INRA, UMR 441 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France; , , , ,
- CNRS, UMR 2594 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France
- Université de Toulouse, Université Paul Sabatier, F-31062 Toulouse, France
| | - Alice Boulanger
- INRA, UMR 441 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France; , , , ,
- CNRS, UMR 2594 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France
- Université de Toulouse, Université Paul Sabatier, F-31062 Toulouse, France
| | - Tristan Boureau
- Université Angers, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), F-49071 Beaucouzé, France;
| | - Sébastien Carrère
- INRA, UMR 441 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France; , , , ,
| | - Sophie Cesbron
- INRA, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), F-49071 Beaucouzé, France; , , , , ,
| | - Nicolas W G Chen
- Agrocampus Ouest, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), F-49071 Beaucouzé, France;
| | - Stéphane Cociancich
- CIRAD, UMR Biologie et Génétique des Interactions Plante-Parasite (BGPI), F-34398 Montpellier, France; , , ,
| | - Armelle Darrasse
- INRA, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), F-49071 Beaucouzé, France; , , , , ,
| | - Nicolas Denancé
- INRA, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), F-49071 Beaucouzé, France; , , , , ,
| | - Marion Fischer-Le Saux
- INRA, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), F-49071 Beaucouzé, France; , , , , ,
| | - Lionel Gagnevin
- IRD, CIRAD, University of Montpellier, Interactions Plantes Micro-organismes Environnement (IPME), F-34394 Montpellier, France; , , ,
| | - Ralf Koebnik
- IRD, CIRAD, University of Montpellier, Interactions Plantes Micro-organismes Environnement (IPME), F-34394 Montpellier, France; , , ,
| | - Emmanuelle Lauber
- INRA, UMR 441 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France; , , , ,
- CNRS, UMR 2594 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France
| | - Laurent D Noël
- INRA, UMR 441 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France; , , , ,
- CNRS, UMR 2594 Laboratoire des Interactions Plantes Micro-organismes (LIPM), F-31326 Castanet-Tolosan, France
| | - Isabelle Pieretti
- CIRAD, UMR Biologie et Génétique des Interactions Plante-Parasite (BGPI), F-34398 Montpellier, France; , , ,
| | - Perrine Portier
- INRA, UMR 1345 Institut de Recherche en Horticulture et Semences (IRHS), F-49071 Beaucouzé, France; , , , , ,
| | - Olivier Pruvost
- CIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), F-97410 Saint-Pierre, La Réunion, France; , ,
| | - Adrien Rieux
- CIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), F-97410 Saint-Pierre, La Réunion, France; , ,
| | - Isabelle Robène
- CIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), F-97410 Saint-Pierre, La Réunion, France; , ,
| | - Monique Royer
- CIRAD, UMR Biologie et Génétique des Interactions Plante-Parasite (BGPI), F-34398 Montpellier, France; , , ,
| | - Boris Szurek
- IRD, CIRAD, University of Montpellier, Interactions Plantes Micro-organismes Environnement (IPME), F-34394 Montpellier, France; , , ,
| | - Valérie Verdier
- IRD, CIRAD, University of Montpellier, Interactions Plantes Micro-organismes Environnement (IPME), F-34394 Montpellier, France; , , ,
| | - Christian Vernière
- CIRAD, UMR Biologie et Génétique des Interactions Plante-Parasite (BGPI), F-34398 Montpellier, France; , , ,
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33
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Minh Tran T, MacIntyre A, Khokhani D, Hawes M, Allen C. Extracellular DNases of Ralstonia solanacearum modulate biofilms and facilitate bacterial wilt virulence. Environ Microbiol 2016; 18:4103-4117. [PMID: 27387368 DOI: 10.1111/1462-2920.13446] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/01/2016] [Indexed: 12/21/2022]
Abstract
Ralstonia solanacearum is a soil-borne vascular pathogen that colonizes plant xylem vessels, a flowing, low-nutrient habitat where biofilms could be adaptive. Ralstonia solanacearum forms biofilm in vitro, but it was not known if the pathogen benefits from biofilms during infection. Scanning electron microscopy revealed that during tomato infection, R. solanacearum forms biofilm-like masses in xylem vessels. These aggregates contain bacteria embedded in a matrix including chromatin-like fibres commonly observed in other bacterial biofilms. Chemical and enzymatic assays demonstrated that the bacterium releases extracellular DNA in culture and that DNA is an integral component of the biofilm matrix. An R. solanacearum mutant lacking the pathogen's two extracellular nucleases (exDNases) formed non-spreading colonies and abnormally thick biofilms in vitro. The biofilms formed by the exDNase mutant in planta contained more and thicker fibres. This mutant was also reduced in virulence on tomato plants and did not spread in tomato stems as well as the wild-type strain, suggesting that these exDNases facilitate biofilm maturation and bacterial dispersal. To our knowledge, this is the first demonstration that R. solanacearum forms biofilms in plant xylem vessels, and the first documentation that plant pathogens use DNases to modulate their biofilm structure for systemic spread and virulence.
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Affiliation(s)
- Tuan Minh Tran
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - April MacIntyre
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA.,Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Devanshi Khokhani
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Martha Hawes
- Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ, 85721, USA
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA
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Mori Y, Inoue K, Ikeda K, Nakayashiki H, Higashimoto C, Ohnishi K, Kiba A, Hikichi Y. The vascular plant-pathogenic bacterium Ralstonia solanacearum produces biofilms required for its virulence on the surfaces of tomato cells adjacent to intercellular spaces. MOLECULAR PLANT PATHOLOGY 2016; 17:890-902. [PMID: 26609568 PMCID: PMC6638453 DOI: 10.1111/mpp.12335] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/08/2015] [Accepted: 10/13/2015] [Indexed: 05/18/2023]
Abstract
The mechanism of colonization of intercellular spaces by the soil-borne and vascular plant-pathogenic bacterium Ralstonia solanacearum strain OE1-1 after invasion into host plants remains unclear. To analyse the behaviour of OE1-1 cells in intercellular spaces, tomato leaves with the lower epidermis layers excised after infiltration with OE1-1 were observed under a scanning electron microscope. OE1-1 cells formed microcolonies on the surfaces of tomato cells adjacent to intercellular spaces, and then aggregated surrounded by an extracellular matrix, forming mature biofilm structures. Furthermore, OE1-1 cells produced mushroom-type biofilms when incubated in fluids of apoplasts including intercellular spaces, but not xylem fluids from tomato plants. This is the first report of biofilm formation by R. solanacearum on host plant cells after invasion into intercellular spaces and mushroom-type biofilms produced by R. solanacearum in vitro. Sugar application led to enhanced biofilm formation by OE1-1. Mutation of lecM encoding a lectin, RS-IIL, which reportedly exhibits affinity for these sugars, led to a significant decrease in biofilm formation. Colonization in intercellular spaces was significantly decreased in the lecM mutant, leading to a loss of virulence on tomato plants. Complementation of the lecM mutant with native lecM resulted in the recovery of mushroom-type biofilms and virulence on tomato plants. Together, our findings indicate that OE1-1 produces mature biofilms on the surfaces of tomato cells after invasion into intercellular spaces. RS-IIL may contribute to biofilm formation by OE1-1, which is required for OE1-1 virulence.
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Affiliation(s)
- Yuka Mori
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Kanako Inoue
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Kenichi Ikeda
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Hitoshi Nakayashiki
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Chikaki Higashimoto
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Kouhei Ohnishi
- Research Institute of Molecular Genetics, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Akinori Kiba
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Yasufumi Hikichi
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan
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35
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Lowe-Power TM, Jacobs JM, Ailloud F, Fochs B, Prior P, Allen C. Degradation of the Plant Defense Signal Salicylic Acid Protects Ralstonia solanacearum from Toxicity and Enhances Virulence on Tobacco. mBio 2016; 7:e00656-16. [PMID: 27329752 PMCID: PMC4916378 DOI: 10.1128/mbio.00656-16] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 05/09/2016] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED Plants use the signaling molecule salicylic acid (SA) to trigger defenses against diverse pathogens, including the bacterial wilt pathogen Ralstonia solanacearum SA can also inhibit microbial growth. Most sequenced strains of the heterogeneous R. solanacearum species complex can degrade SA via gentisic acid to pyruvate and fumarate. R. solanacearum strain GMI1000 expresses this SA degradation pathway during tomato pathogenesis. Transcriptional analysis revealed that subinhibitory SA levels induced expression of the SA degradation pathway, toxin efflux pumps, and some general stress responses. Interestingly, SA treatment repressed expression of virulence factors, including the type III secretion system, suggesting that this pathogen may suppress virulence functions when stressed. A GMI1000 mutant lacking SA degradation activity was much more susceptible to SA toxicity but retained the wild-type colonization ability and virulence on tomato. This may be because SA is less important than gentisic acid in tomato defense signaling. However, another host, tobacco, responds strongly to SA. To test the hypothesis that SA degradation contributes to virulence on tobacco, we measured the effect of adding this pathway to the tobacco-pathogenic R. solanacearum strain K60, which lacks SA degradation genes. Ectopic addition of the GMI1000 SA degradation locus, including adjacent genes encoding two porins and a LysR-type transcriptional regulator, significantly increased the virulence of strain K60 on tobacco. Together, these results suggest that R. solanacearum degrades plant SA to protect itself from inhibitory levels of this compound and also to enhance its virulence on plant hosts like tobacco that use SA as a defense signal molecule. IMPORTANCE Plant pathogens such as the bacterial wilt agent Ralstonia solanacearum threaten food and economic security by causing significant losses for small- and large-scale growers of tomato, tobacco, banana, potato, and ornamentals. Like most plants, these crop hosts use salicylic acid (SA) both indirectly as a signal to activate defenses and directly as an antimicrobial chemical. We found that SA inhibits growth of R. solanacearum and induces a general stress response that includes repression of multiple bacterial wilt virulence factors. The ability to degrade SA reduces the pathogen's sensitivity to SA toxicity and increases its virulence on tobacco.
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Affiliation(s)
- Tiffany M Lowe-Power
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jonathan M Jacobs
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA Institut de Recherche pour le Développement, UMR Interactions Plantes Microorganismes Environnement, Montpellier, France
| | - Florent Ailloud
- UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, CIRAD-INRA, Saint-Pierre, La Réunion, France Laboratoire de la Santé des Végétaux, Agence Nationale Sécurité Sanitaire Alimentaire Nationale, Saint-Pierre, La Réunion, France
| | - Brianna Fochs
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Philippe Prior
- UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, CIRAD-INRA, Saint-Pierre, La Réunion, France
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
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