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Li T, Moreno-Pérez A, Coaker G. Plant Pattern recognition receptors: Exploring their evolution, diversification, and spatiotemporal regulation. CURRENT OPINION IN PLANT BIOLOGY 2024; 82:102631. [PMID: 39303367 DOI: 10.1016/j.pbi.2024.102631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 08/02/2024] [Accepted: 08/29/2024] [Indexed: 09/22/2024]
Abstract
Plant genomes possess hundreds of candidate surface localized receptors capable of recognizing microbial components or modified-self molecules. Surface-localized pattern recognition receptors (PRRs) can recognize proteins, peptides, or structural microbial components as nonself, triggering complex signaling pathways leading to defense. PRRs possess diverse extracellular domains capable of recognizing epitopes, lipids, glycans and polysaccharides. Recent work highlights advances in our understanding of the diversity and evolution of PRRs recognizing pathogen components. We also discuss PRR functional diversification, pathogen strategies to evade detection, and the role of tissue and age-related resistance for effective plant defense.
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Affiliation(s)
- Tianrun Li
- Department of Plant Pathology, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Alba Moreno-Pérez
- Department of Plant Pathology, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA.
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Jibril SM, Wang C, Yang C, Qu H, Yang X, Yang K, Li C, Wang Y. Multiple Chitin- or Avirulent Strain-Triggered Immunity Induces Microbiome Reassembly in Rice. Microorganisms 2024; 12:1323. [PMID: 39065092 PMCID: PMC11279204 DOI: 10.3390/microorganisms12071323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/28/2024] Open
Abstract
Magnaporthe oryzae is one of the most important fungal pathogens of rice. Chitin and avirulent strains can induce two layers of immunity response, pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI), in rice with cognate R genes. However, little is known about the assembly of the rice microbiome induced by PTI and ETI in rice. In this study, we investigate the impact of continuous treatment of the avirulent M. oryzae strain with AvrPi9 and chitin on the bacterial endophytic community of rice varieties harboring resistant gene Pi9 and their antagonistic activity against rice blast fungus. Analysis of the 16S rRNA showed a significant increase in the diversity and microbial co-occurrence network complexity and the number of beneficial taxa-Bacillus, Pseudomonas, Microbacterium, and Stenotrophomonas spp.-following the chitin and avirulent strain treatments. The antifungal assay with bacterial endophytes recovered from the leaves showed few bacteria with antagonistic potential in rice treated with avirulent strains, suggesting that the sequential treatment of the avirulent strain decreased the antagonistic bacteria against M. oryzae. Moreover, we identified Bacillus safensis Ch_66 and Bacillus altitudinis Nc_68 with overall antagonistic activities in vivo and in vitro. Our findings provide a novel insight into rice microbiome assembly in response to different innate immunity reactions.
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Affiliation(s)
- Sauban Musa Jibril
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China (C.Y.); (H.Q.)
- Yunnan-CABI Joint Laboratory for Integrated Prevention and Control of Transboundary Pests, Yunnan Agricultural University, Kunming 650201, China
| | - Chun Wang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China (C.Y.); (H.Q.)
- Yunnan-CABI Joint Laboratory for Integrated Prevention and Control of Transboundary Pests, Yunnan Agricultural University, Kunming 650201, China
| | - Chao Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China (C.Y.); (H.Q.)
- Yunnan-CABI Joint Laboratory for Integrated Prevention and Control of Transboundary Pests, Yunnan Agricultural University, Kunming 650201, China
| | - Hao Qu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China (C.Y.); (H.Q.)
- Yunnan-CABI Joint Laboratory for Integrated Prevention and Control of Transboundary Pests, Yunnan Agricultural University, Kunming 650201, China
| | - Xinyun Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China (C.Y.); (H.Q.)
- Yunnan-CABI Joint Laboratory for Integrated Prevention and Control of Transboundary Pests, Yunnan Agricultural University, Kunming 650201, China
| | - Kexin Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China (C.Y.); (H.Q.)
- Yunnan-CABI Joint Laboratory for Integrated Prevention and Control of Transboundary Pests, Yunnan Agricultural University, Kunming 650201, China
| | - Chengyun Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China (C.Y.); (H.Q.)
- Yunnan-CABI Joint Laboratory for Integrated Prevention and Control of Transboundary Pests, Yunnan Agricultural University, Kunming 650201, China
| | - Yi Wang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China (C.Y.); (H.Q.)
- Yunnan-CABI Joint Laboratory for Integrated Prevention and Control of Transboundary Pests, Yunnan Agricultural University, Kunming 650201, China
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3
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Vimal SR, Singh JS, Kumar A, Prasad SM. The plant endomicrobiome: Structure and strategies to produce stress resilient future crop. CURRENT RESEARCH IN MICROBIAL SCIENCES 2024; 6:100236. [PMID: 38756233 PMCID: PMC11097330 DOI: 10.1016/j.crmicr.2024.100236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024] Open
Abstract
Plants have a microbiome, a diverse community of microorganisms, including bacteria, fungi, and viruses, living inside and on their tissues. Versatile endophytic microorganisms inhabited in every plant part without causing disease and develop endophytic microbiome or endo-microbiome. Plant endo-microbiome are drawn by the nutrient rich micro-environment, and in turn some microbes mutualistically endorse and protect plant from adverse environmental stresses. Plant endo-microbiome interact within well-designed host equilibrium containing xylem, phloem, nutrients, phytohormones, metabolites and shift according to environmental and nutritional change. Plant endo-microbiome regulate and respond to environmental variations, pathogens, herbivores by producing stress regulators, organic acids, secondary metabolites, stress hormones as well as unknown substances and signalling molecules. Endomicrobiome efficiently synthesizes multiple bioactive compounds, stress phytohormones with high competence. The technological innovation as next generation genomics biology and high-throughput multiomics techniques stepping stones on the illumination of critical endo-microbiome communities and functional characterization that aid in improving plant physiology, biochemistry and immunity interplay for best crop productivity. This review article contains deeper insight in endomicrobiome related research work in last years, recruitment, niche development, nutrient dynamics, stress removal mechanisms, bioactive services in plant health development, community architecture and communication, and immunity interplay in producing stress resilient future crop.
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Affiliation(s)
- Shobhit Raj Vimal
- Ranjan Plant Physiology & Biochemistry Laboratory, Department of Botany, University of Allahabad, Prayagraj 211002, Uttar Pradesh, India
| | - Jay Shankar Singh
- Department of Environmental Microbiology, School for Earth and Environmental Sciences, Babasaheb Bhimrao Ambedkar University, Lucknow 226025, Uttar Pradesh, India
| | - Ashwani Kumar
- Metagenomics and Secretomics Research Laboratory, Department of Botany, University of Allahabad (A Central University), Prayagraj 211002, Uttar Pradesh, India
| | - Sheo Mohan Prasad
- Ranjan Plant Physiology & Biochemistry Laboratory, Department of Botany, University of Allahabad, Prayagraj 211002, Uttar Pradesh, India
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4
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Russ D, Fitzpatrick CR, Teixeira PJPL, Dangl JL. Deep discovery informs difficult deployment in plant microbiome science. Cell 2023; 186:4496-4513. [PMID: 37832524 DOI: 10.1016/j.cell.2023.08.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/28/2023] [Accepted: 08/28/2023] [Indexed: 10/15/2023]
Abstract
Plant-associated microbiota can extend plant immune system function, improve nutrient acquisition and availability, and alleviate abiotic stresses. Thus, naturally beneficial microbial therapeutics are enticing tools to improve plant productivity. The basic definition of plant microbiota across species and ecosystems, combined with the development of reductionist experimental models and the manipulation of plant phenotypes with microbes, has fueled interest in its translation to agriculture. However, the great majority of microbes exhibiting plant-productivity traits in the lab and greenhouse fail in the field. Therapeutic microbes must reach détente, the establishment of uneasy homeostasis, with the plant immune system, invade heterogeneous pre-established plant-associated communities, and persist in a new and potentially remodeled community. Environmental conditions can alter community structure and thus impact the engraftment of therapeutic microbes. We survey recent breakthroughs, challenges, and opportunities in translating beneficial microbes from the lab to the field.
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Affiliation(s)
- Dor Russ
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Connor R Fitzpatrick
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Paulo J P L Teixeira
- Department of Biological Sciences, "Luiz de Queiroz" College of Agriculture (ESALQ), University of São Paulo (USP), Piracicaba, SP, Brazil
| | - Jeffery L Dangl
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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5
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Römling U. Cyclic di-GMP signaling-Where did you come from and where will you go? Mol Microbiol 2023; 120:564-574. [PMID: 37427497 DOI: 10.1111/mmi.15119] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 06/17/2023] [Accepted: 06/22/2023] [Indexed: 07/11/2023]
Abstract
Microbes including bacteria are required to respond to their often continuously changing ecological niches in order to survive. While many signaling molecules are produced as seemingly circumstantial byproducts of common biochemical reactions, there are a few second messenger signaling systems such as the ubiquitous cyclic di-GMP second messenger system that arise through the synthesis of dedicated multidomain enzymes triggered by multiple diverse external and internal signals. Being one of the most numerous and widespread signaling system in bacteria, cyclic di-GMP signaling contributes to adjust physiological and metabolic responses in all available ecological niches. Those niches range from deep-sea and hydrothermal springs to the intracellular environment in human immune cells such as macrophages. This outmost adaptability is possible by the modularity of the cyclic di-GMP turnover proteins which enables coupling of enzymatic activity to the diversity of sensory domains and the flexibility in cyclic di-GMP binding sites. Nevertheless, commonly regulated fundamental microbial behavior include biofilm formation, motility, and acute and chronic virulence. The dedicated domains carrying out the enzymatic activity indicate an early evolutionary origin and diversification of "bona fide" second messengers such as cyclic di-GMP which is estimated to have been present in the last universal common ancestor of archaea and bacteria and maintained in the bacterial kingdom until today. This perspective article addresses aspects of our current view on the cyclic di-GMP signaling system and points to knowledge gaps that still await answers.
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Affiliation(s)
- Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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6
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Wang T, Hua C, Deng X. c-di-GMP signaling in Pseudomonas syringae complex. Microbiol Res 2023; 275:127445. [PMID: 37450986 DOI: 10.1016/j.micres.2023.127445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 07/18/2023]
Abstract
The Pseudomonas syringae Complex is one of the model phytopathogenic bacteria for exploring plant-microbe interactions, causing devastating plant diseases and economic losses worldwide. The ubiquitous second messenger bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) plays an important role in the 'lifestyle switch' from single motile cells to biofilm formation and modulates bacterial behavior, thus influencing virulence in Pseudomonas and other bacterial species. However, less is known about the role of c-di-GMP in the P. syringae complex, in which c-di-GMP levels are controlled by diguanylate cyclases (DGCs) and phosphodiesterases (PDEs), such as Chp8, BifA and WspR. Deletion the chemotaxis receptor PscA also influences c-di-GMP levels, suggesting a cross-talk between chemotaxis and c-di-GMP pathways. Another transcription factor, FleQ, plays a dual role (positive or negative) in regulating cellulose synthesis as a c-di-GMP effector, whereas the transcription factor AmrZ regulates local c-di-GMP levels by inhibiting the DGC enzyme AdcA and the PDE enzyme MorA. Our recent research demonstrated that an increase in the c-di-GMP concentration increased biofilm development, siderophore biosynthesis and oxidative stress tolerance, while it decreased the siderophore content, bacterial motility and type III secretion system activity in P. syringae complex. These findings show that c-di-GMP intricately controls virulence in P. syringae complex, indicating that adjusting c-di-GMP levels may be a valuable tactic for defending plants against pathogens. This review highlights recent research on metabolic enzymes, regulatory mechanisms and the phenotypic consequences of c-di-GMP signaling in the P. syringae.
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Affiliation(s)
- Tingting Wang
- Department of Biomedicine, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Canfeng Hua
- Department of Biomedicine, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Xin Deng
- Department of Biomedicine, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China; Shenzhen Research Institute, City University of Hong Kong, Shenzhen, Hong Kong SAR, China; Tung Research Centre, City University of Hong Kong, Hong Kong SAR, China; Chengdu Research Institute, City University of Hong Kong, Chengdu, China.
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Mesny F, Hacquard S, Thomma BPHJ. Co-evolution within the plant holobiont drives host performance. EMBO Rep 2023; 24:e57455. [PMID: 37471099 PMCID: PMC10481671 DOI: 10.15252/embr.202357455] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 07/21/2023] Open
Abstract
Plants interact with a diversity of microorganisms that influence their growth and resilience, and they can therefore be considered as ecological entities, namely "plant holobionts," rather than as singular organisms. In a plant holobiont, the assembly of above- and belowground microbiota is ruled by host, microbial, and environmental factors. Upon microorganism perception, plants activate immune signaling resulting in the secretion of factors that modulate microbiota composition. Additionally, metabolic interdependencies and antagonism between microbes are driving forces for community assemblies. We argue that complex plant-microbe and intermicrobial interactions have been selected for during evolution and may promote the survival and fitness of plants and their associated microorganisms as holobionts. As part of this process, plants evolved metabolite-mediated strategies to selectively recruit beneficial microorganisms in their microbiota. Some of these microbiota members show host-adaptation, from which mutualism may rapidly arise. In the holobiont, microbiota members also co-evolved antagonistic activities that restrict proliferation of microbes with high pathogenic potential and can therefore prevent disease development. Co-evolution within holobionts thus ultimately drives plant performance.
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Affiliation(s)
- Fantin Mesny
- Institute for Plant SciencesUniversity of CologneCologneGermany
| | - Stéphane Hacquard
- Department of Plant Microbe InteractionsMax Planck Institute for Plant Breeding ResearchCologneGermany
- Cluster of Excellence on Plant Sciences (CEPLAS)CologneGermany
| | - Bart PHJ Thomma
- Institute for Plant SciencesUniversity of CologneCologneGermany
- Cluster of Excellence on Plant Sciences (CEPLAS)CologneGermany
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Cyclic di-GMP Signaling Links Biofilm Formation and Mn(II) Oxidation in Pseudomonas resinovorans. mBio 2022; 13:e0273422. [PMID: 36374078 PMCID: PMC9765421 DOI: 10.1128/mbio.02734-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Bioaugmentation of biological sand filters with Mn(II)-oxidizing bacteria (MOB) is used to increase the efficiency of Mn removal from groundwater. While the biofilm-forming ability of MOB is important to achieve optimal Mn filtration, the regulatory link between biofilm formation and Mn(II) oxidation remains unclear. Here, an environmental isolate of Pseudomonas resinovorans strain MOB-513 was used as a model to investigate the role of c-di-GMP, a second messenger crucially involved in the regulation of biofilm formation by Pseudomonas, in the oxidation of Mn(II). A novel role for c-di-GMP in the upregulation of Mn(II) oxidation through induction of the expression of manganese-oxidizing peroxidase enzymes was revealed. MOB-513 macrocolony biofilms showed a strikingly stratified pattern of biogenic Mn oxide (BMnOx) accumulation in a localized top layer. Remarkably, elevated cellular levels of c-di-GMP correlated not only with increased accumulation of BMnOx in the same top layer but also with the appearance of a second BMnOx stratum in the bottom region of macrocolony biofilms, and the expression of mop genes correlated with this pattern. Proteomic analysis under Mn(II) conditions revealed changes in the abundance of a PilZ domain protein. Subsequent analyses supported a model in which this protein sensed c-di-GMP and affected a regulatory cascade that ultimately inhibited mop gene expression, providing a molecular link between c-di-GMP signaling and Mn(II) oxidation. Finally, we observed that high c-di-GMP levels were correlated with higher lyophilization efficiencies and higher groundwater Mn(II) oxidation capacities of freeze-dried bacterial cells, named lyophiles, showing the biotechnological relevance of understanding the role of c-di-GMP in MOB-513. IMPORTANCE The presence of Mn(II) in groundwater, a common source of drinking water, is a cause of water quality impairment, interfering with its disinfection, causing operation problems, and affecting human health. Purification of groundwater containing Mn(II) plays an important role in environmental and social safety. The typical method for Mn(II) removal is based on bacterial oxidation of metals to form insoluble oxides that can be filtered out of the water. Evidence of reducing the start-up periods and enhancing Mn removal efficiencies through bioaugmentation with appropriate biofilm-forming and MOB has emerged. As preliminary data suggest a link between these two phenotypes in Pseudomonas strains, the need to investigate the underlying regulatory mechanisms is apparent. The significance of our research lies in determining the role of c-di-GMP for increased biofilm formation and Mn(II)-oxidizing capabilities in MOB, which will allow the generation of super-biofilm-elaborating and Mn-oxidizing strains, enabling their implementation in biotechnological applications.
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Lü P, Liu Y, Yu X, Shi CL, Liu X. The right microbe-associated molecular patterns for effective recognition by plants. Front Microbiol 2022; 13:1019069. [PMID: 36225366 PMCID: PMC9549324 DOI: 10.3389/fmicb.2022.1019069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 09/08/2022] [Indexed: 11/13/2022] Open
Abstract
Plants are constantly exposed to diverse microbes and thus develop a sophisticated perceive system to distinguish non-self from self and identify non-self as friends or foes. Plants can detect microbes in apoplast via recognition of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) on the cell surface to activate appropriate signaling in response to microbes. MAMPs are highly conserved but essential molecules of microbes and often buried in microbes’ complex structure. Mature MAMPs are released from microbes by invasion-induced hydrolytic enzymes in apoplast and accumulate in proximity of plasma membrane-localized PRRs to be perceived as ligands to activate downstream signaling. In response, microbes developed strategies to counteract these processing. Here, we review how the form, the concentration, and the size of mature MAMPs affect the PRR-mediated immune signaling. In particular, we describe some potential applications and explore potential open questions in the fields.
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Affiliation(s)
- Pengpeng Lü
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, Jiangxi, China
| | - Yi Liu
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, Jiangxi, China
| | - Xixi Yu
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, Jiangxi, China
- School of Life Sciences, Nanchang University, Nanchang, Jiangxi, China
| | | | - Xiaokun Liu
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, Jiangxi, China
- *Correspondence: Xiaokun Liu,
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Sivakumar R, Gunasekaran P, Rajendhran J. Extracytoplasmic sigma factor AlgU contributes to fitness of Pseudomonas aeruginosa PGPR2 during corn root colonization. Mol Genet Genomics 2022; 297:1537-1552. [PMID: 35980488 DOI: 10.1007/s00438-022-01938-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 07/29/2022] [Indexed: 11/28/2022]
Abstract
In bacteria, sigma factors are crucial in determining the plasticity of core RNA polymerase (RNAP) while promoter recognition during transcription initiation. This process is modulated through an intricate regulatory network in response to environmental cues. Previously, an extracytoplasmic function (ECF) sigma factor, AlgU, was identified to positively influence the fitness of Pseudomonas aeruginosa PGPR2 during corn root colonization. In this study, we report that the inactivation of the algU gene encoded by PGPR2_23995 hampers the root colonization ability of PGPR2. An insertion mutant in the algU gene was constructed by allele exchange mutagenesis. The mutant strains displayed threefold decreased root colonization efficiency compared with the wild-type strain when inoculated individually and in the competition assay. The mutant strain was more sensitive to osmotic and antibiotic stresses and showed higher resistance to oxidative stress. On the other hand, the mutant strain showed increased biofilm formation on the abiotic surface, and the expression of the pelB and pslA genes involved in the biofilm matrix formation were up-regulated. In contrast, the expression of algD, responsible for alginate production, was significantly down-regulated in the mutant strain, which is directly regulated by the AlgU sigma factor. The mutant strain also displayed altered motility. The expression of RNA binding protein RsmA was also impeded in the mutant strain. Further, the transcript levels of genes associated with the type III secretion system (T3SS) were analyzed, which revealed a significant down-regulation in the mutant strain. These results collectively provide evidence for the regulatory role of the AlgU sigma factor in modulating gene expression during root colonization.
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Affiliation(s)
- Ramamoorthy Sivakumar
- Department of Genetics, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, India
| | | | - Jeyaprakash Rajendhran
- Department of Genetics, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, India.
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11
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Krishna PS, Woodcock SD, Pfeilmeier S, Bornemann S, Zipfel C, Malone JG. Pseudomonas syringae addresses distinct environmental challenges during plant infection through the coordinated deployment of polysaccharides. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2206-2221. [PMID: 34905021 PMCID: PMC8982409 DOI: 10.1093/jxb/erab550] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 12/13/2021] [Indexed: 06/14/2023]
Abstract
Prior to infection, phytopathogenic bacteria face a challenging environment on the plant surface, where they are exposed to nutrient starvation and abiotic stresses. Pathways enabling surface adhesion, stress tolerance, and epiphytic survival are important for successful plant pathogenesis. Understanding the roles and regulation of these pathways is therefore crucial to fully understand bacterial plant infections. The phytopathogen Pseudomonas syringae pv. tomato (Pst) encodes multiple polysaccharides that are implicated in biofilm formation, stress survival, and virulence in other microbes. To examine how these polysaccharides impact Pst epiphytic survival and pathogenesis, we analysed mutants in multiple polysaccharide loci to determine their intersecting contributions to epiphytic survival and infection. In parallel, we used qRT-PCR to analyse the regulation of each pathway. Pst polysaccharides are tightly coordinated by multiple environmental signals. Nutrient availability, temperature, and surface association strongly affect the expression of different polysaccharides under the control of the signalling protein genes ladS and cbrB and the second messenger cyclic-di-GMP. Furthermore, functionally redundant, combinatorial phenotypes were observed for several polysaccharides. Exopolysaccharides play a role in mediating leaf adhesion, while α-glucan and alginate together confer desiccation tolerance. Our results suggest that polysaccharides play important roles in overcoming environmental challenges to Pst during plant infection.
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Affiliation(s)
- Pilla Sankara Krishna
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Stuart Daniel Woodcock
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Sebastian Pfeilmeier
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Stephen Bornemann
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Cyril Zipfel
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Jacob George Malone
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
- University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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12
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Lamprokostopoulou A, Römling U. Yin and Yang of Biofilm Formation and Cyclic di-GMP Signaling of the Gastrointestinal Pathogen Salmonella enterica Serovar Typhimurium. J Innate Immun 2021; 14:275-292. [PMID: 34775379 PMCID: PMC9275015 DOI: 10.1159/000519573] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/27/2021] [Indexed: 11/24/2022] Open
Abstract
Within the last 60 years, microbiological research has challenged many dogmas such as bacteria being unicellular microorganisms directed by nutrient sources; these investigations produced new dogmas such as cyclic diguanylate monophosphate (cyclic di-GMP) second messenger signaling as a ubiquitous regulator of the fundamental sessility/motility lifestyle switch on the single-cell level. Successive investigations have not yet challenged this view; however, the complexity of cyclic di-GMP as an intracellular bacterial signal, and, less explored, as an extracellular signaling molecule in combination with the conformational flexibility of the molecule, provides endless opportunities for cross-kingdom interactions. Cyclic di-GMP-directed microbial biofilms commonly stimulate the immune system on a lower level, whereas host-sensed cyclic di-GMP broadly stimulates the innate and adaptive immune responses. Furthermore, while the intracellular second messenger cyclic di-GMP signaling promotes bacterial biofilm formation and chronic infections, oppositely, Salmonella Typhimurium cellulose biofilm inside immune cells is not endorsed. These observations only touch on the complexity of the interaction of biofilm microbial cells with its host. In this review, we describe the Yin and Yang interactive concepts of biofilm formation and cyclic di-GMP signaling using S. Typhimurium as an example.
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Affiliation(s)
| | - Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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13
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Lu H, Wei T, Lou H, Shu X, Chen Q. A Critical Review on Communication Mechanism within Plant-Endophytic Fungi Interactions to Cope with Biotic and Abiotic Stresses. J Fungi (Basel) 2021; 7:719. [PMID: 34575757 PMCID: PMC8466524 DOI: 10.3390/jof7090719] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/07/2021] [Accepted: 08/10/2021] [Indexed: 12/28/2022] Open
Abstract
Endophytic fungi infect plant tissues by evading the immune response, potentially stimulating stress-tolerant plant growth. The plant selectively allows microbial colonization to carve endophyte structures through phenotypic genes and metabolic signals. Correspondingly, fungi develop various adaptations through symbiotic signal transduction to thrive in mycorrhiza. Over the past decade, the regulatory mechanism of plant-endophyte interaction has been uncovered. Currently, great progress has been made on plant endosphere, especially in endophytic fungi. Here, we systematically summarize the current understanding of endophytic fungi colonization, molecular recognition signal pathways, and immune evasion mechanisms to clarify the transboundary communication that allows endophytic fungi colonization and homeostatic phytobiome. In this work, we focus on immune signaling and recognition mechanisms, summarizing current research progress in plant-endophyte communication that converge to improve our understanding of endophytic fungi.
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Affiliation(s)
- Hongyun Lu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou 310058, China; (H.L.); (T.W.); (H.L.)
| | - Tianyu Wei
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou 310058, China; (H.L.); (T.W.); (H.L.)
| | - Hanghang Lou
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou 310058, China; (H.L.); (T.W.); (H.L.)
| | - Xiaoli Shu
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China;
| | - Qihe Chen
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou 310058, China; (H.L.); (T.W.); (H.L.)
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14
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Buscaill P, van der Hoorn RAL. Defeated by the nines: nine extracellular strategies to avoid microbe-associated molecular patterns recognition in plants. THE PLANT CELL 2021; 33:2116-2130. [PMID: 33871653 PMCID: PMC8364246 DOI: 10.1093/plcell/koab109] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/07/2021] [Indexed: 05/13/2023]
Abstract
Recognition of microbe-associated molecular patterns (MAMPs) by cell-surface receptors is pivotal in host-microbe interactions. Both pathogens and symbionts establish plant-microbe interactions using fascinating intricate extracellular strategies to avoid recognition. Here we distinguish nine different extracellular strategies to avoid recognition by the host, acting at three different levels. To avoid the accumulation of MAMP precursors (Level 1), microbes take advantage of polymorphisms in both MAMP proteins and glycans, or downregulate MAMP production. To reduce hydrolytic MAMP release (Level 2), microbes shield MAMP precursors with proteins or glycans and inhibit or degrade host-derived hydrolases. And to prevent MAMP perception directly (Level 3), microbes degrade or sequester MAMPs before they are perceived. We discuss examples of these nine strategies and envisage three additional extracellular strategies to avoid MAMP perception in plants.
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Affiliation(s)
- Pierre Buscaill
- The Plant Chemetics Laboratory, Department of Plant Sciences, University of Oxford, OX1 3RB Oxford, UK
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15
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Bible AN, Chang M, Morrell-Falvey JL. Identification of a diguanylate cyclase expressed in the presence of plants and its application for discovering candidate gene products involved in plant colonization by Pantoea sp. YR343. PLoS One 2021; 16:e0248607. [PMID: 34288916 PMCID: PMC8294551 DOI: 10.1371/journal.pone.0248607] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 07/01/2021] [Indexed: 12/03/2022] Open
Abstract
Microbial colonization of plant roots is a highly complex process that requires the coordination and regulation of many gene networks, yet the identities and functions of many of these gene products have yet to be discovered. Pantoea sp. YR343, a gamma-proteobacterium isolated from the rhizosphere of Populus deltoides, forms robust biofilms along the root surfaces of Populus and possesses plant growth-promoting characteristics. In this work, we identified three diguanylate cyclases in the plant-associated microbe Pantoea sp. YR343 that are expressed in the presence of plant roots. One of these diguanylate cyclases, DGC2884, localizes to discrete sites in the cells and its overexpression results in reduced motility and increased EPS production and biofilm formation. We performed a genetic screen by expressing this diguanylate cyclase from an inducible promoter in order to identify candidate gene products that may be involved in root colonization by Pantoea sp. YR343. Further, we demonstrate the importance of other domains in DGC2884 to its activity, which in combination with the genes identified by transposon mutagenesis, may yield insights into the mechanisms of plant association as well as the activity and regulation of homologous enzymes in medically and agriculturally relevant microbes.
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Affiliation(s)
- Amber N. Bible
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States of America
| | - Mang Chang
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, United States of America
| | - Jennifer L. Morrell-Falvey
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States of America
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, United States of America
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16
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Pfeilmeier S, Petti GC, Bortfeld-Miller M, Daniel B, Field CM, Sunagawa S, Vorholt JA. The plant NADPH oxidase RBOHD is required for microbiota homeostasis in leaves. Nat Microbiol 2021; 6:852-864. [PMID: 34194036 PMCID: PMC7612668 DOI: 10.1038/s41564-021-00929-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 05/25/2021] [Indexed: 02/06/2023]
Abstract
The plant microbiota consists of a multitude of microorganisms that can affect plant health and fitness. However, it is currently unclear how the plant shapes its leaf microbiota and what role the plant immune system plays in this process. Here, we evaluated Arabidopsis thaliana mutants with defects in different parts of the immune system for an altered bacterial community assembly using a gnotobiotic system. While higher-order mutants in receptors that recognize microbial features and in defence hormone signalling showed substantial microbial community alterations, the absence of the plant NADPH oxidase RBOHD caused the most pronounced change in the composition of the leaf microbiota. The rbohD knockout resulted in an enrichment of specific bacteria. Among these, we identified Xanthomonas strains as opportunistic pathogens that colonized wild-type plants asymptomatically but caused disease in rbohD knockout plants. Strain dropout experiments revealed that the lack of RBOHD unlocks the pathogenicity of individual microbiota members driving dysbiosis in rbohD knockout plants. For full protection, healthy plants require both a functional immune system and a microbial community. Our results show that the NADPH oxidase RBOHD is essential for microbiota homeostasis and emphasizes the importance of the plant immune system in controlling the leaf microbiota.
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Affiliation(s)
| | | | | | | | | | | | - Julia A. Vorholt
- Corresponding author: Correspondence should be addressed to J.A.V. ()
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17
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Wang H, Yang Z, Swingle B, Kvitko BH. AlgU, a Conserved Sigma Factor Regulating Abiotic Stress Tolerance and Promoting Virulence in Pseudomonas syringae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:326-336. [PMID: 33264045 DOI: 10.1094/mpmi-09-20-0254-cr] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pseudomonas syringae can rapidly deploy specialized functions to deal with abiotic and biotic stresses. Host niches pose specific sets of environmental challenges driven, in part, by immune defenses. Bacteria use a "just-in-time" strategy of gene regulation, meaning that they only produce the functions necessary for survival as needed. Extracytoplasmic function (ECF) sigma factors transduce a specific set of environmental signals and change gene expression patterns by altering RNA polymerase promoter specificity, to adjust bacterial physiology, structure, or behavior, singly or in combination, to improve chances of survival. The broadly conserved ECF sigma factor AlgU affects virulence in both animal and plant pathogens. Pseudomonas syringae AlgU controls expression of more than 800 genes, some of which contribute to suppression of plant immunity and bacterial fitness in plants. This review discusses AlgU activation mechanisms, functions controlled by AlgU, and how these functions contribute to P. syringae survival in plants.[Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. 2021.
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Affiliation(s)
- Haibi Wang
- Department of Plant Pathology, University of Georgia, 120 Carlton St., Athens, GA 30602, U.S.A
| | - Zichu Yang
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Bldg., Ithaca, NY 14853, U.S.A
| | - Bryan Swingle
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Bldg., Ithaca, NY 14853, U.S.A
- Emerging Pests and Pathogens Research Unit, Robert W. Holley Center, United States Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853, U.S.A
| | - Brian H Kvitko
- Department of Plant Pathology, University of Georgia, 120 Carlton St., Athens, GA 30602, U.S.A
- The Plant Center, University of Georgia, Athens, GA 30602, U.S.A
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18
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Fernández-Llamosas H, Díaz E, Carmona M. Motility, Adhesion and c-di-GMP Influence the Endophytic Colonization of Rice by Azoarcus sp. CIB. Microorganisms 2021; 9:microorganisms9030554. [PMID: 33800326 PMCID: PMC7998248 DOI: 10.3390/microorganisms9030554] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 02/18/2021] [Accepted: 03/05/2021] [Indexed: 01/26/2023] Open
Abstract
Proficient crop production is needed to ensure the feeding of a growing global population. The association of bacteria with plants plays an important role in the health state of the plants contributing to the increase of agricultural production. Endophytic bacteria are ubiquitous in most plant species providing, in most cases, plant promotion properties. However, the knowledge on the genetic determinants involved in the colonization of plants by endophytic bacteria is still poorly understood. In this work we have used a genetic approach based on the construction of fliM, pilX and eps knockout mutants to show that the motility mediated by a functional flagellum and the pili type IV, and the adhesion modulated by exopolysaccarides are required for the efficient colonization of rice roots by the endophyte Azoarcus sp. CIB. Moreover, we have demonstrated that expression of an exogenous diguanylate cyclase or phophodiesterase, which causes either an increase or decrease of the intracellular levels of the second messenger cyclic di-GMP (c-di-GMP), respectively, leads to a reduction of the ability of Azoarcus sp. CIB to colonize rice plants. Here we present results demonstrating the unprecedented role of the universal second messenger cyclic-di-GMP in plant colonization by an endophytic bacterium, Azoarcus sp. CIB. These studies pave the way to further strategies to modulate the interaction of endophytes with their target plant hosts.
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19
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Zboralski A, Filion M. Genetic factors involved in rhizosphere colonization by phytobeneficial Pseudomonas spp. Comput Struct Biotechnol J 2020; 18:3539-3554. [PMID: 33304453 PMCID: PMC7711191 DOI: 10.1016/j.csbj.2020.11.025] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/10/2020] [Accepted: 11/12/2020] [Indexed: 12/13/2022] Open
Abstract
Plant growth-promoting rhizobacteria (PGPR) actively colonize the soil portion under the influence of plant roots, called the rhizosphere. Many plant-beneficial Pseudomonas spp. have been characterized as PGPR. They are ubiquitous rod-shaped motile Gram-negative bacteria displaying a high metabolic versatility. Their capacity to protect plants from pathogens and improve plant growth closely depends on their rhizosphere colonization abilities. Various molecular and cellular mechanisms are involved in this complex process, such as chemotaxis, biofilm formation, secondary metabolites biosynthesis, metabolic versatility, and evasion of plant immunity. The burst in Pseudomonas spp. genome sequencing in recent years has been crucial to better understand how they colonize the rhizosphere. In this review, we discuss the recent advances regarding these mechanisms and the underlying bacterial genetic factors required for successful rhizosphere colonization.
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Affiliation(s)
- Antoine Zboralski
- Department of Biology, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - Martin Filion
- Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada
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20
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Quantitative analysis and influences of contact dynamics on bacterial cross-contamination from contaminated fresh produce. J FOOD ENG 2020. [DOI: 10.1016/j.jfoodeng.2019.109771] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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21
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López-Baena FJ, Vinardell JM, Medina C. Regulation of Protein Secretion Systems Mediated by Cyclic Diguanylate in Plant-Interacting Bacteria. Front Microbiol 2019; 10:1289. [PMID: 31263457 PMCID: PMC6584795 DOI: 10.3389/fmicb.2019.01289] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 05/23/2019] [Indexed: 11/13/2022] Open
Abstract
The ubiquitous second messenger cyclic diguanylate (c-di-GMP) is involved in the regulation of different processes in bacteria. In phytopathogens, intracellular fluctuations in the concentration of this molecule contribute to the lifestyle switching from a motile and virulent stage to a sessile and biofilm-forming phase. Among the virulence mechanisms used by bacterial pathogens, different specific type secretion systems (TSSs) and the effector proteins that they translocate are included. Some of these TSS are conceived to suppress host immune responses during bacterial colonization. The modulation of the expression of secretion systems components and/or effector proteins can be influenced by c-di-GMP levels at transcriptional, translational, or post-translational levels and can take place directly by binding to specific or global regulators, or via transducer proteins. Different genera of plant-interacting bacteria have been analyzed to shed some light in the implications of c-di-GMP in the regulation of host plant colonization through protein secretion systems. Expression of (1) adhesins secreted by Type 1 secretion systems to bind the host plant in Pectobacterium (formerly Erwinia) and some beneficial Pseudomonas strains; (2) catalytic exoproteins delivered by Type 2 secretion systems to break plant cell wall in Dickeya; (3) effectors secreted by Type 3 secretion systems to suppress plant immunity in Xanthomonas; or (4) the activity of Type 6 secretion systems to export an ATPase in Pseudomonas, are finely tuned by c-di-GMP levels. In this minireview, we summarize the knowledge available about the implications of c-di-GMP in the regulation of protein secretion in different plant-interacting bacteria. Topic: Secretion systems and effector proteins of phytopathogenic and beneficial bacteria regulated by NSM.
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Affiliation(s)
| | - Jose María Vinardell
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | - Carlos Medina
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
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22
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Quorum-dependent expression of rsmX and rsmY, small non-coding RNAs, in Pseudomonas syringae. Microbiol Res 2019; 223-225:72-78. [DOI: 10.1016/j.micres.2019.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 02/19/2019] [Accepted: 04/11/2019] [Indexed: 01/01/2023]
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23
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Pleiotropic Effects of c-di-GMP Content in Pseudomonas syringae. Appl Environ Microbiol 2019; 85:AEM.00152-19. [PMID: 30850427 PMCID: PMC6498148 DOI: 10.1128/aem.00152-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 02/27/2019] [Indexed: 12/27/2022] Open
Abstract
The present work comprehensively analyzed the transcriptome and phenotypes that were regulated by c-di-GMP in P. syringae. Given that the majority of diguanylate cyclases and phosphodiesterases have not been characterized in P. syringae, this work provided a very useful database for the future study on regulatory mechanism (especially its relationship with T3SS) of c-di-GMP in P. syringae. In particular, we identified three promoters that were sensitive to elevated c-di-GMP levels and inserted them into luciferase-based reporters that effectively respond to intracellular levels of c-di-GMP in P. syringae, which could be used as an economic and efficient way to measure relative c-di-GMP levels in vivo in the future. Although the ubiquitous bacterial secondary messenger cyclic diguanylate (c-di-GMP) has important cellular functions in a wide range of bacteria, its function in the model plant pathogen Pseudomonas syringae remains largely elusive. To this end, we overexpressed Escherichia coli diguanylate cyclase (YedQ) and phosphodiesterase (YhjH) in P. syringae, resulting in high and low in vivo levels of c-di-GMP, respectively. Via genome-wide RNA sequencing of these two strains, we found that c-di-GMP regulates (i) fliN, fliE, and flhA, which are associated with flagellar assembly; (ii) alg8 and alg44, which are related to the exopolysaccharide biosynthesis pathway; (iii) pvdE, pvdP, and pvsA, which are associated with the siderophore biosynthesis pathway; and (iv) sodA, which encodes a superoxide dismutase. In particular, we identified three promoters that are sensitive to elevated levels of c-di-GMP and inserted them into luciferase-based reporters that respond effectively to the c-di-GMP levels in P. syringae; these promoters could be useful in the measurement of in vivo levels of c-di-GMP in real time. Further phenotypic assays validated the RNA sequencing (RNA-seq) results and confirmed the effect on c-di-GMP-associated pathways, such as repressing the type III secretion system (T3SS) and motility while inducing biofilm production, siderophore production, and oxidative stress resistance. Taken together, these results demonstrate that c-di-GMP regulates the virulence and stress response in P. syringae, which suggests that tuning its level could be a new strategy to protect plants from attacks by this pathogen. IMPORTANCE The present work comprehensively analyzed the transcriptome and phenotypes that were regulated by c-di-GMP in P. syringae. Given that the majority of diguanylate cyclases and phosphodiesterases have not been characterized in P. syringae, this work provided a very useful database for the future study on regulatory mechanism (especially its relationship with T3SS) of c-di-GMP in P. syringae. In particular, we identified three promoters that were sensitive to elevated c-di-GMP levels and inserted them into luciferase-based reporters that effectively respond to intracellular levels of c-di-GMP in P. syringae, which could be used as an economic and efficient way to measure relative c-di-GMP levels in vivo in the future.
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24
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Pseudomonas savastanoi Two-Component System RhpRS Switches between Virulence and Metabolism by Tuning Phosphorylation State and Sensing Nutritional Conditions. mBio 2019; 10:mBio.02838-18. [PMID: 30890603 PMCID: PMC6426608 DOI: 10.1128/mbio.02838-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas savastanoi uses a type III secretion system (T3SS) to invade host plants. Our previous studies have demonstrated that a two-component system (TCS), RhpRS, enables P. savastanoi to coordinate the T3SS gene expression, which depends on the phosphorylation state of RhpR under different environmental conditions. Orthologues of RhpRS are distributed in a wide range of bacterial species, indicating a general regulatory mechanism. How RhpRS uses external signals and the phosphorylation state to exercise its regulatory functions remains unknown. We performed chromatin immunoprecipitation sequencing (ChIP-seq) assays to identify the specific binding sites of RhpR and RhpRD70A in either King's B medium (KB [a T3SS-inhibiting medium]) or minimal medium (MM [a T3SS-inducing medium]). We identified 125 KB-dependent binding sites and 188 phosphorylation-dependent binding sites of RhpR. In KB, RhpR directly and positively regulated cytochrome c 550 production (via ccmA) and alcohol dehydrogenase activity (via adhB) but negatively regulated anthranilate synthase activity (via trpG) and protease activity (via hemB). In addition, phosphorylated RhpR (RhpR-P) directly and negatively regulated the T3SS (via hrpR and hopR1), swimming motility (via flhA), c-di-GMP levels (via PSPPH_2590), and biofilm formation (via algD). It positively regulated twitching motility (via fimA) and lipopolysaccharide production (via PSPPH_2653). Our transcriptome sequencing (RNA-seq) analyses identified 474 and 840 new genes that were regulated by RhpR in KB and MM, respectively. We showed nutrient-rich conditions allowed RhpR to directly regulate multiple metabolic pathways of P. savastanoi and phosphorylation enabled RhpR to specifically control virulence and the cell envelope. The action of RhpRS switched between virulence and regulation of multiple metabolic pathways by tuning its phosphorylation and sensing environmental signals in KB, respectively.IMPORTANCE The plant pathogen Pseudomonas savastanoi invades host plants through a type III secretion system, which is strictly regulated by a two-component system called RhpRS. The orthologues of RhpRS are widely distributed in the bacterial kingdom. The master regulator RhpR specifically depends on the phosphorylation state to regulate the majority of the virulence-related genes. Under nutrient-rich conditions, it modulates many important metabolic pathways, which consist of one-fifth of the genome. We propose that RhpRS uses phosphorylation- and nutrition-dependent mechanisms to switch between regulating virulence and metabolism, and this functionality is widely conserved among bacterial species.
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25
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Matilla MA, Krell T. The effect of bacterial chemotaxis on host infection and pathogenicity. FEMS Microbiol Rev 2018; 42:4563582. [PMID: 29069367 DOI: 10.1093/femsre/fux052] [Citation(s) in RCA: 152] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 10/19/2017] [Indexed: 12/26/2022] Open
Abstract
Chemotaxis enables microorganisms to move according to chemical gradients. Although this process requires substantial cellular energy, it also affords key physiological benefits, including enhanced access to growth substrates. Another important implication of chemotaxis is that it also plays an important role in infection and disease, as chemotaxis signalling pathways are broadly distributed across a variety of pathogenic bacteria. Furthermore, current research indicates that chemotaxis is essential for the initial stages of infection in different human, animal and plant pathogens. This review focuses on recent findings that have identified specific bacterial chemoreceptors and corresponding chemoeffectors associated with pathogenicity. Pathogenicity-related chemoeffectors are either host and niche-specific signals or intermediates of the host general metabolism. Plant pathogens were found to contain an elevated number of chemotaxis signalling genes and functional studies demonstrate that these genes are critical for their ability to enter the host. The expanding body of knowledge of the mechanisms underlying chemotaxis in pathogens provides a foundation for the development of new therapeutic strategies capable of blocking infection and preventing disease by interfering with chemotactic signalling pathways.
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Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
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26
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Santamaría-Hernando S, Rodríguez-Herva JJ, Martínez-García PM, Río-Álvarez I, González-Melendi P, Zamorano J, Tapia C, Rodríguez-Palenzuela P, López-Solanilla E. Pseudomonas syringae pv. tomato exploits light signals to optimize virulence and colonization of leaves. Environ Microbiol 2018; 20:4261-4280. [PMID: 30058114 DOI: 10.1111/1462-2920.14331] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 06/13/2018] [Accepted: 06/17/2018] [Indexed: 11/30/2022]
Abstract
Light is pervasive in the leaf environment, creating opportunities for both plants and pathogens to cue into light as a signal to regulate plant-microbe interactions. Light enhances plant defences and regulates opening of stomata, an entry point for foliar bacterial pathogens such as Pseudomonas syringae pv. tomato DC3000 (PsPto). The effect of light perception on gene expression and virulence was investigated in PsPto. Light induced genetic reprogramming in PsPto that entailed significant changes in stress tolerance and virulence. Blue light-mediated up-regulation of type three secretion system genes and red light-mediated down-regulation of coronatine biosynthesis genes. Cells exposed to white light, blue light or darkness before inoculation were more virulent when inoculated at dawn than dusk probably due to an enhanced entry through open stomata. Exposure to red light repressed coronatine biosynthesis genes which could lead to a reduced stomatal re-opening and PsPto entry. Photoreceptor were required for the greater virulence of light-treated and dark-treated PsPto inoculated at dawn as compared to dusk, indicating that these proteins sense the absence of light and contribute to priming of virulence in the dark. These results support a model in which PsPto exploits light changes to maximize survival, entry and virulence on plants.
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Affiliation(s)
- Saray Santamaría-Hernando
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) Campus Montegancedo UPM, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - José J Rodríguez-Herva
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) Campus Montegancedo UPM, Pozuelo de Alarcón, 28223, Madrid, Spain.,Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Madrid, Spain
| | - Pedro M Martínez-García
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) Campus Montegancedo UPM, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Isabel Río-Álvarez
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) Campus Montegancedo UPM, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Pablo González-Melendi
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) Campus Montegancedo UPM, Pozuelo de Alarcón, 28223, Madrid, Spain.,Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Madrid, Spain
| | - Jaime Zamorano
- Departamento de Astrofísica y CC. de la Atmósfera, Universidad Complutense, Madrid, Spain
| | - Carlos Tapia
- Departamento de Astrofísica y CC. de la Atmósfera, Universidad Complutense, Madrid, Spain
| | - Pablo Rodríguez-Palenzuela
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) Campus Montegancedo UPM, Pozuelo de Alarcón, 28223, Madrid, Spain.,Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Madrid, Spain
| | - Emilia López-Solanilla
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) Campus Montegancedo UPM, Pozuelo de Alarcón, 28223, Madrid, Spain.,Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Madrid, Spain
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Chagas FO, Pessotti RDC, Caraballo-Rodríguez AM, Pupo MT. Chemical signaling involved in plant-microbe interactions. Chem Soc Rev 2018; 47:1652-1704. [PMID: 29218336 DOI: 10.1039/c7cs00343a] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Microorganisms are found everywhere, and they are closely associated with plants. Because the establishment of any plant-microbe association involves chemical communication, understanding crosstalk processes is fundamental to defining the type of relationship. Although several metabolites from plants and microbes have been fully characterized, their roles in the chemical interplay between these partners are not well understood in most cases, and they require further investigation. In this review, we describe different plant-microbe associations from colonization to microbial establishment processes in plants along with future prospects, including agricultural benefits.
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Affiliation(s)
- Fernanda Oliveira Chagas
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo (FCFRP-USP), Avenida do Café, s/n, 14040-903, Ribeirão Preto-SP, Brazil.
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28
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Tang H, Zhang Y, Ma Y, Tang M, Shen D, Wang M. Regulation of Nicotine Tolerance by Quorum Sensing and High Efficiency of Quorum Quenching Under Nicotine Stress in Pseudomonas aeruginosa PAO1. Front Cell Infect Microbiol 2018; 8:88. [PMID: 29616198 PMCID: PMC5869914 DOI: 10.3389/fcimb.2018.00088] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 03/06/2018] [Indexed: 01/01/2023] Open
Abstract
Quorum sensing (QS) regulates the behavior of bacterial populations and promotes their adaptation and survival under stress. As QS is responsible for the virulence of vast majority of bacteria, quorum quenching (QQ), the interruption of QS, has become an attractive therapeutic strategy. However, the role of QS in stress tolerance and the efficiency of QQ under stress in bacteria are seldom explored. In this study, we demonstrated that QS-regulated catalase (CAT) expression and biofilm formation help Pseudomonas aeruginosa PAO1 resist nicotine stress. CAT activity and biofilm formation in wild type (WT) and ΔrhlR strains are significantly higher than those in the ΔlasR strain. Supplementation of ΔlasI strain with 3OC12-HSL showed similar CAT activity and biofilm formation as those of the WT strain. LasIR circuit rather than RhlIR circuit is vital to nicotine tolerance. Acylase I significantly decreased the production of virulence factors, namely elastase, pyocyanin, and pyoverdine under nicotine stress compared to the levels observed in the absence of nicotine stress. Thus, QQ is more efficient under stress. To our knowledge, this is the first study to report that QS contributes to nicotine tolerance in P. aeruginosa. This work facilitates a better application of QQ for the treatment of bacterial infections, especially under stress.
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Affiliation(s)
- Huiming Tang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China
| | - Yunyun Zhang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
| | - Yifan Ma
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China
| | - Mengmeng Tang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China
| | - Dongsheng Shen
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
| | - Meizhen Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
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29
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Muriel C, Arrebola E, Redondo-Nieto M, Martínez-Granero F, Jalvo B, Pfeilmeier S, Blanco-Romero E, Baena I, Malone JG, Rivilla R, Martín M. AmrZ is a major determinant of c-di-GMP levels in Pseudomonas fluorescens F113. Sci Rep 2018; 8:1979. [PMID: 29386661 PMCID: PMC5792552 DOI: 10.1038/s41598-018-20419-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/18/2018] [Indexed: 01/17/2023] Open
Abstract
The transcriptional regulator AmrZ is a global regulatory protein conserved within the pseudomonads. AmrZ can act both as a positive and a negative regulator of gene expression, controlling many genes implicated in environmental adaption. Regulated traits include motility, iron homeostasis, exopolysaccharides production and the ability to form biofilms. In Pseudomonas fluorescens F113, an amrZ mutant presents a pleiotropic phenotype, showing increased swimming motility, decreased biofilm formation and very limited ability for competitive colonization of rhizosphere, its natural habitat. It also shows different colony morphology and binding of the dye Congo Red. The amrZ mutant presents severely reduced levels of the messenger molecule cyclic-di-GMP (c-di-GMP), which is consistent with the motility and biofilm formation phenotypes. Most of the genes encoding proteins with diguanylate cyclase (DGCs) or phosphodiesterase (PDEs) domains, implicated in c-di-GMP turnover in this bacterium, appear to be regulated by AmrZ. Phenotypic analysis of eight mutants in genes shown to be directly regulated by AmrZ and encoding c-di-GMP related enzymes, showed that seven of them were altered in motility and/or biofilm formation. The results presented here show that in P. fluorescens, AmrZ determines c-di-GMP levels through the regulation of a complex network of genes encoding DGCs and PDEs.
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Affiliation(s)
- Candela Muriel
- Departamento de Biología, Universidad Autónoma de Madrid, Darwin, 2, 28034, Madrid, Spain
| | - Eva Arrebola
- Departamento de Biología, Universidad Autónoma de Madrid, Darwin, 2, 28034, Madrid, Spain
| | - Miguel Redondo-Nieto
- Departamento de Biología, Universidad Autónoma de Madrid, Darwin, 2, 28034, Madrid, Spain
| | | | - Blanca Jalvo
- Departamento de Biología, Universidad Autónoma de Madrid, Darwin, 2, 28034, Madrid, Spain
| | - Sebastian Pfeilmeier
- Department of Molecular Microbiology, John Innes Centre, Colney Lane, NR47UH, Norwich, UK
| | - Esther Blanco-Romero
- Departamento de Biología, Universidad Autónoma de Madrid, Darwin, 2, 28034, Madrid, Spain
| | - Irene Baena
- Departamento de Biología, Universidad Autónoma de Madrid, Darwin, 2, 28034, Madrid, Spain
| | - Jacob G Malone
- Department of Molecular Microbiology, John Innes Centre, Colney Lane, NR47UH, Norwich, UK
| | - Rafael Rivilla
- Departamento de Biología, Universidad Autónoma de Madrid, Darwin, 2, 28034, Madrid, Spain
| | - Marta Martín
- Departamento de Biología, Universidad Autónoma de Madrid, Darwin, 2, 28034, Madrid, Spain.
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30
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Hacquard S, Spaepen S, Garrido-Oter R, Schulze-Lefert P. Interplay Between Innate Immunity and the Plant Microbiota. ANNUAL REVIEW OF PHYTOPATHOLOGY 2017; 55:565-589. [PMID: 28645232 DOI: 10.1146/annurev-phyto-080516-035623] [Citation(s) in RCA: 233] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The innate immune system of plants recognizes microbial pathogens and terminates their growth. However, recent findings suggest that at least one layer of this system is also engaged in cooperative plant-microbe interactions and influences host colonization by beneficial microbial communities. This immune layer involves sensing of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) that initiate quantitative immune responses to control host-microbial load, whereas diversification of MAMPs and PRRs emerges as a mechanism that locally sculpts microbial assemblages in plant populations. This suggests a more complex microbial management role of the innate immune system for controlled accommodation of beneficial microbes and in pathogen elimination. The finding that similar molecular strategies are deployed by symbionts and pathogens to dampen immune responses is consistent with this hypothesis but implies different selective pressures on the immune system due to contrasting outcomes on plant fitness. The reciprocal interplay between microbiota and the immune system likely plays a critical role in shaping beneficial plant-microbiota combinations and maintaining microbial homeostasis.
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Affiliation(s)
- Stéphane Hacquard
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany;
| | - Stijn Spaepen
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany;
| | - Ruben Garrido-Oter
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany;
- Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Paul Schulze-Lefert
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany;
- Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
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31
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Caballo-Ponce E, Murillo J, Martínez-Gil M, Moreno-Pérez A, Pintado A, Ramos C. Knots Untie: Molecular Determinants Involved in Knot Formation Induced by Pseudomonas savastanoi in Woody Hosts. FRONTIERS IN PLANT SCIENCE 2017; 8:1089. [PMID: 28680437 PMCID: PMC5478681 DOI: 10.3389/fpls.2017.01089] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/06/2017] [Indexed: 05/10/2023]
Abstract
The study of the molecular basis of tree diseases is lately receiving a renewed attention, especially with the emerging perception that pathogens require specific pathogenicity and virulence factors to successfully colonize woody hosts. Pathosystems involving woody plants are notoriously difficult to study, although the use of model bacterial strains together with genetically homogeneous micropropagated plant material is providing a significant impetus to our understanding of the molecular determinants leading to disease. The gammaproteobacterium Pseudomonas savastanoi belongs to the intensively studied Pseudomonas syringae complex, and includes three pathogenic lineages causing tumorous overgrowths (knots) in diverse economically relevant trees and shrubs. As it occurs with many other bacteria, pathogenicity of P. savastanoi is dependent on a type III secretion system, which is accompanied by a core set of at least 20 effector genes shared among strains isolated from olive, oleander, and ash. The induction of knots of wild-type size requires that the pathogen maintains adequate levels of diverse metabolites, including the phytohormones indole-3-acetic acid and cytokinins, as well as cyclic-di-GMP, some of which can also regulate the expression of other pathogenicity and virulence genes and participate in bacterial competitiveness. In a remarkable example of social networking, quorum sensing molecules allow for the communication among P. savastanoi and other members of the knot microbiome, while at the same time are essential for tumor formation. Additionally, a distinguishing feature of bacteria from the P. syringae complex isolated from woody organs is the possession of a 15 kb genomic island (WHOP) carrying four operons and three other genes involved in degradation of phenolic compounds. Two of these operons mediate the catabolism of anthranilate and catechol and, together with another operon, are required for the induction of full-size tumors in woody hosts, but not in non-woody micropropagated plants. The use of transposon mutagenesis also uncovered a treasure trove of additional P. savastanoi genes affecting virulence and participating in diverse bacterial processes. Although there is still much to be learned on what makes a bacterium a successful pathogen of trees, we are already untying the knots.
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Affiliation(s)
- Eloy Caballo-Ponce
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Jesús Murillo
- Departamento de Producción Agraria, ETS de Ingenieros Agrónomos, Universidad Pública de NavarraPamplona, Spain
| | - Marta Martínez-Gil
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Alba Moreno-Pérez
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Adrián Pintado
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Cayo Ramos
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
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32
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Chakravarthy S, Butcher BG, Liu Y, D'Amico K, Coster M, Filiatrault MJ. Virulence of Pseudomonas syringae pv. tomato DC3000 Is Influenced by the Catabolite Repression Control Protein Crc. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:283-294. [PMID: 28384054 DOI: 10.1094/mpmi-09-16-0196-r] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Pseudomonas syringae infects diverse plant species and is widely used as a model system in the study of effector function and the molecular basis of plant diseases. Although the relationship between bacterial metabolism, nutrient acquisition, and virulence has attracted increasing attention in bacterial pathology, it is largely unexplored in P. syringae. The Crc (catabolite repression control) protein is a putative RNA-binding protein that regulates carbon metabolism as well as a number of other factors in the pseudomonads. Here, we show that deletion of crc increased bacterial swarming motility and biofilm formation. The crc mutant showed reduced growth and symptoms in Arabidopsis and tomato when compared with the wild-type strain. We have evidence that the crc mutant shows delayed hypersensitive response (HR) when infiltrated into Nicotiana benthamiana and tobacco. Interestingly, the crc mutant was more susceptible to hydrogen peroxide, suggesting that, in planta, the mutant may be sensitive to reactive oxygen species generated during pathogen-associated molecular pattern-triggered immunity (PTI). Indeed, HR was further delayed when PTI-induced tissues were challenged with the crc mutant. The crc mutant did not elicit an altered PTI response in plants compared with the wild-type strain. We conclude that Crc plays an important role in growth and survival during infection.
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Affiliation(s)
- Suma Chakravarthy
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
| | - Bronwyn G Butcher
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
| | - Yingyu Liu
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
| | - Katherine D'Amico
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
- 2 Emerging Pests & Pathogens Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, U.S.A
| | - Matthew Coster
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
| | - Melanie J Filiatrault
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
- 2 Emerging Pests & Pathogens Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, U.S.A
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33
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Pfeilmeier S, Caly DL, Malone JG. Bacterial pathogenesis of plants: future challenges from a microbial perspective: Challenges in Bacterial Molecular Plant Pathology. MOLECULAR PLANT PATHOLOGY 2016; 17:1298-313. [PMID: 27170435 PMCID: PMC6638335 DOI: 10.1111/mpp.12427] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 05/08/2016] [Accepted: 05/10/2016] [Indexed: 05/03/2023]
Abstract
Plant infection is a complicated process. On encountering a plant, pathogenic microorganisms must first adapt to life on the epiphytic surface, and survive long enough to initiate an infection. Responsiveness to the environment is critical throughout infection, with intracellular and community-level signal transduction pathways integrating environmental signals and triggering appropriate responses in the bacterial population. Ultimately, phytopathogens must migrate from the epiphytic surface into the plant tissue using motility and chemotaxis pathways. This migration is coupled with overcoming the physical and chemical barriers to entry into the plant apoplast. Once inside the plant, bacteria use an array of secretion systems to release phytotoxins and protein effectors that fulfil diverse pathogenic functions (Fig. ) (Melotto and Kunkel, ; Phan Tran et al., ). As our understanding of the pathways and mechanisms underpinning plant pathogenicity increases, a number of central research challenges are emerging that will profoundly shape the direction of research in the future. We need to understand the bacterial phenotypes that promote epiphytic survival and surface adaptation in pathogenic bacteria. How do these pathways function in the context of the plant-associated microbiome, and what impact does this complex microbial community have on the onset and severity of plant infections? The huge importance of bacterial signal transduction to every stage of plant infection is becoming increasingly clear. However, there is a great deal to learn about how these signalling pathways function in phytopathogenic bacteria, and the contribution they make to various aspects of plant pathogenicity. We are increasingly able to explore the structural and functional diversity of small-molecule natural products from plant pathogens. We need to acquire a much better understanding of the production, deployment, functional redundancy and physiological roles of these molecules. Type III secretion systems (T3SSs) are important and well-studied contributors to bacterial disease. Several key unanswered questions will shape future investigations of these systems. We need to define the mechanism of hierarchical and temporal control of effector secretion. For successful infection, effectors need to interact with host components to exert their function. Advanced biochemical, proteomic and cell biological techniques will enable us to study the function of effectors inside the host cell in more detail and on a broader scale. Population genomics analyses provide insight into evolutionary adaptation processes of phytopathogens. The determination of the diversity and distribution of type III effectors (T3Es) and other virulence genes within and across pathogenic species, pathovars and strains will allow us to understand how pathogens adapt to specific hosts, the evolutionary pathways available to them, and the possible future directions of the evolutionary arms race between effectors and molecular plant targets. Although pathogenic bacteria employ a host of different virulence and proliferation strategies, as a result of the space constraints, this review focuses mainly on the hemibiotrophic pathogens. We discuss the process of plant infection from the perspective of these important phytopathogens, and highlight new approaches to address the outstanding challenges in this important and fast-moving field.
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Affiliation(s)
- Sebastian Pfeilmeier
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Delphine L Caly
- Université de Lille, EA 7394, ICV - Institut Charles Viollette, Lille, F-59000, France
| | - Jacob G Malone
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
- University of East Anglia, Norwich, NR4 7TJ, UK.
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34
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Trampari E, Stevenson CEM, Little RH, Wilhelm T, Lawson DM, Malone JG. Bacterial rotary export ATPases are allosterically regulated by the nucleotide second messenger cyclic-di-GMP. J Biol Chem 2015; 290:24470-83. [PMID: 26265469 PMCID: PMC4591828 DOI: 10.1074/jbc.m115.661439] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Indexed: 01/03/2023] Open
Abstract
The widespread second messenger molecule cyclic di-GMP (cdG) regulates the transition from motile and virulent lifestyles to sessile, biofilm-forming ones in a wide range of bacteria. Many pathogenic and commensal bacterial-host interactions are known to be controlled by cdG signaling. Although the biochemistry of cyclic dinucleotide metabolism is well understood, much remains to be discovered about the downstream signaling pathways that induce bacterial responses upon cdG binding. As part of our ongoing research into the role of cdG signaling in plant-associated Pseudomonas species, we carried out an affinity capture screen for cdG binding proteins in the model organism Pseudomonas fluorescens SBW25. The flagella export AAA+ ATPase FliI was identified as a result of this screen and subsequently shown to bind specifically to the cdG molecule, with a KD in the low micromolar range. The interaction between FliI and cdG appears to be very widespread. In addition to FliI homologs from diverse bacterial species, high affinity binding was also observed for the type III secretion system homolog HrcN and the type VI ATPase ClpB2. The addition of cdG was shown to inhibit FliI and HrcN ATPase activity in vitro. Finally, a combination of site-specific mutagenesis, mass spectrometry, and in silico analysis was used to predict that cdG binds to FliI in a pocket of highly conserved residues at the interface between two FliI subunits. Our results suggest a novel, fundamental role for cdG in controlling the function of multiple important bacterial export pathways, through direct allosteric control of export ATPase proteins.
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Affiliation(s)
| | - Clare E M Stevenson
- the Biological Chemistry Department, John Innes Centre, Norwich NR4 7UH, United Kingdom
| | | | - Thomas Wilhelm
- the Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, United Kingdom, and
| | - David M Lawson
- the Biological Chemistry Department, John Innes Centre, Norwich NR4 7UH, United Kingdom
| | - Jacob G Malone
- From the Molecular Microbiology Department and the School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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