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Rico-Jiménez M, Udaondo Z, Krell T, Matilla MA. Auxin-mediated regulation of susceptibility to toxic metabolites, c-di-GMP levels, and phage infection in the rhizobacterium Serratia plymuthica. mSystems 2024; 9:e0016524. [PMID: 38837409 PMCID: PMC11264596 DOI: 10.1128/msystems.00165-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 04/26/2024] [Indexed: 06/07/2024] Open
Abstract
The communication between plants and their microbiota is highly dynamic and involves a complex network of signal molecules. Among them, the auxin indole-3-acetic acid (IAA) is a critical phytohormone that not only regulates plant growth and development, but is emerging as an important inter- and intra-kingdom signal that modulates many bacterial processes that are important during interaction with their plant hosts. However, the corresponding signaling cascades remain largely unknown. Here, we advance our understanding of the largely unknown mechanisms by which IAA carries out its regulatory functions in plant-associated bacteria. We showed that IAA caused important changes in the global transcriptome of the rhizobacterium Serratia plymuthica and multidisciplinary approaches revealed that IAA sensing interferes with the signaling mediated by other pivotal plant-derived signals such as amino acids and 4-hydroxybenzoic acid. Exposure to IAA caused large alterations in the transcript levels of genes involved in amino acid metabolism, resulting in significant metabolic alterations. IAA treatment also increased resistance to toxic aromatic compounds through the induction of the AaeXAB pump, which also confers resistance to IAA. Furthermore, IAA promoted motility and severely inhibited biofilm formation; phenotypes that were associated with decreased c-di-GMP levels and capsule production. IAA increased capsule gene expression and enhanced bacterial sensitivity to a capsule-dependent phage. Additionally, IAA induced the expression of several genes involved in antibiotic resistance and led to changes in the susceptibility and responses to antibiotics with different mechanisms of action. Collectively, our study illustrates the complexity of IAA-mediated signaling in plant-associated bacteria. IMPORTANCE Signal sensing plays an important role in bacterial adaptation to ecological niches and hosts. This communication appears to be particularly important in plant-associated bacteria since they possess a large number of signal transduction systems that respond to a wide diversity of chemical, physical, and biological stimuli. IAA is emerging as a key inter- and intra-kingdom signal molecule that regulates a variety of bacterial processes. However, despite the extensive knowledge of the IAA-mediated regulatory mechanisms in plants, IAA signaling in bacteria remains largely unknown. Here, we provide insight into the diversity of mechanisms by which IAA regulates primary and secondary metabolism, biofilm formation, motility, antibiotic susceptibility, and phage sensitivity in a biocontrol rhizobacterium. This work has important implications for our understanding of bacterial ecology in plant environments and for the biotechnological and clinical applications of IAA, as well as related molecules.
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Affiliation(s)
- Miriam Rico-Jiménez
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Zulema Udaondo
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, Spain
| | - Tino Krell
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Miguel A. Matilla
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
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2
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Zhang X, Li H, Li B, Song K, Sha Y, Liu Y, Dong S, Wang D, Yang L. Microbial Community Shifts in Tea Plant Rhizosphere under Seawater Stress: Enrichment of Beneficial Taxa. Microorganisms 2024; 12:1287. [PMID: 39065056 PMCID: PMC11279268 DOI: 10.3390/microorganisms12071287] [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: 05/15/2024] [Revised: 06/10/2024] [Accepted: 06/18/2024] [Indexed: 07/28/2024] Open
Abstract
Seawater intrusion has a significant impact on the irrigation quality of agricultural water, thereby posing a threat to plant growth and development. We hypothesized that the rhizosphere of tea plants harbors beneficial microorganisms, which may improve the tolerance of tea plants to seawater stress. This study utilized 16s and ITS techniques to analyze microbial community shifts in the tea plant rhizosphere and non-rhizosphere under seawater stress conditions. The findings suggest that seawater stress leads to a reduction in microbial diversity, although the rhizosphere microbial diversity in stressed soils showed a relatively higher level. Moreover, the rhizosphere of the tea plant under seawater stress exhibited an enrichment of plant growth-promoting rhizobacteria alongside a higher presence of pathogenic fungi. Network analysis revealed that seawater stress resulted in the construction of a more complex and stable rhizosphere microbial network compared to normal conditions. Predictions of bacterial potential functions highlighted a greater diversity of functional groups, enhancing resource utilization efficiency. In general, the rhizosphere microorganisms of tea plants are jointly selected by seawater and the host. The microorganisms closely related to the rhizosphere of tea plants are retained and, at the same time, attract beneficial microorganisms that may alleviate stress. These findings provide new insights into plant responses to saline stress and have significant implications for leveraging vegetation to enhance the resilience of coastal saline soils and contribute to economic progress.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Long Yang
- College of Plant Protection and Agricultural Big-Data Research Center, Shandong Agricultural University, Tai’an 271018, China (K.S.); (Y.L.)
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Morris S, Quispe-Arpasi D, Lens PNL. Effect of Rhodococcus opacus PD630 on selenium phytoremediation by Brassica oleracea. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2024; 26:1280-1290. [PMID: 38348969 DOI: 10.1080/15226514.2024.2311725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
The purpose of this study was to evaluate the potential of microbial-enhanced Brassica oleracea for the phytoremediation of seleniferous soils. The effect of selenite (Se(IV)) and selenate (Se(VI)) on B. oleracea (1-100 mg.L-1) was examined through germination (7 d) and pot (30 d) trials. Microbial analysis was conducted to verify the toxic effect of various Se concentrations (1-500 mg.L-1) on Rhodococcus opacus PD360, and to determine if it exhibits plant growth promoter traits. R. opacus PD630 was found to tolerate high concentrations of both Se(IV) and Se(VI), above 100 mg.L-1. R. opacus PD630 reduced Se(IV) and Se(VI) over 7 days, with a Se conversion efficiency between 60 and 80%. Germination results indicated lower concentrations (0-10 mg.L-1) of Se(IV) and Se(VI) gave a higher shoot length (> 4 cm). B. oleracea accumulated 600-1,000 mg.kg-1 dry weight (DW) of Se(IV) and Se(VI), making it a secondary accumulator of Se. Moreover, seeds inoculated with R. opacus PD360 showed increased Se uptake (up to 1,200 mg Se.kg-1 DW). In addition, bioconcentration and translocation factors were greater than one. The results indicate a synergistic effect between R. opacus PD630 and B. oleracea for Se phytoextraction from polluted soils.
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Affiliation(s)
- Sinead Morris
- University of Galway, University Road, H91 TK33, Galway, Ireland
| | - Diana Quispe-Arpasi
- University of Galway, University Road, H91 TK33, Galway, Ireland
- Department of Microbiology, Universidad Tecnológica del Perú, Campus Ate, Carretera Central km 11.6, Ate, Lima, Peru
| | - Piet N L Lens
- University of Galway, University Road, H91 TK33, Galway, Ireland
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4
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Scribani-Rossi C, Molina-Henares MA, Espinosa-Urgel M, Rinaldo S. Exploring the Metabolic Response of Pseudomonas putida to L-arginine. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024. [PMID: 38429473 DOI: 10.1007/5584_2024_797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
Beyond their role as protein-building units, amino acids are modulators of multiple behaviours in different microorganisms. In the root-colonizing beneficial bacterium Pseudomonas putida (recently proposed to be reclassified as alloputida) KT2440, current evidence suggests that arginine functions both as a metabolic indicator and as an environmental signal molecule, modulating processes such as chemotactic responses, siderophore-mediated iron uptake or the levels of the intracellular second messenger cyclic diguanylate (c-di-GMP). Using microcalorimetry and extracellular flux analysis, in this work we have studied the metabolic adaptation of P. putida KT2440 to the presence of L-arginine in the growth medium, and the influence of mutations related to arginine metabolism. Arginine causes rapid changes in the respiratory activity of P. putida, particularly magnified in a mutant lacking the transcriptional regulator ArgR. The metabolic activity of mutants affected in arginine transport and metabolism is also altered during biofilm formation in the presence of the amino acid. The results obtained here further support the role of arginine as a metabolic signal in P. putida and the relevance of ArgR in the adaptation to the amino acid. They also serve as proof of concept on the use of calorimetric and extracellular flux techniques to analyse metabolic responses in bacteria and the impact of different mutant backgrounds on such responses.
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Affiliation(s)
- Chiara Scribani-Rossi
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Rome, Italy
| | - María Antonia Molina-Henares
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidin, CSIC, Granada, Spain
| | - Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidin, CSIC, Granada, Spain.
| | - Serena Rinaldo
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Rome, Italy.
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5
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Costa-Gutierrez SB, Raimondo EE, Vincent PA, de Cristóbal RE. Importance of biofilm formation for promoting plant growth under salt stress in Pseudomonas putida KT2440. J Basic Microbiol 2023; 63:1219-1232. [PMID: 37537345 DOI: 10.1002/jobm.202300215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/20/2023] [Accepted: 07/12/2023] [Indexed: 08/05/2023]
Abstract
An underutilized experimental design was employed to isolate adapted mutants of the model bacterium Pseudomonas putida KT2440. The design involved subjecting a random pool of mini-Tn5 mutants of P. putida KT2440 to multiple rounds of selection in the rhizosphere of soybean plants irrigated with a NaCl solution. The isolated adapted mutants, referred to as MutAd, exhibited a mutation in the gene responsible for encoding the membrane-binding protein LapA, which plays a role in the initial stages of biofilm formation on abiotic surfaces. Two MutAd bacteria, MutAd160 and MutAd185, along with a lapA deletion mutant, were selected for further investigation to examine the impact of this gene on salt tolerance, rhizosphere fitness, production of extracellular polymeric substances (EPS), and promotion of plant growth. Despite the mutants' inability to form biofilms, they were able to attach to soybean seeds and roots. The MutAd bacteria demonstrated an elevated production of EPS when cultivated under saline conditions, which likely compensated for the absence of biofilm formation. MutAd185 bacteria exhibited enhanced root attachment and promoted the growth of soybean plants in slightly saline soils. The proposed experimental design holds promise for expediting bacterial adaptation to the rhizosphere of plants under specific environmental conditions, identifying genetic mutations that enhance bacterial fitness in those conditions, and thereby increasing their capacity to promote plant growth.
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Affiliation(s)
- Stefanie Bernardette Costa-Gutierrez
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) e Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
| | - Enzo Emanuel Raimondo
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI-CONICET), Avenida Belgrano y Pasaje Caseros, San Miguel de Tucumán, Tucumán, Argentina
- Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
| | - Paula Andrea Vincent
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) e Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
| | - Ricardo Ezequiel de Cristóbal
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) e Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
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6
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Espinosa-Urgel M, Ramos-González MI. Becoming settlers: Elements and mechanisms for surface colonization by Pseudomonas putida. Environ Microbiol 2023; 25:1575-1593. [PMID: 37045787 DOI: 10.1111/1462-2920.16385] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/31/2023] [Indexed: 04/14/2023]
Abstract
Pseudomonads are considered to be among the most widespread culturable bacteria in mesophilic environments. The evolutive success of Pseudomonas species can be attributed to their metabolic versatility, in combination with a set of additional functions that enhance their ability to colonize different niches. These include the production of secondary metabolites involved in iron acquisition or having a detrimental effect on potential competitors, different types of motility, and the capacity to establish and persist within biofilms. Although biofilm formation has been extensively studied using the opportunistic pathogen Pseudomonas aeruginosa as a model organism, a significant body of knowledge is also becoming available for non-pathogenic Pseudomonas. In this review, we focus on the mechanisms that allow Pseudomonas putida to colonize biotic and abiotic surfaces and adapt to sessile life, as a relevant persistence strategy in the environment. This species is of particular interest because it includes plant-beneficial strains, in which colonization of plant surfaces may be relevant, and strains used for environmental and biotechnological applications, where the design and functionality of biofilm-based bioreactors, for example, also have to take into account the efficiency of bacterial colonization of solid surfaces. This work reviews the current knowledge of mechanistic and regulatory aspects of biofilm formation by P. putida and pinpoints the prospects in this field.
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Affiliation(s)
- Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Granada, Spain
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7
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Espinosa-Urgel M. Connecting environmental and evolutionary microbiology for the development of new agrobiotechnological tools. Environ Microbiol 2023; 25:87-90. [PMID: 36519350 PMCID: PMC10087822 DOI: 10.1111/1462-2920.16197] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 08/31/2022] [Indexed: 01/21/2023]
Affiliation(s)
- Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
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8
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Abiala M, Sadhukhan A, Muthuvel J, Shekhawat RS, Yadav P, Sahoo L. Rhizosphere Priestia species altered cowpea root transcriptome and enhanced growth under drought and nutrient deficiency. PLANTA 2022; 257:11. [PMID: 36515736 DOI: 10.1007/s00425-022-04047-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
Priestia species isolated from the cowpea rhizosphere altered the transcriptome of cowpea roots by colonization and enhanced nutrient uptake, antioxidant mechanisms, and photosynthesis, protecting cowpea from drought and nutrient deficiency. Cowpea is a significant grain legume crop primarily grown in sub-Saharan Africa, Asia, and South America. Drought and nutrient deficiency affect the growth and yield of cowpea. To address this challenge, we studied the phyto-beneficial effects of stress-tolerant rhizobacteria on the biomass yield of cowpea under water- and nutrient-deficit conditions. Among the bacteria isolated, two rhizobacillus genotypes, C8 (Priestia filamentosa; basonym: Bacillus filamentosus) and C29 (Priestia aryabhattai; basonym: Bacillus aryabhattai) were evaluated for the improvement of seed germination and growth of cowpea under stress. Our study revealed that C8 protected cowpea from stress by facilitating phosphorus and potassium uptake, protecting it from oxidative damage, reducing transpiration, and enhancing CO2 assimilation. A 17% increase in root biomass upon C8 inoculation was concomitant with the induction of stress tolerance genes in cowpea roots predominantly involved in growth and metabolic processes, cell wall organization, ion homeostasis, and cellular responses to phosphate starvation. Our results indicate a metabolic alteration in cowpea root triggered by P. filamentosa, leading to efficient nutrient reallocation in the host plant. We propose inoculation with P. filamentosa as an effective strategy for improving the yield of cowpea in low-input agriculture, where chemical fertilization and irrigation are less accessible to resource-poor farmers.
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Affiliation(s)
- Moses Abiala
- Department of Biological Sciences, College of Basic and Applied Sciences, Mountain Top University, Prayer City, Ogun State, Nigeria.
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Guwahati, Assam, India.
| | - Ayan Sadhukhan
- Department of Bioscience and Bioengineering, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan, India
| | - Jothi Muthuvel
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Guwahati, Assam, India
| | - Rajveer Singh Shekhawat
- Department of Bioscience and Bioengineering, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan, India
| | - Pankaj Yadav
- Department of Bioscience and Bioengineering, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan, India
| | - Lingaraj Sahoo
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Guwahati, Assam, India
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9
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Duque E, Udaondo Z, Molina L, de la Torre J, Godoy P, Ramos JL. Providing octane degradation capability to Pseudomonas putida KT2440 through the horizontal acquisition of oct genes located on an integrative and conjugative element. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:934-946. [PMID: 35651318 PMCID: PMC9795978 DOI: 10.1111/1758-2229.13097] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 05/09/2022] [Accepted: 05/16/2022] [Indexed: 05/17/2023]
Abstract
The extensive use of petrochemicals has produced serious environmental pollution problems; fortunately, bioremediation is considered an efficient way to fight against pollution. In line with Synthetic Biology is that robust microbial chassis with an expanded ability to remove environmental pollutants are desirable. Pseudomonas putida KT2440 is a robust lab microbe that has preserved the ability to survive in the environment and is the natural host for the self-transmissible TOL plasmid, which allows metabolism of toluene and xylenes to central metabolism. We show that the P. putida KT2440 (pWW0) acquired the ability to use octane as the sole C-source after acquisition of an almost 62-kb ICE from a microbial community that harbours an incomplete set of octane metabolism genes. The ICE bears genes for an alkane monooxygenase, a PQQ-dependent alcohol dehydrogenase and aldehyde dehydrogenase but lacks the electron donor enzymes required for the monooxygenase to operate. Host rubredoxin and rubredoxin reductase allow metabolism of octane to octanol. Proteomic assays and mutants unable to grow on octane or octanoic acid revealed that metabolism of octane is mediated by redundant host and ICE enzymes. Octane is oxidized to octanol, octanal and octanoic acid, the latter is subsequently acylated and oxidized to yield acetyl-CoA that is assimilated via the glyoxylate shunt; in fact, a knockout mutant in the aceA gene, encoding isocitrate lyase was unable to grow on octane or octanoic acid.
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Affiliation(s)
- Estrella Duque
- Department of Environmental ProtectionEstación Experimental del Zaidín, CSICGranadaSpain
| | - Zulema Udaondo
- Department of Biomedical InformaticsUniversity of Arkansas for Medical ScienceLittle RockArkansasUSA
| | - Lázaro Molina
- Department of Environmental ProtectionEstación Experimental del Zaidín, CSICGranadaSpain
| | - Jesús de la Torre
- Department of Environmental ProtectionEstación Experimental del Zaidín, CSICGranadaSpain
| | - Patricia Godoy
- Department of Environmental ProtectionEstación Experimental del Zaidín, CSICGranadaSpain
| | - Juan L. Ramos
- Department of Environmental ProtectionEstación Experimental del Zaidín, CSICGranadaSpain
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10
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Singh A, Kumar M, Chakdar H, Pandiyan K, Kumar SC, Zeyad MT, Singh BN, Ravikiran KT, Mahto A, Srivastava AK, Saxena AK. Influence of host genotype in establishing root associated microbiome of indica rice cultivars for plant growth promotion. Front Microbiol 2022; 13:1033158. [PMID: 36452918 PMCID: PMC9702084 DOI: 10.3389/fmicb.2022.1033158] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 10/20/2022] [Indexed: 08/29/2023] Open
Abstract
Rice plants display a unique root ecosystem comprising oxic-anoxic zones, harboring a plethora of metabolic interactions mediated by its root microbiome. Since agricultural land is limited, an increase in rice production will rely on novel methods of yield enhancement. The nascent concept of tailoring plant phenotype through the intervention of synthetic microbial communities (SynComs) is inspired by the genetics and ecology of core rhizobiome. In this direction, we have studied structural and functional variations in the root microbiome of 10 indica rice varieties. The studies on α and β-diversity indices of rhizospheric root microbiome with the host genotypes revealed variations in the structuring of root microbiome as well as a strong association with the host genotypes. Biomarker discovery, using machine learning, highlighted members of class Anaerolineae, α-Proteobacteria, and bacterial genera like Desulfobacteria, Ca. Entotheonella, Algoriphagus, etc. as the most important features of indica rice microbiota having a role in improving the plant's fitness. Metabolically, rice rhizobiomes showed an abundance of genes related to sulfur oxidation and reduction, biofilm production, nitrogen fixation, denitrification, and phosphorus metabolism. This comparative study of rhizobiomes has outlined the taxonomic composition and functional diversification of rice rhizobiome, laying the foundation for the development of next-generation microbiome-based technologies for yield enhancement in rice and other crops.
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Affiliation(s)
- Arjun Singh
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
- ICAR-Central Soil Salinity Research Institute, RRS, Lucknow, India
| | - Murugan Kumar
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
| | - Hillol Chakdar
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
| | - Kuppusamy Pandiyan
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
- Ginning Training Center, ICAR-Central Institute for Research on Cotton Technology, Nagpur, India
| | - Shiv Charan Kumar
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
| | | | | | - K. T. Ravikiran
- ICAR-Central Soil Salinity Research Institute, RRS, Lucknow, India
| | - Arunima Mahto
- National Institute of Plant Genome Research, New Delhi, India
| | | | - Anil Kumar Saxena
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
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11
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Miral A, Kautsky A, Alves-Carvalho S, Cottret L, Guillerm-Erckelboudt AY, Buguet M, Rouaud I, Tranchimand S, Tomasi S, Bartoli C. Rhizocarpon geographicum Lichen Discloses a Highly Diversified Microbiota Carrying Antibiotic Resistance and Persistent Organic Pollutant Tolerance. Microorganisms 2022; 10:1859. [PMID: 36144461 PMCID: PMC9503503 DOI: 10.3390/microorganisms10091859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/06/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
As rock inhabitants, lichens are exposed to extreme and fluctuating abiotic conditions associated with poor sources of nutriments. These extreme conditions confer to lichens the unique ability to develop protective mechanisms. Consequently, lichen-associated microbes disclose highly versatile lifestyles and ecological plasticity, enabling them to withstand extreme environments. Because of their ability to grow in poor and extreme habitats, bacteria associated with lichens can tolerate a wide range of pollutants, and they are known to produce antimicrobial compounds. In addition, lichen-associated bacteria have been described to harbor ecological functions crucial for the evolution of the lichen holobiont. Nevertheless, the ecological features of lichen-associated microbes are still underestimated. To explore the untapped ecological diversity of lichen-associated bacteria, we adopted a novel culturomic approach on the crustose lichen Rhizocarpon geographicum. We sampled R. geographicum in French habitats exposed to oil spills, and we combined nine culturing methods with 16S rRNA sequencing to capture the greatest bacterial diversity. A deep functional analysis of the lichen-associated bacterial collection showed the presence of a set of bacterial strains resistant to a wide range of antibiotics and displaying tolerance to Persistent Organic Pollutants (POPs). Our study is a starting point to explore the ecological features of the lichen microbiota.
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Affiliation(s)
- Alice Miral
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes)—UMR 6226, University of Rennes 1, 35000 Rennes, France
| | - Adam Kautsky
- IGEPP, INRAE, Institut Agro, University of Rennes 1, LIPME, INRAE, 35653 Le Rheu, France
| | - Susete Alves-Carvalho
- IGEPP, INRAE, Institut Agro, University of Rennes 1, LIPME, INRAE, 35653 Le Rheu, France
| | - Ludovic Cottret
- CNRS, Université de Toulouse, 31320 Castanet-Tolosan, France
| | | | - Manon Buguet
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes)—UMR 6226, University of Rennes 1, 35000 Rennes, France
| | - Isabelle Rouaud
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes)—UMR 6226, University of Rennes 1, 35000 Rennes, France
| | - Sylvain Tranchimand
- Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)—UMR 6226, University of Rennes 1, 35000 Rennes, France
| | - Sophie Tomasi
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes)—UMR 6226, University of Rennes 1, 35000 Rennes, France
| | - Claudia Bartoli
- IGEPP, INRAE, Institut Agro, University of Rennes 1, LIPME, INRAE, 35653 Le Rheu, France
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12
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Santamaría‐Hernando S, De Bruyne L, Höfte M, Ramos‐González M. Improvement of fitness and biocontrol properties of
Pseudomonas putida
via an extracellular heme peroxidase. Microb Biotechnol 2022; 15:2652-2666. [PMID: 35986900 PMCID: PMC9518985 DOI: 10.1111/1751-7915.14123] [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: 03/31/2022] [Accepted: 07/18/2022] [Indexed: 11/27/2022] Open
Abstract
The extracellular 373‐kDa PehA heme peroxidase of Pseudomonas putida KT2440 has two enzymatic domains which depend on heme cofactor for their peroxidase activity. A null pehA mutant was generated to examine the impact of PehA in rhizosphere colonization competence and the induction of plant systemic resistance (ISR). This mutant was not markedly hampered in colonization efficiency. However, increase in pehA dosage enhanced colonization fitness about 30 fold in the root and 900 fold in the root apex. In vitro assays with purified His‐tagged enzymatic domains of PehA indicated that heme‐dependent peroxidase activity was required for the enhancement of root tip colonization. Evaluation of live/dead cells confirmed that overexpression of pehA had a positive effect on bacterial cell viability. Following root colonization of rice plants by KT2440 strain, the incidence of rice blast caused by Magnaporthe oryzae was reduced by 65% and the severity of this disease was also diminished in comparison to non‐treated plants. An increase in the pehA dosage was also beneficial for the control of rice blast as compared with gene inactivation. The results suggest that PehA helps P. putida to cope with the plant‐imposed oxidative stress leading to enhanced colonization ability and concomitant ISR‐elicitation.
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Affiliation(s)
- Saray Santamaría‐Hernando
- Department of Environmental Protection Estación Experimental de Zaidín‐Consejo Superior de Investigaciones Científicas (CSIC) Granada Spain
- Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering Ghent University Ghent Belgium
| | - Lieselotte De Bruyne
- Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering Ghent University Ghent Belgium
| | - Monica Höfte
- Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering Ghent University Ghent Belgium
| | - María‐Isabel Ramos‐González
- Department of Environmental Protection Estación Experimental de Zaidín‐Consejo Superior de Investigaciones Científicas (CSIC) Granada Spain
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13
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Upadhyay SK, Srivastava AK, Rajput VD, Chauhan PK, Bhojiya AA, Jain D, Chaubey G, Dwivedi P, Sharma B, Minkina T. Root Exudates: Mechanistic Insight of Plant Growth Promoting Rhizobacteria for Sustainable Crop Production. Front Microbiol 2022; 13:916488. [PMID: 35910633 PMCID: PMC9329127 DOI: 10.3389/fmicb.2022.916488] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 06/09/2022] [Indexed: 12/18/2022] Open
Abstract
The breaking silence between the plant roots and microorganisms in the rhizosphere affects plant growth and physiology by impacting biochemical, molecular, nutritional, and edaphic factors. The components of the root exudates are associated with the microbial population, notably, plant growth-promoting rhizobacteria (PGPR). The information accessible to date demonstrates that PGPR is specific to the plant's roots. However, inadequate information is accessible for developing bio-inoculation/bio-fertilizers for the crop in concern, with satisfactory results at the field level. There is a need to explore the perfect candidate PGPR to meet the need for plant growth and yield. The functions of PGPR and their chemotaxis mobility toward the plant root are triggered by the cluster of genes induced by the components of root exudates. Some reports have indicated the benefit of root exudates in plant growth and productivity, yet a methodical examination of rhizosecretion and its consequences in phytoremediation have not been made. In the light of the afore-mentioned facts, in the present review, the mechanistic insight and recent updates on the specific PGPR recruitment to improve crop production at the field level are methodically addressed.
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Affiliation(s)
- Sudhir K. Upadhyay
- Department of Environmental Science, V.B.S. Purvanchal University, Jaunpur, India
| | | | - Vishnu D. Rajput
- Academy of Biology and Biotechnology, Southern Federal University, Rostov-on-Don, Russia
| | - Prabhat K. Chauhan
- Department of Environmental Science, V.B.S. Purvanchal University, Jaunpur, India
| | - Ali Asger Bhojiya
- Department of Agriculture and Veterinary Sciences, Mewar University, Chittorgarh, India
| | - Devendra Jain
- Department of Molecular Biology and Biotechnology, Maharana Pratap University of Agriculture and Technology, Udaipur, India
| | - Gyaneshwer Chaubey
- Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, India
| | - Padmanabh Dwivedi
- Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India
| | - Bechan Sharma
- Department of Biochemistry, Faculty of Science, University of Allahabad, Allahabad, India
| | - Tatiana Minkina
- Academy of Biology and Biotechnology, Southern Federal University, Rostov-on-Don, Russia
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14
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Oyserman BO, Flores SS, Griffioen T, Pan X, van der Wijk E, Pronk L, Lokhorst W, Nurfikari A, Paulson JN, Movassagh M, Stopnisek N, Kupczok A, Cordovez V, Carrión VJ, Ligterink W, Snoek BL, Medema MH, Raaijmakers JM. Disentangling the genetic basis of rhizosphere microbiome assembly in tomato. Nat Commun 2022; 13:3228. [PMID: 35710629 PMCID: PMC9203511 DOI: 10.1038/s41467-022-30849-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 05/19/2022] [Indexed: 12/31/2022] Open
Abstract
Microbiomes play a pivotal role in plant growth and health, but the genetic factors involved in microbiome assembly remain largely elusive. Here, we map the molecular features of the rhizosphere microbiome as quantitative traits of a diverse hybrid population of wild and domesticated tomato. Gene content analysis of prioritized tomato quantitative trait loci suggests a genetic basis for differential recruitment of various rhizobacterial lineages, including a Streptomyces-associated 6.31 Mbp region harboring tomato domestication sweeps and encoding, among others, the iron regulator FIT and the water channel aquaporin SlTIP2.3. Within metagenome-assembled genomes of root-associated Streptomyces and Cellvibrio, we identify bacterial genes involved in metabolism of plant polysaccharides, iron, sulfur, trehalose, and vitamins, whose genetic variation associates with specific tomato QTLs. By integrating 'microbiomics' and quantitative plant genetics, we pinpoint putative plant and reciprocal rhizobacterial traits underlying microbiome assembly, thereby providing a first step towards plant-microbiome breeding programs.
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Affiliation(s)
- Ben O Oyserman
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands.
- Bioinformatics Group, Wageningen University, Wageningen, The Netherlands.
| | - Stalin Sarango Flores
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
- Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Thom Griffioen
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
| | - Xinya Pan
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
| | - Elmar van der Wijk
- Bioinformatics Group, Wageningen University, Wageningen, The Netherlands
| | - Lotte Pronk
- Bioinformatics Group, Wageningen University, Wageningen, The Netherlands
| | - Wouter Lokhorst
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
| | - Azkia Nurfikari
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
| | - Joseph N Paulson
- Department of Data Sciences, Genentech, Inc. South San Francisco, South San Francisco, CA, USA
| | - Mercedeh Movassagh
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Data Sciences Dana Farber Cancer Institute, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Nejc Stopnisek
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
| | - Anne Kupczok
- Bioinformatics Group, Wageningen University, Wageningen, The Netherlands
| | - Viviane Cordovez
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
| | - Víctor J Carrión
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
- Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Wilco Ligterink
- Wageningen Seed Lab, Laboratory of Plant Physiology, Wageningen University, Wageningen, The Netherlands
| | - Basten L Snoek
- Theoretical Biology and Bioinformatics, Utrecht University, Utrecht, The Netherlands
| | - Marnix H Medema
- Bioinformatics Group, Wageningen University, Wageningen, The Netherlands
- Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Jos M Raaijmakers
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands.
- Institute of Biology, Leiden University, Leiden, The Netherlands.
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15
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Duan S, Declerck S, Zhang L, Feng G. Two-component system in Rahnella aquatilis is impacted by the hyphosphere of the arbuscular mycorrhizal fungus Rhizophagus irregularis. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:119-129. [PMID: 34951128 DOI: 10.1111/1758-2229.13039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 12/13/2021] [Indexed: 06/14/2023]
Abstract
Two-component systems (TCS) are ubiquitous among bacteria, playing key roles in signalling events. However, to what extent the TCS of Rahnella aquatilis (a Phosphate solubilizing bacteria) is influenced by the hyphosphere of the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis is totally unknown. Here, the expression of 16 genes encoding the TCS of R. aquatilis (i.e. involved in carbon-sensing and nutrient-sensing) and of eight genes regulated by the PhoR TCS (i.e. involved in inorganic and organic phosphorus mobilization) were analysed at regular intervals in presence of hyphae of R. irregularis. The study was conducted under in vitro culture conditions with phytate as the unique source of phosphorus. In presence of the AM fungus, the expression of TCS genes involved in carbon-sensing and nutrient-sensing were stimulated. Only, BaeS at 30 and 120 min, and BaeR at 60 min were inhibited. In addition, the PhoR TCS stimulated the expression of genes encoding phosphatase but inhibited the expression of genes involved in gluconic acid production. As the mechanism of coupling environmental changes with cellular physiological changes, TCS plays a pivotal role in regulating specific gene expression in R. aquatilis, recognizing environmental signals. More importantly, TCS genes may regulate bacteria response to hyphal carbon to mobilize phosphorus efficiently in the hyphosphere.
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Affiliation(s)
- Shilong Duan
- College of Resources and Environmental Sciences, MOE Key Laboratory of Plant-Soil Interactions, National Academy of Agriculture Green Development, China Agricultural University, Beijing, 10093, China
| | - Stéphane Declerck
- Université Catholique de Louvain, Earth and Life Institute, Applied Microbiology, Mycology, Croix du Sud 2, bte L7.05.06, Louvain-la-Neuve, B-1348, Belgium
| | - Lin Zhang
- College of Resources and Environmental Sciences, MOE Key Laboratory of Plant-Soil Interactions, National Academy of Agriculture Green Development, China Agricultural University, Beijing, 10093, China
| | - Gu Feng
- College of Resources and Environmental Sciences, MOE Key Laboratory of Plant-Soil Interactions, National Academy of Agriculture Green Development, China Agricultural University, Beijing, 10093, China
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16
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Rico-Jiménez M, Roca A, Krell T, Matilla MA. A bacterial chemoreceptor that mediates chemotaxis to two different plant hormones. Environ Microbiol 2022; 24:3580-3597. [PMID: 35088505 PMCID: PMC9543091 DOI: 10.1111/1462-2920.15920] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/14/2022] [Accepted: 01/20/2022] [Indexed: 11/30/2022]
Abstract
Indole-3-acetic acid (IAA) is the main naturally occurring auxin and is produced by organisms of all kingdoms of life. In addition to the regulation of plant growth and development, IAA plays an important role in the interaction between plants and growth-promoting and phytopathogenic bacteria by regulating bacterial gene expression and physiology. We show here that a IAA metabolizing plant-associated Pseudomonas putida isolate exhibits chemotaxis to IAA that is independent of auxin metabolism. We found that IAA chemotaxis is based on the activity of the PcpI chemoreceptor and heterologous expression of pcpI conferred IAA taxis to different environmental and human pathogenic isolates of the Pseudomonas genus. Using ligand screening, microcalorimetry and quantitative chemotaxis assays, we found that PcpI failed to bind IAA directly, but recognized and mediated chemoattractions to various aromatic compounds, including the phytohormone salicylic acid. The expression of pcpI and its role in the interactions with plants was also investigated. PcpI extends the range of central signal molecules recognized by chemoreceptors. To our knowledge, this is the first report on a bacterial receptor that responds to two different phytohormones. Our study reinforces the multifunctional role of IAA and salicylic acid as intra- and inter-kingdom signal molecules. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Miriam Rico-Jiménez
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Amalia Roca
- Department of Microbiology, Facultad de Farmacia, Campus Universitario de Cartuja, Universidad de Granada, 18071, Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
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17
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Tagua VG, Molina‐Henares MA, Travieso ML, Nisa‐Martínez R, Quesada JM, Espinosa‐Urgel M, Ramos‐González MI. C‐di‐GMP
and biofilm are regulated in
Pseudomonas putida
by the
CfcA
/
CfcR
two‐component system in response to salts. Environ Microbiol 2022; 24:158-178. [DOI: 10.1111/1462-2920.15891] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 12/14/2021] [Accepted: 12/26/2021] [Indexed: 11/30/2022]
Affiliation(s)
- Víctor G. Tagua
- Department of Environmental Protection Estación Experimental del Zaidín, CSIC Granada Spain
| | | | - María L. Travieso
- Department of Environmental Protection Estación Experimental del Zaidín, CSIC Granada Spain
| | - Rafael Nisa‐Martínez
- Department of Environmental Protection Estación Experimental del Zaidín, CSIC Granada Spain
| | - José Miguel Quesada
- Department of Environmental Protection Estación Experimental del Zaidín, CSIC Granada Spain
| | - Manuel Espinosa‐Urgel
- Department of Environmental Protection Estación Experimental del Zaidín, CSIC Granada Spain
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18
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Segura A, Udaondo Z, Molina L. PahT regulates carbon fluxes in Novosphingobium sp. HR1a and influences its survival in soil and rhizospheres. Environ Microbiol 2021; 23:2969-2991. [PMID: 33817928 PMCID: PMC8360164 DOI: 10.1111/1462-2920.15509] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/29/2021] [Accepted: 04/03/2021] [Indexed: 01/23/2023]
Abstract
Novosphingobium sp. HR1a is a good biodegrader of PAHs and aromatic compounds, and also a good colonizer of rhizospheric environments. It was previously demonstrated that this microbe is able to co-metabolize nutrients existing in root exudates together with the PAHs. We have revealed here that PahT, a regulator of the IclR-family, regulates the central carbon fluxes favouring the degradation of PAHs and mono-aromatic compounds, the ethanol and acetate metabolism and the uptake, phosphorylation and further degradation of mono- and oligo-saccharides through a phosphoenolpyruvate transferase system (PTS). As final products of these fluxes, pyruvate and acetyl-CoA are obtained. The pahT gene is located within a genomic region containing two putative transposons that carry all the genes for PAH catabolism; PahT also regulates these genes. Furthermore, encoded in this genomic region, there are genes that are involved in the recycling of phosphoenolpyruvate, from the obtained pyruvate, which is the motor molecule involved in the saccharide uptake by the PTS system. The co-metabolism of PAHs with different carbon sources, together with the activation of the thiosulfate utilization and an alternative cytochrome oxidase system, also regulated by PahT, represents an advantage for Novosphingobium sp. HR1a to survive in rhizospheric environments.
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Affiliation(s)
- Ana Segura
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, Granada, 18008, Spain
| | - Zulema Udaondo
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
| | - Lázaro Molina
- Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, Granada, 18008, Spain
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19
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Bhattacharyya A, Pablo CHD, Mavrodi OV, Weller DM, Thomashow LS, Mavrodi DV. Rhizosphere plant-microbe interactions under water stress. ADVANCES IN APPLIED MICROBIOLOGY 2021; 115:65-113. [PMID: 34140134 DOI: 10.1016/bs.aambs.2021.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Climate change, with its extreme temperature, weather and precipitation patterns, is a major global concern of dryland farmers, who currently meet the challenges of climate change agronomically and with growth of drought-tolerant crops. Plants themselves compensate for water stress by modifying aerial surfaces to control transpiration and altering root hydraulic conductance to increase water uptake. These responses are complemented by metabolic changes involving phytohormone network-mediated activation of stress response pathways, resulting in decreased photosynthetic activity and the accumulation of metabolites to maintain osmotic and redox homeostasis. Phylogenetically diverse microbial communities sustained by plants contribute to host drought tolerance by modulating phytohormone levels in the rhizosphere and producing water-sequestering biofilms. Drylands of the Inland Pacific Northwest, USA, illustrate the interdependence of dryland crops and their associated microbiota. Indigenous Pseudomonas spp. selected there by long-term wheat monoculture suppress root diseases via the production of antibiotics, with soil moisture a critical determinant of the bacterial distribution, dynamics and activity. Those pseudomonads producing phenazine antibiotics on wheat had more abundant rhizosphere biofilms and provided improved tolerance to drought, suggesting a role of the antibiotic in alleviation of drought stress. The transcriptome and metabolome studies suggest the importance of wheat root exudate-derived osmoprotectants for the adaptation of these pseudomonads to the rhizosphere lifestyle and support the idea that the exchange of metabolites between plant roots and microorganisms profoundly affects and shapes the belowground plant microbiome under water stress.
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Affiliation(s)
- Ankita Bhattacharyya
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Clint H D Pablo
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Olga V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - David M Weller
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Linda S Thomashow
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Dmitri V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States.
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20
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Mavrodi OV, McWilliams JR, Peter JO, Berim A, Hassan KA, Elbourne LDH, LeTourneau MK, Gang DR, Paulsen IT, Weller DM, Thomashow LS, Flynt AS, Mavrodi DV. Root Exudates Alter the Expression of Diverse Metabolic, Transport, Regulatory, and Stress Response Genes in Rhizosphere Pseudomonas. Front Microbiol 2021; 12:651282. [PMID: 33936009 PMCID: PMC8079746 DOI: 10.3389/fmicb.2021.651282] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 03/08/2021] [Indexed: 12/20/2022] Open
Abstract
Plants live in association with microorganisms that positively influence plant development, vigor, and fitness in response to pathogens and abiotic stressors. The bulk of the plant microbiome is concentrated belowground at the plant root-soil interface. Plant roots secrete carbon-rich rhizodeposits containing primary and secondary low molecular weight metabolites, lysates, and mucilages. These exudates provide nutrients for soil microorganisms and modulate their affinity to host plants, but molecular details of this process are largely unresolved. We addressed this gap by focusing on the molecular dialog between eight well-characterized beneficial strains of the Pseudomonas fluorescens group and Brachypodium distachyon, a model for economically important food, feed, forage, and biomass crops of the grass family. We collected and analyzed root exudates of B. distachyon and demonstrated the presence of multiple carbohydrates, amino acids, organic acids, and phenolic compounds. The subsequent screening of bacteria by Biolog Phenotype MicroArrays revealed that many of these metabolites provide carbon and energy for the Pseudomonas strains. RNA-seq profiling of bacterial cultures amended with root exudates revealed changes in the expression of genes encoding numerous catabolic and anabolic enzymes, transporters, transcriptional regulators, stress response, and conserved hypothetical proteins. Almost half of the differentially expressed genes mapped to the variable part of the strains’ pangenome, reflecting the importance of the variable gene content in the adaptation of P. fluorescens to the rhizosphere lifestyle. Our results collectively reveal the diversity of cellular pathways and physiological responses underlying the establishment of mutualistic interactions between these beneficial rhizobacteria and their plant hosts.
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Affiliation(s)
- Olga V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Janiece R McWilliams
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Jacob O Peter
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Anna Berim
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Karl A Hassan
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, Australia
| | - Liam D H Elbourne
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Melissa K LeTourneau
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - David R Gang
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Ian T Paulsen
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - David M Weller
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Linda S Thomashow
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Alex S Flynt
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Dmitri V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
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21
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Cavé-Radet A, Correa-Garcia S, Monard C, El Amrani A, Salmon A, Ainouche M, Yergeau É. Phenanthrene contamination and ploidy level affect the rhizosphere bacterial communities of Spartina spp. FEMS Microbiol Ecol 2021; 96:5895320. [PMID: 32821911 DOI: 10.1093/femsec/fiaa156] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/18/2020] [Indexed: 11/13/2022] Open
Abstract
Spartina spp. are widely distributed salt marsh plants that have a recent history of hybridization and polyploidization. These events have resulted in a heightened tolerance to hydrocarbon contaminants, but the effects of this phenomenon on the rhizosphere microbial communities are unknown. Here, we grew two parental Spartina species, their hybrid and the resulting allopolyploid in salt marsh sediments that were contaminated or not with phenanthrene. The DNA from the rhizosphere soil was extracted and the bacterial 16S rRNA gene was amplified and sequenced, whereas the abundances of the genes encoding for the PAH (polycyclic aromatic hydrocarbon) ring-hydroxylating dioxygenase (RHD) of Gram-negative and Gram-positive bacteria were quantified by real-time PCR. Both the contamination and the plant genotype significantly affected the bacterial communities. In particular, the allopolyploid S. anglica harbored a more diverse bacterial community in its rhizosphere. The interspecific hybrid and the allopolyploid also harbored significantly more copies of the PAH-RHD gene of Gram-negative bacteria in their rhizosphere than the parental species, irrespective of the contamination treatments. Overall, our results are showing that the recent polyploidization events in the Spartina affected its rhizosphere bacterial communities, both under normal and contaminated conditions, possibly increasing its phytoremediation potential.
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Affiliation(s)
- Armand Cavé-Radet
- University of Rennes 1, CNRS/UMR 6553/OSUR, Ecosystems - Biodiversity - Evolution, 35042 Rennes Cedex, France
| | - Sara Correa-Garcia
- Institut national de la recherche scientifique, Centre Armand-Frappier Santé Biotechnologie, 531 Boulevard des Prairies, Laval, Québec H7V 1B7, Canada
| | - Cécile Monard
- University of Rennes 1, CNRS/UMR 6553/OSUR, Ecosystems - Biodiversity - Evolution, 35042 Rennes Cedex, France
| | - Abdelhak El Amrani
- University of Rennes 1, CNRS/UMR 6553/OSUR, Ecosystems - Biodiversity - Evolution, 35042 Rennes Cedex, France
| | - Armel Salmon
- University of Rennes 1, CNRS/UMR 6553/OSUR, Ecosystems - Biodiversity - Evolution, 35042 Rennes Cedex, France
| | - Malika Ainouche
- University of Rennes 1, CNRS/UMR 6553/OSUR, Ecosystems - Biodiversity - Evolution, 35042 Rennes Cedex, France
| | - Étienne Yergeau
- Institut national de la recherche scientifique, Centre Armand-Frappier Santé Biotechnologie, 531 Boulevard des Prairies, Laval, Québec H7V 1B7, Canada
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22
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Metagenomics of mine tailing rhizospheric communities and its selection for plant establishment towards bioremediation. Microbiol Res 2021; 247:126732. [PMID: 33743500 DOI: 10.1016/j.micres.2021.126732] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 02/10/2021] [Accepted: 02/17/2021] [Indexed: 11/22/2022]
Abstract
Mining operations often generate tailing dams that contain toxic residues and are a source of contamination when left unconfined. The establishment of a plant community over the tailings has been proposed as a containment strategy known as phytostabilization. Previously, we described naturally occurring mine tailing colonizing plants such as Acacia farnesiana, Brickellia coulteri, Baccharis sarothroides, and Gnaphalium leucocephalum without finding local adaptation. We explored the rhizosphere microbes as contributors in plant establishment and described both the culturable and in situ diversity of rhizospheric bacteria using the 16S rRNA gene and metagenomic shotgun sequencing. We built a synthetic community (SC) of culturable rhizosphere bacteria from the mine tailings. The SC was then the foundation for a serial passes experiment grown in plant-derived nutrient sources, selecting for heavy metals tolerance, community cooperation, and competition. The outcome of the serial passes was named the 'final synthetic community' (FSC). Overall, diversity decreased from in situ uncultivable microbes from roots (399 bacteria genera) to the cultivated communities (291 genera), the SC (94 genera), and the lowest diversity was in the FSC (43 genera). Metagenomic diversity clustered into 94,245 protein families, where we found plant growth promotion-related genes such as the csgBAC and entCEBAH, coded in a metagenome-assembled genome named Kosakonia sp. Nacozari. Finally, we used the FSC to inoculate mine tailing colonizing plants in a greenhouse experiment. The plants with the FSC inocula observed higher relative plant growth rates in sterile substrates. The FSC presents promising features that might make it useful for phytostabilization tailored strategies.
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Huertas-Rosales Ó, Romero M, Chan KG, Hong KW, Cámara M, Heeb S, Barrientos-Moreno L, Molina-Henares MA, Travieso ML, Ramos-González MI, Espinosa-Urgel M. Genome-Wide Analysis of Targets for Post-Transcriptional Regulation by Rsm Proteins in Pseudomonas putida. Front Mol Biosci 2021; 8:624061. [PMID: 33693029 PMCID: PMC7937890 DOI: 10.3389/fmolb.2021.624061] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/21/2021] [Indexed: 12/31/2022] Open
Abstract
Post-transcriptional regulation is an important step in the control of bacterial gene expression in response to environmental and cellular signals. Pseudomonas putida KT2440 harbors three known members of the CsrA/RsmA family of post-transcriptional regulators: RsmA, RsmE and RsmI. We have carried out a global analysis to identify RNA sequences bound in vivo by each of these proteins. Affinity purification and sequencing of RNA molecules associated with Rsm proteins were used to discover direct binding targets, corresponding to 437 unique RNA molecules, 75 of them being common to the three proteins. Relevant targets include genes encoding proteins involved in signal transduction and regulation, metabolism, transport and secretion, stress responses, and the turnover of the intracellular second messenger c-di-GMP. To our knowledge, this is the first combined global analysis in a bacterium harboring three Rsm homologs. It offers a broad overview of the network of processes subjected to this type of regulation and opens the way to define what are the sequence and structure determinants that define common or differential recognition of specific RNA molecules by these proteins.
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Affiliation(s)
- Óscar Huertas-Rosales
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | - Manuel Romero
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Kar-Wai Hong
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Miguel Cámara
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Stephan Heeb
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Laura Barrientos-Moreno
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain.,National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | | | - María L Travieso
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | | | - Manuel Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
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Insights into the early stages of plant-endophytic bacteria interaction. World J Microbiol Biotechnol 2021; 37:13. [PMID: 33392741 DOI: 10.1007/s11274-020-02966-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/21/2020] [Indexed: 12/11/2022]
Abstract
The plant holobiont is a complex entity composed of the plant and the organisms that live in and on it including its microbiota. The plant microbiota includes, among other microorganisms, bacterial endophytes, which are bacteria that can invade living plant tissues without causing symptoms of disease. The interaction between the endophytic bacterial microbiota and their plant host has profound influences on their fitness and depends on biotic and abiotic factors. For these interactions to be established, the bacteria have to be present at the right time, in the right place either colonizing the soil or the seed. In this review we summarize the current knowledge regarding the sources of the bacterial endophytic microbiome and the processes involved in the assemblage of the resulting community during the initial stages of plant development. The adaptations that allow the spatial approximation of soil- and seed-borne bacteria towards infection and colonization of the internal tissues of plants will be addressed in this review.
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25
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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: 45] [Impact Index Per Article: 11.3] [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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26
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Otlewska A, Migliore M, Dybka-Stępień K, Manfredini A, Struszczyk-Świta K, Napoli R, Białkowska A, Canfora L, Pinzari F. When Salt Meddles Between Plant, Soil, and Microorganisms. FRONTIERS IN PLANT SCIENCE 2020; 11:553087. [PMID: 33042180 PMCID: PMC7525065 DOI: 10.3389/fpls.2020.553087] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 08/31/2020] [Indexed: 05/27/2023]
Abstract
In extreme environments, the relationships between species are often exclusive and based on complex mechanisms. This review aims to give an overview of the microbial ecology of saline soils, but in particular of what is known about the interaction between plants and their soil microbiome, and the mechanisms linked to higher resistance of some plants to harsh saline soil conditions. Agricultural soils affected by salinity is a matter of concern in many countries. Soil salinization is caused by readily soluble salts containing anions like chloride, sulphate and nitrate, as well as sodium and potassium cations. Salinity harms plants because it affects their photosynthesis, respiration, distribution of assimilates and causes wilting, drying, and death of entire organs. Despite these life-unfavorable conditions, saline soils are unique ecological niches inhabited by extremophilic microorganisms that have specific adaptation strategies. Important traits related to the resistance to salinity are also associated with the rhizosphere-microbiota and the endophytic compartments of plants. For some years now, there have been studies dedicated to the isolation and characterization of species of plants' endophytes living in extreme environments. The metabolic and biotechnological potential of some of these microorganisms is promising. However, the selection of microorganisms capable of living in association with host plants and promoting their survival under stressful conditions is only just beginning. Understanding the mechanisms of these processes and the specificity of such interactions will allow us to focus our efforts on species that can potentially be used as beneficial bioinoculants for crops.
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Affiliation(s)
- Anna Otlewska
- Faculty of Biotechnology and Food Sciences, Institute of Fermentation Technology and Microbiology, Lodz University of Technology, Lodz, Poland
| | - Melania Migliore
- Research Centre for Agriculture and Environment, Council for Agricultural Research and Economics, Rome, Italy
| | - Katarzyna Dybka-Stępień
- Faculty of Biotechnology and Food Sciences, Institute of Fermentation Technology and Microbiology, Lodz University of Technology, Lodz, Poland
| | - Andrea Manfredini
- Research Centre for Agriculture and Environment, Council for Agricultural Research and Economics, Rome, Italy
| | - Katarzyna Struszczyk-Świta
- Faculty of Biotechnology and Food Sciences, Institute of Molecular and Industrial Biotechnology, Lodz University of Technology, Lodz, Poland
| | - Rosario Napoli
- Research Centre for Agriculture and Environment, Council for Agricultural Research and Economics, Rome, Italy
| | - Aneta Białkowska
- Faculty of Biotechnology and Food Sciences, Institute of Molecular and Industrial Biotechnology, Lodz University of Technology, Lodz, Poland
| | - Loredana Canfora
- Research Centre for Agriculture and Environment, Council for Agricultural Research and Economics, Rome, Italy
| | - Flavia Pinzari
- Institute for Biological Systems, Council of National Research of Italy (CNR), Rome, Italy
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Arginine as an environmental and metabolic cue for cyclic diguanylate signalling and biofilm formation in Pseudomonas putida. Sci Rep 2020; 10:13623. [PMID: 32788689 PMCID: PMC7423604 DOI: 10.1038/s41598-020-70675-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/03/2020] [Indexed: 12/21/2022] Open
Abstract
Cyclic diguanylate (c-di-GMP) is a broadly conserved intracellular second messenger that influences different bacterial processes, including virulence, stress tolerance or social behaviours and biofilm development. Although in most cases the environmental cue that initiates the signal transduction cascade leading to changes in cellular c-di-GMP levels remains unknown, certain l- and d-amino acids have been described to modulate c-di-GMP turnover in some bacteria. In this work, we have analysed the influence of l-amino acids on c-di-GMP levels in the plant-beneficial bacterium Pseudomonas putida KT2440, identifying l-arginine as the main one causing a significant increase in c-di-GMP. Both exogenous (environmental) and endogenous (biosynthetic) l-arginine influence biofilm formation by P. putida through changes in c-di-GMP content and altered expression of structural elements of the biofilm extracellular matrix. The contribution of periplasmic binding proteins forming part of amino acid transport systems to the response to environmental l-arginine was also studied. Contrary to what has been described in other bacteria, in P. putida these proteins seem not to be directly responsible for signal transduction. Rather, their contribution to global l-arginine pools appears to determine changes in c-di-GMP turnover. We propose that arginine plays a connecting role between cellular metabolism and c-di-GMP signalling in P. putida.
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28
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Oni FE, Geudens N, Onyeka JT, Olorunleke OF, Salami AE, Omoboye OO, Arias AA, Adiobo A, De Neve S, Ongena M, Martins JC, Höfte M. Cyclic lipopeptide-producing Pseudomonas koreensis group strains dominate the cocoyam rhizosphere of a Pythium root rot suppressive soil contrasting with P. putida prominence in conducive soils. Environ Microbiol 2020; 22:5137-5155. [PMID: 32524747 DOI: 10.1111/1462-2920.15127] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/31/2020] [Accepted: 06/08/2020] [Indexed: 11/29/2022]
Abstract
Pseudomonas isolates from tropical environments have been underexplored and may form an untapped reservoir of interesting secondary metabolites. In this study, we compared Pseudomonas and cyclic lipopeptide (CLP) diversity in the rhizosphere of a cocoyam root rot disease (CRRD) suppressive soil in Boteva, Cameroon with those from four conducive soils in Cameroon and Nigeria. Compared with other soils, Boteva andosols were characterized by high silt, organic matter, nitrogen and calcium. Besides, the cocoyam rhizosphere at Boteva was characterized by strains belonging mainly to the P. koreensis and P. putida (sub)groups, with representations in the P. fluorescens, P. chlororaphis, P. jessenii and P. asplenii (sub)groups. In contrast, P. putida isolates were prominent in conducive soils. Regarding CLP diversity, Boteva was characterized by strains producing 11 different CLP types with cocoyamide A producers, belonging to the P. koreensis group, being the most abundant. However, putisolvin III-V producers were the most dominant in the rhizosphere of conducive soils in both Cameroon and Nigeria. Furthermore, we elucidated the chemical structure of putisolvin derivatives-putisolvin III-V, and described its biosynthetic gene cluster. We show that high Pseudomonas and metabolic diversity may be driven by microbial competition, which likely contributes to soil suppressiveness to CRRD.
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Affiliation(s)
- Feyisara Eyiwumi Oni
- Phytopathology Laboratory, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.,Unit for Environmental Sciences and Management, Faculty of Natural and Agricultural Sciences, North-West University, Potchefstroom, South Africa
| | - Niels Geudens
- NMR and Structure Analysis Unit, Department of Organic and Macromolecular Chemistry, Faculty of Science, Ghent University, Ghent, Belgium
| | - Joseph T Onyeka
- Plant Pathology Unit, National Root Crops Research Institute (NRCRI), Umudike, Abia, Nigeria
| | - Oluwatoyin Faith Olorunleke
- Phytopathology Laboratory, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Ayodeji Ekundayo Salami
- Department of Crop, Horticulture and Landscape Design, Faculty of Agricultural Sciences, Ekiti State University (EKSU), Ado-Ekiti, Nigeria
| | - Olumide Owolabi Omoboye
- Phytopathology Laboratory, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Anthony Arguelles Arias
- Microbial Processes and Interactions Unit, Faculty of Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Amayana Adiobo
- Institute for Agricultural Research for Development (IRAD), Ekona, Cameroon
| | - Stefaan De Neve
- Research Group of Soil Fertility and Nutrient Management, Department of Environment, Ghent University, Ghent, Belgium
| | - Marc Ongena
- Microbial Processes and Interactions Unit, Faculty of Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - José C Martins
- NMR and Structure Analysis Unit, Department of Organic and Macromolecular Chemistry, Faculty of Science, Ghent University, Ghent, Belgium
| | - Monica Höfte
- Phytopathology Laboratory, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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Sampedro I, Pérez-Mendoza D, Toral L, Palacios E, Arriagada C, Llamas I. Effects of Halophyte Root Exudates and Their Components on Chemotaxis, Biofilm Formation and Colonization of the Halophilic Bacterium Halomonas Anticariensis FP35 T. Microorganisms 2020; 8:E575. [PMID: 32316222 PMCID: PMC7232322 DOI: 10.3390/microorganisms8040575] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 12/25/2022] Open
Abstract
Increase in soil salinity poses an enormous problem for agriculture and highlights the need for sustainable crop production solutions. Plant growth-promoting bacteria can be used to boost the growth of halophytes in saline soils. Salicornia is considered to be a promising salt-accumulating halophyte for capturing large amounts of carbon from the atmosphere. In addition, colonization and chemotaxis could play an important role in Salicornia-microbe interactions. In this study, the role of chemotaxis in the colonization of the halophilic siredophore-producing bacteria, Halomonas anticariensis FP35T, on Salicornia hispanica plants was investigated. The chemotactic response of FP35T to Salicornia root exudates showed optimum dependence at a salt concentration of 5 % NaCl (w/v). Oleanolic acid, the predominant compound in the exudates detected by HPLC and identified by UPLC-HRMS Q-TOF, acts as a chemoattractant. In vitro experiments demonstrated the enhanced positive effects of wild-type H. anticariensis strain FP35T on root length, shoot length, germination and the vigour index of S. hispanica. Furthermore, these positive effects partially depend on an active chemotaxis system, as the chemotaxis mutant H. anticariensis FP35 ΔcheA showed reduced plant growth promotion for all the parameters tested. Overall, our results suggest that chemotaxis responses to root exudates play an important role in interactions between Salicornia and halophilic bacteria, enhance their colonization and boost plant growth promotion. Preliminary results also indicate that root exudates have a positive impact on H. anticariensis FP35T biofilm formation under saline conditions, an effect which totally depends on the presence of the cheA gene.
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Affiliation(s)
- Inmaculada Sampedro
- Department of Microbiology, Pharmacy Faculty, Campus de Cartuja s/n, 18071 Granada, Spain; (D.P.-M.); (E.P.); (I.L.)
- Biomedical Research Center (CIBM), Biotechnology Institute, Avda del Conocimiento s/n, 18100 Armilla, Granada, Spain
| | - Daniel Pérez-Mendoza
- Department of Microbiology, Pharmacy Faculty, Campus de Cartuja s/n, 18071 Granada, Spain; (D.P.-M.); (E.P.); (I.L.)
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Spanish National Research Council (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - Laura Toral
- Xtrem Biotech S.L., European Business Innovation Center, Avenida de la Innovación, 1, 18016 Armilla, Granada, Spain;
| | - Esther Palacios
- Department of Microbiology, Pharmacy Faculty, Campus de Cartuja s/n, 18071 Granada, Spain; (D.P.-M.); (E.P.); (I.L.)
- Biomedical Research Center (CIBM), Biotechnology Institute, Avda del Conocimiento s/n, 18100 Armilla, Granada, Spain
| | - César Arriagada
- Department of Forestry Science, Bioremediation Laboratory, Faculty of Agricultural and Forestry Science, University of La Frontera, 01145 Temuco, Chile;
| | - Inmaculada Llamas
- Department of Microbiology, Pharmacy Faculty, Campus de Cartuja s/n, 18071 Granada, Spain; (D.P.-M.); (E.P.); (I.L.)
- Biomedical Research Center (CIBM), Biotechnology Institute, Avda del Conocimiento s/n, 18100 Armilla, Granada, Spain
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Abstract
Pseudomonas putidais a fast-growing bacterium found mostly in temperate soil and water habitats. The metabolic versatility ofP. putidamakes this organism attractive for biotechnological applications such as biodegradation of environmental pollutants and synthesis of added-value chemicals (biocatalysis). This organism has been extensively studied in respect to various stress responses, mechanisms of genetic plasticity and transcriptional regulation of catabolic genes.P. putidais able to colonize the surface of living organisms, but is generally considered to be of low virulence. A number ofP. putidastrains are able to promote plant growth. The aim of this review is to give historical overview of the discovery of the speciesP. putidaand isolation and characterization ofP. putidastrains displaying potential for biotechnological applications. This review also discusses some major findings inP. putidaresearch encompassing regulation of catabolic operons, stress-tolerance mechanisms and mechanisms affecting evolvability of bacteria under conditions of environmental stress.
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Metabolic and Genomic Traits of Phytobeneficial Phenazine-Producing Pseudomonas spp. Are Linked to Rhizosphere Colonization in Arabidopsis thaliana and Solanum tuberosum. Appl Environ Microbiol 2020; 86:AEM.02443-19. [PMID: 31811040 DOI: 10.1128/aem.02443-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 12/03/2019] [Indexed: 01/01/2023] Open
Abstract
Bacterial rhizosphere colonization is critical for phytobeneficial rhizobacteria such as phenazine-producing Pseudomonas spp. To better understand this colonization process, potential metabolic and genomic determinants required for rhizosphere colonization were identified using a collection of 60 phenazine-producing Pseudomonas strains isolated from multiple plant species and representative of the worldwide diversity. Arabidopsis thaliana and Solanum tuberosum (potato) were used as host plants. Bacterial rhizosphere colonization was measured by quantitative PCR using a newly designed primer pair and TaqMan probe targeting a conserved region of the phenazine biosynthetic operon. The metabolic abilities of the strains were assessed on 758 substrates using Biolog phenotype microarray technology. These data, along with available genomic sequences for all strains, were analyzed in light of rhizosphere colonization. Strains belonging to the P. chlororaphis subgroup colonized the rhizospheres of both plants more efficiently than strains belonging to the P. fluorescens subgroup. Metabolic results indicated that the ability to use amines and amino acids was associated with an increase in rhizosphere colonization capability in A. thaliana and/or in S. tuberosum The presence of multiple genetic determinants in the genomes of the different strains involved in catabolic pathways and plant-microbe and microbe-microbe interactions correlated with increased or decreased rhizosphere colonization capabilities in both plants. These results suggest that the metabolic and genomic traits found in different phenazine-producing Pseudomonas strains reflect their rhizosphere competence in A. thaliana and S. tuberosum Interestingly, most of these traits are associated with similar rhizosphere colonizing capabilities in both plant species.IMPORTANCE Rhizosphere colonization is crucial for plant growth promotion and biocontrol by antibiotic-producing Pseudomonas spp. This colonization process relies on different bacterial determinants which partly remain to be uncovered. In this study, we combined a metabolic and a genomic approach to decipher new rhizosphere colonization determinants which could improve our understanding of this process in Pseudomonas spp. Using 60 distinct strains of phenazine-producing Pseudomonas spp., we show that rhizosphere colonization abilities correlated with both metabolic and genomic traits when these bacteria were inoculated on two distant plants, Arabidopsis thaliana and Solanum tuberosum Key metabolic and genomic determinants presumably required for efficient colonization of both plant species were identified. Upon further validation, these targets could lead to the development of simple screening tests to rapidly identify efficient rhizosphere colonizers.
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Agtuca BJ, Stopka SA, Tuleski TR, do Amaral FP, Evans S, Liu Y, Xu D, Monteiro RA, Koppenaal DW, Paša-Tolić L, Anderton CR, Vertes A, Stacey G. In-Situ Metabolomic Analysis of Setaria viridis Roots Colonized by Beneficial Endophytic Bacteria. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:272-283. [PMID: 31544655 DOI: 10.1094/mpmi-06-19-0174-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Over the past decades, crop yields have risen in parallel with increasing use of fossil fuel-derived nitrogen (N) fertilizers but with concomitant negative impacts on climate and water resources. There is a need for more sustainable agricultural practices, and biological nitrogen fixation (BNF) could be part of the solution. A variety of nitrogen-fixing, epiphytic, and endophytic plant growth-promoting bacteria (PGPB) are known to stimulate plant growth. However, compared with the rhizobium-legume symbiosis, little mechanistic information is available as to how PGPB affect plant metabolism. Therefore, we investigated the metabolic changes in roots of the model grass species Setaria viridis upon endophytic colonization by Herbaspirillum seropedicae SmR1 (fix+) or a fix- mutant strain (SmR54) compared with uninoculated roots. Endophytic colonization of the root is highly localized and, hence, analysis of whole-root segments dilutes the metabolic signature of those few cells impacted by the bacteria. Therefore, we utilized in-situ laser ablation electrospray ionization mass spectrometry to sample only those root segments at or adjacent to the sites of bacterial colonization. Metabolites involved in purine, zeatin, and riboflavin pathways were significantly more abundant in inoculated plants, while metabolites indicative of nitrogen, starch, and sucrose metabolism were reduced in roots inoculated with the fix- strain or uninoculated, presumably due to N limitation. Interestingly, compounds, involved in indole-alkaloid biosynthesis were more abundant in the roots colonized by the fix- strain, perhaps reflecting a plant defense response.
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Affiliation(s)
- Beverly J Agtuca
- Divisions of Plant Sciences and Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, U.S.A
| | - Sylwia A Stopka
- Department of Chemistry, The George Washington University, Washington, DC 20052, U.S.A
| | - Thalita R Tuleski
- Divisions of Plant Sciences and Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, U.S.A
- Department of Biochemistry and Molecular Biology, Federal University of Paraná, CP 19046, 81.531-990 Curitiba, PR, Brazil
| | - Fernanda P do Amaral
- Divisions of Plant Sciences and Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, U.S.A
| | - Sterling Evans
- Divisions of Plant Sciences and Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, U.S.A
| | - Yang Liu
- Department of Electrical Engineering and Computer Science, Informatics Institute and Christopher S. Bond Life Sciences Center, University of Missouri Columbia
| | - Dong Xu
- Department of Electrical Engineering and Computer Science, Informatics Institute and Christopher S. Bond Life Sciences Center, University of Missouri Columbia
| | - Rose Adele Monteiro
- Department of Biochemistry and Molecular Biology, Federal University of Paraná, CP 19046, 81.531-990 Curitiba, PR, Brazil
| | - David W Koppenaal
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99354, U.S.A
| | - Ljiljana Paša-Tolić
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99354, U.S.A
| | - Christopher R Anderton
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99354, U.S.A
| | - Akos Vertes
- Department of Chemistry, The George Washington University, Washington, DC 20052, U.S.A
| | - Gary Stacey
- Divisions of Plant Sciences and Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, U.S.A
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33
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Molina L, Segura A, Duque E, Ramos JL. The versatility of Pseudomonas putida in the rhizosphere environment. ADVANCES IN APPLIED MICROBIOLOGY 2019; 110:149-180. [PMID: 32386604 DOI: 10.1016/bs.aambs.2019.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This article addresses the lifestyle of Pseudomonas and focuses on how Pseudomonas putida can be used as a model system for biotechnological processes in agriculture, and in the removal of pollutants from soils. In this chapter we aim to show how a deep analysis using genetic information and experimental tests has helped to reveal insights into the lifestyle of Pseudomonads. Pseudomonas putida is a Plant Growth Promoting Rhizobacteria (PGPR) that establishes commensal relationships with plants. The interaction involves a series of functions encoded by core genes which favor nutrient mobilization, prevention of pathogen development and efficient niche colonization. Certain Pseudomonas putida strains harbor accessory genes that confer specific biodegradative properties and because these microorganisms can thrive on the roots of plants they can be exploited to remove pollutants via rhizoremediation, making the consortium plant/Pseudomonas a useful tool to combat pollution.
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Affiliation(s)
- Lázaro Molina
- CSIC- Estación Experimental del Zaidín, Granada, Spain
| | - Ana Segura
- CSIC- Estación Experimental del Zaidín, Granada, Spain
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Ryu MH, Zhang J, Toth T, Khokhani D, Geddes BA, Mus F, Garcia-Costas A, Peters JW, Poole PS, Ané JM, Voigt CA. Control of nitrogen fixation in bacteria that associate with cereals. Nat Microbiol 2019; 5:314-330. [DOI: 10.1038/s41564-019-0631-2] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 11/04/2019] [Indexed: 12/23/2022]
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Rolfe SA, Griffiths J, Ton J. Crying out for help with root exudates: adaptive mechanisms by which stressed plants assemble health-promoting soil microbiomes. Curr Opin Microbiol 2019; 49:73-82. [PMID: 31731229 DOI: 10.1016/j.mib.2019.10.003] [Citation(s) in RCA: 152] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/29/2019] [Accepted: 10/03/2019] [Indexed: 01/13/2023]
Abstract
Plants employ immunological and ecological strategies to resist biotic stress. Recent evidence suggests that plants adapt to biotic stress by changing their root exudation chemistry to assemble health-promoting microbiomes. This so-called 'cry-for-help' hypothesis provides a mechanistic explanation for previously characterized soil feedback responses to plant disease, such as the development of disease-suppressing soils upon successive cultivations of take all-infected wheat. Here, we divide the hypothesis into individual stages and evaluate the evidence for each component. We review how plant immune responses modify root exudation chemistry, as well as what impact this has on microbial activities, and the subsequent plant responses to these activities. Finally, we review the ecological relevance of the interaction, along with its translational potential for future crop protection strategies.
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Affiliation(s)
- Stephen A Rolfe
- Plant Production and Protection (P(3)), Institute for Sustainable Food, The University of Sheffield, S10 2TN, UK; Department of Animal and Plant Sciences, The University of Sheffield, S10 2TN, UK
| | - Joseph Griffiths
- Department of Animal and Plant Sciences, The University of Sheffield, S10 2TN, UK
| | - Jurriaan Ton
- Plant Production and Protection (P(3)), Institute for Sustainable Food, The University of Sheffield, S10 2TN, UK; Department of Animal and Plant Sciences, The University of Sheffield, S10 2TN, UK.
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Liu F, Hewezi T, Lebeis SL, Pantalone V, Grewal PS, Staton ME. Soil indigenous microbiome and plant genotypes cooperatively modify soybean rhizosphere microbiome assembly. BMC Microbiol 2019; 19:201. [PMID: 31477026 PMCID: PMC6720100 DOI: 10.1186/s12866-019-1572-x] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 08/21/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Plants have evolved intimate interactions with soil microbes for a range of beneficial functions including nutrient acquisition, pathogen resistance and stress tolerance. Further understanding of this system is a promising way to advance sustainable agriculture by exploiting the versatile benefits offered by the plant microbiome. The rhizosphere is the interface between plant and soil, and functions as the first step of plant defense and root microbiome recruitment. It features a specialized microbial community, intensive microbe-plant and microbe-microbe interactions, and complex signal communication. To decipher the rhizosphere microbiome assembly of soybean (Glycine max), we comprehensively characterized the soybean rhizosphere microbial community using 16S rRNA gene sequencing and evaluated the structuring influence from both host genotype and soil source. RESULTS Comparison of the soybean rhizosphere to bulk soil revealed significantly different microbiome composition, microbe-microbe interactions and metabolic capacity. Soil type and soybean genotype cooperatively modulated microbiome assembly with soil type predominantly shaping rhizosphere microbiome assembly while host genotype slightly tuned this recruitment process. The undomesticated progenitor species, Glycine soja, had higher rhizosphere diversity in both soil types tested in comparison to the domesticated soybean genotypes. Rhizobium, Novosphingobium, Phenylobacterium, Streptomyces, Nocardioides, etc. were robustly enriched in soybean rhizosphere irrespective of the soil tested. Co-occurrence network analysis revealed dominant soil type effects and genotype specific preferences for key microbe-microbe interactions. Functional prediction results demonstrated converged metabolic capacity in the soybean rhizosphere between soil types and among genotypes, with pathways related to xenobiotic degradation, plant-microbe interactions and nutrient transport being greatly enriched in the rhizosphere. CONCLUSION This comprehensive comparison of the soybean microbiome between soil types and genotypes expands our understanding of rhizosphere microbe assembly in general and provides foundational information for soybean as a legume crop for this assembly process. The cooperative modulating role of the soil type and host genotype emphasizes the importance of integrated consideration of soil condition and plant genetic variability for future development and application of synthetic microbiomes. Additionally, the detection of the tuning role by soybean genotype in rhizosphere microbiome assembly provides a promising way for future breeding programs to integrate host traits participating in beneficial microbiota assembly.
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Affiliation(s)
- Fang Liu
- Department of Entomology and Plant Pathology, University of Tennessee, 153 Plant Biotechnology Building, 2505 E.J. Chapman Drive, Knoxville, TN 37996 USA
| | - Tarek Hewezi
- Department of Plant Science, University of Tennessee, 252 Ellington Plant Sciences Building, 2431 Joe Johnson Drive, Knoxville, TN 37996 USA
| | - Sarah L. Lebeis
- Department of Microbiology, University of Tennessee, 513 Ken and Blaire Mossman Bldg, 1311 Cumberland Avenue, Knoxville, TN 37996 USA
| | - Vince Pantalone
- Department of Plant Science, University of Tennessee, 254 Plant Biotechnology Building, 2505 E.J. Chapman Drive, Knoxville, TN 37996 USA
| | - Parwinder S. Grewal
- College of Science, University of Texas Rio Grande Valley, 1201 W. University Drive, Edinburg, TX 78539 USA
| | - Margaret E. Staton
- Department of Entomology and Plant Pathology, University of Tennessee, 154 Plant Biotechnology Building, 2505 E.J. Chapman Drive, Knoxville, TN 37996 USA
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Plant beneficial endophytic bacteria: Mechanisms, diversity, host range and genetic determinants. Microbiol Res 2019; 221:36-49. [DOI: 10.1016/j.micres.2019.02.001] [Citation(s) in RCA: 258] [Impact Index Per Article: 51.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 12/11/2018] [Accepted: 02/01/2019] [Indexed: 12/13/2022]
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López-Farfán D, Reyes-Darias JA, Matilla MA, Krell T. Concentration Dependent Effect of Plant Root Exudates on the Chemosensory Systems of Pseudomonas putida KT2440. Front Microbiol 2019; 10:78. [PMID: 30761113 PMCID: PMC6363813 DOI: 10.3389/fmicb.2019.00078] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/15/2019] [Indexed: 12/28/2022] Open
Abstract
Plant root colonization by rhizobacteria can protect plants against pathogens and promote plant growth, and chemotaxis to root exudates was shown to be an essential prerequisite for efficient root colonization. Since many chemoattractants control the transcript levels of their cognate chemoreceptor genes, we have studied here the transcript levels of the 27 Pseudomonas putida KT2440 chemoreceptor genes in the presence of different maize root exudate (MRE) concentrations. Transcript levels were increased for 10 chemoreceptor genes at low MRE concentrations, whereas almost all receptor genes showed lower transcript levels at high MRE concentrations. The exposure of KT2440 to different MRE concentrations did not alter c-di-GMP levels, indicating that changes in chemoreceptor transcripts are not mediated by this second messenger. Data suggest that rhizosphere colonization unfolds in a temporal fashion. Whereas at a distance to the root, exudates enhance chemoreceptor gene transcript levels promoting in turn chemotaxis, this process is reversed in root vicinity, where the necessity of chemotaxis toward the root may be less important. Insight into KT2440 signaling processes were obtained by analyzing mutants defective in the three cheA paralogous genes. Whereas a mutant in cheA1 showed reduced c-di-GMP levels and impaired biofilm formation, a cheA2 mutant was entirely deficient in MRE chemotaxis, indicating the existence of homologs of the P. aeruginosawsp and che (chemotaxis) pathways. Signaling through both pathways was important for efficient maize root colonization. Future studies will show whether the MRE concentration dependent effect on chemoreceptor gene transcript levels is a feature shared by other species.
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Affiliation(s)
- Diana López-Farfán
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - José A Reyes-Darias
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Miguel A Matilla
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Tino Krell
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
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Colonization efficiency of Pseudomonas putida is influenced by Fis-controlled transcription of nuoA-N operon. PLoS One 2018; 13:e0201841. [PMID: 30071101 PMCID: PMC6072106 DOI: 10.1371/journal.pone.0201841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 07/22/2018] [Indexed: 02/07/2023] Open
Abstract
Root colonization of plant growth-promoting bacteria is a complex multistep process that is influenced by several factors. For example, during adherence to plant roots, bacteria have to endure reactive oxygen species (ROS) produced by plants. In this study, we report that the global transcriptional regulator Fis is involved in the regulation of ROS-tolerance of Pseudomonas putida and thereby affects barley root colonization. Fis overexpression reduced both ROS-tolerance and adherence to barley roots and activated the transcription of the nuoA-N operon encoding NADH dehydrogenase I, the first enzyme of a membrane-bound electron-transport chain. The nuoA-N knockout mutation in the fis-overexpression background increased the ROS-tolerance and adherence to barley roots. We show that nuoA has two transcriptional start sites located 104 and 377 nucleotides upstream of the coding sequence, indicating the presence of two promoters. The DNase I footprint analysis revealed four Fis binding sites: Fis-nuo1 to Fis-nuo4, situated between these two promoters. Site-directed mutagenesis in a promoter-lacZ reporter and β-galactosidase assay further confirmed direct binding of Fis to Fis-nuo2 and probably to Fis-nuo4 but not to Fis-nuo1 and Fis-nuo3. Additionally, the results implied that Fis binding to Fis-nuo4 could affect transcription of the nuoA-N operon by modification of upstream DNA topology. Moreover, our transposon mutagenesis results indicated that Fis might be involved in the regulation of several alternative ROS detoxification processes utilizing NADH.
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Ledermann R, Bartsch I, Müller B, Wülser J, Fischer HM. A Functional General Stress Response of Bradyrhizobium diazoefficiens Is Required for Early Stages of Host Plant Infection. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:537-547. [PMID: 29278144 DOI: 10.1094/mpmi-11-17-0284-r] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Phylogenetically diverse bacteria respond to various stress conditions by mounting a general stress response (GSR) resulting in the induction of protection or damage repair functions. In α-proteobacteria, the GSR is induced by a regulatory cascade consisting of the extracytoplasmic function (ECF) σ factor σEcfG, its anti-σ factor NepR, and the anti-anti-σ factor PhyR. We have reported previously that σEcfG and PhyR of Bradyrhizobium diazoefficiens (formerly named Bradyrhizobium japonicum), the nitrogen-fixing root nodule symbiont of soybean and related legumes, are required for efficient symbiosis; however, the precise role of the GSR remained undefined. Here, we analyze the symbiotic defects of a B. diazoefficiens mutant lacking σEcfG by comparing distinct infection stages of enzymatically or fluorescently tagged wild-type and mutant bacteria. Although root colonization and root hair curling were indistinguishable, the mutant was not competitive, and showed delayed development of emerging nodules and only a few infection threads. Consequently, many of the mutant-induced nodules were aborted, empty, or partially colonized. Congruent with these results, we found that σEcfG was active in bacteria present in root-hair-entrapped microcolonies and infection threads but not in root-associated bacteria and nitrogen-fixing bacteroids. We conclude that GSR-controlled functions are crucial for synchronization of infection thread formation, colonization, and nodule development.
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Affiliation(s)
- Raphael Ledermann
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Ilka Bartsch
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Barbara Müller
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Janine Wülser
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Hans-Martin Fischer
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
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The activity of the C4-dicarboxylic acid chemoreceptor of Pseudomonas aeruginosa is controlled by chemoattractants and antagonists. Sci Rep 2018; 8:2102. [PMID: 29391435 PMCID: PMC5795001 DOI: 10.1038/s41598-018-20283-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/15/2018] [Indexed: 11/10/2022] Open
Abstract
Chemotaxis toward organic acids has been associated with colonization fitness and virulence and the opportunistic pathogen Pseudomonas aeruginosa exhibits taxis toward several tricarboxylic acid intermediates. In this study, we used high-throughput ligand screening and isothermal titration calorimetry to demonstrate that the ligand binding domain (LBD) of the chemoreceptor PA2652 directly recognizes five C4-dicarboxylic acids with KD values ranging from 23 µM to 1.24 mM. In vivo experimentation showed that three of the identified ligands act as chemoattractants whereas two of them behave as antagonists by inhibiting the downstream chemotaxis signalling cascade. In vitro and in vivo competition assays showed that antagonists compete with chemoattractants for binding to PA2652-LBD, thereby decreasing the affinity for chemoattractants and the subsequent chemotactic response. Two chemosensory pathways encoded in the genome of P. aeruginosa, che and che2, have been associated to chemotaxis but we found that only the che pathway is involved in PA2652-mediated taxis. The receptor PA2652 is predicted to contain a sCACHE LBD and analytical ultracentrifugation analyses showed that PA2652-LBD is dimeric in the presence and the absence of ligands. Our results indicate the feasibility of using antagonists to interfere specifically with chemotaxis, which may be an alternative strategy to fight bacterial pathogens.
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Matilla MA, Krell T. Plant Growth Promotion and Biocontrol Mediated by Plant-Associated Bacteria. PLANT MICROBIOME: STRESS RESPONSE 2018. [DOI: 10.1007/978-981-10-5514-0_3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Huertas‐Rosales Ó, Romero M, Heeb S, Espinosa‐Urgel M, Cámara M, Ramos‐González MI. The Pseudomonas putida CsrA/RsmA homologues negatively affect c-di-GMP pools and biofilm formation through the GGDEF/EAL response regulator CfcR. Environ Microbiol 2017; 19:3551-3566. [PMID: 28677348 PMCID: PMC6849547 DOI: 10.1111/1462-2920.13848] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/21/2017] [Accepted: 06/23/2017] [Indexed: 11/30/2022]
Abstract
Expression of cfcR, encoding the only GGDEF/EAL response regulator in Pseudomonas putida, is transcriptionally regulated by RpoS, ANR and FleQ, and the functionality of CfcR as a diguanylate cyclase requires the multisensor CHASE3/GAF hybrid histidine kinase named CfcA. Here an additional level of cfcR control, operating post-transcriptionally via the RNA-binding proteins RsmA, RsmE and RsmI, is unraveled. Specific binding of the three proteins to an Rsm-binding motif (5'CANGGANG3') encompassing the translational start codon of cfcR was confirmed. Although RsmA exhibited the highest binding affinity to the cfcR transcript, single deletions of rsmA, rsmE or rsmI caused minor derepression in CfcR translation compared to a ΔrsmIEA triple mutant. RsmA also showed a negative impact on c-di-GMP levels in a double mutant ΔrsmIE through the control of cfcR, which is responsible for most of the free c-di-GMP during stationary phase in static conditions. In addition, a CfcR-dependent c-di-GMP boost was observed during this stage in ΔrsmIEA confirming the negative effect of Rsm proteins on CfcR translation and explaining the increased biofilm formation in this mutant compared to the wild type. Overall, these results suggest that CfcR is a key player in biofilm formation regulation by the Rsm proteins in P. putida.
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Affiliation(s)
- Óscar Huertas‐Rosales
- Department of Environmental ProtectionEstación Experimental del Zaidín, CSICProfesor Albareda, 1, Granada 18008Spain
| | - Manuel Romero
- Centre for Biomolecular Sciences, School of Life SciencesUniversity of NottinghamNottingham NG7 2RDUK
| | - Stephan Heeb
- Centre for Biomolecular Sciences, School of Life SciencesUniversity of NottinghamNottingham NG7 2RDUK
| | - Manuel Espinosa‐Urgel
- Department of Environmental ProtectionEstación Experimental del Zaidín, CSICProfesor Albareda, 1, Granada 18008Spain
| | - Miguel Cámara
- Centre for Biomolecular Sciences, School of Life SciencesUniversity of NottinghamNottingham NG7 2RDUK
| | - María Isabel Ramos‐González
- Department of Environmental ProtectionEstación Experimental del Zaidín, CSICProfesor Albareda, 1, Granada 18008Spain
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Fernández M, Matilla MA, Ortega Á, Krell T. Metabolic Value Chemoattractants Are Preferentially Recognized at Broad Ligand Range Chemoreceptor of Pseudomonas putida KT2440. Front Microbiol 2017; 8:990. [PMID: 28620365 PMCID: PMC5449446 DOI: 10.3389/fmicb.2017.00990] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 05/17/2017] [Indexed: 12/18/2022] Open
Abstract
Bacteria have evolved a wide range of chemoreceptors with different ligand specificities. Typically, chemoreceptors bind ligands with elevated specificity and ligands serve as growth substrates. However, there is a chemoreceptor family that has a broad ligand specificity including many compounds that are not of metabolic value. To advance the understanding of this family, we have used the PcaY_PP (PP2643) chemoreceptor of Pseudomonas putida KT2440 as a model. Using Isothermal Titration Calorimetry we showed here that the recombinant ligand binding domain (LBD) of PcaY_PP recognizes 17 different C6-ring containing carboxylic acids with KD values between 3.7 and 138 μM and chemoeffector affinity correlated with the magnitude of the chemotactic response. Mutation of the pcaY_PP gene abolished chemotaxis to these compounds; phenotype that was restored following gene complementation. Growth experiments using PcaY_PP ligands as sole C-sources revealed functional relationships between their metabolic potential and affinity for the chemoreceptor. Thus, only 7 PcaY_PP ligands supported growth and their KD values correlated with the length of the bacterial lag phase. Furthermore, PcaY_PP ligands that did not support growth had significantly higher KD values than those that did. The receptor has thus binds preferentially compounds that serve as C-sources and amongst them those that rapidly promote growth. Tightest binding compounds were quinate, shikimate, 3-dehydroshikimate and protocatechuate, which are at the interception of the biosynthetic shikimate and catabolic quinate pathways. Analytical ultracentrifugation studies showed that ligand free PcaY_PP-LBD is present in a monomer-dimer equilibrium (KD = 57.5 μM). Ligand binding caused a complete shift to the dimeric state, which appears to be a general feature of four-helix bundle LBDs. This study indicates that the metabolic potential of compounds is an important parameter in the molecular recognition by broad ligand range chemoreceptors.
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Affiliation(s)
- Matilde Fernández
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas,Granada, Spain
| | - Miguel A Matilla
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas,Granada, Spain
| | - Álvaro Ortega
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas,Granada, Spain
| | - Tino Krell
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas,Granada, Spain
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Global Transcriptional Responses to Osmotic, Oxidative, and Imipenem Stress Conditions in Pseudomonas putida. Appl Environ Microbiol 2017; 83:AEM.03236-16. [PMID: 28130298 DOI: 10.1128/aem.03236-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 01/19/2017] [Indexed: 12/24/2022] Open
Abstract
Bacteria cope with and adapt to stress by modulating gene expression in response to specific environmental cues. In this study, the transcriptional response of Pseudomonas putida KT2440 to osmotic, oxidative, and imipenem stress conditions at two time points was investigated via identification of differentially expressed mRNAs and small RNAs (sRNAs). A total of 440 sRNA transcripts were detected, of which 10% correspond to previously annotated sRNAs, 40% to novel intergenic transcripts, and 50% to novel transcripts antisense to annotated genes. Each stress elicits a unique response as far as the extent and dynamics of the transcriptional changes. Nearly 200 protein-encoding genes exhibited significant changes in all stress types, implicating their participation in a general stress response. Almost half of the sRNA transcripts were differentially expressed under at least one condition, suggesting possible functional roles in the cellular response to stress conditions. The data show a larger fraction of differentially expressed sRNAs than of mRNAs with >5-fold expression changes. The work provides detailed insights into the mechanisms through which P. putida responds to different stress conditions and increases understanding of bacterial adaptation in natural and industrial settings.IMPORTANCE This study maps the complete transcriptional response of P. putida KT2440 to osmotic, oxidative, and imipenem stress conditions at short and long exposure times. Over 400 sRNA transcripts, consisting of both intergenic and antisense transcripts, were detected, increasing the number of identified sRNA transcripts in the strain by a factor of 10. Unique responses to each type of stress are documented, including both the extent and dynamics of the gene expression changes. The work adds rich detail to previous knowledge of stress response mechanisms due to the depth of the RNA sequencing data. Almost half of the sRNAs exhibit significant expression changes under at least one condition, suggesting their involvement in adaptation to stress conditions and identifying interesting candidates for further functional characterization.
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Pandin C, Le Coq D, Canette A, Aymerich S, Briandet R. Should the biofilm mode of life be taken into consideration for microbial biocontrol agents? Microb Biotechnol 2017; 10:719-734. [PMID: 28205337 PMCID: PMC5481536 DOI: 10.1111/1751-7915.12693] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 01/19/2017] [Accepted: 01/20/2017] [Indexed: 11/26/2022] Open
Abstract
Almost one‐third of crop yields are lost every year due to microbial alterations and diseases. The main control strategy to limit these losses is the use of an array of chemicals active against spoilage and unwanted pathogenic microorganisms. Their massive use has led to extensive environmental pollution, human poisoning and a variety of diseases. An emerging alternative to this chemical approach is the use of microbial biocontrol agents. Biopesticides have been used with success in several fields, but a better understanding of their mode of action is necessary to better control their activity and increase their use. Very few studies have considered that biofilms are the preferred mode of life of microorganisms in the target agricultural biotopes. Increasing evidence shows that the spatial organization of microbial communities on crop surfaces may drive important bioprotection mechanisms. The aim of this review is to summarize the evidence of biofilm formation by biocontrol agents on crops and discuss how this surface‐associated mode of life may influence their biology and interactions with other microorganisms and the host and, finally, their overall beneficial activity.
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Affiliation(s)
- Caroline Pandin
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Dominique Le Coq
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France.,Micalis Institute, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Alexis Canette
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Stéphane Aymerich
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Romain Briandet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
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Foster ZSL, Sharpton TJ, Grünwald NJ. Metacoder: An R package for visualization and manipulation of community taxonomic diversity data. PLoS Comput Biol 2017; 100:1738-50. [PMID: 28222096 DOI: 10.3732/ajb.1200572] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 03/07/2017] [Accepted: 02/10/2017] [Indexed: 05/20/2023] Open
Abstract
Community-level data, the type generated by an increasing number of metabarcoding studies, is often graphed as stacked bar charts or pie graphs that use color to represent taxa. These graph types do not convey the hierarchical structure of taxonomic classifications and are limited by the use of color for categories. As an alternative, we developed metacoder, an R package for easily parsing, manipulating, and graphing publication-ready plots of hierarchical data. Metacoder includes a dynamic and flexible function that can parse most text-based formats that contain taxonomic classifications, taxon names, taxon identifiers, or sequence identifiers. Metacoder can then subset, sample, and order this parsed data using a set of intuitive functions that take into account the hierarchical nature of the data. Finally, an extremely flexible plotting function enables quantitative representation of up to 4 arbitrary statistics simultaneously in a tree format by mapping statistics to the color and size of tree nodes and edges. Metacoder also allows exploration of barcode primer bias by integrating functions to run digital PCR. Although it has been designed for data from metabarcoding research, metacoder can easily be applied to any data that has a hierarchical component such as gene ontology or geographic location data. Our package complements currently available tools for community analysis and is provided open source with an extensive online user manual.
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Affiliation(s)
- Zachary S L Foster
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Thomas J Sharpton
- Department of Microbiology, Oregon State University, Corvallis, Oregon, United States of America
- Department of Statistics, Oregon State University, Corvallis, Oregon, United States of America
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA-ARS, Corvallis, Oregon, United States of America
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Agulló L, Romero-Silva MJ, Domenech M, Seeger M. p-Cymene Promotes Its Catabolism through the p-Cymene and the p-Cumate Pathways, Activates a Stress Response and Reduces the Biofilm Formation in Burkholderia xenovorans LB400. PLoS One 2017; 12:e0169544. [PMID: 28072820 PMCID: PMC5224996 DOI: 10.1371/journal.pone.0169544] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 12/18/2016] [Indexed: 11/19/2022] Open
Abstract
p-Cymene is an aromatic terpene that is present in diverse plant species. The aims of this study were to study the p-cymene metabolism in the model aromatic-degrading bacterium Burkholderia xenovorans LB400, and its response to p-cymene. The catabolic p-cymene (cym) and p-cumate (cmt) genes are clustered on the LB400 major chromosome. B. xenovorans LB400 was able to grow on p-cymene as well as on p-cumate as a sole carbon and energy sources. LB400 growth attained higher cell concentration at stationary phase on p-cumate than on p-cymene. The transcription of the key cymAb and cmtAb genes, and p-cumate dioxygenase activity were observed in LB400 cells grown on p-cymene and on p-cumate, but not in glucose-grown cells. Diverse changes on LB400 proteome were observed in p-cymene-grown cells compared to glucose-grown cells. An increase of the molecular chaperones DnaK, GroEL and ClpB, the organic hydroperoxide resistance protein Ohr, the alkyl hydroperoxide reductase AhpC and the copper oxidase CopA during growth on p-cymene strongly suggests that the exposure to p-cymene constitutes a stress condition for strain LB400. Diverse proteins of the energy metabolism such as enolase, pyruvate kinase, aconitase AcnA, succinyl-CoA synthetase beta subunit and ATP synthase beta subunit were induced by p-cymene. Electron microscopy showed that p-cymene-grown cells exhibited fuzzy outer and inner membranes and an increased periplasm. p-Cymene induced diverse membrane and transport proteins including the p-cymene transporter CymD. Biofilm formation was reduced during growth in p-cymene in strain LB400 compared to glucose-grown cells that may be associated with a decrease of diguanylate cyclase protein levels. Overall, these results indicate active p-cymene and p-cumate catabolic pathways in B. xenovorans LB400. In addition, this study showed that p-cymene activated a stress response in strain LB400 and reduced its biofilm formation.
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Affiliation(s)
- Loreine Agulló
- Molecular Microbiology and Environmental Biotechnology Laboratory, Department of Chemistry & Center for Nanotechnology and Systems Biology, Centro de Biotecnología, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - María José Romero-Silva
- Molecular Microbiology and Environmental Biotechnology Laboratory, Department of Chemistry & Center for Nanotechnology and Systems Biology, Centro de Biotecnología, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Mirian Domenech
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain
| | - Michael Seeger
- Molecular Microbiology and Environmental Biotechnology Laboratory, Department of Chemistry & Center for Nanotechnology and Systems Biology, Centro de Biotecnología, Universidad Técnica Federico Santa María, Valparaíso, Chile
- * E-mail:
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Martín-Mora D, Ortega A, Reyes-Darias JA, García V, López-Farfán D, Matilla MA, Krell T. Identification of a Chemoreceptor in Pseudomonas aeruginosa That Specifically Mediates Chemotaxis Toward α-Ketoglutarate. Front Microbiol 2016; 7:1937. [PMID: 27965656 PMCID: PMC5126104 DOI: 10.3389/fmicb.2016.01937] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 11/17/2016] [Indexed: 12/21/2022] Open
Abstract
Pseudomonas aeruginosa is an ubiquitous pathogen able to infect humans, animals, and plants. Chemotaxis was found to be associated with the virulence of this and other pathogens. Although established as a model for chemotaxis research, the majority of the 26 P. aeruginosa chemoreceptors remain functionally un-annotated. We report here the identification of PA5072 (named McpK) as chemoreceptor for α-ketoglutarate (αKG). High-throughput thermal shift assays and isothermal titration calorimetry studies (ITC) of the recombinant McpK ligand binding domain (LBD) showed that it recognizes exclusively α-ketoglutarate. The ITC analysis indicated that the ligand bound with positive cooperativity (Kd1 = 301 μM, Kd2 = 81 μM). McpK is predicted to possess a helical bimodular (HBM) type of LBD and this and other studies suggest that this domain type may be associated with the recognition of organic acids. Analytical ultracentrifugation (AUC) studies revealed that McpK-LBD is present in monomer-dimer equilibrium. Alpha-KG binding stabilized the dimer and dimer self-dissociation constants of 55 μM and 5.9 μM were derived for ligand-free and αKG-bound forms of McpK-LBD, respectively. Ligand-induced LBD dimer stabilization has been observed for other HBM domain containing receptors and may correspond to a general mechanism of this protein family. Quantitative capillary chemotaxis assays demonstrated that P. aeruginosa showed chemotaxis to a broad range of αKG concentrations with maximal responses at 500 μM. Deletion of the mcpK gene reduced chemotaxis over the entire concentration range to close to background levels and wild type like chemotaxis was recovered following complementation. Real-time PCR studies indicated that the presence of αKG does not modulate mcpK expression. Since αKG is present in plant root exudates it was investigated whether the deletion of mcpK altered maize root colonization. However, no significant changes with respect to the wild type strain were observed. The existence of a chemoreceptor specific for αKG may be due to its central metabolic role as well as to its function as signaling molecule. This work expands the range of known chemoreceptor types and underlines the important physiological role of chemotaxis toward tricarboxylic acid cycle intermediates.
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Affiliation(s)
- David Martín-Mora
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Alvaro Ortega
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - José A Reyes-Darias
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Vanina García
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Diana López-Farfán
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
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LapF and Its Regulation by Fis Affect the Cell Surface Hydrophobicity of Pseudomonas putida. PLoS One 2016; 11:e0166078. [PMID: 27812186 PMCID: PMC5094663 DOI: 10.1371/journal.pone.0166078] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/21/2016] [Indexed: 11/19/2022] Open
Abstract
The ability of bacteria to regulate cell surface hydrophobicity is important for the adaptation to different environmental conditions. The hydrophobicity of cell surface can be determined by several factors, including outer membrane and surface proteins. In this study, we report that an adhesin LapF influences cell surface hydrophobicity of Pseudomonas putida. Cells lacking LapF are less hydrophobic than wild-type cells in stationary growth phase. Moreover, the overexpression of the global regulator Fis decreases surface hydrophobicity by repressing the expression of lapF. Flow cytometry analysis revealed that bacteria producing LapF are more viable when confronted with methanol (a hydrophilic compound) but are more susceptible to 1-octanol (a hydrophobic compound). Thus, these results revealed that LapF is the hydrophobicity factor for the cell surface of P. putida.
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