scholarly journals Biocontrol of Ralstonia solanacearum by Treatment with Lytic Bacteriophages

2011 ◽  
Vol 77 (12) ◽  
pp. 4155-4162 ◽  
Author(s):  
Akiko Fujiwara ◽  
Mariko Fujisawa ◽  
Ryosuke Hamasaki ◽  
Takeru Kawasaki ◽  
Makoto Fujie ◽  
...  
Keyword(s):  
Cell Density ◽  
Ralstonia Solanacearum ◽  
Experimental Period ◽  
The Other ◽  
Bacterial Cells ◽  
Effective Prevention ◽  
Tomato Plants ◽  
Content Type ◽  
Tomato Seedlings ◽  
Lower Cell Density

ABSTRACTRalstonia solanacearumis a Gram-negative bacterium and the causative agent of bacterial wilt in many important crops. We treatedR. solanacearumwith three lytic phages: φRSA1, φRSB1, and φRSL1. Infection with φRSA1 and φRSB1, either alone or in combination with the other phages, resulted in a rapid decrease in the host bacterial cell density. Cells that were resistant to infection by these phages became evident approximately 30 h after phage addition to the culture. On the other hand, cells infected solely with φRSL1 in a batch culture were maintained at a lower cell density (1/3 of control) over a long period. Pretreatment of tomato seedlings with φRSL1 drastically limited penetration, growth, and movement of root-inoculated bacterial cells. All φRSL1-treated tomato plants showed no symptoms of wilting during the experimental period, whereas all untreated plants had wilted by 18 days postinfection. φRSL1 was shown to be relatively stable in soil, especially at higher temperatures (37 to 50°C). Active φRSL1 particles were recovered from the roots of treated plants and from soil 4 months postinfection. Based on these observations, we propose an alternative biocontrol method using a unique phage, such as φRSL1, instead of a phage cocktail with highly virulent phages. Using this method, φRSL1 killed some but not all bacterial cells. The coexistence of bacterial cells and the phage resulted in effective prevention of wilting.

scholarly journals Repression of VvpM Protease Expression by Quorum Sensing and the cAMP-cAMP Receptor Protein Complex inVibrio vulnificus

2018 ◽  
Vol 200 (7) ◽  
Author(s):  
Jeong-A Kim ◽  
Mi-Ae Lee ◽  
You-Chul Jung ◽  
Bo-Ram Jang ◽  
Kyu-Ho Lee
Keyword(s):  
Transcription Factors ◽  
Stationary Phase ◽  
Cell Density ◽  
Transcription Initiation ◽  
Vibrio Vulnificus ◽  
The Other ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Content Type ◽  
Camp Receptor

ABSTRACTSepticemia-causingVibrio vulnificusproduces at least three exoproteases, VvpE, VvpS, and VvpM, all of which participate in interactions with human cells. Expression of VvpE and VvpS is induced in the stationary phase by multiple transcription factors, including sigma factor S, SmcR, and the cAMP-cAMP receptor protein (cAMP-CRP) complex. Distinct roles of VvpM, such as induction of apoptosis, lead us to hypothesize VvpM expression is different from that of the other exoproteases. Its transcription, which was found to be independent of sigma S, is induced at the early exponential phase and then becomes negligible upon entry into the stationary phase. SmcR and CRP were studied regarding the control ofvvpMexpression. Transcription ofvvpMwas repressed by SmcR and cAMP-CRP complex individually, which specifically bound to the regions −2 to +20 and +6 to +27, respectively, relative to thevvpMtranscription initiation site. Derepression ofvvpMgene expression was 10- to 40-fold greater in ansmcR crpdouble mutant than in single-gene mutants. Therefore, these results show that the expression ofV. vulnificusexoproteases is differentially regulated, and in this way, distinct proteases can engage in specific interactions with a host.IMPORTANCEAn opportunistic human pathogen,Vibrio vulnificusproduces multiple extracellular proteases that are involved in diverse interactions with a host. The total exoproteolytic activity is detected mainly in the supernatants of the high-cell-density cultures. However, some proteolytic activity derived from a metalloprotease, VvpM, was present in the supernatants of the low-cell-density cultures sampled at the early growth period. In this study, we present the regulatory mechanism for VvpM expression via repression by at least two transcription factors. This type of transcriptional regulation is the exact opposite of those for expression of the otherV. vulnificusexoproteases. Differential regulation of each exoprotease's production then facilitates the pathogen's participation in the distinct interactions with a host.

scholarly journals Genome-Wide Identification of Ralstonia solanacearum Genes Required for Survival in Tomato Plants

mSystems ◽  
2021 ◽  
Author(s):  
Yaxing Su ◽  
Yanan Xu ◽  
Hailing Liang ◽  
Gaoqing Yuan ◽  
Xiaogang Wu ◽  
...  
Keyword(s):  
Ralstonia Solanacearum ◽  
Tomato Plant ◽  
Pathogenic Mechanism ◽  
Hostile Environment ◽  
Full Understanding ◽  
Tomato Plants ◽  
Content Type ◽  
Genome Wide

Tomato plant xylem is a nutritionally limiting and dynamically changing habitat. Studies on how R. solanacearum survives in this hostile environment are important for our full understanding of the pathogenic mechanism of this bacterium.

scholarly journals Integrated Approach for Detection of Nonculturable Cells of Ralstonia solanacearum in Asymptomatic Pelargonium spp. Cuttings

2008 ◽  
Vol 98 (8) ◽  
pp. 949-955 ◽  
Author(s):  
E. Marco-Noales ◽  
E. Bertolini ◽  
C. Morente ◽  
M. M. López
Keyword(s):  
Ralstonia Solanacearum ◽  
Physiological State ◽  
Integrated Approach ◽  
Screening Tests ◽  
Physiological Status ◽  
Bacterial Cells ◽  
Tomato Plants ◽  
Solid Media ◽  
Latently Infected ◽  
Nonculturable Cells

Ralstonia solanacearum (biovar 2, race 3) is a soil and water-borne pathogen that causes serious diseases in several solanaceous hosts. It can also infect geranium plants, posing an important threat to their culture when latently infected cuttings are imported from countries where the pathogen is endemic. R. solanacearum can be present in very low numbers in asymptomatic geranium cuttings, and/or in a particular stressed physiological state that escapes direct isolation on the solid media usually employed. Consequently, an integrated protocol has been developed to analyze asymptomatic geranium cuttings routinely. The first screening tests include isolation and co-operational-polymerase chain reaction (Co-PCR), based on the simultaneous and co-operational action of three primers from 16S rRNA of R. solanacearum. This method was selected as the most sensitive one, able to detect only 1 cell/ml including nonculturable cells. When isolation is negative but Co-PCR is positive, the bioassay in tomato plants is proposed, since stressed bacterial cells or those present in low numbers that do not grow on solid media can be recovered from inoculated tomato plants and retain pathogenicity. This methodology has been demonstrated to be useful and has allowed us to assess the relevance of the physiological status of bacterial cells and its implications in detection. It also reveals the risk of introducing R. solanacearum through asymptomatic geranium material when relying only on bacterial isolation.

scholarly journals Ralstonia solanacearum Requires PopS, an Ancient AvrE-Family Effector, for Virulence and To Overcome Salicylic Acid-Mediated Defenses during Tomato Pathogenesis

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Jonathan M. Jacobs ◽  
Annett Milling ◽  
Raka M. Mitra ◽  
Clifford S. Hogan ◽  
Florent Ailloud ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Species Complex ◽  
Plant Defenses ◽  
Natural Infection ◽  
Wild Type ◽  
Tomato Plants ◽  
Content Type ◽  
Type Iii

ABSTRACTDuring bacterial wilt of tomato, the plant pathogen Ralstonia solanacearum upregulates expression ofpopS, which encodes a type III-secreted effector in the AvrE family. PopS is a core effector present in all sequenced strains in theR. solanacearumspecies complex. The phylogeny ofpopSmirrors that of the species complex as a whole, suggesting that this is an ancient, vertically inherited effector needed for association with plants. ApopSmutant ofR. solanacearumUW551 had reduced virulence on agriculturally importantSolanumspp., including potato and tomato plants. However, thepopSmutant had wild-type virulence on a weed host,Solanum dulcamara, suggesting that some species can avoid the effects of PopS. ThepopSmutant was also significantly delayed in colonization of tomato stems compared to the wild type. Some AvrE-type effectors from gammaproteobacteria suppress salicylic acid (SA)-mediated plant defenses, suggesting that PopS, a betaproteobacterial ortholog, has a similar function. Indeed, thepopSmutant induced significantly higher expression of tomato SA-triggered pathogenesis-related (PR) genes than the wild type. Further, pretreatment of roots with SA exacerbated thepopSmutant virulence defect. Finally, thepopSmutant had no colonization defect on SA-deficient NahG transgenic tomato plants. Together, these results indicate that this conserved effector suppresses SA-mediated defenses in tomato roots and stems, which areR. solanacearum’s natural infection sites. Interestingly, PopS did not trigger necrosis when heterologously expressed inNicotianaleaf tissue, unlike the AvrE homolog DspEPccfrom the necrotrophPectobacterium carotovorumsubsp.carotovorum. This is consistent with the differing pathogenesis modes of necrosis-causing gammaproteobacteria and biotrophicR. solanacearum.IMPORTANCEThe type III-secreted AvrE effector family is widely distributed in high-impact plant-pathogenic bacteria and is known to suppress plant defenses for virulence. We characterized the biology of PopS, the only AvrE homolog made by the bacterial wilt pathogenRalstonia solanacearum. To our knowledge, this is the first study ofR. solanacearumeffector function in roots and stems, the natural infection sites of this pathogen. Unlike the functionally redundantR. solanacearumeffectors studied to date, PopS is required for full virulence and wild-type colonization of two natural crop hosts.R. solanacearumis a biotrophic pathogen that causes a nonnecrotic wilt. Consistent with this, PopS suppressed plant defenses but did not elicit cell death, unlike AvrE homologs from necrosis-causing plant pathogens. We propose that AvrE family effectors have functionally diverged to adapt to the necrotic or nonnecrotic lifestyle of their respective pathogens.

scholarly journals Viability, Stability and Biocontrol Activity in Planta of Specific Ralstonia Solanacearum Bacteriophages After Their Conservation Prior to Commercialization and Use

2021 ◽  
Author(s):  
Belén Álvarez ◽  
Laura Gadea-Pallás ◽  
Alejandro Rodríguez ◽  
Begonya Vicedo ◽  
Àngela Figàs-Segura ◽  
...  
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Reference Strain ◽  
Specific Activity ◽  
Experimental Period ◽  
In Planta ◽  
Tomato Plants ◽  
Preservation Method ◽  
Biocontrol Activity ◽  
Susceptible Tomato

Ralstonia solanacearum is a pathogen that causes bacterial wilt producing severe damage in staple solanaceous crops. Traditional control has low efficacy and/or environmental impact. Recently, the bases of a new biotechnological method by lytic bacteriophages vRsoP-WF2, vRsoP-WM2 and vRsoP-WR2 with specific activity against R. solanacearum were established. However, some aspects remain unknown, such as the survival and maintenance of the lytic activity after submission to a preservation method as the lyophilization. To this end, viability and stability of lyophilized vRsoP-WF2, vRsoP-WM2 and vRsoP-WR2 and their capacity for bacterial wilt biocontrol have been determined against one pathogenic Spanish reference strain of R. solanacearum in susceptible tomato plants in different conditions and making use of various cryoprotectants. The assays carried out have shown satisfactory results with respect to the viability and stability of the bacteriophages after the lyophilization process, maintaining high titres throughout the experimental period, also with respect to the capacity of the bacteriophages for the biological control of bacterial wilt, controlling this disease in more than 50% of the plants. The results offer good prospects for the use of lyophilization as a conservation method for the lytic bacteriophages of R. solanacearum in view of their commercialization as biocontrol agents.

scholarly journals Translocation and Distribution of C14 Photosynthates in Watermelon and Tomato

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 760A-760
Author(s):  
Sang Gyu Lee* ◽  
Chiwon W. Lee
Keyword(s):  
Fruit Development ◽  
Liquid Scintillation ◽  
Experimental Period ◽  
Development Stage ◽  
The Other ◽  
Natural Light ◽  
Tomato Plants ◽  
Mature Leaves

The pattern of translocation and distribution of C14 labeled photo-assimilates in watermelon and tomato grown in the greenhouse and field was characterized. Each of the mature leaves of the plant at active fruit development stage was exposed to 14CO2 (20 μCi radio activity) for 40 min and the leaves, stems, fruit, and roots were harvested 3, 6, 9, or 12 hours after treatment. One half of the plants were grown under natural light and the other half in the dark during the experimental period. The activity of C14 in the dry tissues of the leaves, stems, fruits, and roots was determined, using a liquid scintillation analyzer. Both watermelon and tomato plants grown in the greenhouse and field contained C14 in all tissue types 3 hr after treatment, regardless of exposure to light or dark during the experimental period. Watermelon and tomato, respectively, transferred 22% to 61% and 9% to 26% C14 from the source leaf in 3 hours. Fruit tissues served as the strongest sink, with the highest percentages of C14 transfer in watermelon (99%) and tomato (90%) in plants grown in the field. The rate of C14 translocation was highest when plants were kept in the dark after 14CO2 feeding. In general, total translocation of C14 compounds from the source leaf was higher in watermelon than in tomato plants. For both watermelon and tomato, most field-grown plants showed a higher rate of C14 translocation as compared to greenhouse grown plants for a given period of time.

scholarly journals Ecological Role of Volatile Organic Compounds Emitted by Pantoea agglomerans as Interspecies and Interkingdom Signals

2021 ◽  
Vol 9 (6) ◽  
pp. 1186
Author(s):  
Maria Vasseur-Coronado ◽  
Anthi Vlassi ◽  
Hervé Dupré du Boulois ◽  
Rainer Schuhmacher ◽  
Alexandra Parich ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Dimethyl Disulfide ◽  
Dry Weight ◽  
Plant Growth Promoting Rhizobacteria ◽  
Pantoea Agglomerans ◽  
Bacterial Cells ◽  
Tomato Plants ◽  
Tomato Seedlings ◽  
Volatile Organic

Volatile organic compounds (VOCs) play an essential role in microbe–microbe and plant–microbe interactions. We investigated the interaction between two plant growth-promoting rhizobacteria, and their interaction with tomato plants. VOCs produced by Pantoea agglomerans MVC 21 modulates the release of siderophores, the solubilisation of phosphate and potassium by Pseudomonas (Ps.) putida MVC 17. Moreover, VOCs produced by P. agglomerans MVC 21 increased lateral root density (LRD), root and shoot dry weight of tomato seedlings. Among the VOCs released by P. agglomerans MVC 21, only dimethyl disulfide (DMDS) showed effects similar to P. agglomerans MVC 21 VOCs. Because of the effects on plants and bacterial cells, we investigated how P. agglomerans MVC 21 VOCs might influence bacteria–plant interaction. Noteworthy, VOCs produced by P. agglomerans MVC 21 boosted the ability of Ps. putida MVC 17 to increase LRD and root dry weight of tomato seedlings. These results could be explained by the positive effect of DMDS and P. agglomerans MVC 21 VOCs on acid 3-indoleacetic production in Ps. putida MVC 17. Overall, our results clearly indicated that P. agglomerans MVC 21 is able to establish a beneficial interaction with Ps. putida MVC 17 and tomato plants through the emission of DMDS.

scholarly journals The Iron-Dependent Regulator Fur Controls Pheromone Signaling Systems and Luminescence in the Squid Symbiont Vibrio fischeri ES114

2013 ◽  
Vol 79 (6) ◽  
pp. 1826-1834 ◽  
Author(s):  
Alecia N. Septer ◽  
Noreen L. Lyell ◽  
Eric V. Stabb
Keyword(s):  
Cell Density ◽  
Vibrio Vulnificus ◽  
Vibrio Fischeri ◽  
Content Type ◽  
Signaling Systems ◽  
Master Regulators ◽  
Pheromone Signaling ◽  
Coordinate Group ◽  
Regulatory Link ◽  
Lower Cell Density

ABSTRACTBacteria often use pheromones to coordinate group behaviors in specific environments. While high cell density is required for pheromones to achieve stimulatory levels, environmental cues can also influence pheromone accumulation and signaling. For the squid symbiontVibrio fischeriES114, bioluminescence requires pheromone-mediated regulation, and this signaling is induced in the host to a greater extent than in culture, even at an equivalent cell density. Our goal is to better understand this environment-specific control over pheromone signaling and bioluminescence. Previous work withV. fischeriMJ1 showed that iron limitation induces luminescence, and we recently found that ES114 encounters a low-iron environment in its host. Here we show that ES114 induces luminescence at lower cell density and achieves brighter luminescence in low-iron media. This iron-dependent effect on luminescence required ferric uptake regulator (Fur), which we propose influences two pheromone signaling master regulators, LitR and LuxR. Genetic and bioinformatic analyses suggested that under low-iron conditions, Fur-mediated repression oflitRis relieved, enabling more LitR to perform its established role as an activator ofluxR. Interestingly, Fur may similarly control the LitR homolog SmcR ofVibrio vulnificus. These results reveal an intriguing regulatory link between low-iron conditions, which are often encountered in host tissues, and pheromone-dependent master regulators.

scholarly journals Quantitative Immunofluorescence of Regulatedeps Gene Expression in Single Cells of Ralstonia solanacearum

1999 ◽  
Vol 65 (6) ◽  
pp. 2356-2362 ◽  
Author(s):  
Yaowei Kang ◽  
Elke Saile ◽  
Mark A. Schell ◽  
Timothy P. Denny
Keyword(s):  
Gene Expression ◽  
Ralstonia Solanacearum ◽  
Virulence Genes ◽  
Single Cells ◽  
Short Circuit ◽  
Acid Methyl Ester ◽  
Bacterial Cells ◽  
Phytopathogenic Bacterium ◽  
Tomato Plants ◽  
Quantitative Immunofluorescence

ABSTRACT Ralstonia solanacearum, a phytopathogenic bacterium, uses an environmentally sensitive and complex regulatory network to control expression of multiple virulence genes. Part of this network is an unusual autoregulatory system that produces and senses 3-hydroxypalmitic acid methyl ester. In culture, this autoregulatory system ensures that expression of virulence genes, such as those of the eps operon encoding biosynthesis of the acidic extracellular polysaccharide, occurs only at high cell density (>107 cells/ml). To determine if regulation follows a similar pattern within tomato plants, we first developed a quantitative immunofluorescence (QIF) method that measures the relative amount of a target protein within individual bacterial cells. ForR. solanacearum, QIF was used to determine the amount of β-galactosidase protein within wild-type cells containing a stable eps-lacZ reporter allele. When cultured cells were examined to test the method, QIF accurately detected both low and high levels of eps gene expression. QIF analysis ofR. solanacearum cells recovered from stems of infected tomato plants showed that expression of epsduring pathogenesis was similar to that in culture. These results suggest that there are no special signals or conditions within plants that override or short-circuit the regulatory processes observed inR. solanacearum in culture. Because QIF is a robust, relatively simple procedure that uses generally accessible equipment, it should be useful in many situations where gene expression in single bacterial cells must be determined.

scholarly journals Twitching and Swimming Motility Play a Role in Ralstonia solanacearum Pathogenicity

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Jordi Corral ◽  
Pau Sebastià ◽  
Núria S. Coll ◽  
Jordi Barbé ◽  
Jesús Aranda ◽  
...  
Keyword(s):  
Plant Pathogen ◽  
Ralstonia Solanacearum ◽  
Biofilm Formation ◽  
Natural Transformation ◽  
Plant Colonization ◽  
Twitching Motility ◽  
Tomato Plants ◽  
Content Type ◽  
First Time ◽  
Root Attachment

ABSTRACT Ralstonia solanacearum is a bacterial plant pathogen causing important economic losses worldwide. In addition to the polar flagella responsible for swimming motility, this pathogen produces type IV pili (TFP) that govern twitching motility, a flagellum-independent movement on solid surfaces. The implication of chemotaxis in plant colonization, through the control flagellar rotation by the proteins CheW and CheA, has been previously reported in R. solanacearum. In this work, we have identified in this bacterium homologues of the Pseudomonas aeruginosa pilI and chpA genes, suggested to play roles in TFP-associated motility analogous to those played by the cheW and cheA genes, respectively. We demonstrate that R. solanacearum strains with a deletion of the pilI or the chpA coding region show normal swimming and chemotaxis but altered biofilm formation and reduced twitching motility, transformation efficiency, and root attachment. Furthermore, these mutants displayed wild-type growth in planta and impaired virulence on tomato plants after soil-drench inoculations but not when directly applied to the xylem. Comparison with deletion mutants for pilA and fliC—encoding the major pilin and flagellin subunits, respectively—showed that both twitching and swimming are required for plant colonization and full virulence. This work proves for the first time the functionality of a pilus-mediated pathway encoded by pil-chp genes in R. solanacearum, demonstrating that pilI and chpA genes are bona fide motility regulators controlling twitching motility and its three related phenotypes: virulence, natural transformation, and biofilm formation. IMPORTANCE Twitching and swimming are two bacterial movements governed by pili and flagella. The present work identifies for the first time in the Gram-negative plant pathogen Ralstonia solanacearum a pilus-mediated chemotaxis pathway analogous to that governing flagellum-mediated chemotaxis. We show that regulatory genes in this pathway control all of the phenotypes related to pili, including twitching motility, natural transformation, and biofilm formation, and are also directly implicated in virulence, mainly during the first steps of the plant infection. Our results show that pili have a higher impact than flagella on the interaction of R. solanacearum with tomato plants and reveal new types of cross-talk between the swimming and twitching motility phenotypes: enhanced swimming in bacteria lacking pili and a role for the flagellum in root attachment.

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