scholarly journals Ralstonia solanacearum Needs Motility for Invasive Virulence on Tomato

2001 ◽  
Vol 183 (12) ◽  
pp. 3597-3605 ◽  
Author(s):  
Julie Tans-Kersten ◽  
Huayu Huang ◽  
Caitilyn Allen
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Soft Agar ◽  
Cell Protein ◽  
In Planta ◽  
Tomato Plants ◽  
Bacterial Wilt Disease ◽  
Virulence Assay ◽  
Flagellar Filament

ABSTRACT Ralstonia solanacearum, a widely distributed and economically important plant pathogen, invades the roots of diverse plant hosts from the soil and aggressively colonizes the xylem vessels, causing a lethal wilting known as bacterial wilt disease. By examining bacteria from the xylem vessels of infected plants, we found thatR. solanacearum is essentially nonmotile in planta, although it can be highly motile in culture. To determine the role of pathogen motility in this disease, we cloned, characterized, and mutated two genes in the R. solanacearum flagellar biosynthetic pathway. The genes for flagellin, the subunit of the flagellar filament (fliC), and for the flagellar motor switch protein (fliM) were isolated based on their resemblance to these proteins in other bacteria. As is typical for flagellins, the predicted FliC protein had well-conserved N- and C-terminal regions, separated by a divergent central domain. The predicted R. solanacearum FliM closely resembled motor switch proteins from other proteobacteria. Chromosomal mutants lackingfliC or fliM were created by replacing the genes with marked interrupted constructs. Since fliM is embedded in the fliLMNOPQR operon, the aphAcassette was used to make a nonpolar fliM mutation. Both mutants were completely nonmotile on soft agar plates, in minimal broth, and in tomato plants. The fliC mutant lacked flagella altogether; moreover, sheared-cell protein preparations from the fliC mutant lacked a 30-kDa band corresponding to flagellin. The fliM mutant was usually aflagellate, but about 10% of cells had abnormal truncated flagella. In a biologically representative soil-soak inoculation virulence assay, both nonmotile mutants were significantly reduced in the ability to cause disease on tomato plants. However, the fliC mutant had wild-type virulence when it was inoculated directly onto cut tomato petioles, an inoculation method that did not require bacteria to enter the intact host from the soil. These results suggest that swimming motility makes its most important contribution to bacterial wilt virulence in the early stages of host plant invasion and colonization.

scholarly journals Bacterial Tomato Pathogen Ralstonia solanacearum Invasion Modulates Rhizosphere Compounds and Facilitates the Cascade Effect of Fungal Pathogen Fusarium solani

2020 ◽  
Vol 8 (6) ◽  
pp. 806
Author(s):  
Lv Su ◽  
Lifan Zhang ◽  
Duoqian Nie ◽  
Eiko E. Kuramae ◽  
Biao Shen ◽  
...  
Keyword(s):  
Phenolic Acids ◽  
Bacterial Wilt ◽  
Fusarium Solani ◽  
Ralstonia Solanacearum ◽  
High Throughput Sequencing ◽  
Rhizosphere Soil ◽  
Wilt Disease ◽  
Tomato Plants ◽  
Bacterial Wilt Disease ◽  
Pathogen Invasion

Soil-borne pathogen invasions can significantly change the microbial communities of the host rhizosphere. However, whether bacterial Ralstonia solanacearum pathogen invasion influences the abundance of fungal pathogens remains unclear. In this study, we combined high-throughput sequencing, qPCR, liquid chromatography and soil culture experiments to analyze the rhizosphere fungal composition, co-occurrence of fungal communities, copy numbers of functional genes, contents of phenolic acids and their associations in healthy and bacterial wilt-diseased tomato plants. We found that R. solanacearum invasion increased the abundance of the soil-borne pathogen Fusarium solani. The concentrations of three phenolic acids in the rhizosphere soil of bacterial wilt-diseased tomato plants were significantly higher than those in the rhizosphere soil of healthy tomato plants. In addition, the increased concentrations of phenolic acids significantly stimulated F. solani growth in the soil. Furthermore, a simple fungal network with fewer links, nodes and hubs (highly connected nodes) was found in the diseased tomato plant rhizosphere. These results indicate that once the symptom of bacterial wilt disease is observed in tomato, the roots of the wilt-diseased tomato plants need to be removed in a timely manner to prevent the enrichment of other fungal soil-borne pathogens. These findings provide some ecological clues for the mixed co-occurrence of bacterial wilt disease and other fungal soil-borne diseases.

scholarly journals Role of Extracellular Polysaccharide and Endoglucanase in Root Invasion and Colonization of Tomato Plants by Ralstonia solanacearum

1997 ◽  
Vol 87 (12) ◽  
pp. 1264-1271 ◽  
Author(s):  
Elke Saile ◽  
Jeff A. McGarvey ◽  
Mark A. Schell ◽  
Timothy P. Denny
Keyword(s):  
Ralstonia Solanacearum ◽  
Extracellular Polysaccharide ◽  
Wild Type ◽  
In Planta ◽  
Tomato Plants ◽  
Potted Plants ◽  
Stem Infection ◽  
Soil Infestation ◽  
Plant Stem

Ralstonia solanacearum is a soilborne plant pathogen that normally invades hosts through their roots and then systemically colonizes aerial tissues. Previous research using wounded stem infection found that the major factor in causing wilt symptoms was the high-molecular-mass acidic extracellular polysaccharide (EPS I), but the β-1,4-endoglucanase (EG) also contributes to virulence. We investigated the importance of EPS I and EG for invasion and colonization of tomato by infesting soil of 4-week-old potted plants with either a wild-type derivative or genetically well-defined mutants lacking EPS I, EG, or EPS I and EG. Bacteria of all strains were recovered from surface-disinfested roots and hypocotyls as soon as 4 h after inoculation; that bacteria were present internally was confirmed using immunofluorescence microscopy. However, the EPS-minus mutants did not colonize stems as rapidly as the wild type and the EG-minus mutant. Inoculations of wounded petioles also showed that, even though the mutants multiplied as well as the wild type in planta, EPS-minus strains did not spread as well throughout the plant stem. We conclude that poor colonization of stems by EPS-minus strains after petiole inoculation or soil infestation is due to reduced bacterial movement within plant stem tissues.

scholarly journals Using the Ralstonia solanacearum Tat Secretome To Identify Bacterial Wilt Virulence Factors

2007 ◽  
Vol 73 (12) ◽  
pp. 3779-3786 ◽  
Author(s):  
Enid T. Gonz�lez ◽  
Darby G. Brown ◽  
Jill K. Swanson ◽  
Caitilyn Allen
Keyword(s):  
Virulence Factors ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Acid Tolerance ◽  
Bioinformatic Analysis ◽  
Wild Type ◽  
In Planta ◽  
Tomato Plants ◽  
Tat System

ABSTRACT To identify secreted virulence factors involved in bacterial wilt disease caused by the phytopathogen Ralstonia solanacearum, we mutated tatC, a key component of the twin-arginine translocation (Tat) secretion system. The R. solanacearum tatC mutation was pleiotropic; its phenotypes included defects in cell division, nitrate utilization, polygalacturonase activity, membrane stability, and growth in plant tissue. Bioinformatic analysis of the R. solanacearum strain GMI1000 genome predicted that this pathogen secretes 70 proteins via the Tat system. The R. solanacearum tatC strain was severely attenuated in its ability to cause disease, killing just over 50% of tomato plants in a naturalistic soil soak assay where the wild-type parent killed 100% of the plants. This result suggested that elements of the Tat secretome may be novel bacterial wilt virulence factors. To identify contributors to R. solanacearum virulence, we cloned and mutated three genes whose products are predicted to be secreted by the Tat system: RSp1521, encoding a predicted AcvB-like protein, and two genes, RSc1651 and RSp1575, that were identified as upregulated in planta by an in vivo expression technology screen. The RSc1651 mutant had wild-type virulence on tomato plants. However, mutants lacking either RSp1521, which appears to be involved in acid tolerance, or RSp1575, which encodes a possible amino acid binding protein, were significantly reduced in virulence on tomato plants. Additional bacterial wilt virulence factors may be found in the Tat secretome.

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 Rhizobacterial community structure in grafted tomato plants infected by Ralstonia solanacearum

2020 ◽  
Vol 21 (10) ◽  
Author(s):  
Lisa Navitasari ◽  
TRI JOKO ◽  
RUDI HARI MURTI ◽  
TRIWIDODO ARWIYANTO
Keyword(s):  
Community Structure ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Wilt Disease ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Distinct Region ◽  
Tomato Plants ◽  
Bacterial Wilt Disease ◽  
Significant Difference

Abstract. Navitasari L, Joko T, Murti RH, Arwiyanto T. 2020. Rhizobacterial community structure in grafted tomato plants infected by Ralstonia solanacearum. Biodiversitas 21: 4888-4895. Bacterial wilt disease caused by Ralstonia solanacearum is a devastating soil-borne vascular disease of tomato leading to a 100% yield loss. One of the alternatives to suppress the infestation of R. solanacearum infestation is the application of grafting techniques, which has been studied and successfully practiced by tomato growers. However, the infestation mode of R. solanacearum and the rhizobacterial community structure in grafted tomato plants are poorly reported. In this study, the rhizobacterial community structure in grafted tomato plants infected by R. solanacearum was investigated. The experiment was conducted on tomato germplasms with the implementation of tube grafting using resistant rootstocks (Amelia from Indonesia, H.7996 from Asian Vegetable Research Development Center/AVRDC) and susceptible scion (Servo from Indonesia). The rhizobacterial community structure was analyzed by metagenomic study under 16S rRNA genes sequencing with a distinct region (16SV3-V4) that was amplified using a specific primer (16SV4: 515F-806R) 5’-GTGCCAGCMGCCGCGGTAA and 5’GGACTACHVHHHTWTCTAAT. The results indicated that the grafted tomato plants and resistant rootstocks that were infected by R. solanacearum showed significantly lower intensity of bacterial wilt disease compared to the susceptible scion. The rhizobacterial community structure in the grafted tomato plants infected by R. solanacearum was indicated by predominant phyla of Proteobacteria, Firmicutes, and Actinobacteria with dominant genera of Pseudomonas and Bacillus. Besides, significant difference was also indicated by species of Geitlerinema sp. in the grafted tomatoes infected by R. solanacearum.

scholarly journals The RSc0454-Encoded FAD-Linked Oxidase Is Indispensable for Pathogenicity in Ralstonia solanacearum GMI1000

2019 ◽  
Vol 32 (6) ◽  
pp. 697-707
Author(s):  
Xun Hu ◽  
Zhiwen Zhao ◽  
Tao Zhuo ◽  
Xiaojing Fan ◽  
Huasong Zou
Keyword(s):  
Lactate Dehydrogenase ◽  
Succinate Dehydrogenase ◽  
Gene Transcription ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Cell Aggregation ◽  
Wilt Disease ◽  
In Planta ◽  
Bacterial Wilt Disease ◽  
Dehydrogenase Gene

Ralstonia solanacearum is the causal agent of bacterial wilt disease. Here, we report that a large FAD-linked oxidase encoded by RSc0454 in GMI1000 is required for pathogenicity. The FAD-linked oxidase encoded by RSc0454 is composed of 1,345 amino acids, including DUF3683, lactate dehydrogenase (LDH), and succinate dehydrogenase (SDH) domains. The RSc0454 protein showed both LDH and SDH activities. To investigate its role in pathogenicity, a deletion mutant of the RSc0454 gene was constructed in GMI1000, which was impaired in its ability to cause bacterial wilt disease in tomato. A single DUF3683, LDH, or SDH domain was insufficient to restore bacterial pathogenicity. Mutagenesis of the RSc0454 gene did not affect growth rate but caused cell aggregation at the bottom of the liquid nutrient medium, which was reversed by exogenous applications of lactate, fumarate, pyruvate, and succinate. qRT-PCR and promoter LacZ fusion experiments demonstrated that RSc0454 gene transcription was induced by lactate and fumarate (both substrates of LDH). Compared with the downregulation of the succinate dehydrogenase gene sdhBADC and the lactate dehydrogenase gene ldh, RSc0454 gene transcription was enhanced in planta. This suggests that the oxidase encoded by RSc0454 was involved in a redox balance, which is in line with the different living conditions of R. solanacearum.

scholarly journals Selection and Formulation of Endophytic Bacteria as Plant Resistance Elicitor against Wilt Disease of Tomato

2019 ◽  
Vol 3 (2) ◽  
pp. 103
Author(s):  
Arika Purnawati ◽  
Wiwik Harjani ◽  
Herry Nirwanto
Keyword(s):  
Plant Resistance ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Endophytic Bacteria ◽  
Bacterial Isolate ◽  
Disease Incidence ◽  
Wilt Disease ◽  
Seed Coating ◽  
In Planta ◽  
Bacterial Wilt Disease

<p>Wilt disease of <em>Solanaceae</em> caused by <em>Ralstonia solanacearum</em> reduce the crop quality and negatively affect the crop product. The objective of this research was to discover of endophytic bacteria formulation that effectively decreases bacterial which cause wilt disease on <em>Solanaceae</em>. The research consisted of purification of <em>Ralstonia solanacearum</em>, endophytic bacteria were obtained from the sample and the screening of endophytic bacteria using this following assay: antagonist assay, seedling assay and <em>in planta</em> assay. The results showed that in antagonist assay, the bacterial isolate code PS<sub>1</sub>, PS<sub>2</sub>, and PS<sub>8 </sub>could inhibit growth of <em>R. solanacearum. </em>From the seedling assay, it obtained that all of the isolates increased of percentage of germination, seed coating and powder formulation can decrease disease incidence of bacterial wilt disease.</p>

scholarly journals Interactions with Hosts at Cool Temperatures, Not Cold Tolerance, Explain the Unique Epidemiology of Ralstonia solanacearum Race 3 Biovar 2

2009 ◽  
Vol 99 (10) ◽  
pp. 1127-1134 ◽  
Author(s):  
Annett Milling ◽  
Fanhong Meng ◽  
Timothy P. Denny ◽  
Caitilyn Allen
Keyword(s):  
North American ◽  
Ralstonia Solanacearum ◽  
Potato Tubers ◽  
In Planta ◽  
Plant Host ◽  
Tomato Plants ◽  
North American Strain ◽  
Tropical Highlands ◽  
American Strain ◽  
Warm Temperate

Most strains of the bacterial wilt pathogen Ralstonia solanacearum are tropical, but race 3 biovar 2 (R3bv2) strains can attack plants in temperate zones and tropical highlands. The basis of this distinctive ecological trait is not understood. We compared the survival of tropical, R3bv2, and warm-temperate North American strains of R. solanacearum under different conditions. In water at 4°C, North American strains remained culturable the longest (up to 90 days), whereas tropical strains remained culturable for the shortest time (≈40 days). However, live/dead staining indicated that cells of representative strains remained viable for >160 days. In contrast, inside potato tubers, R3bv2 strain UW551 survived >4 months at 4°C, whereas North American strain K60 and tropical strain GMI1000 were undetectable after <70 days in tubers. GMI1000 and UW551 grew similarly in minimal medium at 20 and 28°C and, although both strains wilted tomato plants rapidly at 28°C, UW551 was much more virulent at 20°C, killing all inoculated plants under conditions where GMI100 killed just over half. Thus, differences among the strains in the absence of a plant host were not predictive of their behavior in planta at cooler temperatures. These data indicate that interaction with plants is required for expression of the temperate epidemiological trait of R3bv2.

scholarly journals Trehalose induces tomato defenses and increases drought tolerance and bacterial wilt disease resistance

2021 ◽  
Author(s):  
April M MacIntyre ◽  
Valerian Meline ◽  
Zachary Gorman ◽  
Steven P Augustine ◽  
Carolyn J Dye ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Stomatal Conductance ◽  
Water Use ◽  
Bacterial Wilt ◽  
Xylem Sap ◽  
Wilt Disease ◽  
Tomato Plants ◽  
Bacterial Wilt Disease ◽  
Infected Tomato ◽  
Use Efficiency

Ralstonia solanacearum causes plant bacterial wilt disease, leading to severe crop losses. Xylem sap from R. solanacearum-infected tomato is enriched in host produced trehalose. Water stressed plants accumulate the disaccharide trehalose, which increases drought tolerance via abscisic acid (ABA) signaling networks. Because infected plants have reduced water flow, we hypothesized that bacterial wilt physiologically mimics drought stress, which trehalose could mitigate. Transcriptomic responses of susceptible vs. resistant tomato plants to R. solanacearum infection revealed differential expression of drought-associated genes, including those involved in ABA and trehalose metabolism. ABA was enriched in xylem sap from R. solanacearum-infected plants. Treating roots with ABA lowered stomatal conductance and reduced R. solanacearum stem colonization. Treating roots with trehalose increased ABA in xylem sap and reduced plant water use by reducing stomatal conductance and temporarily improving water use efficiency. Further, trehalose-treated plants were more resistant to bacterial wilt disease. Trehalose treatment also upregulated expression of salicylic acid (SA)-dependent defense genes, increased xylem sap levels of SA and other antimicrobial compounds, and increased wilt resistance of SA-insensitive NahG tomato plants. Additionally, trehalose treatment increased xylem concentrations of jasmonic acid and related oxylipins. Together, these data show that exogenous trehalose reduced both water stress and bacterial wilt disease and triggered systemic resistance. This suite of responses revealed unexpected linkages between plant responses to biotic and abiotic stress and suggests that that R. solanacearum-infected tomato plants produce more trehalose to improve water use efficiency and increase wilt disease resistance. In turn, R. solanacearum degrades trehalose as a counter-defense.

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