Efficacy of the Biopesticide NECO in the control of Ralstonia solancearum, causal agent of tomato bacterial wilt in Côte d’Ivoire

The tomato crop is confronted to numerous soilborne pathogens, including Ralstonia solanacearum, which considerably limits its production. In order to control this bacterium, a biological control approach has been considered by evaluating the efficacy of the NECO biopesticide against this bacteriosis. In vitro confrontations were carried out using a range of five concentrations of the biopesticide. In vivo, NECO solutions of 5 and 10 mL/L were incorporated into soil previously infested with R. solanacearum before transplanting tomato plants. Zones of bacterial growth inhibition were observed after the application of the NECO biopesticide. Results showed that the 20 mL/L concentration resulted in a higher inhibition rate. The biopesticide at the 10 mL/L concentration significantly reduced the incidence of bacterial wilt (54.05%) under in vivo conditions. The NECO biopesticide could be used as a control agent for Ralstonia solanacearum.

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Effect of Allium fistulosum Extract on Ralstonia solanacearum Populations and Tomato Bacterial Wilt

Plant Disease ◽

10.1094/pdis-07-11-0601 ◽

2012 ◽

Vol 96 (5) ◽

pp. 687-692 ◽

Cited By ~ 20

Author(s):

Péninna Deberdt ◽

Benjamin Perrin ◽

Régine Coranson-Beaudu ◽

Pierre-François Duyck ◽

Emmanuel Wicker

Keyword(s):

Bacterial Wilt ◽

Ralstonia Solanacearum ◽

Management Strategies ◽

Antimicrobial Effect ◽

Allium Fistulosum ◽

Inhibition Assay ◽

In Vivo Experiments ◽

Tomato Bacterial Wilt

To control bacterial wilt (Ralstonia solanacearum, phylotype IIB/4NPB), the antimicrobial effect of Allium fistulosum aqueous extract was assessed as a preplant soil treatment. Three concentrations of extract (100, 50, and 25%, 1:1 [wt/vol]) were evaluated by in vitro inhibition assay and in vivo experiments in a growth chamber. In vitro, A. fistulosum (100 and 50%) suppressed growth of R. solanacearum. Preplant treatment of the soil with A. fistulosum extract significantly reduced the R. solanacearum populations. No pathogen was detected in the soil after treatment with 100% concentrated extract from the third day after application until the end of the experiment. A. fistulosum also significantly reduced the incidence of tomato bacterial wilt. In the untreated control, the disease affected 61% of the plants whereas, with 100 and 50% extracts, only 6 and 14% of the plants, respectively, were affected. These results suggest that A. fistulosum extracts could be used in biocontrol-based management strategies for bacterial wilt of tomato.

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Phytobiocidal management of bacterial wilt of tomato caused by Ralstonia solanacearum (Smith) Yabuuchi

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2016143-9012 ◽

2016 ◽

Vol 14 (3) ◽

pp. e1006 ◽

Cited By ~ 7

Author(s):

Naseerud Din ◽

Musharaf Ahmad ◽

Muhammad Siddique ◽

Asad Ali ◽

Ishrat Naz ◽

...

Keyword(s):

Medicinal Plants ◽

Bacterial Wilt ◽

Ralstonia Solanacearum ◽

Nerium Oleander ◽

Calotropis Procera ◽

Melia Azedarach ◽

Aqueous Extracts ◽

Tagetes Patula

Phytobiocides are a good alternative to chemicals in managing bacterial diseases including bacterial wilt of tomato caused by Ralstonia solanacearum. In the present research study, finely ground dried powders of seven widely available medicinal plants/weeds species viz., Peganum harmala (esfand or wild rue), Calotropis procera (sodom apple), Melia azedarach (white cedar), Allium sativum (garlic), Adhatoda vasica (malabar nut), Tagetes patula (marigold) and Nerium oleander (oleander) were assessed for their anti-microbial activity, both in-vitro (10% w/v) and in-vivo (10, 20, 30, and 40 g/kg of potted soil) against R. solanacearum. Aqueous extracts (prepared as 10% w/v, soaking for 48-72 h and filtering) of C. procera, A. vasica, and T. patula inhibited the in-vitro growth of the bacterial pathogen over 60% of that produced by the standard antibiotic streptomycin. A. sativum, N. oleander and P. harmala aqueous extracts were less effective while M. azedarach showed no effect against R. solanacearum. The higher dose (40 g/kg of soil) of C. procera, A. vasica and T. patula decreased disease severity quite effectively and increased yield and plant growth characters as much as the standard antibiotic did. No phytotoxicity of medicinal plants powder was observed on tomato plants. Alkaloids, flavonoids, tannins, saponins and terpenoids were detected in the aqueous extracts of T. patula and A. vasica whereas C. procera was found to have only alkaloids, flavonoids, tannins and saponins. Our data suggest that dried powders of T. patula, C. procera and A. vasica (40 g/kg of soil) could be used as an effective component in the integrated disease management programs against bacterial wilt of tomato.

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SKRINING KETAHANAN SOMAKLON NILAM TERHADAPP PENYAKIT LAYU BAKTERI (Ralstonia solanacearum)

Jurnal Penelitian Tanaman Industri ◽

10.21082/littri.v21n3.2015.131-138 ◽

2016 ◽

Vol 21 (3) ◽

pp. 131

Author(s):

S. Y. HARTATI ◽

E. HADIPOENTYANTI ◽

AMALIA AMALIA ◽

NURSALAM NURSALAM

Keyword(s):

Bacterial Wilt ◽

Ralstonia Solanacearum ◽

Screening Method ◽

Wilt Disease ◽

Resistance Screening ◽

Bacterial Wilt Disease ◽

House Condition ◽

Moderately Resistant

ABSTRAKLayu bakteri yang disebabkan oleh Ralstonia solanacearum merupakan salah satu penyakit penting pada tanaman nilam. Perakitan varietas nilam tahan terhadap penyakit tersebut yang dilakukan melalui induksi keragaman somaklonal telah menghasilkan beberapa somaklon yang tahan terhadap R. solanacearum secara in-vitro. Tujuan penelitian adalah menguji tingkat ketahanan somaklon tersebut terhadap penyakit layu pada kondisi rumah kaca (in-vivo). Penelitian disusun dalam Rancangan Acak Lengkap dengan 27 perlakuan, 3 ulangan, dan 10 tanaman/ulangan. Sebagian akar dari somaklon nilam dilukai (dipotong), selanjutnya diinokulasi (disiram) dengan suspensi R. solanacearum dengan berbagai konsentrasi 105, 107, dan 109 cfu/ml, sebanyak 50 ml/tanaman. Hasil penelitian menunjukkan, bahwa somaklon yang diinokulasi dengan konsentrasi 105 cfu/ml, 50 ml/tanaman semuanya tidak menunjukkan gejala layu. Somaklon yang diinokulasi dengan konsentrasi 107 dan 109cfu/ml, 50 ml/tanaman, sebagian layu dan mati. Dari somaklon yang7diinokulasi dengan konsentrasi 10 cfu/ml, 50 ml/tanaman, 8 di antaranyamenunjukkan respon sangat tahan, 4 tahan, dan 5 agak tahan. Ke 17 somaklon tersebut mempunyai intensitas penyakit <50% dan semua lebih tahan dari pada varietas Sidikalang (agak toleran). Dari 17 somaklon yang diinokulasi dengan konsentrasi 109 cfu/ml, 50 ml/tanaman, 2 di antaranya sangat tahan dan 7 somaklon tahan. Teknik skrining ini dapat digunakan sebagai metode standar untuk pengujian ketahanan nilam terhadap penyakit layu.Kata kunci: Skrining ketahanan, somaklon, nilam, penyakit layu, R. solanacearum. ABSTRACTResistance-Screening of Patchouli Somaclones on Bacterial Wilt Disease (Ralstonia solanacearum) Bacterial wilt caused by Ralstonia solanacearum is one of the most important diseases on patchouli. The developing patchouli resistance varieties against wilt disease conducted through the induction of somaclonal variation produced resistant patchouli somaclones against R. solanacearum (in-vitro). The aim of this research was to screen the resistance of those patchouli somaclones against wilt disease under a glass house condition (in-vivo). The research was conducted in a Randomized Completely Design with 27 treatments, 3 replicates, and 10 plants/ replicate. Some roots of the patchouli somaclones were wounded (cut), then inoculated (drenched) with R. solanacearum suspension in concentration of 105, 107, and 109 cfu/ml; 50 ml/plant. The result showed, that all the patchouli somaclones inoculated with R. solanacearum 105 cfu/ml, 50 ml/plant were not show any wilt sympthom. Whereas, some somaclones inoculated with the higher concentration 107 and 109 cfu/ml, 50 ml/plant were wilted and died. Among the somaclones inoculated with the concentration of 107 cfu/ml, 50 ml/plant, 8 of them were highly resistant, 4 were resistant, and 5 were moderately resistant. The disease intencity of those 17 somaclones were <50% and they were more resistant than the Sidikalang variety (moderately tolerant). Among those 17 somaclones inoculated with the concentration of 109 cfu/ml, 50 ml/plant, 2 of them were highly resistant and 7 were resistant. This screening method could be used as a standard protocol for patchouli resistance screening against wilt disease.Kata kunci: Screening resistance, somaclone, patchouli, wilt disease, R. solanacearum.

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Sustainable Management of Soil-Borne Bacterium Ralstonia solanacearum In Vitro and In Vivo through Fungal Metabolites of Different Trichoderma spp.

Sustainability ◽

10.3390/su13031491 ◽

2021 ◽

Vol 13 (3) ◽

pp. 1491

Author(s):

Yancui Guo ◽

Zhenyu Fan ◽

Xiong Yi ◽

Yuhong Zhang ◽

Raja Asad Ali Khan ◽

...

Keyword(s):

Bacterial Wilt ◽

Bacterial Population ◽

Sem Analysis ◽

Wilt Disease ◽

Fungal Metabolites ◽

Trichoderma Spp ◽

Tomato Plants ◽

Bacterial Wilt Disease

The efficacy of traditional control measures for the management of plant pathogens is decreasing, and the resistance of these pathogens to pesticides is increasing, which poses a serious threat to global food security. The exploration of novel and efficient management measures to combat plant disease is an urgent need at this time. In this study, fungal metabolites from three Trichoderma spp. (T. harzianum, T. virens and T. koningii) were prepared on three different growth media (STP, MOF and supermalt (SuM)). The fungal metabolites were tested in vitro and in vivo from March–April 2020 under greenhouse conditions in a pot experiment utilizing completely randomized design to test their management of the bacterial wilt disease caused by R. solanacearum in tomato plants. The effect of the fungal metabolites on bacterial cell morphology was also investigated through scanning electron microscopy (SEM) analysis. In vitro investigation showed that the fungal metabolites of T. harzianum obtained on the STP medium were the most effective in inhibiting in vitro bacterial growth and produced a 17.6 mm growth inhibition zone. SEM analysis confirms the rupture of the cell walls and cell membranes of the bacterium, along with the leakage of its cell contents. Generally, fungal metabolites obtained on an STP medium showed higher activity than those obtained on the other two media, and these metabolites were then evaluated in vivo according to three application times (0 days before transplantation (DBT), 4 DBT and 8 DBT) in a greenhouse trial to examine their ability to manage R. solanacearum in tomato plants. Consistent with in vitro results, the results from the greenhouse studies showed a level of higher anti-bacterial activity of T. harzianum metabolites than they did for the metabolites of other fungi, while among the three application times, the longest time (8 DBT) was more effective in controlling bacterial wilt disease in tomato plants. Metabolites of T. harzianum applied at 8 DBT caused the maximum decrease in soil bacterial population (1.526 log cfu/g), resulting in the lowest level of disease severity (area under disease progressive curve (AUDPC) value: 400), and maximum plant freshness (with a resulting biomass of 36.7 g, a root length of 18.3 cm and a plant height of 33.0 cm). It can be concluded that T. harzianum metabolites obtained on an STP medium, when applied after 8 DBT, can suppress soil bacterial population and enhance plant growth, and thus can be used as a safe, environmentally-conscious and consumer-friendly approach to managing bacterial wilt disease in tomato plants and possibly other crops.

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Antibacterial Activity of Wild Mushroom Extracts on Bacterial Wilt Pathogen Ralstonia solanacearum

Plant Disease ◽

10.1094/pdis-08-14-0812-re ◽

2016 ◽

Vol 100 (2) ◽

pp. 453-464 ◽

Cited By ~ 3

Author(s):

Jana Erjavec ◽

Maja Ravnikar ◽

Jože Brzin ◽

Tine Grebenc ◽

Andrej Blejec ◽

...

Keyword(s):

Antibacterial Activity ◽

Bacterial Wilt ◽

Ralstonia Solanacearum ◽

Microtiter Plate ◽

Screening Tests ◽

Wild Mushroom ◽

Early Screening ◽

Mushroom Species

In total, 150 protein extracts from 94 different basidiomycete and ascomycete wild mushroom species were tested for antibacterial activity against the quarantine plant-pathogen bacterium Ralstonia solanacearum. In in vitro microtiter plate assays, 15 extracts with moderate to high antibacterial activities were identified: 11 completely inhibited bacterial growth and 4 showed partial inhibition. Of these 15 extracts, 5 were further tested and 3 extracts slowed disease progression and reduced disease severity in artificially inoculated tomato and potato plants. However, the in vitro activities of the extracts did not always correlate with their in vivo activities, which emphasizes the importance of performing early screening tests also in vivo. Testing of selected extracts against 12 R. solanacearum strains identified 6 with potential for broader applicability. Further analysis of extracts from Amanita phalloides and Clitocybe geotropa showed that the active substances are proteins with an approximate size of 180 kDa. To our knowledge, this is the first in vitro and in vivo study that demonstrates that mushroom protein extracts can be promising for treatment of bacterial wilt caused by R. solanacearum.

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Efficacy of Leaf Oil from Pimenta racemosa var. racemosa in Controlling Bacterial Wilt of Tomato

Plant Disease ◽

10.1094/pdis-04-17-0593-re ◽

2018 ◽

Vol 102 (1) ◽

pp. 124-131

Author(s):

Péninna Deberdt ◽

Isabelle Davezies ◽

Régine Coranson-Beaudu ◽

Alexandra Jestin

Keyword(s):

Essential Oil ◽

Bacterial Wilt ◽

Tomato Plants ◽

In Vivo Experiments ◽

Leaf Oil ◽

Pimenta Racemosa ◽

In Vitro Antibacterial Activity ◽

Further Development

Bacterial wilt, caused by Ralstonia solanacearum, is a major plant disease throughout the Caribbean. The ability of the essential oil from Pimenta racemosa var. racemosa to control bacterial wilt of tomato (R. solanacearum, phylotype IIB/4NPB) was investigated. Lemongrass (chemotype 1)-, aniseed (chemotype 2)-, and clove (chemotype 3)-scented chemotypes of P. racemosa var. racemosa essential oil were tested. Six concentrations of emulsified essential oil (from 0.01 to 0.14% [v/v]) were evaluated by in vitro culture amendment assays and by in vivo experiments in greenhouse. Chemotype 3 displayed remarkable in vitro antibacterial activity against R. solanacearum, because the minimum inhibitory concentration was only 0.03%, compared with 0.14% for chemotypes 1 and 2. In greenhouse experiments, no incidence of bacterial wilt was observed in tomato plants grown in soil treated with chemotype 3 of P. racemosa var. racemosa at a concentration of 0.14%. In the untreated control soil, 62% of plants displayed symptoms of bacterial wilt. Treatment with chemotype 3 significantly increased the growth of tomato plants compared with untreated controls. These results suggest that chemotype 3 of P. racemosa var. racemosa essential oil is a good candidate for further development as a soil biofumigant for the control of tomato bacterial wilt.

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

Applied and Environmental Microbiology ◽

10.1128/aem.02999-06 ◽

2007 ◽

Vol 73 (12) ◽

pp. 3779-3786 ◽

Cited By ~ 24

Author(s):

Enid T. Gonzï¿½lez ◽

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.

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Phytochemical Composition and Antibacterial Activity of Fruit Extract of Solanum incanum L. against Ralstonia solanacearum

Asian Journal of Applied Chemistry Research ◽

10.9734/ajacr/2021/v9i430218 ◽

2021 ◽

pp. 1-16

Author(s):

Lucy N. Karanja ◽

Isaac O. K’Owino ◽

Phanice T. Wangila ◽

Rose C. Ramkat

Keyword(s):

Antibacterial Activity ◽

Plant Extract ◽

Bacterial Wilt ◽

Ralstonia Solanacearum ◽

In Vivo Studies ◽

Post Inoculation ◽

Phytochemical Composition ◽

Ft Ir

Aims: To determine the phytochemical composition and antibacterial activity of Solanum incanum fruits against Ralstonia solanacearum. Study Design: Experimental design involving completely randomized design Place and Duration of Study: The study was conducted at department of Chemistry and Biochemistry, School of Sciences and Aerospace studies, Moi University, Kenya, between January and June 2021. Methodology: Extraction was done by maceration using ethanol as the extracting solvent. Phytochemical screening was done following standard procedures. Total Phenolic Content (TPC) and Total Flavonoid Content (TFC) were determined using the Folin–Ciocalteu colorimetric method and aluminum chloride colorimetric assay respectively. The extract was further analyzed using Gas Chromatography Mass spectroscopy (GC-MS) and Fourier transformed Infrared (FT-IR). In vitro antibacterial activity was determined using disc diffusion method while in vivo studies was done under greenhouse conditions. Results: Phytochemical analysis showed presence of alkaloids, glycosides, steroids, tannins, flavonoids, phenols, saponins and terpenoids. The TPC and TFC were found to be 84.997 ± 0.2 mg GAE/g and 20.535 ± 0.2 mg/g QE of dried sample respectively. GC-MS analysis revealed the presence of 15 compounds, (9E)-1-Methoxy-9-Octadecene (26.85%), 9-Octadecenamide (Z) (21.43%), E-15-Heptadecenal (7.28%), E-14-Hexadecenal (6.28%), 2,4-Di-tert-butylphenol (4.96%) among others. FT-IR analysis revealed presence of OH, C-H, N-H, CO functional groups at wavenumbers 3348 cm-1, 2931 cm-1, 1589 cm-1, and 1218 cm-1 respectively. The antibacterial activity for in vitro studies at concentrations 0.01, 0.05, 0.10, and 0.15 g/10 mL, the diameters of zone of inhibition were 20.75 ± 1.3, 25.75 ± 0.5, 27.25 ± 0.5, and 30.75 ± 0.5 mm respectively. This was comparable (P= .02) to that of ampicillin (positive control) which had zones of inhibition of 26.75 ± 0.5, 28.75 ± 0.5, 31.75 ± 0.4, and 35.00 ± 0.0 mm at the concentrations respectively. For the in vivo studies the plant extract and ampicillin delayed the development of the disease by eight and ten days post-inoculation respectively while symptoms of bacterial wilt for water treatment (negative control) were observed four days post-inoculation. Conclusion: The plant extract had remarkable antibacterial activity and can be used to make viable formulations to control the devastating bacterial wilt disease.

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Caffeic Acid in Tobacco Root Exudate Defends Tobacco Plants From Infection by Ralstonia solanacearum

Frontiers in Plant Science ◽

10.3389/fpls.2021.690586 ◽

2021 ◽

Vol 12 ◽

Author(s):

Shili Li ◽

Jing Pi ◽

Hongjiang Zhu ◽

Liang Yang ◽

Xingguo Zhang ◽

...

Keyword(s):

Caffeic Acid ◽

Bacterial Wilt ◽

Ralstonia Solanacearum ◽

Pathogenic Bacteria ◽

Root Exudate ◽

Phenylalanine Ammonia Lyase ◽

Field Experiments ◽

Highly Active

In rhizospheres, chemical barrier-forming natural compounds play a key role in preventing pathogenic bacteria from infecting plant roots. Here, we sought to identify specific phenolic exudates in tobacco (Nicotiana tobaccum) plants infected by the soil-borne pathogen Ralstonia solanacearum that may exhibit antibacterial activity and promote plant resistance against pathogens. Among detected phenolic acids, only caffeic acid was significantly induced in infected plants by R. solanacearum relative to healthy plants, and the concentration of caffeic acid reached 1.95 μg/mL. In vivo, caffeic acid at 200 μg/mL was highly active against R. solanacearum and obviously damaged the membrane structure of the R. solanacearum cells, resulting in the thinning of the cell membrane and irregular cavities in cells. Moreover, caffeic acid significantly inhibited biofilm formation by repressing the expression of the lecM and epsE genes. In vitro, caffeic acid could effectively activate phenylalanine ammonia-lyase (PAL) and peroxidase (POD) and promote the accumulation of lignin and hydroxyproline. In pot and field experiments, exogenous applications of caffeic acid significantly reduced and delayed the incidence of tobacco bacterial wilt. Taken together, all these results suggest that caffeic acid played a crucial role in defending against R. solanacearum infection and was a potential and effective antibacterial agent for controlling bacterial wilt.

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Ralstonia solanacearum Needs Motility for Invasive Virulence on Tomato

Journal of Bacteriology ◽

10.1128/jb.183.12.3597-3605.2001 ◽

2001 ◽

Vol 183 (12) ◽

pp. 3597-3605 ◽

Cited By ~ 201

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.

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