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1
Wang, Hui, Ying Luo, Haofu Dai, and Wenli Mei. "Antibacterial Activity against Ralstonia solanacearum of Phenolic Constituents Isolated from Dragon's Blood." Natural Product Communications 8, no. 3 (March 2013): 1934578X1300800. http://dx.doi.org/10.1177/1934578x1300800316.
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Ralstonia solanacearum is a worldwide and devastating plant pathogen infesting over 200 host species. Synthetic bactericides against the pathogen have only achieved limited success and always cause both crop contamination and environmental pollution. However, natural bactericides are effective for protecting cultivated crops from destruction by disease, without the adverse effects of chemical bactericides. In this paper, fifteen phenolic constituents from dragon's blood were screened for their antimicrobial activity against Ralstonia solanacearum, and all exhibited inhibitory activity. These compounds are potential leading compounds for the development of bactericides against wilt diseases caused by Ralstonia solanacearum.
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Li, Mei, Thomas Pommier, Yue Yin, Jianing Wang, Shaohua Gu, Alexandre Jousset, Joost Keuskamp, et al. "Indirect reduction of Ralstonia solanacearum via pathogen helper inhibition." ISME Journal 16, no. 3 (October 20, 2021): 868–75. http://dx.doi.org/10.1038/s41396-021-01126-2.
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AbstractThe rhizosphere microbiome forms a first line of defense against soilborne pathogens. To date, most microbiome enhancement strategies have relied on bioaugmentation with antagonistic microorganisms that directly inhibit pathogens. Previous studies have shown that some root-associated bacteria are able to facilitate pathogen growth. We therefore hypothesized that inhibiting such pathogen helpers may help reduce pathogen densities. We examined tripartite interactions between a model pathogen, Ralstonia solanacearum, two model helper strains and a collection of 46 bacterial isolates recovered from the tomato rhizosphere. This system allowed us to examine the importance of direct (effects of rhizobacteria on pathogen growth) and indirect (effects of rhizobacteria on helper growth) pathways affecting pathogen growth. We found that the interaction between rhizosphere isolates and the helper strains was the major determinant of pathogen suppression both in vitro and in vivo. We therefore propose that controlling microbiome composition to prevent the growth of pathogen helpers may become part of sustainable strategies for pathogen control.
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Saha, A., H. Mandal, and D. Saha. "Isolation and identification of a virulent Ralstonia solanacearum by fliC gene amplification and induction of chitinase by 2-amino butyric acid for control of bacterial wilt in tomato plants." NBU Journal of Plant Sciences 7, no. 1 (2013): 95–100. http://dx.doi.org/10.55734/nbujps.2013.v07i01.013.
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Ralstonia solanacearum is a devastating, soil borne bacterial pathogen of tomato. The pathogen is nonmotile in planta but highly motile in culture. On the basis of physiological and biochemical characteristics 26 isolates have been purified and identified as Ralstonia solanacearum. The flic gene is responsible for the movement of bacteria. Ralstonia specific fliC gene amplification is the indication of virulence of the pathogen. In the present study one R. solanacearum isolate has been identified by PCR amplification of the fliC gene using fliC gene specific primer. Following isolation and identification of the virulent isolate, fresh tomato plants were induced by application of 2- amino butyric acid (ABA). The defense enzyme, chitinase was estimated in treated plants. Treated inoculated plants did not show any visible symptoms of wilt even after 14 days of inoculation. Significantly it was observed that chitinase was increased in the 2-ABA-treated plants and also in the treated-inoculated plants. The increased chitinase activity in the treated plants showed that 2-ABA has the resistance inducing capacity in tomato plants against Ralstonia solanacearum.
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Flores-Cruz, Zomary, and Caitilyn Allen. "Ralstonia solanacearum Encounters an Oxidative Environment During Tomato Infection." Molecular Plant-Microbe Interactions® 22, no. 7 (July 2009): 773–82. http://dx.doi.org/10.1094/mpmi-22-7-0773.
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Ralstonia solanacearum genes that are induced during tomato infection suggested that this pathogen encounters reactive oxygen species (ROS) during bacterial wilt pathogenesis. The genomes of R. solanacearum contain multiple redundant ROS-scavenging enzymes, indirect evidence that this pathogen experiences intense oxidative stress during its life cycle. Over 9% of the bacterium's plant-induced genes were also upregulated by hydrogen peroxide in culture, suggesting that oxidative stress may be linked to life in the plant host. Tomato leaves infected by R. solanacearum contained hydrogen peroxide, and concentrations of this ROS increased as pathogen populations increased. Mutagenesis of a plant-induced predicted peroxidase gene, bcp, resulted in an R. solanacearum strain with reduced ability to detoxify ROS in culture. The bcp mutant caused slightly delayed bacterial wilt disease onset in tomato. Moreover, its virulence was significantly reduced on tobacco plants engineered to overproduce hydrogen peroxide, demonstrating that Bcp is necessary for detoxification of plant-derived hydrogen peroxide and providing evidence that host ROS can limit the success of this pathogen. These results reveal that R. solanacearum is exposed to ROS during pathogenesis and that it has evolved a redundant and efficient oxidative stress response to adapt to the host environment and cause disease.
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Feng, Jinlin. "ITRAQ-Based Proteomic Analysis of The Response to Ralstonia solanacearum in Potato." Pakistan Journal of Agricultural Sciences 59, no. 02 (January 1, 2022): 165–71. http://dx.doi.org/10.21162/pakjas/22.1347.
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Bacterial wilt is a serious disease of potato (Solanum tuberosum L.) caused by the soil-borne pathogenic bacterium Ralstonia solanacearum. Detecting changes in protein abundance in potato plants in response to R. solanacearum is a pivotal step in uncovering the molecular interactions of plant pathogens. In this study, using the disease-resistant cultivar ‘Zhongshu 3’, we analyzed protein expression in potato seedlings inoculated with R. solanacearum every 12 h for a total of 72 h using isobaric tags for relative and absolute quantitation-based proteomics. Our results indicate that pathogenesis-related proteins, stressrelated proteins, non-specific lipid transfer proteins, small heat shock proteins, and osmotin-like proteins were up-regulated in response to pathogen infection at different time points. The accumulation of these proteins in response to biotic stress suggests that these proteins play an important role in pathogen resistance. Our findings will provide an important basis for characterizing the role of these proteins in increasing plant resistance to pathogens and in breeding bacterial wilt-resistant plants.
6
Teli, Kalavati, H. M. Shweta, M. K. Prasanna Kumar, Bharath Kunduru, and B. S. Chandra Shekar. "Isolation, identification and molecular characterization of Ralstonia solanacerum isolates collected from Southern Karnataka." Journal of Applied and Natural Science 10, no. 3 (September 1, 2018): 886–93. http://dx.doi.org/10.31018/jans.v10i3.1747.
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Bacterial wilt caused by Ralstonia solanacearum, is the major threat to tomato cultivation in all tomato growing areas of Karnataka. R. solanacearum was isolated from the infected host plants collected from different locations of southern Karnataka. The identity of the isolates was established using morphological, biochemical, and molecular analysis using species specific PCR primers. The race and biovar specificity of pathogen was determined through pathogenicity test on different host plants and the ability of isolates to use carbohydrates, respectively. Phylotype classification was done by phylotype specific multiplex PCR using phylotype specific primers. All the bacterial isolates showed the characteristic creamy white fluidal growth with pink centre on the Tetrazolium chloride medium. Further, the isolates amplified at 280 bp, which confirmed the identity of pathogen as Ralstonia solanacearum. Our results showed that all isolates belonged to Race 1 of the pathogen. Among different isolates obtained, four isolates each were identified to be Biovar III and Biovar IIIA, repectively, while two isolates were identified as Biovar IIIB. All the ten isolates were affiliated to Phylotype I of Ralstonia solanaceraum species complex. These findings may help in devising the management practices for bacterial wilt of tomato in southern Karnataka.
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Salanoubat, M., S. Genin, F. Artiguenave, J. Gouzy, S. Mangenot, M. Arlat, A. Billault, et al. "Genome sequence of the plant pathogen Ralstonia solanacearum." Nature 415, no. 6871 (January 2002): 497–502. http://dx.doi.org/10.1038/415497a.
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Ojesola, C. O., A. K. Akintokun, P. O. Akintokun, and A. R. Oloyede. "In-Vitro Antagonistic Effect of Bacillus thuringiensis on Ralstonia solanacearum, the Causal Agent of Bacterial Wilt Disease of Tomato (Lycopersicon esculentum Mill)." Nigerian Journal of Biotechnology 37, no. 2 (March 23, 2021): 177–93. http://dx.doi.org/10.4314/njb.v37i2.18.
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Tomato (Lycopersicon esculentum, Mill) is a rich source of vitamins, minerals and lycopene, which has many health benefits. However, its production is hampered by bacterial wilt caused by Ralstonia solanacearum resulting in significant yield losses. Use of chemicals in the control of plant pathogens has detrimental effects on humans and the environment in terms of leaving residues in soil which later find their way into underground waters. Therefore, it is desirable to find an alternative to chemical control of this bacterial pathogen. This study investigates the potential of native Bacillus thuringiensis (Bt) for biological control of Ralstonia solanacearum (Rs) under laboratory conditions. B. thuringiensis was isolated from cultivated soil, non- cultivated soil, stagnant water, sawdust, horse dung, grain dust, dead leaves and poultry manure. R. solanacearum was isolated from stem exudates of bacterial wilt infected plants and its pathogenicity assay was carried out using 2-week-old seedlings of Beske tomato variety. The Bt and R. solanacearum isolates were then characterized phenotypically. Bt isolates were further identified using endospore and parasporal staining techniques. All the Bt isolates were tested for in-vitro antagonistic activity on R. solanacearum using agar well diffusion method. Isolates Bt2, Bt16, Bt17, Bt32 and Bt34 were confirmed as Bacillus thuringiensis while isolate Rs was confirmed as R. solanacearum. Beske showed wilting symptoms from the fourth day of inoculation and eventual death of seedlings. The zone of inhibition exhibited ranged from 0.0 mm to 20.0 mm.
Keywords: Bacillus thuringiensis, In-vitro, Bacterial wilt, Ralstonia solanacearum, Tomato
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Machado, Patrícia da S., Acelino C. Alfenas, Marcelo M. Coutinho, Cláudio M. Silva, Ann H. Mounteer, Luiz A. Maffia, Rodrigo G. de Freitas, and Camila da S. Freitas. "Eradication of Plant Pathogens in Forest Nursery Irrigation Water." Plant Disease 97, no. 6 (June 2013): 780–88. http://dx.doi.org/10.1094/pdis-08-12-0721-re.
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Interest in rational use and reuse of water has increased in recent years, especially in forest nurseries. However, before water can be reused in nurseries, it must be properly treated to eradicate plant pathogens to reduce risks of pathogen dispersal and losses to disease. In the present study, the efficacy of irrigation water treatment by ultrafiltration and conventional physical-chemical treatment was studied to eliminate Botrytis cinerea, Cylindrocladium candelabrum, Ralstonia solanacearum, and Xanthomonas axonopodis, the pathogens most commonly found in Brazilian forest nurseries. Ultrafiltration eradicated over 99% of R. solanacearum, X. axonopodis, and B. cinerea and 100% of C. candelabrum. The few remaining cells or conidia of R. solanacearum and B. cinerea did not induce disease in irrigated rooted cuttings. Flocculation and fast sand filtration used in physical-chemical treatment completely eliminated C. candelabrum but the other pathogens were only removed after chlorination of the filtered water. Both forms of treatment are viable, practical, and safe methods for plant pathogen removal from irrigation water.
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Zhao, Cuizhu, Huijuan Wang, Yao Lu, Jinxue Hu, Ling Qu, Zheqing Li, Dongdong Wang, et al. "Deep Sequencing Reveals Early Reprogramming of Arabidopsis Root Transcriptomes Upon Ralstonia solanacearum Infection." Molecular Plant-Microbe Interactions® 32, no. 7 (July 2019): 813–27. http://dx.doi.org/10.1094/mpmi-10-18-0268-r.
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Bacterial wilt caused by the bacterial pathogen Ralstonia solanacearum is one of the most devastating crop diseases worldwide. The molecular mechanisms controlling the early stage of R. solanacearum colonization in the root remain unknown. Aiming to better understand the mechanism of the establishment of R. solanacearum infection in root, we established four stages in the early interaction of the pathogen with Arabidopsis roots and determined the transcriptional profiles of these stages of infection. A total 2,698 genes were identified as differentially expressed genes during the initial 96 h after infection, with the majority of changes in gene expression occurring after pathogen-triggered root-hair development observed. Further analysis of differentially expressed genes indicated sequential activation of multiple hormone signaling cascades, including abscisic acid (ABA), auxin, jasmonic acid, and ethylene. Simultaneous impairment of ABA receptor genes promoted plant wilting symptoms after R. solanacearum infection but did not affect primary root growth inhibition or root-hair and lateral root formation caused by R. solanacearum. This indicated that ABA signaling positively regulates root defense to R. solanacearum. Moreover, transcriptional changes of genes involved in primary root, lateral root, and root-hair formation exhibited high temporal dynamics upon infection. Taken together, our results suggest that successful infection of R. solanacearum on roots is a highly programmed process involving in hormone crosstalk.
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Castillo, Jos� A., and Jean T. Greenberg. "Evolutionary Dynamics of Ralstonia solanacearum." Applied and Environmental Microbiology 73, no. 4 (December 22, 2006): 1225–38. http://dx.doi.org/10.1128/aem.01253-06.
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ABSTRACT We investigated the genetic diversity, extent of recombination, natural selection, and population divergence of Ralstonia solanacearum samples obtained from sources worldwide. This plant pathogen causes bacterial wilt in many crops and constitutes a serious threat to agricultural production due to its very wide host range and aggressiveness. Five housekeeping genes, dispersed around the chromosome, and three virulence-related genes, located on the megaplasmid, were sequenced from 58 strains belonging to the four major phylogenetic clusters (phylotypes). Whereas genetic variation is high and consistent for all housekeeping loci studied, virulence-related gene sequences are more diverse. Phylogenetic and statistical analyses suggest that this organism is a highly diverse bacterial species containing four major, deeply separated evolutionary lineages (phylotypes I to IV) and a weaker subdivision of phylotype II into two subgroups. Analysis of molecular variations showed that the geographic isolation and spatial distance have been the significant determinants of genetic variation between phylotypes. R. solanacearum displays high clonality for housekeeping genes in all phylotypes (except phylotype III) and significant levels of recombination for the virulence-related egl and hrpB genes, which are limited mainly to phylotype strains III and IV. Finally, genes essential for species survival are under purifying selection, and those directly involved in pathogenesis might be under diversifying selection.
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Jacobs, Jonathan M., and Caitilyn Allen. "Disease Resistance Against a Broad-Host-Range Pathogen." Plant Health Progress 14, no. 1 (January 2013): 32. http://dx.doi.org/10.1094/php-2013-1125-03-rs.
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The bacterial wilt pathogen Ralstonia solanacearum causes major agricultural losses on many crop hosts worldwide. Resistance breeding is the best way to control bacterial wilt disease, but the biological basis for bacterial wilt resistance is unknown. We found that R. solanacearum uses an AvrE-family, Type III-secreted effector called PopS to overcome plant defenses and cause disease on tomato. Orthologs of PopS are widely conserved across distinct classes of plant pathogenic bacteria and could provide novel, durable targets for resistance. Accepted for publication 25 September 2013. Published 25 November 2013.
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MULYA, KARDEN, HENI HENI, SUPRIADI SUPRIADI, and ESTHER M. ADHI. "PRODUKSI ENSIM KARBOKSI METIL SELULASE DAN EKSO-POLIGALAKTURONASE SERTA PERANANNYA DALAM MENENTUKAN TINGKAT PATOGENSITAS." Jurnal Penelitian Tanaman Industri 7, no. 2 (July 15, 2020): 49. http://dx.doi.org/10.21082/jlittri.v7n2.2001.49-53.
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<p><strong>Carboxy methyl selulase and exo-polygalacturonase enzymes production and their role in determining the pathogenicity of Ralstonia solanacearum isolated from ginger</strong></p><p>Bacterial wilt disease on ginger (Zingiber oicinale Roscoe) caused by Ralstonia solanacearum is the most destructive disease Infected tissues show macerated symptom on infected hosts indicating that the pathogen produces plant digestive enzymes. This research was aimed at analizing carboxymethylccllulasc (CMC-ase) and exopolygalacturonase (cxo-PG) enzymes production by the pathogen. In vitro production of CMC-ase of both virulent and avirulcnt isolates of R solanacearum was measured from diameter of clearing zone around bacterial colony on CMC medium whereas exo-PG was measured by the reduction of Na- polygalacturonatc by filtrate of the pathogen culture. Virulence of the pathogen was tested on tomato cultivar Gondol Hijau by pouring 50 ml of pathogen suspension (I07 cfu/ml) around roots of the plant and it was also tested on ginger cultivar Jahe Putih Besar by pricking suspension of pathogen into rhizome and basal pscudostcm of the plant. The results showed that CMC-ase and and PG-asc were produced by virulent isolates of R. solanacearum al 2.23 cm clear zone and 0.662 mg eq. glucose/ml/hour/ODiti, respectively. The avirulent isolates, however. correlated with disease intensity of the isolates. Disease intensity of the virulent isolates was 0.6 and 0.96 on tomato and on ginger plants respectively, whereas the avirulent isolates was 0.04 and 0.00 respectively. Therefore, CMC-ase and exo-PG are important in determining pathogenicity level of/?, solanacearum.</p>
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Rado, R., N. Rakotoarimanga, FR Fienena, O. Andriambeloson, B. Andrianarisoa, S. Ravelomanantsoa, and V. Rahetlah. "Biocontrol of potato wilt by selective rhizospheric and endophytic bacteria associated with potato plant." African Journal of Food, Agriculture, Nutrition and Development 15, no. 68 (February 23, 2015): 9762–76. http://dx.doi.org/10.18697/ajfand.68.15005.
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Ralstonia solanacearum is the causative agent of wilt disease in plants, which constitutes a severe problem to agricultural crops, particularly for potato production in Madagascar. The present study focuses on the isolation, in vitro and in vivo assays of potential rhizospheric and endophytic bacteria associated with healthy potato plant, capable to inhibit the growth of Ralstonia solanacearum for controlling potato bacterial wilt. A total of 77 bacteria strains were isolated from six soil rhizospheric samples and six vegetal material samples of healthy potatoes in the district of Antsirabe II. Forty of them were telluric actinomycetes, 25 were endophytic actinomycetes and 12 were fluorescent Pseudomonas spp. An additional 30 phytopathogenic isolates were obtained from six rhizopsheric soil samples of diseased potatoes. Morphological, cultural, biochemical characterization and molecular identification with the Ralstonia solanacearum specific primers 759/760 revealed that 24 of the pathogenic isolates belong to the Ralstonia solanacearum species, biovar two; the causal agent of potato bacterial wilt. Isolates from healthy plants were, then, examined in vitro and in vivo for their antagonistic activity against Ralstonia solanacearum strain for their potential to improve potato plant growth. In vitro antagonism of actinomycete and Pseudomonas isolates against Ralstonia solanacearum development was performed using agar diffusion technique, while in vivo tests were conducted under greenhouse conditions. Ten antagonistic strains including two Pseudomonas, four telluric actinomycetes, and four endophytic actinomycetes inhibited the tested Ralstonia strain. Four strains, E7, E13 (endophytic actinomycete from root potatoes), S25 (telluric actinomycetes) and P7 (fluorescent Pseudomonas), showed high antagonistic activity against the pathogen with zones of inhibition from 23 to 40 mm. Of the fours strains tested in greenhouse, E7 significantly reduced (p < 0.05) the percentage of Ralstonia solanacearum that infected plants by 72.04%. The isolates E13 and S25 have also been demonstrated to improve plant growth by increase of plant height to 44.63% and 44.84%, fresh weight to 68.75% and 75.85% and dry weight to 86.17% and 115.42%, respectively compared with non-treated control. Morphological and cultural characterization of these three active isolates showed that they belong to the genus Streptomyces. The antagonism of these isolates against Ralstonia solanacearum according to in vitro and in vivo tests results, along with their high efficiency as regards the improvement of plant development, suggests that these three actinomycete strains E7, E13 and S25 could be useful for biocontrol of potato bacterial wilt.
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Abiodun, Durojaye Hammed, and Owoeye Tolulope Abisola. "Evaluation of stored potato (Solanum tuberosum L.) for soft rot bacteria in Ibadan, Nigeria." Journal of Agriculture and Applied Biology 2, no. 1 (May 19, 2021): 53–60. http://dx.doi.org/10.11594/jaab.02.01.07.
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Potato (Solanum tuberosum L.) is a tuberous crop from the Sola-naceae family which is a source of starch and food to many in Nige-ria, however, its production is being hampered in field and storage by bacterial pathogen which causes rot of the stored tubers. To this end, the study aimed at screening potatoes from different stores within Ibadan for the evaluation and diversity of bacteria pathogens responsible for rot in potatoes. Damaged stored potato samples were collected from different locations in Ibadan for studies, these samples were isolated for bacterial pathogen and characterized bio-chemically and observed under the microscope for identification. Three genera of bacteria were observed to be responsible for potato rot in the study and they include Pectobacterium carotovorum, Pseu-domonas syringae and Ralstonia solanacearum. Of all the isolated bacteria, Pectobacterium carotovorum has the highest occurrence with a frequency of 60%, while Pseudomonas syringae has a fre-quency of 33% and Ralstonia solanacearum has a frequency of 27%. The pathogenicity of the isolates were tested and this revealed that Pectobacterium carotovorum is the most virulent with a severity score of 4.3, while Ralstonia solanacearum follows with a score of 3.3 and a score of 2.7 was recorded for Pseudomonas syringae, while the control had a score of 0. The diversity and differences shown in the isolated bacteria indicated that potato rot is a serious disease which is caused by different bacteria and need an integrated ap-proach for its control from the field of harvesting to the storage house.
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Lou, Haibo, Xiaobing Wang, Jun Chen, Bozhi Wang, and Wei Wang. "Transcriptomic response ofRalstonia solanacearumto antimicrobialPseudomonas fluorescensSN15-2 metabolites." Canadian Journal of Microbiology 64, no. 11 (November 2018): 816–25. http://dx.doi.org/10.1139/cjm-2018-0094.
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To develop efficient biocontrol agents, it is essential to investigate the response of soil-borne plant pathogens to such agents. For example, the response of Ralstonia solanacearum, the tomato wilt pathogen, to antimicrobial metabolites of Pseudomonas fluorescens is unknown. Thus, we assessed the effects of P. fluorescens SN15-2 fermentation broth on R. solanacearum by transmission electron microscopy and transcriptome technology. RNA sequencing identified 109 and 155 genes that are significantly upregulated and downregulated, respectively, in response to P. fluorescens metabolites, many of which are associated with the cell membrane and cell wall, and with nucleotide acid metabolism, iron absorption, and response to oxidative stress. This study highlights the effectiveness of P. fluorescens metabolites against the tomato wilt pathogen and helps clarify the underlying molecular mechanisms.
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Huang, Chaokun, Yuexia Wang, Yanjuan Yang, Chuan Zhong, Michitaka Notaguchi, and Wenjin Yu. "A Susceptible Scion Reduces Rootstock Tolerance to Ralstonia solanacearum in Grafted Eggplant." Horticulturae 5, no. 4 (December 12, 2019): 78. http://dx.doi.org/10.3390/horticulturae5040078.
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The bacterial wilt pathogen (Ralstonia solanacearum) is a highly pathogenic soil-borne bacterium that invades the vascular system of a host plant leading to plant wilting and death. In agricultural systems, tolerant rootstocks are usually used to enhance disease resistance and tolerance in crop plants to soil-borne pathogens. Here, two distinct eggplant cultivars with different tolerances to R. solanacearum infection, the disease-tolerant cultivar ‘S21′ and the disease-susceptible cultivar ‘Rf’, were used to investigate if scion tolerance level can affect tolerance of rootstock upon an infection of the same pathogen. Three scion/rootstock grafted combinations were considered: Rf/S21, S21/S21, and Rf/Rf. Plants that resulted from the combination Rf/S21, composed of the susceptible scion grafts, showed weak tolerance to R. solanacearum infection, and exhibited the poorest growth compared to the tolerant scion grafts (S21/S21). As expected, the combination Rf/Rf showed the lowest level of disease tolerance. Furthermore, a high level of exopolysaccharides (EPSs) and cell wall degrading enzymes (CWDEs) were detected in susceptible scion grafts. These factors are involved in plant growth inhibition due to blocking transport between scion and rootstock and damage of vascular tissues in the plant. A high level of reactive oxygen species (ROS) and active oxygen scavenging enzymes were also detected in susceptible scion grafts. Excess accumulation of these substances harms the dynamic balance in plant vascular systems. These results indicated that the use of a susceptible scion in scion/rootstock eggplant grafts contributed to a reduction in rootstock tolerance to Ralstonia solanacearum.
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Sedighian, Nasim, Marjon Krijger, Tanvi Taparia, S. Mohsen Taghavi, Emmanuel Wicker, Jan M. van der Wolf, and Ebrahim Osdaghi. "Genome Resource of Two Potato Strains of Ralstonia solanacearum Biovar 2 (Phylotype IIB Sequevar 1) and Biovar 2T (Phylotype IIB Sequevar 25) Isolated from Lowlands in Iran." Molecular Plant-Microbe Interactions® 33, no. 7 (July 2020): 872–75. http://dx.doi.org/10.1094/mpmi-02-20-0026-a.
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Ralstonia solanacearum, the causal agent of bacterial wilt and brown rot disease, is one of the major pathogens of solanaceous crops, including potato, around the globe. Biovar 2T (phylotype II/sequevar 25) of R. solanacearum is adapted to tropical lowlands and is only reported in South America and Iran. Thus far, no genome resource of the biovar 2T of the pathogen has been available. Here, we present the near-complete genome sequences of the biovar 2T strain CFBP 8697 as well as strain CFBP 8695 belonging to biovar 2 race 3, both isolated from potato in Iran. The genomic data of biovar 2T will extend our understanding of the virulence features of R. solanacearum and pave the way for research on biovar 2T functional and interaction genetics.
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Gong, Xin, Ziyun Zhang, Hui Wang, Huixin Li, Feng Hu, Manqiang Liu, Lin Jiang, Xiaoyun Chen, and Chao Ma. "Synergies between Heat Disturbance and Inoculum Size Promote the Invasion Potential of a Bacterial Pathogen in Soil." Microorganisms 10, no. 3 (March 16, 2022): 630. http://dx.doi.org/10.3390/microorganisms10030630.
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Inoculum size contributes to the invasion potential of pathogens in the soil. However, the role of inoculum size in determining the fate of pathogens in disturbed soils remains unclear. Herein, we investigated the survival rates of a bacterial pathogen, Ralstonia solanacearum, in soils subjected to heat as a simulated disturbance. Our results revealed that heating increased soil resource availability but reduced resource differentiation between R. solanacearum and indigenous bacterial communities. In both non-heated and heated soils, invader abundances increased with inoculum size, with a greater magnitude in heated soils. Inoculum size and heat-induced increases in soil-available carbon and nitrogen best predicted invasion success. Altogether, our findings suggested that the invasion by soil pathogens could be predicted by synergies between heat perturbation and inoculum size.
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Siregar, Bayo A., Abdul Gafur, Pranita Nuri, H. Halimah, Budi Tjahjono, and G. D. Golani. "First Report on Infection of Eucalyptus pellita Seeds by Ralstonia solanacearum." Environmental Sciences Proceedings 3, no. 1 (November 11, 2020): 94. http://dx.doi.org/10.3390/iecf2020-07904.
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Bacterial wilt is one of major threats to eucalyptus plantations which may cause significant losses. Until now, study about bacterial wilt on Eucalyptus pellita in Indonesia has been very limited, especially about the presence of the pathogen on or in the seeds. This study aims to provide evidence of the existence of the R. solanacearum bacterium on or in E. pellita seeds. Detection of seed-borne bacteria is determined by several approaches such as (i) direct detection using universal and selective media in the laboratory, (ii) the nursery test, and (iii) species-specific molecular detection. The results of our study indicate that R. solanacearum can be detected from eucalyptus seeds using universal and selective media in the laboratory, nursery test, and molecular-based detection using the Enrichment PCR method. The bacterial inoculum is also proven to exist both on the surface of and inside the eucalyptus seeds. This is the first report that R. solanacearum is a seed-borne pathogen in E. pellita seeds. Previous studies in different agricultural systems show that the effective method used to control the pathogen is through seed treatments using biological, physical, and chemical approaches.
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Laili, Nur, Takafumi Mukaihara, Hidenori Matsui, Mikihiro Yamamoto, Yoshiteru Noutoshi, Kazuhiro Toyoda, and Yuki Ichinose. "Role of Trehalose Synthesis in Ralstonia syzygii subsp. indonesiensis PW1001 in Inducing Hypersensitive Response on Eggplant (Solanum melongena cv. Senryo-nigou)." Plant Pathology Journal 37, no. 6 (December 1, 2021): 566–79. http://dx.doi.org/10.5423/ppj.oa.06.2021.0087.
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Ralstonia syzygii subsp. indonesiensis (Rsi, former name: Ralstonia solanacearum phylotype IV) PW1001, a causal agent of potato wilt disease, induces hypersensitive response (HR) on its non-host eggplant (Solanum melongena cv. Senryo-nigou). The disaccharide trehalose is involved in abiotic and biotic stress tolerance in many organisms. We found that trehalose is required for eliciting HR on eggplant by plant pathogen Rsi PW1001. In R. solanacearum, it is known that the OtsA/OtsB pathway is the dominant trehalose synthesis pathway, and otsA and otsB encode trehalose-6-phosphate (T6P) synthase and T6P phosphatase, respectively. We generated otsA and otsB mutant strains and found that these mutant strains reduced the bacterial trehalose concentration and HR induction on eggplant leaves compared to wild-type. Trehalose functions intracellularly in Rsi PW1001 because addition of exogenous trehalose did not affect the HR level and ion leakage. Requirement of trehalose in HR induction is not common in R. solanacearum species complex because mutation of otsA in Ralstonia pseudosolanacearum (former name: Ralstonia solanacearum phylotype I) RS1002 did not affect HR on the leaves of its non-host tobacco and wild eggplant Solanum torvum. Further, we also found that each otsA and otsB mutant had reduced ability to grow in a medium containing NaCl and sucrose, indicating that trehalose also has an important role in osmotic stress tolerance.
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Wairuri, Charles K., Jacquie E. van der Waals, Antoinette van Schalkwyk, and Jacques Theron. "Ralstonia solanacearum Needs Flp Pili for Virulence on Potato." Molecular Plant-Microbe Interactions® 25, no. 4 (April 2012): 546–56. http://dx.doi.org/10.1094/mpmi-06-11-0166.
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Type IV pili are virulence factors in various bacteria. Several subclasses of type IV pili have been described according to the characteristics of the structural prepilin subunit. Although type IVa pili have been implicated in the virulence of Ralstonia solanacearum, type IVb pili have not previously been described in this plant pathogen. Here, we report the characterization of two distinct tad loci in the R. solanacearum genome. The tad genes encode functions necessary for biogenesis of the Flp subfamily of type IVb pili initially described for the periodontal pathogen Aggregatibacter actinomycetemcomitans. To determine the role of the tad loci in R. solanacearum virulence, we mutated the tadA2 gene located in the megaplasmid that encodes a predicted NTPase previously reported to function as the energizer for Flp pilus biogenesis. Characterization of the tadA2 mutant revealed that it was not growth impaired in vitro or in planta, produced wild-type levels of exopolysaccharide galactosamine, and exhibited swimming and twitching motility comparable with the wild-type strain. However, the tadA2 mutant was impaired in its ability to cause wilting of potato plants. This is the first report where type IVb pili in a phytopathogenic bacterium contribute significantly to plant pathogenesis.
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Kubota, R., B. G. Vine, A. M. Alvarez, and D. M. Jenkins. "Detection of Ralstonia solanacearum by Loop-Mediated Isothermal Amplification." Phytopathology® 98, no. 9 (September 2008): 1045–51. http://dx.doi.org/10.1094/phyto-98-9-1045.
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Ralstonia solanacearum is a pathogenic bacterium that causes wilt in over 200 plant species. Here we report a rapid and sensitive detection of R. solanacearum using an isothermal method for copying DNA known as loop-mediated amplification (LAMP). A set of four primers was designed to replicate the gene coding for the flagellar subunit, fliC, and conditions for detection were optimized to complete in 60 min at 65°C. Magnesium pyrophosphate resulting from the amplification reaction could be detected optically as an increase in the solution turbidity, and the DNA products spread in a reproducible ladder-like banding pattern after electrophoresis in an agarose gel. Replication of the fliC gene was detected only from R. solanacearum. The detection limit of this LAMP assay was between 104 to 106 colony forming units/ml, and the technique may be useful for developing rapid and sensitive detection methods for the R. solanacearum pathogen in soil and water.
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Erjavec, Jana, Maja Ravnikar, Jože Brzin, Tine Grebenc, Andrej Blejec, Mateja Želko Gosak, Jerica Sabotič, Janko Kos, and Tanja Dreo. "Antibacterial Activity of Wild Mushroom Extracts on Bacterial Wilt Pathogen Ralstonia solanacearum." Plant Disease 100, no. 2 (February 2016): 453–64. http://dx.doi.org/10.1094/pdis-08-14-0812-re.
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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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Yonzone, R., S. Khalko, BR Sharma, S. Hembram, M. Soniya Devi, and B. Das. "Correlation on Population Dynamics and Disease Incidence Of Bacterial Wilt Instigating Pathogen (Ralstonia Solanacearum) Under Different Intercropping System." Bangladesh Journal of Botany 51, no. 4 (December 29, 2022): 807–12. http://dx.doi.org/10.3329/bjb.v51i4.63500.
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Ginger (Zingiber officinale Rose) is one of the important spice crops grown organically in the hill zone of West Bengal. Among the various diseases that cause constrains to the organic ginger production Ralstonia solanacearum causes serious threats to the ginger growers. An experiment was conducted to study the influence of different intercropping patterns on yield, population dynamics, and disease incidence of R. solanacearumin ginger crop under organic management practice. Observation on population dynamics of R. solanacearum under different intercropping patterns revealed that the marigold when intercropped with ginger had a maximum influence on population build-up during 2019 and 2020. Also, it has the potentialities to reduce the population load thereby reducing the disease incidence and increasing the rhizome yield. Therefore, marigold can be incorporated as an intercrop in organic ginger cultivation for reducing the bacterial wilt disease. Bangladesh J. Bot. 51(4): 807-812, 2022 (December)
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García, Raymond O., Jim P. Kerns, and Lindsey Thiessen. "Ralstonia solanacearum Species Complex: A Quick Diagnostic Guide." Plant Health Progress 20, no. 1 (January 1, 2019): 7–13. http://dx.doi.org/10.1094/php-04-18-0015-dg.
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Ralstonia solanacearum (Smith 1896) Yabuuchi et al. 1996 is ranked second among the top 10 most economically important plant pathogenic bacteria. The soil-borne bacterium affects over 200 plant species worldwide, including economically and nutritionally important crops, such as potato (Solanum tuberosum), tomato (Solanum lycopersicum), and bananas (Musa spp.). R. solanacearum is a species complex, meaning that the species is composed of strains with differential characteristics, including different metabolic requirements, centers of origin, host range, and ideal environmental conditions for infection. Its nature and the fact that it is a species complex can make R. solanacearum a difficult bacterium to work with, especially when lacking experience. Inappropriate isolation or storage of the pathogen can lead to inaccurate diagnostics or misleading conclusions. Thus, the objectives of this diagnostic guide are to provide adequate methods for isolation, storage, and identification and to discuss other relevant aspects related to this important plant pathogenic bacterium.
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Michel, Vincent V., and T. W. Mew. "Effect of a Soil Amendment on the Survival of Ralstonia solanacearum in Different Soils." Phytopathology® 88, no. 4 (April 1998): 300–305. http://dx.doi.org/10.1094/phyto.1998.88.4.300.
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The effect of a soil amendment (SA) composed of urea (200 kg of N per ha) and CaO (5,000 kg/ha) on the survival of Ralstonia solanacearum in four Philippine soils was investigated in a series of laboratory experiments. Within 3 weeks after application, the SA either caused an initial decrease, a final decline, or no change in the pathogen population, depending on the particular soil type. An initial decrease occurred in a soil with a basic pH and resulted in a significantly (P < 0.001) lower pathogen population immediately and at 1 week after amending the soil. This decrease was probably due to the high pH in the soil during urea hydrolysis. A final decline in the R. solanacearum population after 3 weeks occurred in two soils in which nitrite accumulated after 1 week. In these soils, no decline in bacterial levels occurred when nitrite formation was inhibited by 2-chloro-6-trichloromethylpyridine. In the soil with low pH, no nitrite accumulated and the R. solanacearum population did not decline. The suppressive effects of pH and nitrite on R. solanacearum growth were confirmed by in vitro experiments. Ammonium reduced the growth of R. solanacearum, but was not suppressive. Interactions of pH with ammonium and nitrite also occurred, whereby ammonium reduced growth of R. solanacearum only at pH 9 and nitrite was suppressive only at pH 5. Nitrate had no effect on R. solanacearum growth in vitro.
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Planas-Marquès, Marc, Jonathan P. Kressin, Anurag Kashyap, Dilip R. Panthee, Frank J. Louws, Nuria S. Coll, and Marc Valls. "Four bottlenecks restrict colonization and invasion by the pathogen Ralstonia solanacearum in resistant tomato." Journal of Experimental Botany 71, no. 6 (December 24, 2019): 2157–71. http://dx.doi.org/10.1093/jxb/erz562.
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Abstract Ralstonia solanacearum is a bacterial vascular pathogen causing devastating bacterial wilt. In the field, resistance against this pathogen is quantitative and is available for breeders only in tomato and eggplant. To understand the basis of resistance to R. solanacearum in tomato, we investigated the spatio-temporal dynamics of bacterial colonization using non-invasive live monitoring techniques coupled to grafting of susceptible and resistant varieties. We found four ‘bottlenecks’ that limit the bacterium in resistant tomato: root colonization, vertical movement from roots to shoots, circular vascular bundle invasion, and radial apoplastic spread in the cortex. Radial invasion of cortical extracellular spaces occurred mostly at late disease stages but was observed throughout plant infection. This study shows that resistance is expressed in both root and shoot tissues, and highlights the importance of structural constraints to bacterial spread as a resistance mechanism. It also shows that R. solanacearum is not only a vascular pathogen but spreads out of the xylem, occupying the plant apoplast niche. Our work will help elucidate the complex genetic determinants of resistance, setting the foundations to decipher the molecular mechanisms that limit pathogen colonization, which may provide new precision tools to fight bacterial wilt in the field.
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Yang, Sheng, Yuanyuan Shi, Longyun Zou, Jinfeng Huang, Lei Shen, Yuzhu Wang, Deyi Guan, and Shuilin He. "Pepper CaMLO6 Negatively Regulates Ralstonia solanacearum Resistance and Positively Regulates High Temperature and High Humidity Responses." Plant and Cell Physiology 61, no. 7 (April 28, 2020): 1223–38. http://dx.doi.org/10.1093/pcp/pcaa052.
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Abstract Plant mildew-resistance locus O (MLO) proteins influence susceptibility to powdery mildew. However, their roles in plant responses to other pathogens and heat stress remain unclear. Here, we showed that CaMLO6, a pepper (Capsicum annuum) member of MLO clade V, is a protein targeted to plasma membrane and probably endoplasmic reticulum. The transcript expression level of CaMLO6 was upregulated in the roots and leaves of pepper plants challenged with high temperature and high humidity (HTHH) and was upregulated in leaves but downregulated in roots of plants infected with the bacterial pathogen Ralstonia solanacearum. CaMLO6 was also directly upregulated by CaWRKY40 upon HTHH but downregulated by CaWRKY40 upon R. solanacearum infection. Virus-induced gene silencing of CaMLO6 significantly decreased pepper HTHH tolerance and R. solanacearum susceptibility. Moreover, CaMLO6 overexpression enhanced the susceptibility of Nicotiana benthamiana and pepper plants to R. solanacearum and their tolerance to HTHH, effects that were associated with the expression of immunity- and thermotolerance-associated marker genes, respectively. These results suggest that CaMLO6 acts as a positive regulator in response to HTHH but a negative regulator in response to R. solanacearum. Moreover, CaMLO6 is transcriptionally affected by R. solanacearum and HTHH; these transcriptional responses are at least partially regulated by CaWRKY40.
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Xue, Hao, Rosa Lozano-Durán, and Alberto P. Macho. "Insights into the Root Invasion by the Plant Pathogenic Bacterium Ralstonia solanacearum." Plants 9, no. 4 (April 16, 2020): 516. http://dx.doi.org/10.3390/plants9040516.
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The plant pathogenic bacterium Ralstonia solanacearum, causal agent of the devastating bacterial wilt disease, is a soil-borne microbe that infects host plants through their roots. The initial mutual recognition between host plants and bacteria and the ensuing invasion of root tissues by R. solanacearum are critical steps in the establishment of the infection, and can determine the outcome of the interaction between plant and pathogen. In this minireview, we will focus on the early stages of the bacterial invasion, offering an overview of the defence mechanisms deployed by the host plants, the manipulation exerted by the pathogen in order to promote virulence, and the alterations in root development concomitant to bacterial colonization.
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Li, Z., S. Wu, X. Bai, Y. Liu, J. Lu, Y. Liu, B. Xiao, X. Lu, and L. Fan. "Genome Sequence of the Tobacco Bacterial Wilt Pathogen Ralstonia solanacearum." Journal of Bacteriology 193, no. 21 (October 12, 2011): 6088–89. http://dx.doi.org/10.1128/jb.06009-11.
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Denny, Timothy P. "Ralstonia solanacearum – a plant pathogen in touch with its host." Trends in Microbiology 8, no. 11 (November 2000): 486–89. http://dx.doi.org/10.1016/s0966-842x(00)01860-6.
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Wei, Zhong, Jie Hu, Yi'an Gu, Shixue Yin, Yangchun Xu, Alexandre Jousset, Qirong Shen, and Ville-Petri Friman. "Ralstonia solanacearum pathogen disrupts bacterial rhizosphere microbiome during an invasion." Soil Biology and Biochemistry 118 (March 2018): 8–17. http://dx.doi.org/10.1016/j.soilbio.2017.11.012.
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Pontes, Nadson C., Miriam F. Fujinawa, and José R. Oliveira. "Selective media for detection and quantification of Brazilian Ralstonia solanacearum isolates in soil." Horticultura Brasileira 35, no. 1 (March 2017): 41–47. http://dx.doi.org/10.1590/s0102-053620170107.
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ABSTRACT The efficacy of five selective media described in the literature for the detection of Ralstonia solanacearum in soil was evaluated using isolates from different regions of Brazil. The selective media were evaluated regarding their sensitivity, target-pathogen repression index, capacity for suppressing contaminating microorganisms and recovery rate of the pathogen in soil. No bacterial growth was observed at the concentrations tested for FSM and SM-1 media. Some isolates grew on the PCCG medium with the addition of antimicrobial agents, but only at concentrations of 106 cfu/mL. For the SM and SMSA-E media, adequate sensitivity for the detection of R. solanacearum in soil was observed, enabling detection at a concentration of approximately 103 cfu/gram of soil. SMSA-E (Selective Medium South Africa - Elphinstone) was found to be the most effective in suppressing the growth of contaminating microorganisms, resulting in the lowest rate of repression of R. solanacearum and the highest recovery rate of the bacterium in the soil.
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Raihanah, Rizka, Dewi Fitriyanti, and Elly Liestiany. "Pengujian Beberapa Varietas Cabai Besar (Capsicum annuum L.) Terhadap Lama Periode Inkubasi dan Tingkat Ketahanannya Terhadap Layu Bakteri Ralstonia solanacearum." JURNAL PROTEKSI TANAMAN TROPIKA 6, no. 3 (September 14, 2023): 747–55. http://dx.doi.org/10.20527/jptt.v6i3.2170.
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Large chilies (Capsicum annuum L.) are one of the important vegetable commodities. One of the Plant Pest Organisms that causes large chili production to decline is bacterial wilt disease. Bacterial wilt disease in chili cultivation is usually caused by the bacteria Ralstonia solanacearum. Ralstonia solanacearum is a soil-borne pathogen that is able to live in soil without a host. This bacterium has a relatively large number of hosts in the form of horticultural plants, ornamental plants and weeds. This study aims to test five varieties of large chili plants (Capsicum annuum L.) against bacterial wilt disease (Ralstonia solanacearum). Research was carried out at the Phytopathology Laboratory and at the Banjarbaru Agricultural Faculty Experimental Farm. This research used 5 varieties, namely Limosin, Beton F1, Pilar F1, Darmais F1 and Gada Mk F1 with 4 replications. The Limosin variety has the longest incubation period, namely 39 days, while the Pilar F1 and Gada Mk F1 varieties have the fastest incubation period, namely 30 days. The varieties Beton F1, Pilar F1 and Gada Mk F1 show resistant varieties with percentages of 15%, 10% and 5%, while the Limosin variety shows slightly susceptible varieties with a percentage of 50%.
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Álvarez, Belén, María M. López, and Elena G. Biosca. "Influence of Native Microbiota on Survival of Ralstonia solanacearum Phylotype II in River Water Microcosms." Applied and Environmental Microbiology 73, no. 22 (September 14, 2007): 7210–17. http://dx.doi.org/10.1128/aem.00960-07.
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ABSTRACT Ralstonia solanacearum phylotype II biovar 2 causes bacterial wilt in solanaceous hosts, producing severe economic losses worldwide. Waterways can be major dissemination routes of this pathogen, which is able to survive for long periods in sterilized water. However, little is known about its survival in natural water when other microorganisms, such as bacteriophages, other bacteria, and protozoa, are present. This study looks into the fate of a Spanish strain of R. solanacearum inoculated in water microcosms from a Spanish river, containing different microbiota fractions, at 24°C and 14°C, for a month. At both temperatures, R. solanacearum densities remained constant at the initial levels in control microcosms of sterile river water while, by contrast, declines in the populations of the introduced strain were observed in the nonsterile microcosms. These decreases were less marked at 14°C. Lytic bacteriophages present in this river water were involved in the declines of the pathogen populations, but indigenous protozoa and bacteria also contributed to the reduced persistence in water. R. solanacearum variants displaying resistance to phage infection were observed, but only in microcosms without protozoa and native bacteria. In water microcosms, the temperature of 14°C was more favorable for the survival of this pathogen than 24°C, since biotic interactions were slower at the lower temperature. Similar trends were observed in microcosms inoculated with a Dutch strain. This is the first study demonstrating the influence of different fractions of water microorganisms on the survival of R. solanacearum phylotype II released into river water microcosms.
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Sakthivel, K., V. Baskaran, K. Abirami, K. Manigundan, and R. K. Gautam. "Cross-Infectivity of Ralstonia solanacearum from Marigold Grown in Andaman Islands." Journal of Horticultural Sciences 11, no. 2 (December 31, 2016): 179–81. http://dx.doi.org/10.24154/jhs.v11i2.92.
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Bacterial wilt disease, caused by Ralstonia solanacearum, is one of the major concerns for marigold cultivation in Andaman Islands. Cross-infectivity potential of the bacterial wilt pathogen, isolated from marigold, was tested in other common vegetable-hosts of the Island. Pathogen identity was confirmed by morphological identification and Biolog based phenotypic fingerprinting. Cross-infectivity tests revealed tomato to be the most susceptible among the three solanaceous hosts tested. Highest wilt incidence was observed in tomato and marigold (100%) plants, followed by 55.6% in brinjal and 22.3% in chilli, upon artificial soil inoculation. Our study enlightens pathogenic potential of the bacterial wilt pathogen in important vegetable crops of Andaman Islands and can help formulate suitable management practices for successful management of the pathogen.
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Williamson, Lynn, Kazuhiro Nakaho, Brian Hudelson, and Caitilyn Allen. "Ralstonia solanacearum Race 3, Biovar 2 Strains Isolated from Geranium Are Pathogenic on Potato." Plant Disease 86, no. 9 (September 2002): 987–91. http://dx.doi.org/10.1094/pdis.2002.86.9.987.
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Ralstonia solanacearum race 3, biovar 2 is a soilborne bacterium that causes potato brown rot disease in temperate and subtropical climates. Recent outbreaks of this disease in Europe have caused serious losses, but the pathogen had not been identified in the United States. However, in 1999, strains of R. solanacearum were isolated from wilting geraniums growing in Wisconsin greenhouses. Physiological and biochemical tests of the Wisconsin strains and a similar strain from South Dakota demonstrated that the strains belong to R. solanacearum subgroup biovar 2, which is largely synonymous with the race 3 subgroup, a classification based on host range. These results were confirmed by polymerase chain reaction analyses in which race 3, biovar 2-specific primers amplified a fragment of the expected size. This is the first report of race 3, biovar 2 in the United States, and it is the first known occurrence of race 3, biovar 2 in Wiscon-sin. The geranium strains were highly pathogenic on both geranium and potato. The presence of R. solanacearum race 3, biovar 2 in the United States raises concern that the bacterium could move from ornamental plants into potato fields, where it could cause both direct economic damage and quarantine problems. A commercial indirect enzyme-linked immunosorbent assay for R. solanacearum produced some false negatives for these strains, indicating that current indexing may not be sufficient to identify this destructive pathogen.
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Ling, Ling, Xiaoyang Han, Xiao Li, Xue Zhang, Han Wang, Lida Zhang, Peng Cao, et al. "A Streptomyces sp. NEAU-HV9: Isolation, Identification, and Potential as a Biocontrol Agent against Ralstonia solanacearum of Tomato Plants." Microorganisms 8, no. 3 (March 1, 2020): 351. http://dx.doi.org/10.3390/microorganisms8030351.
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Ralstonia solanacearum is an important soil-borne bacterial plant pathogen. In this study, an actinomycete strain named NEAU-HV9 that showed strong antibacterial activity against Ralstonia solanacearum was isolated from soil using an in vitro screening technique. Based on physiological and morphological characteristics and 98.90% of 16S rRNA gene sequence similarity with Streptomyces panaciradicis 1MR-8T, the strain was identified as a member of the genus Streptomyces. Tomato seedling and pot culture experiments showed that after pre-inoculation with the strain NEAU-HV9, the disease occurrence of tomato seedlings was effectively prevented for R. solanacearum. Then, a bioactivity-guided approach was employed to isolate and determine the chemical identity of bioactive constituents with antibacterial activity from strain NEAU-HV9. The structure of the antibacterial metabolite was determined as actinomycin D on the basis of extensive spectroscopic analysis. To our knowledge, this is the first report that actinomycin D has strong antibacterial activity against R. solanacearum with a MIC (minimum inhibitory concentration) of 0.6 mg L−1 (0.48 μmol L−1). The in vivo antibacterial activity experiment showed that actinomycin D possessed significant preventive efficacy against R. solanacearum in tomato seedlings. Thus, strain NEAU-HV9 could be used as BCA (biological control agent) against R. solanacearum, and actinomycin D might be a promising candidate for a new antibacterial agent against R. solanacearum.
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Lowe, Tiffany M., Florent Ailloud, and Caitilyn Allen. "Hydroxycinnamic Acid Degradation, a Broadly Conserved Trait, Protects Ralstonia solanacearum from Chemical Plant Defenses and Contributes to Root Colonization and Virulence." Molecular Plant-Microbe Interactions® 28, no. 3 (March 2015): 286–97. http://dx.doi.org/10.1094/mpmi-09-14-0292-fi.
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Plants produce hydroxycinnamic acid (HCA) defense compounds to combat pathogens, such as the bacterium Ralstonia solanacearum. We showed that an HCA degradation pathway is genetically and functionally conserved across diverse R. solanacearum strains. Further, a feruloyl-CoA synthetase (Δfcs) mutant that cannot degrade HCA was less virulent on tomato plants. To understand the role of HCA degradation in bacterial wilt disease, we tested the following hypotheses: HCA degradation helps the pathogen i) grow, as a carbon source; ii) spread, by reducing HCA-derived physical barriers; and iii) survive plant antimicrobial compounds. Although HCA degradation enabled R. solanacearum growth on HCA in vitro, HCA degradation was dispensable for growth in xylem sap and root exudate, suggesting that HCA are not significant carbon sources in planta. Acetyl-bromide quantification of lignin demonstrated that R. solanacearum infections did not affect the gross quantity or distribution of stem lignin. However, the Δfcs mutant was significantly more susceptible to inhibition by two HCA, namely, caffeate and p-coumarate. Finally, plant colonization assays suggested that HCA degradation facilitates early stages of infection and root colonization. Together, these results indicated that ability to degrade HCA contributes to bacterial wilt virulence by facilitating root entry and by protecting the pathogen from HCA toxicity.
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Benezech, Claire, Alexandre Le Scornet, and Benjamin Gourion. "Medicago-Sinorhizobium-Ralstonia: A Model System to Investigate Pathogen-Triggered Inhibition of Nodulation." Molecular Plant-Microbe Interactions® 34, no. 5 (May 2021): 499–503. http://dx.doi.org/10.1094/mpmi-11-20-0319-sc.
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How plants deal with beneficial and pathogenic microorganisms and how they can tolerate beneficial ones and face pathogens at the same time are questions that remain puzzling to plant biologists. Legume plants are good models to explore those issues, as their interactions with nitrogen-fixing bacteria called rhizobia results in a drastic and easy-to-follow phenotype of nodulation. Intriguingly, despite massive and chronic infection, legume defense reactions are essentially suppressed during the whole symbiotic process, raising a question about a potential negative effect of plant immune responses on the establishment of nodulation. In the present study, we used the model legume, Medicago truncatula, coinoculated with mutualistic and phytopathogenic bacteria, Sinorhizobium medicae and Ralstonia solanacearum, respectively. We show that the presence of R. solanacearum drastically inhibits the nodulation process. The type III secretion system of R. solanacearum, which is important for the inhibition of pathogen-associated molecular pattern–triggered immunity (PTI), strongly contributes to inhibit nodulation. Thus, our results question the negative effect of PTI on nodulation. By including a pathogenic bacterium in the interaction system, our study provides a new angle to address the influence of the biotic environment on the nodulation process. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
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Okiro, Lilian A., Matthew A. Tancos, Steven G. Nyanjom, Christine D. Smart, and Monica L. Parker. "Comparative Evaluation of LAMP, qPCR, Conventional PCR, and ELISA to Detect Ralstonia solanacearum in Kenyan Potato Fields." Plant Disease 103, no. 5 (May 2019): 959–65. http://dx.doi.org/10.1094/pdis-03-18-0489-re.
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Bacterial wilt caused by Ralstonia solanacearum is considered among the most damaging diseases of potato in Sub-Saharan Africa and the most significant biotic constraint of potato production alongside late blight. Unlike late blight, which can be managed by chemical means, R. solanacearum can only be managed through cultural methods and clean seed. Laboratory testing to certify seed before planting is required to confirm the absence of the pathogen in Kenya. A loop-mediated isothermal amplification (LAMP) assay was developed using the UDP-(3-O-acyl)-N-acetylglucosamine deacetylase gene (IpxC) to screen seed potato for R. solanacearum strains. The assay was assessed using DNA extracted from R. solanacearum and other soil and potato pathogens to demonstrate specificity and sensitivity. The LAMP assay was validated using field samples from different potato growing regions of Kenya collected over two growing seasons and compared with established nucleic acid and protein-based assays. The IpxC LAMP assay was found to be specific and sensitive to R. solanacearum, detecting as low as 2.5 pg/µl of R. solanacearum DNA. Of the 47 potentially infected field samples collected, both IpxC LAMP and quantitative polymerase chain reaction (PCR) detected R. solanacearum DNA in 90% of the samples, followed by conventional PCR (86%) and ELISA (75%). This IpxC LAMP assay is a promising diagnostic tool to rapidly screen for R. solanacearum in seed potato with high sensitivity in Kenya. [Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .
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Pfund, Christine, Julie Tans-Kersten, F. Mark Dunning, Jose M. Alonso, Joseph R. Ecker, Caitilyn Allen, and Andrew F. Bent. "Flagellin Is Not a Major Defense Elicitor in Ralstonia solanacearum Cells or Extracts Applied to Arabidopsis thaliana." Molecular Plant-Microbe Interactions® 17, no. 6 (June 2004): 696–706. http://dx.doi.org/10.1094/mpmi.2004.17.6.696.
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The phytopathogenic bacterium Ralstonia solanacearum requires motility for full virulence, and its flagellin is a candidate pathogen-associated molecular pattern that may elicit plant defenses. Boiled extracts from R. solanacearum contained a strong elicitor of defense-associated responses. However, R. solanacearum flagellin is not this elicitor, because extracts from wild-type bacteria and fliC or flhDC mutants defective in flagellin production all elicited similar plant responses. Equally important, live R. solanacearum caused similar disease on Arabidopsis ecotype Col-0, regardless of the presence of flagellin in the bacterium or the FLS2-mediated flagellin recognition system in the plant. Unlike the previously studied flg22 flagellin peptide, a peptide based on the corresponding conserved N-terminal segment of R. solanacearum, flagellin did not elicit any response from Arabidopsis seedlings. Thus recognition of flagellin plays no readily apparent role in this pathosystem. Flagellin also was not the primary elicitor of responses in tobacco. The primary eliciting activity in boiled R. solanacearum extracts applied to Arabidopsis was attributable to one or more proteins other than flagellin, including species purifying at approximately 5 to 10 kDa and also at larger molecular masses, possibly due to aggregation. Production of this eliciting activity did not require hrpB (positive regulator of type III secretion), pehR (positive regulator of polygalacturonase production and motility), gspM (general secretion pathway), or phcA (LysR-type global virulence regulator). Wild-type R. solanacearum was virulent on Arabidopsis despite the presence of this elicitor in pathogen extracts.
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Gashaw, Tsigie, Baye Sitotaw, and Solomon Yilma. "Evaluation of Rhizosphere Bacterial Antagonists against Ralstonia solanacearum Causing Tomato (Lycopersicon esculentum) Wilt in Central Ethiopia." International Journal of Agronomy 2022 (April 11, 2022): 1–9. http://dx.doi.org/10.1155/2022/6341555.
Full textAbstract:
Tomato (Lycopersicon esculentum) is one of the most commonly grown vegetables in Ethiopia. However, diseases such as bacterial wilt caused by Ralstonia solanacearum have been limiting the production. The rhizosphere is an important source of antagonistic bacteria against soilborne pathogens. This study aimed to investigate the antagonistic potential of rhizosphere bacteria against R. solanacearum in vitro. The pathogen was isolated from wilted tomato plants and tested for hypersensitivity reactions to ascertain the virulent R. solanacearum. Antagonistic rhizobacteria were also isolated from the rhizosphere of healthy tomatoes. Isolates were identified based on cultural characteristics and biochemical tests. The antagonistic effect of rhizobacteria against R. solanacearum was tested in vitro. In addition, the growth of rhizobacterial isolates was determined at different levels of temperature, pH, and NaCl. Of the 36 randomly collected colonies, 7 isolates were identified as Ralstonia spp., all of which were grouped under R. solanacearum biovar III. Similarly, 57 rhizobacteria were isolated, and only 14 had shown antagonistic effects against R. solanacearum. The antagonistic rhizobacteria were identified as Pseudomonas or Bacillus species. Significantly higher ( p ≤ 0.05) antagonistic activity (14.66 mm inhibition zone) was recorded by Pseudomonas isolate (P6) than recorded by the rest of the isolates and the positive control. Nine rhizobacterial isolates (out of 14) demonstrated higher or equal inhibition zones recorded by the positive controls. All isolates grew at temperatures ranging 15–45°C, pH 5–9, and 2–5% NaCl. The Bacillus spp. grew at all conditions except at pH 3, showing that they can tolerate wide range of growth conditions. The results of this study showed the presence of potential antagonistic bacteria against R. solanacearum in the study area, which can be used for the control of bacterial wilt of tomato as an alternative management option. Further study is required to determine the efficacy at greenhouse and field conditions.
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Oljira, Temesgen, and Sefawdin Berta. "Isolation and Characterization of Wilt-Causing Pathogens of Local Growing Pepper (Capsicum annuum L.) in Gurage Zone, Ethiopia." International Journal of Agronomy 2020 (December 1, 2020): 1–8. http://dx.doi.org/10.1155/2020/6638683.
Full textAbstract:
The yield of pepper (Capsicum annuum L.) is extremely threatened by different diseases in Ethiopia. The objective of the study was isolation of wilt-causing pathogens and susceptibility test of local growing pepper. Eighteen pepper farming fields were selected for disease assessment study. The samples of Mareko Fana, Dubi, and Mitmita local cultivar pepper’s pods, seeds, leaves, stems, and roots were collected, surface sterilized, and cultured on potato dextrose agar (PDA). Selective peptone pentachloronitrobenzene (PCNB) agar medium was used for fungus. Similarly, for bacteria isolation, nutrient agar (NA) was used. Morphological and biochemical tests revealed eleven fungal isolates of Fusarium oxysporum f. sp. that were isolated. The pathogenicity test confirmed nine of them were virulent to Mareko Fana, Dubi, and Mitmita local pepper. It is confirmed that Fusarium oxysporum f. sp. is the pathogen Fusarium oxysporum f. sp. capsici. Besides, Ralstonia solanacearum was identified as a bacterium pathogen causing complex pepper wilt disease. The highest mean PDI was registered in Remuga Keble (93.0%) and the lowest in Buyi Keble (58.3%). Similarly, the highest mean PSI was recorded in Buyi Keble (87.0%) and the lowest PSI (54.5%) was registered in Tawlla Keble. Among 60 seeds, Mareko local pepper inoculated by F. oxysporum f. sp. and R. solanacearum shows the highest susceptibility of 55 (91.0%) and 30 (50.0%), respectively. However, Mitmita local pepper was registered as the lowest susceptibility to both F. oxysporum f. sp. and R. solanacearum of 28.3% and 30.0%, respectively. Based on the finding, it can be concluded that pepper wilt was caused by a complex of fungus Fusarium oxysporum f. sp. capsici and bacteria Ralstonia solanacearum sp. in the study area. So, it is recommended that an integrated disease management approach should be implemented to manage the complex diseases of the site.
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MacIntyre, April M., John X. Barth, Molly C. Pellitteri Hahn, Cameron O. Scarlett, Stéphane Genin, and Caitilyn Allen. "Trehalose Synthesis Contributes to Osmotic Stress Tolerance and Virulence of the Bacterial Wilt Pathogen Ralstonia solanacearum." Molecular Plant-Microbe Interactions® 33, no. 3 (March 2020): 462–73. http://dx.doi.org/10.1094/mpmi-08-19-0218-r.
Full textAbstract:
The xylem-dwelling plant pathogen Ralstonia solanacearum changes the chemical composition of host xylem sap during bacterial wilt disease. The disaccharide trehalose, implicated in stress tolerance across all kingdoms of life, is enriched in sap from R. solanacearum–infected tomato plants. Trehalose in xylem sap could be synthesized by the bacterium, the plant, or both. To investigate the source and role of trehalose metabolism during wilt disease, we evaluated the effects of deleting the three trehalose synthesis pathways in the pathogen: TreYZ, TreS, and OtsAB, as well as its sole trehalase, TreA. A quadruple treY/treS/otsA/treA mutant produced 30-fold less intracellular trehalose than the wild-type strain missing the trehalase enzyme. This trehalose-nonproducing mutant had reduced tolerance to osmotic stress, which the bacterium likely experiences in plant xylem vessels. Following naturalistic soil-soak inoculation of tomato plants, this triple mutant did not cause disease as well as wild-type R. solanacearum. Further, the wild-type strain out-competed the trehalose-nonproducing mutant by over 600-fold when tomato plants were coinoculated with both strains, showing that trehalose biosynthesis helps R. solanacearum overcome environmental stresses during infection. An otsA (trehalose-6-phosphate synthase) single mutant behaved similarly to ΔtreY/treS/otsA in all experimental settings, suggesting that the OtsAB pathway is the dominant trehalose synthesis pathway in R. solanacearum.
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Álvarez, B., J. Vasse, V. Le-Courtois, D. Trigalet-Démery, M. M. López, and A. Trigalet. "Comparative Behavior of Ralstonia solanacearum Biovar 2 in Diverse Plant Species." Phytopathology® 98, no. 1 (January 2008): 59–68. http://dx.doi.org/10.1094/phyto-98-1-0059.
Full textAbstract:
Ralstonia solanacearum causes bacterial wilt in numerous plant species worldwide. Although biovar 2 mostly affects solanaceous crops, identification of new hosts remains a matter of concern since there is still no clear-cut distinction between host and nonhost plants. In this work we provide data based on histological studies on the status of 20 plant species, most of them of potential interest in crop rotation. Plants were watered with a β-glucuronidase-expressing derivative of R. solanacearum biovar 2, and after a month of incubation, sections of roots and stems were analyzed to localize the pathogen on surface, in cortex and/or xylem. Depending on whether the xylem was colonized or not, plants were classified as hosts or nonhosts, respectively. Hosts generally affected in a few xylem vessels or occasionally in all xylem bundles were classified as tolerant. These included some cabbage, kidney bean, and rutabaga cultivars, and the weed bittersweet nightshade (Solanum dulcamara). Nonhosts were the cultivars tested of alfalfa, barley, black radish, carrot, celery, colocynth, fennel, fiber flax, field bean, field pea, horseradish, maize, and zucchini. However, barley and maize, though nonhosts, may act as reservoirs for the pathogen. The present work constitutes a basis for further studies on cropping systems in fields where R. solanacearum has been detected.
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Champoiseau, Patrice G., Jeffrey B. Jones, and Caitilyn Allen. "Ralstonia solanacearum Race 3 Biovar 2 Causes Tropical Losses and Temperate Anxieties." Plant Health Progress 10, no. 1 (January 2009): 35. http://dx.doi.org/10.1094/php-2009-0313-01-rv.
Full textAbstract:
R. solanacearum Race 3 biovar 2, which causes potato brown rot and Southern wilt of geranium, is a high-consequence quarantine pathogen in Europe and North America and causes large crop losses in tropical highlands. This practical review emphasizes prevention, detection, diagnosis, and effective management of diseases caused by this destructive pathogen. Accepted for publication 17 January 2009. Published 13 March 2009.
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Wullings, B. A., A. R. Van Beuningen, J. D. Janse, and A. D. L. Akkermans. "Detection of Ralstonia solanacearum, Which Causes Brown Rot of Potato, by Fluorescent In Situ Hybridization with 23S rRNA-Targeted Probes." Applied and Environmental Microbiology 64, no. 11 (November 1, 1998): 4546–54. http://dx.doi.org/10.1128/aem.64.11.4546-4554.1998.
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ABSTRACT During the past few years, Ralstonia(Pseudomonas) solanacearum race 3, biovar 2, was repeatedly found in potatoes in Western Europe. To detect this bacterium in potato tissue samples, we developed a method based on fluorescent in situ hybridization (FISH). The nearly complete genes encoding 23S rRNA of five R. solanacearum strains and oneRalstonia pickettii strain were PCR amplified, sequenced, and analyzed by sequence alignment. This resulted in the construction of an unrooted tree and supported previous conclusions based on 16S rRNA sequence comparison in which R. solanacearum strains are subdivided into two clusters. Based on the alignments, two specific probes, RSOLA and RSOLB, were designed forR. solanacearum and the closely related Ralstonia syzygii and blood disease bacterium. The specificity of the probes was demonstrated by dot blot hybridization with RNA extracted from 88 bacterial strains. Probe RSOLB was successfully applied in FISH detection with pure cultures and potato tissue samples, showing a strong fluorescent signal. Unexpectedly, probe RSOLA gave a less intense signal with target cells. Potato samples are currently screened by indirect immunofluorescence (IIF). By simultaneously applying IIF and the developed specific FISH, two independent targets for identification of R. solanacearumare combined, resulting in a rapid (1-day), accurate identification of the undesired pathogen. The significance of the method was validated by detecting the pathogen in soil and water samples and root tissue of the weed host Solanum dulcamara (bittersweet) in contaminated areas.
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Lee, Ingyeong, Yeong Son Kim, Jin-Won Kim, and Duck Hwan Park. "Genetic and Pathogenic Characterization of Bacterial Wilt Pathogen, Ralstonia pseudosolanacearum (Ralstonia solanacearum Phylotype I), on Roses in Korea." Plant Pathology Journal 36, no. 5 (October 1, 2020): 440–49. http://dx.doi.org/10.5423/ppj.oa.06.2020.0095.
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