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Ralstonia syzygii, the Blood Disease Bacterium and Some Asian R. solanacearum Strains Form a Single Genomic Species Despite Divergent Lifestyles  [PDF]
Beno?t Remenant, Jean-Charles de Cambiaire, Gilles Cellier, Jonathan M. Jacobs, Sophie Mangenot, Valérie Barbe, Aurélie Lajus, David Vallenet, Claudine Medigue, Mark Fegan, Caitilyn Allen, Philippe Prior
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024356
Abstract: The Ralstonia solanacearum species complex includes R. solanacearum, R. syzygii, and the Blood Disease Bacterium (BDB). All colonize plant xylem vessels and cause wilt diseases, but with significant biological differences. R. solanacearum is a soilborne bacterium that infects the roots of a broad range of plants. R. syzygii causes Sumatra disease of clove trees and is actively transmitted by cercopoid insects. BDB is also pathogenic to a single host, banana, and is transmitted by pollinating insects.?Sequencing and DNA-DNA hybridization studies indicated that despite their phenotypic differences, these three plant pathogens are actually very closely related, falling into the Phylotype IV subgroup of the R. solanacearum species complex. To better understand the relationships among these bacteria, we sequenced and annotated the genomes of R. syzygii strain R24 and BDB strain R229. These genomes were compared to strain PSI07, a closely related Phylotype IV tomato isolate of R. solanacearum, and to five additional R. solanacearum genomes. Whole-genome comparisons confirmed previous phylogenetic results: the three phylotype IV strains share more and larger syntenic regions with each other than with other R. solanacearum strains. Furthermore, the genetic distances between strains, assessed by an in-silico equivalent of DNA-DNA hybridization, unambiguously showed that phylotype IV strains of BDB, R. syzygii and R. solanacearum form one genomic species. Based on these comprehensive data we propose a revision of the taxonomy of the R. solanacearum species complex. The BDB and R. syzygii genomes encoded no obvious unique metabolic capacities and contained no evidence of horizontal gene transfer from bacteria occupying similar niches. Genes specific to R. syzygii and BDB were almost all of unknown function or extrachromosomal origin. Thus, the pathogenic life-styles of these organisms are more probably due to ecological adaptation and genomic convergence during vertical evolution than to the acquisition of DNA by horizontal transfer.
Simple sequence repeats and compositional bias in the bipartite Ralstonia solanacearum GMI1000 genome
Tom Coenye, Peter Vandamme
BMC Genomics , 2003, DOI: 10.1186/1471-2164-4-10
Abstract: Our data show that both replicons are very similar in respect to distribution and composition of SSRs and presence of compositional biases. Minor variations in SSR and compositional biases observed may be attributable to minor differences in gene expression and regulation of gene expression or can be attributed to the small sample numbers observed.The observed similarities indicate that both replicons have shared a similar evolutionary history and thus suggest that the megaplasmid was not recently acquired from other organisms by lateral gene transfer but is a part of an ancestral R. solanacearum chromosome.The paradigm that bacterial genomes consist of a single circular chromosome is no longer valid. Linear chromosomes have been identified in Borrellia burgdorferi [1], various Streptomyces species [2,3], Agrobacterium tumefaciens [4] and various other species. In addition, it is now appreciated that genomes of several bacterial taxa consist of multiple replicons. Most organisms with a multi- or bipartite genome structure belong to the α-Proteobacteria (including Rhodobacter sphaeroides [5,6] and various Rhizobium [7,8], Agrobacterium [4,8], Brucella [9,10] and Azospirillum [11] species) or the β-Proteobacteria. Most isolates from species belonging to the β-proteobacterial genera Burkholderia and Ralstonia harbour multiple replicons, including members of the Burkholderia cepacia complex [12-16], Burkholderia gladioli [15], Burkholderia pseudomallei [17], Burkholderia glumae [13], Burkholderia glathei [13], Burkholderia sp. LB400 [18], Ralstonia pickettii [13], Ralstonia eutropha [13] and Ralstonia metallidurans [18]. Multiple replicons may have arisen from the need to achieve higher overall replication rates [19]. The origin of these multiple replicons is at present unclear but it has been suggested that they could have their origin in gene duplication followed by divergence; in this case intrachromosomal recombinational events within a duplicated region could give
Characterization of Ralstonia solanacearum causing bacterial wilt in ginger  [cached]
Indian Phytopathology , 2012,
Abstract: Bacterial wilt pathogen Ralstonia solanacearum isolated from ginger, tomato, Chromolaena, chilli and potato, characterized for biovar, pathogenicity, infectivity titer, and intrinsic antibiotic resistance. The isolates were also characterized on the basis of their membrane protein pattern and amenability of the isolates for serological detection (NCM-ELISA) using R. solanacearum specific antibodies. All the ginger isolates were highly fluidal with characteristic spiral pink center on 2,3,5-triphenyl tetrazolium chlorideamended medium. Among the isolates characterized nine belongs to biovar 3 while one from potato to biovar 2. Among the various isolates tested, only ginger ones except one from Assam induced cent percent wilting in ginger cv. Himachal within a week. Plants were wilted even at a concentration of 3.2 X 102 cfu ml- 1 in stem inoculation while in soil inoculation it was 105 cfu ml- 1 . All the isolates were resistant to antibiotics tetracycline, polymyxin B sulphate and chloramphenicol and isolates GRS Tms and its spontaneous mutant were resistant to Rifamycin. Isolates were detected with NCM-ELISA and biovars on the basis of membrane protein pattern on SDS-PAGE and biovar specific protein from R. solanacearum could be isolated.
Prevalence of Races and Biotypes of Ralstonia Solanacearum in India
Krishnappa Nagarathna Chandrashekara, Mothukapalli Krishnareddy Prasannakumar, Manthirachalam Deepa, Akella Vani, Abdul Nazir Ahmad Khan
Journal of Plant Protection Research , 2012, DOI: 10.2478/v10045-012-0009-4
Abstract: Bacterial wilt caused by Ralstonia solanacearum is the most destructive disease of plants. Fifty-seven isolates of R. solanacearum causing wilt on different host plants viz., tomato (Solanum lycopersicum), brinjal (S. melongena), potato (S. tuberosum), bird of paradise (Strelitzia reginae), ginger (Zingiber officinale), chili (Capsicum annuum), capsicum (Capsicum annuum), davana (Artemisia pallens) and coleus (Coleus forskohlii) were collected from the different agro climatic zones of Karnataka and other parts of India. In this study, 57 isolates were differentiated into race on the basis of their pathogenicity and their ability to infect different host. The isolates were established as race-1. None of the isolates infected mulberry and banana. Fifty-four isolates oxidized and utilized both the disaccharides and sugar alcohols. These isolates were positioned as biovars-3 according to Haywards classification system. Three isolates from Kerala, two ginger, and one tomato strain were not able to utilize dulcitol and lactose. Hence, they were categorized into a new taxo group within the system and designated as biovar-3B for the first time in India. There were 54 isolates which were confirmed as race-1, biovar-3, and 3 isolates were confirmed as race-1, biovar-3B by morphological, physiological, biochemical and pathogenicity studies. Two sets of primers (OLI1 & Y2 and Y1 & Y2) were used in this study to authenticate the organism. Furthermore, the identity of the isolates was confirmed by a serological diagnostic kit obtained from the International Potato Research Center, Lima, Peru, and single chain variable fragment antibody specific to R. solanacearum.
Utilization of plant growth promoting Bacillus subtilis isolates for the management of bacterial wilt incidence in tomato caused by Ralstonia solanacearum race 1 biovar 3  [cached]
Indian Phytopathology , 2012,
Abstract: Bacterial wilt of tomato caused by Ralstonia solanacearum race 1 biovar 3 is one of the most economically important diseases of tomato in India. Bacillus subtilis isolates were isolated from rhizospheric soil of wilt infected tomato plants from different agro-climatic regions of India. These isolates were evaluated for their antagonistic ability to reduce incidence of bacterial wilt of tomato and plant growth promoting attributes. Twenty-four and 48 h old cultures of B. subtilis BS-5 inhibited growth of R. solanacearum by forming area of inhibition zone 4.90 cm2 and 5.87cm2 respectively under in vitro
Linear reduction of propagules of Ralstonia solanacearum in soil by cake and chemicals  [cached]
Indian Phytopathology , 2011,
Abstract: In Alfisol of east India plateau soil application of karanj (Pongamia glabra) cake, bleaching powder (CaClO3), lime (CaCO3) and seedling dip and spray of streptocycline resulted in reduction of initial population of Ralstonia solanacearum (R.s.) in soil in post monsoon seasons of 1998-99 to 2001-02. The percent reductions in initial population of R.s. noted at 90 d after transplanting of tomato were 30.5 and 33.2 at 10 and 20 q karanj (Pongamia) cake ha-1
Characterization of isolates of Ralstonia solanacearum biovar 2, pathogenic to Eucalyptus "urograndis" hybrids
Eder Marques,Carlos H. Uesugi,Marisa A.S.V. Ferreira,Denise V. de Rezende
Tropical Plant Pathology , 2012, DOI: 10.1590/s1982-56762012000600004
Abstract: The objective of this study was to characterize isolates of biovar 2 of Ralstonia solanacearum pathogenic to eucalyptus "urograndis" hybrid by means of biochemical tests, as well as evaluation of host range and identification by PCR with primers for species, biovar and phylotype. Carbohydrate utilization assays revealed that the eucalyptus isolates belong to phenotype Tropical of biovar 2 (2T). From artificial inoculations it was possible to reproduce symptoms or recover the bacterium from: eucalyptus, potato, tomato, eggplant, datura, geranium, turnip, mustard, nasturtium, beetroot, sunflower, bean, French marigold, horseradish tree, and cashew. The PCR assays confirmed that the isolates belong to biovar 2, phylotype II of the bacterium. The confirmation of new biovar naturally infecting eucalyptus indicates that R. solanacearum easily adapts to new hosts.
Sele??o de isolados de estreptomicetos para controle de Ralstonia solanacearum em tomateiro
Gava, Carlos Alberto Tu?o;Pereira, Jo?o Carlos;Fernandes, Maria do Carmo;Neves, Maria Cristina Prata;
Pesquisa Agropecuária Brasileira , 2002, DOI: 10.1590/S0100-204X2002001000004
Abstract: the bacterial wilt caused by ralstonia solanacearum causes high damages in tomato (lycopersicon esculentum mill.) culture, mainly under temperature above 25oc and high relative humidity. because conventional methods of control have shown low efficiency, biological control is a promising alternative. this work aimed to select isolates of streptomycetes for r. solanacearum control in tomato. differences were found among the isolates in the in vitro inhibition of the pathogen either in time or ph range. the streptomycetes isolates grew differently in the rhizosphere of seedlings and plantlets of tomato. the isolates sp164, sf232, sac326 and sg384 showed the highest population densities. in the experiment conducted in soil infested with r. solanacearum, plants treated with the isolate sg384 presented best control level 48 days after sowing, period after which all control plants were dead.
Transcriptome Analysis of Quantitative Resistance-Specific Response upon Ralstonia solanacearum Infection in Tomato  [PDF]
Takeaki Ishihara, Ichiro Mitsuhara, Hideki Takahashi, Kazuhiro Nakaho
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046763
Abstract: Bacterial wilt, caused by the soil-borne bacterium Ralstonia solanacearum, is a lethal disease of tomato, but the molecular mechanisms of the host resistance responses to R. solanacearum remain unclear. In this study, we report the first work describing the transcriptome of cultivar resistance and susceptible tomato cultivar after inoculation with R. solanacearum. To elucidate the characteristics of resistance early in the interaction, we analyzed microarrays for resistant cultivar LS-89 and susceptible cultivar Ponderosa 1 day after stem inoculation. No change in gene expression was detected for Ponderosa, but expression levels of over 140 genes, including pathogenesis-related, hormone signaling and lignin biosynthesis genes, increased in LS-89. Expression of β-1,3-glucanase genes increased substantially. In an immunohistochemical study, glucanase in LS-89 accumulated in the xylem and pith tissues surrounding xylem vessels filled with R. solanacearum. The expression of these genes also increased in four other resistant cultivars, but changed little in four susceptible cultivars in response to R. solanacearum, suggesting that similar reactions occur in other cultivars. These gene expression profiles will serve as fundamental information to elucidate the molecular mechanisms in the resistance response to R. solanacearum in tomato.
Characteristics of Ralstonia solanacearum Strains of Potato Wilt Disease from Nepal and Thailand  [PDF]
Shambhu P Dhital,Nanda Thaveechai,Sundar K Shrestha
Nepal Agriculture Research Journal , 2000, DOI: 10.3126/narj.v4i0.4868
Abstract: Characterization of strains of Ralstonia solanacearum , the causal agent of potato bacterial wilt disease from Nepal and Thailand was performed based on pathogenicity, biochemical/physiological and serological tests. Fifteen R. solanacearum strains isolated from wilt infected potato plants and tubers grown in Nepal were characterized as race 3, biovar II based on the pathogenicity on different host plants, hypersensitive reaction on tobacco leaf and utilization of some sugars. Results of pathogenicity test show that all strains from Nepal had limited host range. Degree of virulence of all strains varied from high to medium in potato and tomato and medium to low in eggplant. They did not cause wilting in tobacco, pepper and peanut plants. Six strains from Thailand were characterized as biovar II and III. Additionally, comparisons on the physiological, biological and serological characters of seven strains from Nepal and six from Thailand revealed similar characters. Race 3 and biovar II of the pathogen was widely spread over potato growing areas of mid and high hills of Nepal. Both biovars II and III were prevalent in the potato growing areas of Thailand but biovar III was the most dominating one. Key words: Bacterial wilt; Potato; Pseudomonas solanacearum ; Ralstonia solanacearum DOI: http://dx.doi.org/10.3126/narj.v4i0.4868 Nepal Agriculture Research Journal Vol. 4&5, 2001/2002 Page: 42-47 Uploaded date: 9 June, 2011
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