Strains Of Ralstonia Solanacearum Research Articles

A LysR-type regulator influencing swimming motility, galactose utilization, and virulence in Ralstonia solanacearum GMI1000

BackgroundLysR-type transcriptional regulators (LTTRs) are one of the largest families of regulators in prokaryotic organism, which help the bacterium adapt to diverse conditions by controlling a wide array of regulons, encompassing genes responsible for nitrogen and carbon fixation, oxidative stress response, bacterial virulence, and the breakdown of diverse compounds. Ralstonia solanacearum strain GMI1000 possesses 80 LTTR genes, yet the precise roles and functional contributions of only three of these LTTRs have been conclusively established among the total. In this work, our group reveal a novel LTTR member LysR7 (RS_RS02375) that exerts multiple regulatory roles in motility, carbon metabolism and virulence.ResultsIn this investigation, an in-frame deletion mutant ΔlysR7 and a complemented strain CΔlysR7 were prepared. The mutant ΔlysR7 had increased swimming motility on semi-soft medium and showed a reduced replication rate in nutrient-rich medium and in planta. Moreover, ΔlysR7 was unable to grow on nutrient-limited medium, supplemented with galactose as a single carbon resource. RT-qPCR analysis and GUS activity detection indicated that the expression of lysR7 was induced in the presence of galactose. The mutant ΔlysR7 caused weaker wilt disease on either Solanum lycopersicum or Capsicum annuum plants compared to both wild type GMI1000 and CΔlysR7. Transcriptome analysis revealed that 12 upregulated and 8 downregulated differentially expressed genes (DEGs) in ΔlysR7 were restored in CΔlysR7 relative to wild type. In particular, the expression of hrpG, a key gene responsible for type III secretion system, was downregulated. KEGG analysis revealed that, except for lysR7 gene, the 19 DEGs were most enriched in microbial metabolism in diverse environments and metabolic pathways.ConclusionsThe data indicate that LysR7 regulates multiple processes in association with motility, galactose metabolism and virulence in R. solanacearum. The study offers valuable evidence to understand comprehensive regulatory mechanisms mediated by LTTR family members in R. solanacearum.Graphical

Duality of H2O2 detoxification and immune activation of Ralstonia solanacearum alkyl hydroperoxide reductase C (AhpC) in tobacco

Although microbial pathogens utilize various strategies to evade plant immunity, host plants have evolved powerful defense mechanisms that can be activated in preparation for threat by infective organisms. Here, we identified one 24 kDa alkyl hydroperoxide reductase C (AhpC) from the culture supernatant of Ralstonia solanacearum strain FQY-4 (denoted RsAhpC) in the presence of host roots. RsAhpC contributes to H2O2 detoxification and the pathogenicity of R. solanacearum. However, the introduction of RsAhpC into the apoplast could activate immune defense, leading to suppression of pathogen colonization in both Nicotiana benthamiana and the Honghua Dajinyuan (HD) cultivar of N. tabacum. Consequently, overexpression of RsAhpC in the HD cultivar enhanced the resistance of tobacco to bacterial wilt disease caused by FQY-4. Overall, this study provides insight into the arms race between pathogens and their plant hosts. Specifically, it is firstly reported that plants can sense pathogen-derived AhpC to activate defenses, in addition to the role of AhpC in pathogen ROS detoxification. Therefore, the macromolecule AhpC produced by Ralstonia solanacearum has the ability to enhance plant defense as an elicitor, which provides a practical strategy for disease resistance breeding.

Morphological and Biochemical Characterization of Strains of Ralstonia solanacearum, Causal Agent of Bacterial Wilt in Tomatoes in Cameroon and Screening of Virulent Strains

Ralstonia solanacearum is a major constraint in tomato production. The aim of this work was to identify the different biovars and races of R. solanacearum which infect tomato plants in Cameroon and determine the most virulent in a gnotobiotic environment. Thirty (30) samples were collected in the field of 03 different agro-ecological zones considered as major tomato production area in Cameroon. The bacteria were isolated on modified Kelman solid medium, and identified based on morphological and biochemical characterization. The pathogenicity test was performed in a gnotobiotic environment by root inoculation. Twenty-nine (29) isolates showed colonies characteristic of virulent strains. Water, motility, catalase, KOH, Kovac oxidase, glucose reduction, and sucrose tests were positive. However, gram staining, spore production, arginine test and sulfate reduction were negative. The biovar tests carried out revealed the presence16.66% biovar 2 (bv 2) and 76.66% biovar 3(bv 3). The tobacco hypersensitivity tests carried out revealed the presence of two (02) races: race 1 and race 3 (majority). A predominance of race3 biovar 3 was observed in Cameroon. Results from pathogenicity test revealed that two (02) strains, FM6 (race 3 bv2) and BFo (race 3 bv 3) were high virulent, causing up to 100% loss of seedlings on the sixth day post-inoculation.

Boosting Tomato Resilience in Tanzania: Grafting to Combat Bacterial Wilt and Abiotic Stress

The grafting technique has successfully mitigated crop losses from diseases and stress in vegetable production; however, vegetable grafting in Tanzania is very limited. Field and greenhouse experiments conducted in Tanzania’s mainland and islands compared the response of tomato determinate cv. ‘Tanya’ to production challenges when ungrafted and grafted onto five tomato rootstocks (‘Hawaii 7796’, ‘Tengeru 1997’, ‘Tengeru 2010’, ‘R3034’, and ‘Shelter’), one eggplant variety (‘EG 203’), and one wild Solanum species (Solanum elaeagnifolium). The visual symptoms of bacterial wilt varied significantly with location and season, ranging from 8 to 100%, attributed to varying bacterial wilt pressures and strains of Ralstonia solanacearum isolated (Phylotype I sequevars 17, 18, and 31). ‘EG203’ and ‘Hawaii 7796’ emerged as the most effective rootstocks, reducing wilting by 49.8 and 51.0% and improving yield by 57.2% and 27.7% on average across experiments conducted in three locations (Moshi, Pemba, and Unguja) over two seasons. Combining reduced water supply with grafting resulted in an average reduction in wilting of 76%, while also boosting yields by an average of 3.6 times in experiments conducted in Arusha over two seasons. Grafting onto ‘Hawaii 7796’ and ‘Shelter’ significantly improved ‘Tanya’ yields by 38.3% and 41.6% on average over two seasons, only under standard nutrient application rates. While certain rootstocks improved crop performance, yields across various sites and seasons were significantly hampered by pest pressure. These findings support grafting’s potential to mitigate damage from common stresses, emphasizing the need for further research to identify suitable rootstocks for optimizing returns on investments in grafted plants in Tanzania.

Effects of plant tissue permeability on invasion and population bottlenecks of a phytopathogen

Pathogen genetic diversity varies in response to environmental changes. However, it remains unclear whether plant barriers to invasion could be considered a genetic bottleneck for phytopathogen populations. Here, we implement a barcoding approach to generate a pool of 90 isogenic and individually barcoded Ralstonia solanacearum strains. We used 90 of these strains to inoculate tomato plants with different degrees of physical permeability to invasion (intact roots, wounded roots and xylem inoculation) and quantify the phytopathogen population dynamics during invasion. Our results reveal that the permeability of plant roots impacts the degree of population bottleneck, genetic diversity, and composition of Ralstonia populations. We also find that selection is the main driver structuring pathogen populations when barriers to infection are less permeable, i.e., intact roots, the removal of root physical and immune barriers results in the predominance of stochasticity in population assembly. Taken together, our study suggests that plant root permeability constitutes a bottleneck for phytopathogen invasion and genetic diversity.

Biological characteristics and ability of Streptomyces rochei BT02 to inhibit the Ralstonia solanacearum causing bacterial wilt disease

In the agricultural field, actinomycetes are outstanding biological control agents to inhibit the growth of pathogenic microorganisms. Based on the manual of bacterial classification of the International Streptomyces Project (ISP) and the 16S-rRNA gene sequence, the actinomycete BT02 strain was named Streptomyces rochei BT02. This strain contains two polyketide synthase type I (pks-I) and polyketide synthase type II (pks-II) genes related to antibiotic synthesis. The result showed that the actinomycetes S. rochei BT02 grow well at 31οC, 1% salt, pH 7.0, and assimilate different carbon and nitrogen sources. The S. rochei BT02 showed antibacterial activity against three tested strains of Ralstonia solanacearum (Minimum inhibitory concentration =15 mg/ml). In greenhouse conditions, this strain reduced 43.5% the wilt disease index. That demonstrated that S. rochei BT02 could be a promising source for the production of bioproducts.

Part II: Impedance-based DNA biosensor for detection of isolated strains of phytopathogen Ralstonia solanacearum

In Part I, we demonstrated the complete development of a label-free, ultra-low sample volume requiring DNA-based biosensor to detect Ralstonia solanacearum, an aerobic non-spore-forming, Gram-negative, plant pathogenic bacterium, using non-faradaic electrochemical impedance spectroscopy (nf-EIS). We also presented the sensor's sensitivity, specificity, and electrochemical stability. In this article, we highlight the specificity study of the developed DNA-based impedimetric biosensor to detect various strains of R. solanacearum. We have collected seven isolates of R. solanacearum isolated from locally infected host plants (eggplant, potato, tomato, chilli, and ginger) from different parts of Goa, India. The pathogenicity of these isolates was tested on the eggplant, and the pathogen was confirmed by microbiological plating and polymerase chain reaction (PCR). We further report the insight into the DNA hybridization on the surface of Interdigitated Electrodes (IDEs) and the expansion of the Randles model for more accurate analysis. The interpretation of the sensor specificity is clearly demonstrated by the capacitance change observed at the electrode–electrolyte interface.

Focus Issue Articles on Diagnostic Assay Development and Validation: The Science of Getting It Right

Focus Issue Articles on Diagnostic Assay Development and Validation: The Science of Getting It Right

Characterization and Association of Rips Repertoire to Host Range of Novel Ralstonia solanacearum Strains by In Silico Approaches.

Ralstonia solanacearum species complex (RSSC) cause several phytobacteriosis in many economically important crops around the globe, especially in the tropics. In Brazil, phylotypes I and II cause bacterial wilt (BW) and are indistinguishable by classical microbiological and phytopathological methods, while Moko disease is caused only by phylotype II strains. Type III effectors of RSSC (Rips) are key molecular actors regarding pathogenesis and are associated with specificity to some hosts. In this study, we sequenced and characterized 14 newly RSSC isolates from Brazil's Northern and Northeastern regions, including BW and Moko ecotypes. Virulence and resistance sequences were annotated, and the Rips repertoire was predicted. Confirming previous studies, RSSC pangenome is open as α≅0.77. Genomic information regarding these isolates matches those for R. solanacearum in NCBI. All of them fit in phylotype II with a similarity above 96%, with five isolates in phylotype IIB and nine in phylotype IIA. Almost all R. solanacearum genomes in NCBI are actually from other species in RSSC. Rips repertoire of Moko IIB was more homogeneous, except for isolate B4, which presented ten non-shared Rips. Rips repertoire of phylotype IIA was more diverse in both Moko and BW, with 43 common shared Rips among all 14 isolates. New BW isolates shared more Rips with Moko IIA and Moko IIB than with other public BW genome isolates from Brazil. Rips not shared with other isolates might contribute to individual virulence, but commonly shared Rips are good avirulence candidates. The high number of Rips shared by new Moko and BW isolates suggests they are actually Moko isolates infecting solanaceous hosts. Finally, infection assays and Rips expression on different hosts are needed to better elucidate the association between Rips repertoire and host specificities.

Complete Genome Sequences of Ralstonia solanacearum Strains Isolated from Infected Ginger Plants.

We present the complete genome sequences of Ralstonia solanacearum strains isolated from ginger plants. Strains MAFF 211471, MAFF 211479, MAFF 211491, MAFF 301560, MAFF 241647, and MAFF 241648 contain 69, 64, 65, 69, 72, and 64 type III effector genes, respectively.

Chryseochelins-structural characterization of novel citrate-based siderophores produced by plant protecting Chryseobacterium spp.

Bacteria secrete siderophores whose function is to acquire iron. In recent years, the siderophores of several Chryseobacterium species were shown to promote the health and growth of various plants such as tomato or rice. However, the chemical nature of Chryseobacterium siderophores remained unexplored despite great interest. In this work, we present the purification and structure elucidation by nuclear magnetic resonance (NMR) spectroscopy and tandem mass spectrometry (MS/MS) of chryseochelin A, a novel citrate-based siderophore secreted by three Chryseobacterium strains involved in plant protection. It contains the unusual building blocks 3-hydroxycadaverine and fumaric acid. Furthermore, the unstable structural isomer chryseochelin B and its stable derivative containing fatty acid chains, named chryseochelin C, were identified by mass spectrometric methods. The latter two incorporate an unusual ester connectivity to the citrate moiety showing similarities to achromobactin from the plant pathogen Dickeya dadantii. Finally, we show that chryseochelin A acts in a concentration-dependent manner against the plant-pathogenic Ralstonia solanacearum strain by reducing its access to iron. Thus, our study provides valuable knowledge about the siderophores of Chryseobacterium strains, which have great potential in various applications.

Complete Genome Sequence of Ralstonia solanacearum Strain Bs715, a Member of Biovar 4 and a Strong Pathogen of Bacterial Wilt on Solanum lycopersicum.

Ralstonia solanacearum is a notorious pathogen of bacterial wilt on Solanum lycopersicum. Most isolates from diseased tomato tissues are biovar 3, and their genomes are publicly available; however, information on biovar 4 strains is limited. Here, the complete genome sequence of R. solanacearum Bs715, a biovar 4 strain, is presented.

New Strategy for Inducing Resistance against Bacterial Wilt Disease Using an Avirulent Strain of Ralstonia solanacearum.

Ralstonia solanacearum is one of the globally significant plant pathogens that infect a wide host range of economically important plants. A study was conducted to evaluate the hypothesis that an avirulent strain of R. solanacearum can act as a biocontrol mediator for managing potato bacterial wilt. Virulent R. solanacearum was isolated and identified (GenBank accession number; OP180100). The avirulent strain was obtained from the virulent strain through storage for 3 weeks until the development of deep red colonies. The virulent strain had higher lytic activity than the avirulent strain. Tubers’ treatments by the avirulent strain of R. solanacearum, (supernatant, boiled supernatant, and dead cells) significantly reduced plant disease rating and increased the growth, physiological activities, and biomass of potato compared to the untreated, infected control. The major components detected by GC–MS in the supernatant revealed 10.86% palmitic acid (virulent), and 18.03% 1,3-dioxolane, 2,4,5-trimethyl- (avirulent), whereas the major component in the boiled supernatant was 2-hydroxy-gamma-butyrolactone in the virulent (21.17%) and avirulent (27.78%) strains. This is the first research that assessed the influence of boiled supernatant and dead cells of virulent and avirulent R. solanacearum strains in controlling bacterial wilt disease. Additional work is encouraged for further elucidation of such a topic.

An avirulent Ralstonia solanacearum strain FJAT1458 outcompetes with virulent strain and induces tomato plant resistance against bacterial wilt.

Bacterial wilt (BW) caused by Ralstonia solanacearum (RS) is considered as one of the most destructive plant diseases. An avirulent strain of RS, FJAT1458, is a potential biocontrol agent of BW. In this study, the mechanism of FJAT1458 against BW was evaluated. FJAT1458 was tagged with the red fluorescent protein gene, and the resulting strain was named as FJAT1458-RFP. When FJAT1458-RFP and FJAT91-GFP (a virulent strain of RS labelled with the green fluorescent protein gene), were co-inoculated in potted tomato plants, the colonization of FJAT91-GFP reached an almost undetectable level at 7 days post-inoculation (dpi) in the roots and at 9 dpi in rhizosphere soil. When they were co-inoculated in a hydroponic tomato growing system, numbers of the two strains were similar at 3 dpi in the root tissues; however, FJAT91-GFP was not detected at 9 dpi while FJAT1458-RFP maintained 1.77 × 105 CFU g-1 . The inoculation of FJAT1458-RFP alone or combination with FJAT91-GFP significantly increased tomato root activity. Moreover, expression levels of the defense-related genes PR-1a, GLUA, and CHI3 in tomato roots were significantly up-regulated by FJAT1458-RFP and co-inoculation of FJAT1458-RFP and FJAT91-GFP at 5 dpi, compared to the control (water, CK) treatment. Noteworthy, expression levels of GLUA in the treatments of FJAT1458-RFP and FJAT1458-RFP + FJAT91-GFP were 12.22- and 12.05-fold higher than that in the CK at 5 dpi, respectively. The results suggested that the avirulent strain FJAT1458-RFP could suppress colonization of the virulent strain in tomato roots, and induce tomato plant resistance against BW. © 2022 Society of Chemical Industry.

DEVELOPMENT OF SPECIFIC PRIMERS FOR 16S rRNA GENE ANALYSIS IN THE DETECTION OF Ralstonia solanacearum SPECIES COMPLEX

Members of Ralstonia solanacearum species complex (RSSC) are causal agents of vascular wilt disease in more than 450 crop species, including solanaceous plants such as potatoes, tomatoes, bell pepper, eggplant, etc. These phytopathogens cause serious yield loss mostly in solanaceous crops which are grown in tropical, subtropical, and temperate regions of the world. Yield losses comprise 80%–100% in potato, up to 91% for tomato, 10%–30% in tobacco, 33%–90% in banana, and reduce crop productivity and yield. PCR-methods are specific, sensitive and cost-effective approaches for the detection and identification of RSSC members. The objective of this study was to compare specificity of routinely used primer mix for PCR RSSC detection with the newly developed pairs of species-specific primers for ease of use diagnostics in a laboratory. Materials and Methods. The conserved genomic regions of the 16S rRNA sequences of R. solanacearum, R. pseudosolanacearum, and R. syzygii were selected for the design of primers for this study. Newly created primer species specificity was tested in PCR using the DNA of the two targets and 13 non-target strains of bacteria. Results. Three pairs of newly created primers Rs-28(F)/Rs-193(R), Rs-28(F)/OLI-160(R), Rs28(F)/OLI248(R) produced single specific fragments for bacterial strains of Ralstonia solanacearum: 166 bp, 132 bp, and 220 bp. products respectively. No PCR products were obtained during amplification with the negative control or non-target DNA templates from other bacterial species. Conclusion. Designed primers can be used for the development of PCR system for the qualitative and quantitative detection of RSSC members.

Complete genome sequence of the kiwifruit bacterial canker pathogen Pseudomonas savastanoi strain MHT1

BackgroundPseudomonas savastanoi is an important plant pathogen that infects and causes symptoms in a variety of economically important crops, causing considerable loss of yield and quality. Because there has been no research reported to date on bacterial canker of kiwifruit (Actinidia chinensis) plants caused by P. savastanoi and, in particular, no in-depth studies of the complete genome sequence or pathogenic mechanism, long-lasting and environmentally friendly control measures against this pathogen in kiwifruit are lacking. This study therefore has both theoretical value and practical significance.ResultsWe report the complete genome sequence of P. savastanoi strain MHT1, which was first reported as the pathogen causing bacterial canker in kiwifruit plants. The genome consists of a 6.00-Mb chromosome with 58.5% GC content and 5008 predicted genes. Comparative genome analysis of four sequenced genomes of representative P. savastanoi strains revealed that 230 genes are unique to the MHT1 strain and that these genes are enriched in antibiotic metabolic processes and metabolic pathways, which may be associated with the drug resistance and host range observed in this strain. MHT1 showed high syntenic relationships with different P. savastanoi strains. Furthermore, MHT1 has eight conserved effectors that are highly homologous to effectors from P. syringae, Pseudomonas amygdali, and Ralstonia solanacearum strains. The MHT1 genome contains six genomic islands and two prophage sequences. In addition, 380 genes were annotated as antibiotic resistance genes and another 734 as encoding carbohydrate-active enzymes.ConclusionThe whole-genome sequence of this kiwifruit bacterial canker pathogen extends our knowledge of the P. savastanoi genome, sets the stage for further studies of the interaction between kiwifruit and P. savastanoi, and provides an important theoretical foundation for the prevention and control of bacterial canker.

Genetic stability of virulent, intermediate, and avirulent strains of Ralstonia solanacearum after extensive, consecutive subculturing

An avirulent strain, FJAT1458, was demonstrated to possess a high level of biocontrol efficiency against bacterial wilt (BW). Assessing the genetic stability of this avirulent strain is essential for ensuring its safety and efficacy for use in field applications. In the present study, the genetic stability of three R. solanacearum strains with different levels of virulence was evaluated over the course of 50 generations of subculturing. Pathogenicity tests revealed that the virulent strain, FJAT91, and the intermediate strain, FJAT445, transformed into avirulent strains, but FJAT1458 remained avirulent after the same number of subcultures. Colonization tests revealed that the colonization pattern of the F1 generation of the avirulent FJAT1458 strain was similar to that of the F50 generation, but the virulent strain was rarely detected in later stages of infection. High performance liquid chromatography revealed that the number and type of chromatographic peaks produced by the avirulent strain did not exhibit any changes over the course of subculturing, however, the pattern of peaks produced by the virulent and intermediate strains changed noticeably over the course of 50 generations of subculturing. Moreover, exopolysaccharide I (EPS I) content, β-1,4-endoglucanase (Egl) activity, and swimming and swarming motility significantly decreased in the virulent and intermediate strains but were stable in the avirulent strain over the course of subculturing. The relative expression level of hrpB, phcA, eps, and egl, genes associated with virulence, significantly decreased in the virulent and intermediate strains over the course of 10 to 20 generations of subculturing but remained relatively stable in the avirulent strain across 50 generations. In conclusion, the avirulent strain remained genetically stable, while the virulent and intermediate strains exhibited genetic instability, over the course of 50 generations of subculturing.

Screening of phenotypic conversion mutant strains of Ralstonia solanacearum for effective biological control of Verticillium wilt in eggplant

Ralstonia solanacearum causes bacterial wilt and undergoes spontaneous phenotypic conversion (PC) from its wild-type form to non-pathogenic form. We previously reported that the pre-inoculation of PC mutants in Solanum plants suppressed bacterial wilt. In the present study, we clarified the inoculation method of PC mutants and PC mutant strains for effective control the eggplant Verticillium wilt caused by Verticillium dahliae, a soil-borne fungal plant pathogen. We first investigated three different methods for pre-inoculating PC mutants in the five-leaf-stage seedlings of eggplant: Method A involved soaking plant roots in the PC mutant suspension immediately before challenge-inoculation with V. dahliae; Method B involved irrigation with the PC mutant suspension in pots at 7 days before challenge-inoculation with the pathogen; and Method C involved soaking plant roots in the PC mutant suspension at 3 weeks before challenge-inoculation with the pathogen. The highest biological control was achieved with Method A. To quickly and easily select effective PC mutants for biological control of Verticillium wilt in a growth chamber, a simplified evaluation method based on Method A was applied using the young (two-leaf-stage) seedlings of eggplant. Furthermore, we investigated the biological control efficacies of 27 PC mutants against Verticillium wilt in eggplants using the simplified evaluation method in vivo, and growth inhibition of V. dahliae by PC mutants in vitro. However, no relationship existed between the biological control and growth inhibition of V. dahliae, suggesting that it is unlikely to be involved as the main factor affecting the biological control by PC mutants. Three PC mutants, 8345PC, 8109PC, and 8107PC, which showed high biological control efficacies in the simplified evaluation method (64.6%, 66.0%, and 68.9%, respectively), were evaluated for their biological control using five-leaf-stage eggplant seedlings in greenhouse test. Among these three mutants, the 8107PC strain showed the highest biological control of 43.3% and was selected as the most effective PC mutant for suppressing Verticillium wilt in eggplant. Thus, the use of PC mutants is expected to be effective in the control of Verticillium wilt in eggplant.

The putative sensor histidine kinase PhcK is required for the full expression of phcA encoding the global transcriptional regulator to drive the quorum‐sensing circuit of Ralstonia solanacearum strain OE1‐1

A gram‐negative plant‐pathogenic bacterium Ralstonia solanacearum strain OE1‐1 produces and extracellularly secretes methyl 3‐hydroxymyristate (3‐OH MAME), and senses the chemical as a quorum‐sensing (QS) signal, activating QS. During QS a functional global transcriptional regulator PhcA, through the 3‐OH MAME‐dependent two‐component system, induces the production of virulence factors including a major extracellular polysaccharide EPS I and ralfuranone. To elucidate the mechanisms of phcA regulation underlying the QS system, among Tn5‐mutants from the strain OE1‐1, we identified a mutant of RSc1351 gene (phcK), encoding a putative sensor histidine kinase, that exhibited significantly decreased QS‐dependent cell aggregation. We generated a phcK‐deletion mutant (ΔphcK) that produced significantly less EPS I and ralfuranone than the wild‐type strain OE1‐1. Quantitative reverse transcription PCR assays showed that the phcA expression level was significantly down‐regulated in the ΔphcK mutant but not in other QS mutants. The transcriptome data generated with RNA sequencing technology revealed that the expression levels of 88.2% of the PhcA‐positively regulated genes were down‐regulated in the ΔphcK mutant, whereas the expression levels of 85.9% of the PhcA‐negatively regulated genes were up‐regulated. Additionally, the native phcK‐expressing complemented ΔphcK strain and the ΔphcK mutant transformed with phcA controlled by a constitutive promoter recovered their cell aggregation phenotypes. Considered together, the results of this study indicate that phcK is required for full phcA expression, thereby driving the QS circuit of R. solanacearum strain OE1‐1. This is the first report of the phcA transcriptional regulation of R. solanacearum.

Complete Genome Sequence of the Plant Pathogen Ralstonia solanacearum Strain CIAT-078, Isolated in Colombia, Obtained Using Oxford Nanopore Technology.

Moko is one of the main diseases affecting banana and plantain in Colombia. Here, we report the genome sequence of the causal agent, the bacterium Ralstonia solanacearum (Smith) strain CIAT-078, collected in 2004 from affected plantains in central-west Colombia. The assembled genome was obtained using Oxford Nanopore Technology.