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The highly destructive soil-borne pathogen Ralstonia solanacerum (Smith) Yabuuchi et al. (RS) affects a variety of solanaceous plants and causes catastrophic diseases leading to massive economic losses across the globe. Biochemical assays separate this bacterium's strains into 5 races and 5 biovars by host range. This bacterium's race 1 biovar 1, which is endemic to the south-eastern United States, infects many different vegetable and ornamental species. Some solanaceous vegetables and ornamental crops are infected by RS race 3 biovar 2, which causes brown rot, bacterial wilt, and Moko disease. The race 3 biovar 3 is not hosted by tobacco. The most devastating RS diseases affect solanaceous crops like potatoes, tobacco, pepper, tomatoes, and eggplant. This review offers a thorough examination of this bacterium's impacts on solanaceous crops, emphasizing their economic impact. It also emphasizes the importance of integrated disease management, including current developments in control methods (biological, physical, chemical, cultural, and integrated) and bio-control effectiveness and suppression mechanisms, to combat deadly bacterial wilt diseases. Avirulent RS, Pseudomonas, Bacillus, and Streptomyces spp. strains are examples of well-known Biological Control Agents (BCAs). Research shows that plant waste, animal manure, and organic materials reduce bacterial wilt. It's crucial to incorporate pest management for bacterial wilt infections. This review also identifies intriguing possibilities for future study and collaboration on this bacterium. Understanding this bacterium's complexity and using effective management measures can lessen its detrimental effects on agriculture. [ABSTRACT FROM AUTHOR]

Knowledge of the genetic control of disease tolerance is necessary for effective transfer of desirable genes in resultant progenies leading to development of disease tolerant cultivars and hybrids. Bacterial wilt (BW) disease-resistant varieties of tomato (Solanum lycopersicum L.) express differential reactions to bacterial biovars distributed in specific regions. Genetic control of host tolerance to BW disease was studied using the generations P1, P2, F1, F2, BC1, BC2 of three tolerant × susceptible crosses ("Utkal Kumari × CLN- 2460E;" "Utkal Kumari × CLN-2764A;" "Utkal Deepti × CLN-2460E") involving two tolerant ("Utkal Kumari," "Utkal Deepti"), and two susceptible ("CLN-2460E" and "CLN-2764A") genotypes exposed to the virulent bacterial biovars III and VI. The inheritance pattern indicated tolerance to BW disease was conditioned by a single dominant gene in three crosses when exposed to both biovars. Genetic control of bacterial wilt resistance did not depend on the interaction between genotype and bacterial biovars tested. Predominance of non-additive gene action and duplicate epistasis for conditioning of first appearance and incidence of BW disease in crosses indicated hindrance in progress through conventional selection. Selection for improvement of BW disease-related traits should be delayed to later segregating generations. The modified bulk method of selection appeared to be best for improving BW disease-related traits of tomato. Tomato hybrids tolerant to BW disease could be developed with the involvement of one parent tolerant to this disease. [ABSTRACT FROM AUTHOR]

Bacterial wilt, caused by Ralstonia solanacearum, is the most serious and common disease that affects tomatoes globally. Tomato bacterial wilt is among the worst and most prevalent diseases in Ethiopia. It causes substantial tomato production losses in various parts of the country. The purpose of this study was to isolate and characterize Ralstonia solanacearum causing wilt disease in tomato. Ralstonia solanacearum isolates were isolated from wilted tomato stem samples using Casamino Acid Peptone Glucose Agar (CPG) plates and incubated at 28 ± 2 °C for 48 h. Bacterial colonies showing big, irregular smooth, and cream-white, were considered presumptive Ralstonia solanacearum isolates. Morphological, biochemical, and pathological characterization were used for identification of the bacterium. Biovar identification was determined based on the utilization of carbohydrates. A total of 76 Ralstonia solanacearum isolates were screened and identified as Ralstonia solanacearum. Out of all the isolates, 28.9% of the isolates were isolated from Mecha, followed by Fogera (27.6%), Dera (23.7%), and Bahir Dar Zuria (19.7%) districts. The pathogenicity test results also revealed that all Ralstonia solanacearum isolates tested caused wilt symptoms in tomato plants and had varying levels of virulence on tomato plants, ranging from highly virulent (G1B1, G2M2, G3H1, and G4F3 isolates) to moderately virulent (G1B1, G2M1, G2M3, G3H2, G4F1, and G4F2 isolates). Besides, 48 Ralstonia solanacearum isolates were identified as Biovar II, and 28 Ralstonia solanacearum isolates were identified as biovar III. The overall findings of this study could provide valuable information for integrated tomato bacterial wilt disease management. The molecular characterization should be carried out on Ralstonia solanacearum in different host ranges. [ABSTRACT FROM AUTHOR]

Twenty-six Japanese strains of potato pathogen Ralstonia solanacearum species complex (phylotypes I and IV) were evaluated in vitro for virulence on potato lines Saikai 35 (resistant) and Aiyutaka (susceptible) at 24 °C and 28 °C. Numerous strains resulted in significantly lower disease indices for Saikai 35 than Aiyutaka. Responses to temperature were highly diverse, and virulence varied greatly among strains. Hierarchical and nonhierarchical clustering classified the strains into five pathotypes, which did not correspond to any previous classification schemes including phylotypes. Cultivar selections for breeding stably resistant varieties in target geographic areas should thus be based on pathotypes. [ABSTRACT FROM AUTHOR]

Abstract Background Brucellosis is an infectious zoonotic bacterial disease of humans and other animals. In the Republic of South Africa (RSA), animal brucellosis is widespread and the current available data on the prevalence of this disease rely solely on serological testing. The primary limitation of brucellosis serology is the lack of discriminatory powers to differentiate between Brucella species and biovars as well as the cross‐reactivity observed with other Gram‐negative bacteria. Aim The aim of this study was to conduct a retrospective laboratory‐based survey on Brucella species and biovars isolated from various animal species in SA between 2008 and 2018. Material and Methods The isolation of Brucella species and biovar typing was performed using conventional microbiological techniques. Results and Discussion A total of 963 strains of Brucella species were included in this study with a frequency of detection for B. abortus (n = 883; 91.6%) followed by B. melitensis (n = 42; 4.4%), B. ovis (n = 29; 3.0%) and B. canis (n = 9; 0.9%). Of the 883 strains of B. abortus, 90.1% were typed as B. abortus biovar‐1 while 5.7% as B. abortus biovar‐2, and 3.3% and 0.5% were B. abortus S19 and B. abortus RB51 vaccine strains, respectively. Among the 42 B. melitensis strains, 71.4% were reported as B. melitensis biovar‐1 and 26.2% as B. melitensis biovar‐3 while 2.4% was B. melitensis biovar‐2. Conclusion A retrospective study, such as this one, provides useful information that can be critical in formulating policies and strategies for the control and eradication of brucellosis in animal populations in RSA.

Abstract Serotyping is the most common method to characterize field isolates of Actinobacillus (A.) pleuropneumoniae, the etiological agent of porcine pleuropneumonia. Based on serology, many farms seem to be infected and antibodies against a wide variety of serovars are detectable, but, so far it is unknown to what degree respective serovars contribute to outbreaks of clinical manifest disease. In this study, 213 German A. pleuropneumoniae field isolates retrieved for diagnostic purposes from outbreaks of porcine pleuropneumonia between 2010 and 2019 were genetically serotyped and analyzed regarding their apx-toxin gene profile using molecular methods. Serotyping revealed a prominent role of serovar 2 in clinical cases (64% of all isolates) and an increase in the detection of this serovar since 2010 in German isolates. Serovar 9/11 followed as the second most frequent serovar with about 15% of the isolates. Furthermore, very recently described serovars 16 (n = 2) and 18 (n = 8) were detected. Most isolates (93.4%) showed apx-profiles typical for the respective serovar. However, this does not hold true for isolates of serovar 18, as 75% (n = 6) of all isolates of this serovar deviated uniformly from the “typical” apx-gene profile of the reference strain 7311555. Notably, isolates from systemic lesions such as joints or meninges did not harbor the complete apxICABD operon which is considered typical for highly virulent strains. Furthermore, the extremely low occurrence (n = 1) of NAD independent (biovar II) isolates in German A. pleuropneumoniae was evident in our collection of clinical isolates.

Abstract Background Corynebacterium diphtheriae, the agent of diphtheria, is a genetically diverse bacterial species. Although antimicrobial resistance has emerged against several drugs including first-line penicillin, the genomic determinants and population dynamics of resistance are largely unknown for this neglected human pathogen. Methods Here, we analyzed the associations of antimicrobial susceptibility phenotypes, diphtheria toxin production, and genomic features in C. diphtheriae. We used 247 strains collected over several decades in multiple world regions, including the 163 clinical isolates collected prospectively from 2008 to 2017 in France mainland and overseas territories. Results Phylogenetic analysis revealed multiple deep-branching sublineages, grouped into a Mitis lineage strongly associated with diphtheria toxin production and a largely toxin gene-negative Gravis lineage with few toxin-producing isolates including the 1990s ex-Soviet Union outbreak strain. The distribution of susceptibility phenotypes allowed proposing ecological cutoffs for most of the 19 agents tested, thereby defining acquired antimicrobial resistance. Penicillin resistance was found in 17.2% of prospective isolates. Seventeen (10.4%) prospective isolates were multidrug-resistant (≥ 3 antimicrobial categories), including four isolates resistant to penicillin and macrolides. Homologous recombination was frequent (r/m = 5), and horizontal gene transfer contributed to the emergence of antimicrobial resistance in multiple sublineages. Genome-wide association mapping uncovered genetic factors of resistance, including an accessory penicillin-binding protein (PBP2m) located in diverse genomic contexts. Gene pbp2m is widespread in other Corynebacterium species, and its expression in C. glutamicum demonstrated its effect against several beta-lactams. A novel 73-kb C. diphtheriae multiresistance plasmid was discovered. Conclusions This work uncovers the dynamics of antimicrobial resistance in C. diphtheriae in the context of phylogenetic structure, biovar, and diphtheria toxin production and provides a blueprint to analyze re-emerging diphtheria.

Loop-mediated isothermal amplification (LAMP) was designed to rapidly detect biovars 1 and 3 of Pseudomonas syringae pv. actinidiae (Psa), a serious, global kiwifruit pathogen, using two primer sets targeting biovar-specific type III effector genes. Each primer set was specific for the targeted biovars, and no signals were obtained for any other biovars. Detection limits of the assay were tenfold higher than that of the conventional PCR method for both biovars. The primer set to detect biovar 3 was highly sensitive at detecting this biovar directly from leaf lesions. [ABSTRACT FROM AUTHOR]

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Abstract Background Yersinia pestis is the flea-transmitted etiological agent of bubonic plague. Sylvatic plague consists of complex tripartite interactions between diverse flea and wild rodent species, and pathogen strains. Transmission by flea bite occurs primarily by the Y. pestis biofilm-mediated foregut blockage and regurgitation mechanism, which has been largely detailed by studies in the model interaction between Y. pestis KIM6+ and Xenopsylla cheopis. Here, we test if pathogen-specific traits influence this interaction by determining the dynamics of foregut blockage development in X. cheopis fleas among extant avirulent pCD1-Y. pestis strains, KIM6+ and CO92, belonging to distinct biovars, and a non-circulating mutant CO92 strain (CO92gly), restored for glycerol fermentation; a key biochemical difference between the two biovars. Methods Separate flea cohorts infected with distinct strains were evaluated for (i) blockage development, bacterial burdens and flea foregut blockage pathology, and (ii) for the number of bacteria transmitted by regurgitation during membrane feeding. Strain burdens per flea was determined for fleas co-infected with CO92 and KIM6+ strains at a ratio of 1:1. Results Strains KIM6+ and CO92 developed foregut blockage at similar rates and peak temporal incidences, but the CO92gly strain showed significantly greater blockage rates that peak earlier post-infection. The KIM6+ strain, however, exhibited a distinctive foregut pathology wherein bacterial colonization extended the length of the esophagus up to the feeding mouthparts in ~65% of blocked fleas; in contrast to 32% and 26%, respectively, in fleas blocked with CO92 and CO92gly. The proximity of KIM6+ to the flea mouthparts in blocked fleas did not result in higher regurgitative transmission efficiencies as all strains transmitted variable numbers of Y. pestis, albeit slightly lower for CO92gly. During competitive co-infection, strains KIM6+ and CO92 were equally fit maintaining equivalent infection proportions in fleas over time. Conclusions We demonstrate that disparate foregut blockage pathologies exhibited by distinct extant Y. pestis strain genotypes do not influence transmission efficiency from X. cheopis fleas. In fact, distinct extant Y. pestis genotypes maintain equivalently effective blockage and transmission efficiencies which is likely advantageous to maintaining continued successful plague spread and establishment of new plague foci.

Background: Brucellosis is an infectious zoonotic bacterial disease of humans and other animals. In the Republic of South Africa (RSA), animal brucellosis is widespread and the current available data on the prevalence of this disease rely solely on serological testing. The primary limitation of brucellosis serology is the lack of discriminatory powers to differentiate between Brucella species and biovars as well as the cross‐reactivity observed with other Gram‐negative bacteria. Aim: The aim of this study was to conduct a retrospective laboratory‐based survey on Brucella species and biovars isolated from various animal species in SA between 2008 and 2018. Material and Methods: The isolation of Brucella species and biovar typing was performed using conventional microbiological techniques. Results and Discussion: A total of 963 strains of Brucella species were included in this study with a frequency of detection for B. abortus (n = 883; 91.6%) followed by B. melitensis (n = 42; 4.4%), B. ovis (n = 29; 3.0%) and B. canis (n = 9; 0.9%). Of the 883 strains of B. abortus, 90.1% were typed as B. abortus biovar‐1 while 5.7% as B. abortus biovar‐2, and 3.3% and 0.5% were B. abortus S19 and B. abortus RB51 vaccine strains, respectively. Among the 42 B. melitensis strains, 71.4% were reported as B. melitensis biovar‐1 and 26.2% as B. melitensis biovar‐3 while 2.4% was B. melitensis biovar‐2. Conclusion: A retrospective study, such as this one, provides useful information that can be critical in formulating policies and strategies for the control and eradication of brucellosis in animal populations in RSA. [ABSTRACT FROM AUTHOR]

Purpose: Pseudomonas syringae pv. actinidiae causes bacterial canker of kiwifruit and is responsible for severe economic losses and emergence of drug-resistant bacteria. Bacteriophages are viruses that infect target bacterial hosts and may be the best strategy to prevent and control kiwifruit canker disease. The objective of this experiment was to monitor the prevalence of Pseudomonas syringae pv. actinidiae and provide insight for the use of phages in biological control. Materials and methods: In this study, 52 strains of Pseudomonas syringae pv. actinidiae were isolated from 68 stem samples of kiwi plant (cv. Hongyang & Jinkui). Following polymerase chain reaction (PCR) analysis, 15 isolates belonging to biovar 3 were identified, one of which was named XWY0007 and used as the target strain to isolate the phages. Thirty-six phages were isolated and purified from a total of 51 surface water samples collected in Shanghai. All phages were identified by transmission electron microscopy (TEM) and their host ranges were evaluated. Three phages, designated φXWY0013, φXWY0014 and φXWY0026 were selected and further characterised using one-step growth curve and stability at different temperatures and pH. Results and conclusions: The isolated phages are promising for use as antimicrobials against bacterial canker in kiwi. This report is regarding Pseudomonas syringae pv. actinidiae and its phages from major areas of kiwifruit cultivation.

Abstract Background Pasteurella multocida is responsible for significant economic losses in pigs worldwide. In clinically diseased pigs, most P. multocida isolates are characterised as subspecies multocida, biovar 2 or 3 and capsular type A or D; however, there is little information regarding subspecies, biovars, and other capsular types of P. multocida isolates in Korea. Here, we provided information covering an extended time period regarding P. multocida in pigs with pneumonia in Korea using phenotypic and genotypic characterisations and data associated with the minimum inhibitory concentrations. Results The overall prevalence of P. multocida between 2008 and 2016 was 16.8% (240/1430), with 85% of the P. multocida isolates (204/240) coinfected with other respiratory pathogens. Of the 240 isolates, 166 were included in this study; all of these P. multocida isolates were characterised as subspecies multocida and the most prevalent phenotypes were represented by biovar 3 (68.7%; n = 114) and capsular type A (69.9%; n = 116). Additionally, three capsular type F isolates were identified, with this representing the first report of such isolates in Korea. All biovar 1 and 2 isolates were capsular types F and A, respectively. The virulence-associated gene distribution was variable; all capsular type A and D isolates harboured pmHAS and hsf-1, respectively (P

In the Philippines, bacterial wilt caused by Ralstonia solanacearum is one of the most important diseases affecting vegetables and banana. In this study, 89 strains of R. solanacearum isolated from various hosts were screened for their biovar, phylotype, pathogenicity, and genetic diversity. Foreign strains were included for comparison with these Philippine strains. Results of the biochemical and multiplex‐PCR tests divided the Philippine strains into five biovars (1, 2, 3, 4, and N2) and three phylotypes (I, II, and IV). Three potato strains belonged to biovar N2/phylotype IV. Pathogenicity tests divided the strains into five pathogenicity types based on their virulence in tomato, potato, eggplant, sweet pepper, and tobacco. Strains classified as biovar N2 were weakly pathogenic to potato (pathogenicity type III) and almost all strains isolated from banana were not pathogenic to the test plants except potato (pathogenicity type V). The results of AFLP analysis divided the strains into four clusters. Cluster 1 was composed of strains isolated from solanaceous crops, ginger (Zingiber officinale), and Morus sp. from the Philippines and other Asian countries. Cluster 2 grouped the potato strains (biovar N2) from the Philippines and Japan and blood disease bacterium strains from Indonesia. Cluster 3 contained the local and foreign strains isolated from potato (biovar 2) and banana (biovar 1). Cluster 4 consisted only of the tomato strain from the USA. [ABSTRACT FROM AUTHOR]

Serotyping is the most common method to characterize field isolates of Actinobacillus (A.) pleuropneumoniae, the etiological agent of porcine pleuropneumonia. Based on serology, many farms seem to be infected and antibodies against a wide variety of serovars are detectable, but, so far it is unknown to what degree respective serovars contribute to outbreaks of clinical manifest disease. In this study, 213 German A. pleuropneumoniae field isolates retrieved for diagnostic purposes from outbreaks of porcine pleuropneumonia between 2010 and 2019 were genetically serotyped and analyzed regarding their apx-toxin gene profile using molecular methods. Serotyping revealed a prominent role of serovar 2 in clinical cases (64% of all isolates) and an increase in the detection of this serovar since 2010 in German isolates. Serovar 9/11 followed as the second most frequent serovar with about 15% of the isolates. Furthermore, very recently described serovars 16 (n = 2) and 18 (n = 8) were detected. Most isolates (93.4%) showed apx-profiles typical for the respective serovar. However, this does not hold true for isolates of serovar 18, as 75% (n = 6) of all isolates of this serovar deviated uniformly from the "typical" apx-gene profile of the reference strain 7311555. Notably, isolates from systemic lesions such as joints or meninges did not harbor the complete apxICABD operon which is considered typical for highly virulent strains. Furthermore, the extremely low occurrence (n = 1) of NAD independent (biovar II) isolates in German A. pleuropneumoniae was evident in our collection of clinical isolates. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the success of Brucella spp. isolation in ruminant abortion cases by using different selective media. To this end, 58 samples from ruminant abortion cases were utilized. 4 selective media; namely, Farrell Medium (FM), CITA Medium (CM), Modified Thayer Martin (MTM) and Jones & Morgan (JM) were preferred for isolation. In addition to these, one medium with antibiotics was used to extend the range of the results. Suspensions prepared from organ and fetal stomach contents were inoculated to media plates and incubated at 37Co for 5-8 days in 5-10% CO2 condition. Conventional biotyping method was used to identify Brucella isolates within the level of species and biovar. MTM (67.2%) and Farrell (65.5%) outperformed the other media with regards to isolation rate. However, regarding the inhibition ability against contaminant microrganisms, Farrell (86.2%) and CITA (72%) have the highest and second highest percentages respectively. The media’s inhibition ability was examined in the samples in which Brucella spp. isolation occurred to be able to investigate the correlations between isolation and inhibition. Lower isolation percentage was observed in the samples in which the media displayed the lowest inhibition ability against contaminants. In this context, using two different selective media with high inhibition ability against contaminants may be recommended to enhance the isolation rate. Moreover, the components stimulating the growth of Brucella strains might be added to the media to obtain better results.

Background: Yersinia pestis is the flea-transmitted etiological agent of bubonic plague. Sylvatic plague consists of complex tripartite interactions between diverse flea and wild rodent species, and pathogen strains. Transmission by flea bite occurs primarily by the Y. pestis biofilm-mediated foregut blockage and regurgitation mechanism, which has been largely detailed by studies in the model interaction between Y. pestis KIM6+ and Xenopsylla cheopis. Here, we test if pathogen-specific traits influence this interaction by determining the dynamics of foregut blockage development in X. cheopis fleas among extant avirulent pCD1-Y. pestis strains, KIM6+ and CO92, belonging to distinct biovars, and a non-circulating mutant CO92 strain (CO92gly), restored for glycerol fermentation; a key biochemical difference between the two biovars. Methods: Separate flea cohorts infected with distinct strains were evaluated for (i) blockage development, bacterial burdens and flea foregut blockage pathology, and (ii) for the number of bacteria transmitted by regurgitation during membrane feeding. Strain burdens per flea was determined for fleas co-infected with CO92 and KIM6+ strains at a ratio of 1:1. Results: Strains KIM6+ and CO92 developed foregut blockage at similar rates and peak temporal incidences, but the CO92gly strain showed significantly greater blockage rates that peak earlier post-infection. The KIM6+ strain, however, exhibited a distinctive foregut pathology wherein bacterial colonization extended the length of the esophagus up to the feeding mouthparts in ~65% of blocked fleas; in contrast to 32% and 26%, respectively, in fleas blocked with CO92 and CO92gly. The proximity of KIM6+ to the flea mouthparts in blocked fleas did not result in higher regurgitative transmission efficiencies as all strains transmitted variable numbers of Y. pestis, albeit slightly lower for CO92gly. During competitive co-infection, strains KIM6+ and CO92 were equally fit maintaining equivalent infection proportions in fleas over time. Conclusions: We demonstrate that disparate foregut blockage pathologies exhibited by distinct extant Y. pestis strain genotypes do not influence transmission efficiency from X. cheopis fleas. In fact, distinct extant Y. pestis genotypes maintain equivalently effective blockage and transmission efficiencies which is likely advantageous to maintaining continued successful plague spread and establishment of new plague foci. [ABSTRACT FROM AUTHOR]

Bacterial wilt of potato caused by Ralstonia solanacearum is a severe threat to potato cultivation in Kerman province, located in southeastern Iran and the third largest potato producer in the country. The present study intends to determine the precise phylogenetic position, sequevar, and genetic diversity of R. solanacearum strains associated with the disease. To this end, the major potato-growing regions of the province (Jiroft and Laleh Zaar) were surveyed to collect tuber samples from affected potato plants showing typical wilt symptoms. Twenty-three strains were collectively purified and subjected to phenotypic and genotypic characterization. Biochemical tests showed that all the strains belonged to R. solanacearum biovar 2A. Furthermore, phylotype-specific multiplex polymerase chain reaction results indicated that the strains belonged to phylotype II. For sequevar typing as well as the determination of the phylotype subcluster (IIA/IIB), polymerase chain reaction amplicons of the endoglucanase precursor gene of 11 representative strains were sequenced. In phylogenetic analysis, the strains were grouped with the reference strains of phylotype IIB-1 retrieved from the GenBank. Then, to assess genetic diversity, 19 selected strains were subjected to genomic fingerprinting, i.e., amplified fragment length polymorphism (AFLP) using seven primer pair combinations. The AFLP data showed heterogeneity among the strains of R. solanacearum and were grouped into four clusters. With our knowledge, this is the first report of the phylotype, and sequevar determination (i.e., IIB-1) in addition to AFLP-based genomic fingerprinting of R. solanaceraum strains causing potato wilt in southeastern Iran. [ABSTRACT FROM AUTHOR]

In 2006 and 2007, 75 strains of Ralstonia solanacearum were collected from wilting tomato, pepper and eggplant in Benin. The distribution and the incidence of tomato bacterial wilt in the field were assessed by counting wilted tomato plants on 3 plots of 50 m2 per field. The isolated bacterial strains, including the reference strain, were identified using ELISA, pathogenicity test and carbohydrate oxidation. Bacterial wilt is widely distributed in Benin and was found in five of the eight agro-ecological zones (AEZ) of Benin, which correspond to eight of the 12 districts of Benin. The disease was more severe in ferralitic soil (AEZ V), in valleys and lowlands (AEZ IV) and in highlands (AEZ I). The incidence of tomato bacterial wilt was up to 71%. No R. solanacearum strains were isolated from AEZ II, AEZ VII and AEZ VIII. Strains identified as R. solanacearum were more widely distributed in the south than the center and the north of Benin. Based on biochemical characteristics, Beninese R. solanacearum strains were grouped into biovar I/race1 and biovar III/race 1.

Objective of the study is to design the DNA-microarray for differentiation of Y. pestis strains of the main and non-main subspecies and biovars of the main subspecies. Materials and methods. Efficiency analysis for the devised means was conducted using 62 Y. pestis strains of various subspecies and biovars, isolated in the natural foci of Russia and neighboring countries. Results and conclusions. Selected have been the DNA-targets, probes and primers – calculated. Enhanced is the method of sub-specific and biovar differentiation of Y. pestis strains by means of DNA-microarray. DNA-chip with “Med24”, “glpD(-93)”, and “45” targets allows for prompt differentiation of the strains of the main and non-main subspecies and biovars of the main subspecies based on the presence and absence of fluorescent signal by the specific for the main subspecies and its biovars DNA-targets.

Bacterial wilt caused by Ralstonia solanacearum E.F. Smith is one of the destructive diseases of solanaceous vegetables specially tomato (Lycopersicon esculentum L.) and eggplant (Solanum melongena L.). Experiments were conducted to determine biovar types existing among the strains or isolates of Nepal and variation in virulence in some vegetables belonging to solanaceae family. A total of 39 isolates infecting tomato, eggplant, chilli and potato collected from different parts of Nepal were analyzed for biovar types on the basis of 3 disaccharides and 3 hexose alcohols oxidation test. Experiments were conducted to determine variation in virulence or aggressiveness of some of the isolates under screen house conditions using three host differentials such as Pusa Ruby (susceptible), Bishesh (moderately resistant) and Srijana (resistant) tomato cultivars. Of the 39 isolates, 23 were biovar III, three biovar II, three biovar IV, and one was biovar I. Nine isolates could not be differentiated into any of the five biovars. For breeding and epidemiological purposes it is very important to analyze the variability of aggressiveness. A total of 5 isolates collected from different places were included in the test. Isolates from Bhaktapur was found the most virulent causing wilt in the variety Bishesh (moderately resistant). Other isolates had the negative impact with zero wilt on the differentials used. Isolates from Jungekhola of Dhading district did not induce wilt even on susceptible variety (Pusa Ruby), but exhibited only senescence reaction. The result indicated that there is some slight variation among the isolates tested. Some effective management tactics might be needed in those locations where highly aggressive or virulent strain of bacterial wilt is prevalent, because resistant variety may not be stable in such locations.

Bacterial canker disease of kiwifruit currently occurs in at least 15 countries, causing serious damage. The causative agent of the disease is Pseudomonas syringae pv. actinidiae (Psa), which is genetically diverse and is currently classified into five biovars, namely, biovars 1, 2, 3, 5 and 6. In Japan, four biovars except biovar 2 have been found so far. These biovars have been confirmed to have differences in the virulence and composition of pathogenicity‐related genes, such as toxin biosynthesis and type III effector genes. Biovars 1 and 6 possess the tox island, a genomic island of approximately 38 kb, which contains phaseolotoxin biosynthesis genes (argK‐tox cluster) and is confirmed to have been acquired from other bacteria through horizontal transfers. Also, on the megaplasmid possessed by biovar 6, there exist coronatine biosynthesis genes, and biovar 6 has the ability to produce two phytotoxins, phaseolotoxin and coronatine. In 2014, biovar 3, considered to be of foreign origin, was confirmed for the first time in Japan. Biovar 5, whose virulence is relatively weak, is distributed only in a limited area. In addition to the tox island and various plasmids, a large number of mobile genetic elements are confirmed to be present on the Psa genomes, which might have played a major role in helping Psa to acquire new features. In order to understand how Psa acquired the ability to infect kiwifruit systemically, it is important to make polyphasic comparisons with related pathovars, such as P. syringae pv. theae and pv. actinidifoliorum. [ABSTRACT FROM AUTHOR]

A baseline for genetic diversity of Ralstonia solanacearum species complex (RSSC) causing bacterial wilt of field and greenhouse grown Solanum lycopersicum (tomato) in Louisiana was established based on biovar, phylotype and phylogenetic analysis of the egl gene sequence. RSCC strains were characterized as Biovars 1, 3 and 6 and belonged to phylotypes I and II. Phylotypes were subdivided into sequevars based on differences in the nucleotide sequence of the egl gene. Phylotype II strains clustered with closely related North American strains in sequevar 7 and phylotype I strains clustered with Asian strains in sequevar 14. All three RSCC strains isolated from greenhouse grown tomato were phylotype II sequevar 7 and were identical to strain AW1 from tomato in Alabama (AL). While all RSCC strains were pathogenic on tomato 'Roma', only six induced a hypersensitive reponse (HR) on Nicotiana tabacum. Four of the HR positive strains were also pathogenic on pepper 'Yolo Wonder'. This is the first study to characterize RSSC strains causing bacterial wilt of tomato in Louisiana and confirms that strains originating from Asia are present in North America. Genetic characterization of RSCC strains currently present in Louisiana is the first step towards the development of strain-specific management practices, including the identification of strain-specific host resistance. [ABSTRACT FROM AUTHOR]

Purpose: Pseudomonas syringae pv. actinidiae causes bacterial canker of kiwifruit and is responsible for severe economic losses and emergence of drug-resistant bacteria. Bacteriophages are viruses that infect target bacterial hosts and may be the best strategy to prevent and control kiwifruit canker disease. The objective of this experiment was to monitor the prevalence of Pseudomonas syringae pv. actinidiae and provide insight for the use of phages in biological control. Materials and methods: In this study, 52 strains of Pseudomonas syringae pv. actinidiae were isolated from 68 stem samples of kiwi plant (cv. Hongyang & Jinkui). Following polymerase chain reaction (PCR) analysis, 15 isolates belonging to biovar 3 were identified, one of which was named XWY0007 and used as the target strain to isolate the phages. Thirty-six phages were isolated and purified from a total of 51 surface water samples collected in Shanghai. All phages were identified by transmission electron microscopy (TEM) and their host ranges were evaluated. Three phages, designated φXWY0013, φXWY0014 and φXWY0026 were selected and further characterised using one-step growth curve and stability at different temperatures and pH. Results and conclusions: The isolated phages are promising for use as antimicrobials against bacterial canker in kiwi. This report is regarding Pseudomonas syringae pv. actinidiae and its phages from major areas of kiwifruit cultivation. [ABSTRACT FROM AUTHOR]

Tomato production in the Gangetic plains of eastern India is threatened by high incidence of bacterial wilt (BW) disease caused by Ralstonia solanacearum. Understanding the genetic control of tolerance through utilization of tolerant genotype is the prerequisite to frame effective resistant breeding strategy. Genetic control of host tolerance to BW disease was studied employing six generations (P1, P2, F1, F2, BC1, BC2) of two crosses between one tolerant (Utkal Kumari) and two susceptible (CLN-2498D and CLN-2777F) genotype(s) in presence of the predominant virulent strain (Biovar IIIA) of Ralstonia solanacearum through χ2 test and generation mean analysis. It emerged that tolerance to BW disease was conditioned predominantly by single dominant gene in two Tolerant × Susceptible crosses however, significance of scaling tests revealed involvement of duplicate epistasis suggesting somewhat complex inheritance pattern for the tolerance. Area under disease progress-curve (AUDPC) suggested that cumulative disease progress was less in tolerant genotypes of segregating generations. Duplicate epistasis controlling BW disease incidence suggested mild selection intensity in earlier generation, while intense in later generations of the segregating population in tomato. In this situation, modified bulk method of selection is recommended, in which selection is performed after attaining the homozygosity for maximum heterozygous loci. However, development of hybrids involving at least one tolerant parent is the best option for breeding tomato against BW disease. [ABSTRACT FROM AUTHOR]

Pseudomonas syringae pv. actinidiae, the causal agent of canker in kiwifruit, can be divided into three biovars (biovars 1, 2, and 3). Strains belonging to biovar 1 produce phaseolotoxin and were isolated in Japan and Italy before 2008. Strains of biovar 2 produce coronatine instead of phaseolotoxin and have been isolated only in Korea. Strains belonging to biovar 3 produce neither phaseolotoxin nor coronatine and are responsible for the global outbreak of bacterial canker of kiwifruit in recent years. The biovar 3-specific primer set was developed in a previous work. In this study, two sets of PCR primers specific to strains of biovars 1 and 2, respectively, were developed based on random amplified polymorphic DNA analyses. Primers PsaJ-F and PsaJ-R produced a 481-bp region with genomic DNA of biovar 1 strains, whereas primers PsaK-F and PsaK-R amplified a 413-bp region present only in the genome of biovar 2 strains.

Thirty-eight isolates of Ralstonia solanacearum were isolated from wilted eggplants from seven states of India, i.e. Uttarakhand, Himachal Pradesh, Jharkhand, Odisha, West Bengal, Karnataka and Meghalaya on TTC medium to study their genetic diversity using BOX, ERIC and REP-PCR’s. All isolates of R. solanacearum produced fluidal, irregular pinkish-white colonies and they belonged to biovar 3, race 1 and phylotype I. The study also included five out-group bacteria (Bacillus subtilis DTBS-5, Pseudomonas fluorescence DTPF-3, Xanthomonas campestris pv. campestris Xcc-C4, X. citri subsp. citri Xac-C63 and X. oryzae pv. oryzae Xoo-4). The isolates of R. solanacearum and out group bacteria were grouped into10 DNA types at 75% similarity coefficient. Maximum 11 isolates of R. solanacearum isolated from West Bengal were grouped into DNA Type 2. The isolates collected from Uttarakhand grouped into DNA types 6, 7, 8 and 10. However, all out-group bacteria were clearly separated from the isolates of R. solanacearum as DNA type 9. Multilocus sequence analysis of 18 isolates of R. solanacearum along with sequences obtained from NCBI database of 2 out- group bacteria (Burkholderia multivoransATCC-17616 and X. campestris pv. campestris ATCC-33913) was done using sequences of hrpB (hypersensitive response gene), fliC (flagelline protein) and egl (endoglucanase gene). Sequence comparisons showed high level of variability within these three regions of the genome involved in pathogenicity. On the basis of phylogenetic analysis, the selective pressure on virulence-related genes of R. solanacearum was identified. This genetic diversity presents major challenges for developing effective long-term management strategies to control the wilt disease of eggplant.

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. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the success of Brucella spp. isolation in ruminant abortion cases by using different selective media. To this end, 58 samples from ruminant abortion cases were utilized. 4 selective media; namely, Farrell Medium (FM), CITA Medium (CM), Modified Thayer Martin (MTM) and Jones & Morgan (JM) were preferred for isolation. In addition to these, one medium with antibiotics was used to extend the range of the results. Suspensions prepared from organ and fetal stomach contents were inoculated to media plates and incubated at 37Co for 5-8 days in 5-10% CO2 condition. Conventional biotyping method was used to identify Brucella isolates within the level of species and biovar. MTM (67.2%) and Farrell (65.5%) outperformed the other media with regards to isolation rate. However, regarding the inhibition ability against contaminant microrganisms, Farrell (86.2%) and CITA (72%) have the highest and second highest percentages respectively. The media's inhibition ability was examined in the samples in which Brucella spp. isolation occurred to be able to investigate the correlations between isolation and inhibition. Lower isolation percentage was observed in the samples in which the media displayed the lowest inhibition ability against contaminants. In this context, using two different selective media with high inhibition ability against contaminants may be recommended to enhance the isolation rate. Moreover, the components stimulating the growth of Brucella strains might be added to the media to obtain better results. [ABSTRACT FROM AUTHOR]

Abstract: Bacterial wilt of Curcuma alismatifolia (Patumma) caused by Ralstonia solanacearum is a major disease affecting the quality of rhizome exports. Traditionally, R. solanacearum is classified into five races based on differences in host range and six biovars based on biochemical properties. Recently a classification scheme based on phylotypes and sequevars was presented by the scientific community as a tool for determining phylogenetic relationships within R. solanacearum. This study used traditional and molecular methods to identify R. solanacearum strains from Patumma. All the strains were identified as biovar 4. A phylotype‐specific multiplex PCR‐based phylotyping of all the isolates detected the phylotype I‐specific amplicon of 144 bp and the R. solanacearum‐specific 281 bp amplicon. Phylogenetic analyses of endoglucanase (egl) sequences clustered all three strains of Patumma into phylotype I, sequevar 48 with reference strains M2 and M6. The study determined that the R. solanacearum strains from Patumma belong to biovar 4, phylotype I that originated from Asia, and sequevar 48. Significance and Impact of the Study: Phylotype and sequevar of Ralstonia solanacearum were associated with geographic region and geographic distribution. This is the first study to identify phylotype and sequevar of R. solanacearum from Patumma in Chiang Mai, Thailand. This will be useful for study of disease epidemiology and could help management for control of bacterial wilt diseases in this host. [ABSTRACT FROM AUTHOR]

Genetic diversity of 13 isolates of Ralstonia solanacearum causing bacterial wilt in hot pepper and bell pepper (Capsicum annuum L.) from 6 states of India was assessed. All isolates of R. solanacearum belonged to biovar 3, race 1 and phylotype I. These isolates consisted of 4 distinct DNA types at 75% similarity coefficient using ERIC, BOX and REPPCRs techniques. Multilocus sequence analysis of hrpB, fliC and egl genes of 6 isolates of R. solanacearum along with 2 out group bacteria was done and they showed high level of variability within these three regions of the genome involving in pathogenicity. [ABSTRACT FROM AUTHOR]

Abstract: Bacterial wilt, caused by Ralstonia solanacearum species complex is a key yield‐limiting factor on crops in Guangdong province, China. The genetic diversity of 110 R. solanacearum strains collected from 16 host plants in different areas of Guangdong province was analysed using biovar and phylotype classification schemes. Of 110 strains, fifty‐five strains belong to biovar 3, fifty‐two strains belong to biovar 4, two strains belong to biovar 2 and one strain belonged to biovar 1. Phylotype‐specific multiplex PCR showed that 108 strains belonged to phylotype I (biovars 1, 3, 4) and two strains belonged to phylotype II (biovar 2). The result of phylogenetic relationships analysis based on egl gene sequences demonstrated that 108 strains of phylotype I were grouped into nine previously described sequevars and a new sequevar 57, and two strains of phylotype II were grouped into sequevar 1. Sequevars 15, 34 and 44 widely distributed in Guangdong were predominant sequevars. Sequevar 45 was first reported on potato and pumpkin in China. These results revealed the genetic structure and phylogenetic relationships of R. solanacearum population in Guangdong and will be helpful in bacterial wilt‐resistance breeding. [ABSTRACT FROM AUTHOR]