scholarly journals Multiple Introductions of Tomato Pathogen Clavibacter michiganensis subsp. michiganensis into Iran as Revealed by a Global-Scale Phylogeographic Analysis

2019 ◽  
Vol 85 (24) ◽  
Author(s):  
Maryam Ansari ◽  
S. Mohsen Taghavi ◽  
Habiballah Hamzehzarghani ◽  
Miryam Valenzuela ◽  
María Ines Siri ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Housekeeping Genes ◽  
Global Scale ◽  
Phylogenetic Position ◽  
Bacterial Canker ◽  
Clavibacter Michiganensis ◽  
Content Type ◽  
Canker Disease ◽  
Multiple Introductions ◽  
History Of

ABSTRACT Tomato bacterial canker caused by Clavibacter michiganensis subsp. michiganensis is one of the most important seed-borne tomato diseases around the globe. The disease was initially reported in 1993 in Iran, and it became a rising threat for the multibillion dollar tomato industry of the country during the last decade. In this study, using phylogeographic analyses, we determined genetic diversity and geographic distribution of C. michiganensis subsp. michiganensis in Iran. Our field surveys showed that the pathogen is expanding into the southern and eastern areas of the country. Furthermore, multilocus sequence analysis and typing (MLSA/MLST) using the sequences of five housekeeping genes (atpD, gyrB, ppk, recA, and rpoB) revealed that 37 C. michiganensis subsp. michiganensis strains isolated in Iran had high genetic diversity and placed in 15 sequence types (STs), while all the available 184 worldwide C. michiganensis subsp. michiganensis sequences were placed in 43 STs. MLSA divided the worldwide C. michiganensis subsp. michiganensis strains into two phylogroups (I and II). Among the 37 strains isolated in Iran, 30 strains clustered in phylogroup I, while 7 strains clustered in phylogroup II. Phylogeographic data inferred from the allelic profile of the five housekeeping genes suggested multiple introductions of C. michiganensis subsp. michiganensis inoculum into Iran, while the geographic origin of the Iranian C. michiganensis subsp. michiganensis strains remains undetermined. Further analyses using higher numbers of strains are warranted to decipher the evolutionary history of C. michiganensis subsp. michiganensis in Iran. Additionally, stricter seed/transplant inspections are recommended to reduce the risk of pathogen expansion to areas with no history of the disease. IMPORTANCE Clavibacter michiganensis subsp. michiganensis, the causal agent of tomato bacterial canker disease, is one of the economically important pathogens of solanaceous crops (e.g., eggplant, pepper, and tomato) around the world. The disease occurs in many countries, with a particular importance in regions characterized by high precipitation and humid environmental conditions. As a seed-borne pathogen, C. michiganensis subsp. michiganensis is included in the A2 (high risk) list of quarantine pathogens by the European and Mediterranean Plant Protection Organization (EPPO). Bacterial canker disease was reported for the first time in 1993 in Iran, while the geographic distribution, genetic diversity, and phylogenetic position of the causal agent remain undetermined. In this study, using the multilocus sequence analysis and typing (MLSA/MLST) approach, we provided a phylogeographic scheme for the C. michiganensis subsp. michiganensis strains isolated in Iran. Furthermore, global-scale phylogenetic analyses led to determination of phylogenetic position of Iranian C. michiganensis subsp. michiganensis strains among worldwide population of the pathogen. Based on diversity parameters and population structure, we suggest relatively higher genetic diversity of the bacterial canker pathogen in Iran than has so far been observed in the other areas of the world. Results obtained in this study provide a novel insight into the genetic diversity and population structure of the bacterial canker pathogen on a global scale.

scholarly journals Comparative Genomics and Phylogenetic Analyses Suggest Several Novel Species within the Genus Clavibacter, Including Nonpathogenic Tomato-Associated Strains

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Ebrahim Osdaghi ◽  
Touraj Rahimi ◽  
S. Mohsen Taghavi ◽  
Maryam Ansari ◽  
Sadegh Zarei ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Comparative Genomics ◽  
Plant Pathogens ◽  
Phylogenetic Analyses ◽  
Taxonomic Status ◽  
Sensu Stricto ◽  
Bacterial Canker ◽  
Agricultural Crops ◽  
Content Type ◽  
Canker Disease

ABSTRACT Members of the genus Clavibacter are economically important bacterial plant pathogens infecting a set of diverse agricultural crops (e.g., alfalfa, corn, potato, tomato, and wheat). Tomato-associated Clavibacter sp. strains account for a great portion of the genetic diversity of the genus, and C. michiganensis sensu stricto (formerly C. michiganensis subsp. michiganensis), causing bacterial canker disease, is considered one of the most destructive seed-borne agents for the crop worldwide. However, current taxonomic descriptions of the genus do not reflect the existing diversity of the strains, resulting in unsatisfactory results in quarantine surveys for the pathogens. In this study, we used all the available genome sequences of Clavibacter sp. strains, including the type strains of newly described subspecies, to provide precise insight into the diversity of tomato-associated members of the genus and further clarify the taxonomic status of the strains using genotypic and phenotypic features. The results of phylogenetic analyses revealed the existence of nine hypothetical new species among the investigated strains. None of the three new subspecies (i.e., C. michiganensis subsp. californiensis, C. michiganensis subsp. chilensis, and C. michiganensis subsp. phaseoli) is included within the tomato-pathogenic C. michiganensis sensu stricto lineage. Although comparative genomics revealed the lack of chp and tomA pathogenicity determinant gene clusters in the nonpathogenic strains, a number of pathogenicity-related genes were noted to be present in all the strains regardless of their pathogenicity characteristics. Altogether, our results indicate a need for a formal taxonomic reconsideration of tomato-associated Clavibacter sp. strains to facilitate differentiation of the lineages in quarantine inspections. IMPORTANCE Clavibacter spp. are economically important bacterial plant pathogens infecting a set of diverse agricultural crops, such as alfalfa, corn, pepper, potato, tomato, and wheat. A number of plant-pathogenic members of the genus (e.g., C. michiganensis sensu stricto and C. sepedonicus, infecting tomato and potato plants, respectively) are included in the A2 (high-risk) list of quarantine pathogens by the European and Mediterranean Plant Protection Organization (EPPO). Although tomato-associated members of Clavibacter spp. account for a significant portion of the genetic diversity in the genus, only the strains belonging to C. michiganensis sensu stricto (formerly C. michiganensis subsp. michiganensis) cause bacterial canker disease of tomato and are subjected to the quarantine inspections. Hence, discrimination between the pathogenic and nonpathogenic Clavibacter sp. strains associated with tomato seeds and transplants plays a pivotal role in the accurate detection and cost-efficient management of the disease. On the other hand, detailed information on the genetic contents of different lineages of the genus would lead to the development of genome-informed specific detection techniques. In this study, we have provided an overview of the phylogenetic and genomic differences between the pathogenic and nonpathogenic tomato-associated Clavibacter sp. strains. We also noted that the taxonomic status of newly introduced subspecies of C. michiganensis (i.e., C. michiganensis subsp. californiensis, C. michiganensis subsp. chilensis, and C. michiganensis subsp. phaseoli) should be reconsidered.

scholarly journals Molecular Typing Reveals High Genetic Diversity of Xanthomonas translucens Strains Infecting Small-Grain Cereals in Iran

2019 ◽  
Vol 85 (20) ◽  
Author(s):  
Moein Khojasteh ◽  
S. Mohsen Taghavi ◽  
Pejman Khodaygan ◽  
Habiballah Hamzehzarghani ◽  
Gongyou Chen ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Global Scale ◽  
Population Diversity ◽  
Bacterial Leaf Streak ◽  
High Genetic Diversity ◽  
Center Of Origin ◽  
Content Type ◽  
Xanthomonas Translucens ◽  
Insight Into

ABSTRACT This study provides a phylogeographic insight into the population diversity of Xanthomonas translucens strains causing bacterial leaf streak disease of small-grain cereals in Iran. Among the 65 bacterial strains isolated from wheat, barley, and gramineous weeds in eight Iranian provinces, multilocus sequence analysis and typing (MLSA and MLST) of four housekeeping genes (dnaK, fyuA, gyrB, and rpoD), identified 57 strains as X. translucens pv. undulosa, while eight strains were identified as X. translucens pv. translucens. Although the pathogenicity patterns on oat and ryegrass weed species varied among the strains, all X. translucens pv. undulosa strains were pathogenic on barley, Harding’s grass, rye (except for XtKm35) and wheat, and all X. translucens pv. translucens strains were pathogenic on barley and Harding’s grass, while none of the latter group was pathogenic on rye or wheat (except for XtKm18). MLST using the 65 strains isolated in Iran, as well as the sequences of the four genes from 112 strains of worldwide origin retrieved from the GenBank database, revealed higher genetic diversity (i.e., haplotype frequency, haplotype diversity, and percentage of polymorphic sites) among the Iranian population of X. translucens than among the North American strains of the pathogen. High genetic diversity of the BLS pathogen in Iran was in congruence with the fact that the Iranian Plateau is considered the center of origin of cultivated wheat. However, further studies using larger collections of strains are warranted to precisely elucidate the global population diversity and center of origin of the pathogen. IMPORTANCE Bacterial leaf streak (BLS) of small-grain cereals (i.e., wheat and barley) is one of the economically important diseases of gramineous crops worldwide. The disease occurs in many countries across the globe, with particular importance in regions characterized by high levels of precipitation. Two genetically distinct xanthomonads—namely, Xanthomonas translucens pv. undulosa and X. translucens pv. translucens—have been reported to cause BLS disease on small-grain cereals. As seed-borne pathogens, the causal agents are included in the A2 list of quarantine pathogens by the European and Mediterranean Plant Protection Organization (EPPO). Despite its global distribution and high economic importance, the population structure, genetic diversity, and phylogeography of X. translucens remain undetermined. This study, using MLSA and MLST, provides a global-scale phylogeography of X. translucens strains infecting small-grain cereals. Based on the diversity parameters, neutrality indices, and population structure, we observe higher genetic diversity of the BLS pathogen in Iran, which is geographically close to the center of origin of common wheat, than has so far been observed in other areas of the world, including North America. The results obtained in this study provide a novel insight into the genetic diversity and population structure of the BLS pathogen of small-grain cereals on a global scale.

scholarly journals Evolution of the U.S. Biological Select AgentRathayibacter toxicus

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Edward W. Davis ◽  
Javier F. Tabima ◽  
Alexandra J. Weisberg ◽  
Lucas Dantas Lopes ◽  
Michele S. Wiseman ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Adaptive Immune System ◽  
The United States ◽  
Genomic Diversity ◽  
Data Set ◽  
Important Species ◽  
Content Type ◽  
Low Genetic Diversity ◽  
History Of ◽  
Short Palindromic Repeat

ABSTRACTRathayibacter toxicusis a species of Gram-positive, corynetoxin-producing bacteria that causes annual ryegrass toxicity, a disease often fatal to grazing animals. A phylogenomic approach was employed to model the evolution ofR. toxicusto explain the low genetic diversity observed among isolates collected during a 30-year period of sampling in three regions of Australia, gain insight into the taxonomy ofRathayibacter, and provide a framework for studying these bacteria. Analyses of a data set of more than 100 sequencedRathayibactergenomes indicated thatRathayibacterforms nine species-level groups.R. toxicusis the most genetically distant, and evidence suggested that this species experienced a dramatic event in its evolution. Its genome is significantly reduced in size but is colinear to those of sister species. Moreover,R. toxicushas low intergroup genomic diversity and almost no intragroup genomic diversity between ecologically separated isolates.R. toxicusis the only species of the genus that encodes a clustered regularly interspaced short palindromic repeat (CRISPR) locus and that is known to host a bacteriophage parasite. The spacers, which represent a chronological history of infections, were characterized for information on past events. We propose a three-stage process that emphasizes the importance of the bacteriophage and CRISPR in the genome reduction and low genetic diversity of theR. toxicusspecies.IMPORTANCERathayibacter toxicusis a toxin-producing species found in Australia and is often fatal to grazing animals. The threat of introduction of the species into the United States led to its inclusion in the Federal Select Agent Program, which makesR. toxicusa highly regulated species. This work provides novel insights into the evolution ofR. toxicus.R. toxicusis the only species in the genus to have acquired a CRISPR adaptive immune system to protect against bacteriophages. Results suggest that coexistence with the bacteriophage NCPPB3778 led to the massive shrinkage of theR. toxicusgenome, species divergence, and the maintenance of low genetic diversity in extant bacterial groups. This work contributes to an understanding of the evolution and ecology of an agriculturally important species of bacteria.

scholarly journals Phylogenetic Analysis and Polyphasic Characterization of Clavibacter michiganensis Strains Isolated from Tomato Seeds Reveal that Nonpathogenic Strains Are Distinct from C. michiganensis subsp. michiganensis

2012 ◽  
Vol 78 (23) ◽  
pp. 8388-8402 ◽  
Author(s):  
Marie-Agnès Jacques ◽  
Karine Durand ◽  
Geoffrey Orgeur ◽  
Samuel Balidas ◽  
Céline Fricot ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Genetic Relatedness ◽  
False Negative ◽  
Seed Transmission ◽  
16S Rrna Gene Sequencing ◽  
Housekeeping Genes ◽  
Diagnostic Tools ◽  
Rrna Gene ◽  
Clavibacter Michiganensis ◽  
Content Type

ABSTRACTThe genusClavibactercomprises one species and five subspecies of plant-pathogenic bacteria, four of which are classified as quarantine organisms due to the high economic threat they pose.Clavibacter michiganensissubsp.michiganensisis one of the most important pathogens of tomato, but the recommended diagnostic tools are not satisfactory due to false-negative and/or -positive results. To provide a robust analysis of the genetic relatedness among a worldwide collection ofC. michiganensissubsp.michiganensisstrains, relatives (strains from the four otherC. michiganensissubspecies), and nonpathogenicClavibacter-like strains isolated from tomato, we performed multilocus sequence-based analysis and typing (MLSA and MLST) based on six housekeeping genes (atpD,dnaK,gyrB,ppK,recA, andrpoB). We compared this “framework” with phenotypic and genotypic characteristics such as pathogenicity on tomato, reaction to two antisera by immunofluorescence and to five PCR identification tests, and the presence of four genes encoding the mainC. michiganensissubsp.michiganensispathogenicity determinants. We showed thatC. michiganensissubsp.michiganensisis monophyletic and is distinct from its closest taxonomic neighbors. The nonpathogenicClavibacter-like strains were identified asC. michiganensisusing 16S rRNA gene sequencing. These strains, while cross-reacting withC. michiganensissubsp.michiganensisidentification tools, are phylogenetically distinct from the pathogenic strains but belong to theC. michiganensisclade.C. michiganensissubsp.michiganensisclonal complexes linked strains from highly diverse geographical origins and also strains isolated over long periods of time in the same location. This illustrates the importance of seed transmission in the worldwide dispersion of this pathogen and its survival and adaptation abilities in a new environment once introduced.

scholarly journals Proposal to reclassify Streptobacillus hongkongensis into a novel genus as Pseudostreptobacillus hongkongensis gen. nov., comb. nov.

2020 ◽  
Vol 70 (4) ◽  
pp. 2366-2368 ◽  
Author(s):  
Tobias Eisenberg ◽  
Stefanie P. Glaeser ◽  
Jochen Blom ◽  
Peter Kämpfer
Keyword(s):  
Type Species ◽  
Core Genome ◽  
Housekeeping Genes ◽  
Phylogenetic Position ◽  
Rrna Gene ◽  
Protein Coding ◽  
Content Type ◽  
Phenotypic Differences ◽  
Link Type ◽  
The 16S Rrna Gene

The reclassification of Streptobacillus hongkongensis as Pseudostreptobacillus hongkongensis gen. nov., comb. nov. is proposed because of the separate phylogenetic position on the basis of the 16S rRNA gene sequence phylogeny, the combined analysis of the three protein-coding housekeeping genes groEL, gyrB and recA and a core genome sequence phylogeny to all other Streptobacillus species that is supported by phenotypic differences. The species Pseudostreptobacillus hongkongensis is the type species of the genus. The type strain is HKU33T, JCM 18691T, NCTC 13659T, DSM 26322T.

scholarly journals Clavibacter michiganensis subsp. capsici subsp. nov., causing bacterial canker disease in pepper

2016 ◽  
Vol 66 (10) ◽  
pp. 4065-4070 ◽  
Author(s):  
Eom-Ji Oh ◽  
Chungyun Bae ◽  
Han-Beoyl Lee ◽  
In Sun Hwang ◽  
Hyok-In Lee ◽  
...  
Keyword(s):  
Bacterial Canker ◽  
Clavibacter Michiganensis ◽  
Canker Disease ◽  
Clavibacter Michiganensis Subsp

scholarly journals Tracking of Anopheles stephensi in Ethiopia using mitochondrial DNA reveals pattern of spread

2021 ◽  
Author(s):  
Tamar E Carter ◽  
Solomon Yared ◽  
Dejene Getachew ◽  
Joseph Spear ◽  
Sae Hee Choi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
South Asian ◽  
Anopheles Stephensi ◽  
Phylogenetic Analyses ◽  
Eastern Ethiopia ◽  
Multiple Introductions ◽  
Minimum Spanning Network ◽  
History Of ◽  
Spread Analysis ◽  
The Impact

The recent detection of the South Asian malaria vector Anopheles stephensi in the Horn of Africa (HOA) raises concerns about the impact of this mosquito on malaria transmission in the region. The mode and history of introduction is important for predicting the likelihood of continued introduction and future spread. Analysis of An. stephensi genetic diversity and population structure can provide insight into the history of the mosquito in the HOA. We investigated genetic diversity of An. stephensi in eastern Ethiopia where detection suggests a range expansion to this region to understand the history of this invasive population. We sequenced the cytochrome oxidase subunit I (COI) and cytochrome B gene (CytB) in 187 An. stephensi collected from 10 sites in Ethiopia in 2018. Phylogenetic analyses using a maximum-likelihood approach and minimum spanning network were conducted for Ethiopian sequences. Molecular identification of bloodmeal sources was also performed using universal vertebrate CytB sequencing. Six COI-CytB haplotypes were observed based on five segregating sites, with the highest number of haplotypes in the northeastern sites (Semera, Bati, and Gewana towns) relative to the southeastern sites (Kebridehar, Godey, and Degehabur) in eastern Ethiopia. In the phylogenetic and network analysis, we observed population differentiation based on the distribution of the haplotypes across the northeastern and central sites (Erer Gota, Dire Dawa, and Awash Sebat Kilo) compared to the southeastern sites and evidence of a South Asian origin of the HOA An. stephensi lineages. The presence of the putative South Asian haplotype of origin at sites closest to Ethiopia's northeastern borders support route of introductions into Ethiopia from the northeast. Finally, molecular bloodmeal analysis revealed evidence of feeding on bovines, goats, dogs, and humans, as well as evidence of multiple (mixed) blood meals. In conclusion, we find support for the hypothesis for the recent expansion of An. stephensi into southeastern Ethiopia with multiple introductions. We also find evidence that supports the hypothesis that HOA An. stephensi populations originate from South Asia rather than the Arabian Peninsula. The evidence of both zoophagic and anthropophagic feeding support the potential for livestock movement to play a role in vector spread in this region.

scholarly journals Multilocus Sequence Analysis of Xanthomonads Causing Bacterial Spot of Tomato and Pepper Plants Reveals Strains Generated by Recombination among Species and Recent Global Spread of Xanthomonas gardneri

2014 ◽  
Vol 81 (4) ◽  
pp. 1520-1529 ◽  
Author(s):  
Sujan Timilsina ◽  
Mustafa O. Jibrin ◽  
Neha Potnis ◽  
Gerald V. Minsavage ◽  
Misrak Kebede ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Sequence Analysis ◽  
Housekeeping Genes ◽  
Global Distribution ◽  
Multilocus Sequence Analysis ◽  
Regional Differentiation ◽  
Bacterial Spot ◽  
Content Type ◽  
Global Spread ◽  
Pathogen Populations

ABSTRACTFourXanthomonasspecies are known to cause bacterial spot of tomato and pepper, but the global distribution and genetic diversity of these species are not well understood. A collection of bacterial spot-causing strains from the Americas, Africa, Southeast Asia, and New Zealand were characterized for genetic diversity and phylogenetic relationships using multilocus sequence analysis of six housekeeping genes. By examining strains from different continents, we found unexpected phylogeographic patterns, including the global distribution of a single multilocus haplotype ofX. gardneri, possible regional differentiation inX. vesicatoria, and high species diversity on tomato in Africa. In addition, we found evidence of multiple recombination events betweenX. euvesicatoriaandX. perforans.Our results indicate that there have been shifts in the species composition of bacterial spot pathogen populations due to the global spread of dominant genotypes and that recombination between species has generated genetic diversity in these populations.

scholarly journals Limiting Populations and Spread of Clavibacter michiganensis subsp. michiganensis on Seedling Tomatoes in the Greenhouse

Plant Disease ◽  
2002 ◽  
Vol 86 (5) ◽  
pp. 535-542 ◽  
Author(s):  
N. A. Werner ◽  
D. W. Fulbright ◽  
R. Podolsky ◽  
J. Bell ◽  
M. K. Hausbeck
Keyword(s):  
Bacterial Canker ◽  
Susceptible Cultivar ◽  
Copper Hydroxide ◽  
Clavibacter Michiganensis ◽  
Canker Disease ◽  
Resistant Cultivars ◽  
Tomato Seedlings ◽  
Greenhouse Tomato ◽  
Clavibacter Michiganensis Subsp ◽  
Pathogen Populations

Symptomless greenhouse tomato transplants may harbor high populations of Clavibacter michiganensis subsp. michiganensis, the causal agent of bacterial canker, leading to yield loss in the field. The objective of this study was to determine whether resistant cultivars, acibenzolar-S-methyl, avirulent strains of C. michiganensis subsp. michiganensis, or standard bactericides reduce pathogen populations and spread among greenhouse tomato seedlings. All treatments limited pathogen populations compared with the untreated inoculated susceptible cultivar in 1996 and 1998, but not in 1997. In 1996, copper hydroxide alone or mixed with mancozeb or streptomycin limited pathogen populations relative to acibenzolar-S-methyl, acibenzolar-S-methyl mixed with copper hydroxide, and avirulent strains. Copper hydroxide mixed with streptomycin limited pathogen populations compared with copper hydroxide mixed with mancozeb. Adding copper hydroxide to acibenzolar-S-methyl limited pathogen populations compared with acibenzolar-S-methyl alone. In 1998, treatments did not differ significantly from each other in limiting pathogen populations. The treatments limited spread of the bacterium only in 1997. Copper hydroxide mixed with mancozeb limited spread compared with copper hydroxide mixed with streptomycin. Pathogen spread was also reduced among resistant cultivars compared with the susceptible cultivar treated with streptomycin. In the field, the untreated inoculated susceptible cultivar produced yields that were 61% (1996) and 93% (1997) of those produced by the uninoculated susceptible cultivar. Fruit spotting occurred regardless of treatment. To prevent severe bacterial canker disease in the field, growers should initiate and sustain bactericide applications to tomato transplants while in the greenhouse to suppress pathogen populations. Cultivar resistance and acibenzolar-S-methyl may be helpful in disease management of bacterial canker on tomato.

scholarly journals Bacterial Canker Disease on Populus × euramericana Caused by Lonsdalea populi in Serbia

Forests ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1080
Author(s):  
Milica Zlatković ◽  
Imola Tenorio-Baigorria ◽  
Tamás Lakatos ◽  
Tímea Tóth ◽  
András Koltay ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Test Chamber ◽  
Housekeeping Genes ◽  
Rrna Gene ◽  
Bacterial Disease ◽  
Bacterial Canker ◽  
Canker Disease ◽  
Populus Euramericana ◽  
First Report ◽  
Eastern Cottonwood

Populus × euramericana (Dode) Guinier clone (cl.) “I-214” is a fast-growing interspecific hybrid between Eastern cottonwood (P. deltoides Bartr. ex Marsh) and European black poplar (Populus nigra L.). Populus × euramericana was introduced into Serbia in the 1950s and has become one of the most widely grown poplar species. In September 2019, cankers were observed on stems and branches of P. × euramericana cl. “I-214” trees in a two-year-old poplar plantation in the province of Vojvodina, Serbia. The canker tissue was soft and watery, and a colorless fluid that smelled rotten flowed from the cracks in the bark, suggesting possible bacterial disease. After two weeks, diseased trees experienced crown die-back and oozing of foamy, odorous exudates and this study aimed to identify the causal agent of the disease. Canker margins and exudates were collected from 20 symptomatic trees. The associated bacterium was isolated and identified using biochemical characteristics, phylogenetic analyses based on 16S rRNA gene sequences, and multilocus sequence analyses (MLSA) based on partial sequencing of three housekeeping genes (gyrB, infB, and atpD). The pathogen was identified as Lonsdalea populi. Pathogenicity tests were conducted on rooted cuttings of P. × euramericana cl. “I-214” in an environmental test chamber and demonstrated that the isolated bacterial strain was able to reproduce symptoms of softened, water-soaked cankers and exudation. To the best of our knowledge, this is the first report of L. populi causing bacterial canker disease on P. × euramericana cl. “I-214” in Serbia and in southeastern Europe (SEE). It is also the first report of a bacterial disease on hybrid poplars, including P. × euramericana in this country and in SEE. If the disease spreads into new areas, selection for L. populi resistance may need to be integrated into future poplar breeding programs.

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