Lonsdalea Quercina Research Articles

Chemotactic activity of products of Elizabethkingia anophelis derived from Aedes albopictus against RAW264 murine macrophage cell line.

Dengue viruses enter dermal macrophages which are derived from other tissues after mosquito bites. We examined chemotactic factors derived from the dengue vector mosquito, Aedes albopictus, toward a RAW264 murine macrophage cell line. We found that Elizabethkingia anophelis that was isolated from mosquitoes exhibited migration-inducing activity toward RAW264 cells. The active substances were extracted using ethyl acetate to induce chemotactic movements. Chemotactic activity was eluted in the several fractions using the reversed-phase chromatography, suggesting that multiple substances were responsible for the activity. We isolated three bacterial colonies from the wild A. albopictus mosquitoes collected in Toyama Park, Tokyo prefecture, Japan. The bacterial 16S rRNA gene sequences were the most similar to those of Lonsdalea quercina. These bacteria also exhibited migration-inducing activity toward RAW264 cells. The migration-inducing activity of mosquito bacteria might be a new aspect of mosquito-mediated viral infections.

Canker and dieback of Alnus rubra is caused by Lonsdalea quercina.

Understanding the ecology of pathogens is important for disease management. Recently a devastating canker disease was found on red alder (Alnus rubra) planted as landscape trees. Bacteria were isolated from two groups of symptomatic trees located approximately 1 kilometer apart and one strain from each group was used to complete Koch's postulates. Results showed that these bacteria can not only cause disease on red alder but also on two other alder species. Unexpectedly, analyses of genome sequences of bacterial strains identified them as Lonsdalea quercina, a pathogenic species previously known to cause dieback of oak species, but not alder. Additionally, a core genome phylogeny clustered bacterial strains isolated from red alder within a subclade of L. quercina strains isolated from symptomatic oak trees. Consistent with the close phylogenetic relationship, there was no obvious evidence for divergence in genome composition of strains isolated from red alder and oak. Altogether, findings indicate that L. quercina is a potential threat to Alnus species.

Defining the Pathobiomes Associated with Drippy Blight in Colorado and Drippy Nut in California

Drippy blight, an emergent bacterial disease of oaks, was described recently from urban oaks in the Front Range of Colorado, USA. This disease, which causes branch dieback and oozing of bacterial exudates from cankers, is caused by Lonsdalea quercina and primarily affects red oaks, with Northern red oak (Quercus rubra) the most susceptible. Drippy nut is a similar, less acute condition that exists in California, USA and affects acorns of interior live oak (Quercus wislizenii) and coastal live oak (Quercus agrifolia). The objective of this study was to compare the microbial communities of drippy blight in Colorado to those of drippy nut in California, and determine if other pathogenic fungal or bacterial taxa are associated with the diseases. Symptomatic and asymptomatic tissues were sampled in California and Colorado, and metagenomic analyses were performed to describe the fungal and bacterial communities. We found a suite of bacterial species, dominated by taxa within the genus Zymobacter, that were associated with symptomatic tissues for both drippy nut and drippy blight. L. quercina is the main pathogenic associate of both diseases. We found fungal yeasts associated with symptomatic tissues, and although not pathogens, these taxa were present in the pathobiome of drippy nut and drippy blight in California and Colorado. We did, however, identify taxa belonging to Gnomoniopsis, a known pathogen, associated with California symptomatic samples. Our study found an overlapping suite of bacterial associates of drippy blight and drippy nut, though more variation occurred within the fungal genera associated with these oak diseases.

Population genomic analysis of an emerging pathogen Lonsdalea quercina affecting various species of oaks in western North America

Understanding processes leading to disease emergence is important for effective disease management and prevention of future epidemics. Utilizing whole genome sequencing, we studied the phylogenetic relationship and diversity of two populations of the bacterial oak pathogen Lonsdalea quercina from western North America (Colorado and California) and compared these populations to other Lonsdalea species found worldwide. Phylogenetic analysis separated Colorado and California populations into two Lonsdalea clades, with genetic divergence near species boundaries, suggesting long isolation and populations that differ in genetic structure and distribution and possibly their polyphyletic origin. Genotypes collected from different host species and habitats were randomly distributed within the California cluster. Most Colorado isolates from introduced planted trees, however, were distinct from three isolates collected from a natural stand of Colorado native Quercus gambelii, indicating cryptic population structure. The California identical core genotypes distribution varied, while Colorado identical core genotypes were always collected from neighboring trees. Despite its recent emergence, the Colorado population had higher nucleotide diversity, possibly due to its long presence in Colorado or due to migrants moving with nursery stock. Overall, results suggest independent pathogen emergence in two states likely driven by changes in host-microbe interactions due to ecosystems changes. Further studies are warranted to understand evolutionary relationships among L. quercina from different areas, including the red oak native habitat in northeastern USA.

Prediction and Analysis of miRNA Targets in Poplar in Response to the Infection of <i>Lonsdalea quercina</i> subsp <i>Populi</i>

Euramerican poplar bacterial canker disease caused by  Lonsdalea quercina  subsp.  Populi  is one of the stem diseases and seriously harmful to the growth and survival of poplar. MiRNAs play crucial roles in the regulation of the stress response of plants. To identify target genes of miRNAs responsive to the infection of this pathogen and provide candidate genes to the molecular breeding of forest disease resistance, the mature sequences of poplar miRNAs in miRBase database were used as probes to in silico predict the differentially expressed targets in poplar ‘Zhonglin 46’ inoculated with bacterial canker by using psRNATarget in this investigation. A total of 566 target genes of 276 miRNAs belonging to 127 miRNA families were screened, and these targets were found to be involved in multiple pathways such as plant pathogen interaction, plant hormone signaling, and phenylpropanoid biosynthesis, suggesting that these miRNAs were involved in the regulation of the response to  L. quercina  infection. Combined with GO analysis, KEGG pathway enrichment and gene function annotation of target genes, it was showed that miRNAs including miR482, miR6459, miR7812 and miR7835 were predicted to target genes encoding RPS2, NBS-LRR, AUX1, CCR, and Ca 2+  transmembrane transport protein genes, which were involved in the resistance regulation of poplar to  L. quercina  infection. Six of the nine differentially expressed genes targeted by miR7835 encode the CCR enzyme in the phenylpropanol biosynthesis pathway, which might be involved in the defense response of poplars by affecting the synthesis of lignin. The miRNA:mRNA regulatory gene pairs found in this investigation enlarged the gene resources of molecular breeding of forest disease resistance, and provided new clues for the research of the molecular regulatory mechanism of disease resistance in trees.

Insects Visiting Drippy Blight Diseased Red Oak Trees Are Contaminated with the Pathogenic Bacterium Lonsdalea quercina.

The focus of investigation in this study was to consider the potential of arthropods in the dissemination of the bacterium involved in drippy blight disease, Lonsdalea quercina. Arthropod specimens were collected and tested for the presence of the bacterium with molecular markers. The bacterium L. quercina was confirmed on 12 different insect samples from three orders (Coleoptera, Hemiptera, and Hymenoptera) and eight families (Buprestidae, Coccinellidae, Dermestidae, Coreidae, Pentatomidae and/or Miridae, Apidae, Formicidae, and Vespidae). Approximately half of the insects found to carry the bacterium were in the order Hymenoptera. Estimates of the insects that are contaminated with the bacterium, and likely carry it between trees, is conservative because the documented insects represent only a subset of the insect orders that were observed feeding on the bacterium or present on diseased trees yet were not able to be tested. The insects contaminated with L. quercina exhibited diverse life histories, where some had a facultative relationship with the bacterium and others sought it out as a food source. These findings demonstrate that a diverse set of insects naturally occur on diseased trees and may disseminate L. quercina.

Drippy Blight, a Disease of Red Oaks in Colorado, U.S., Produced from the Combined Effect of the Scale Insect Allokermes galliformis and the Bacterium Lonsdalea quercina subsp. Quercina

Drippy blight is an emergent disease of red oaks, caused by the interaction between a kermes scale insect (Allokermes galliformis) and a bacterium (Lonsdalea quercina subsp. quercina). Multi-locus sequence analysis was used to confirm the bacterial pathogen’s identity and its relationship to other phylogenetically related Enterobacteriaceae species. Further, Koch’s postulates were performed on sapling red oaks. Prior to the discovery of drippy blight disease in Colorado, in the United States, the bacterium was reported on oak trees in California but was limited to acorn infections. The scale insect, A. galliformis, was previously known to occur on pin oak in the eastern United States but was not previously associated with either this bacterium or the production of significant branch dieback associated with drippy blight. In addition to a description of this new disease, this research documents a host range expansion of L. quercina subsp. quercina to northern red oak (Quercus rubra), Shumard oak (Q. shumardii), and pin oak (Q. palustris) and extends the reported host range of A. galliformis to include northern red and Shumard oaks.

A Large-Scale Mutational Analysis of Two-Component Signaling Systems of Lonsdalea quercina Revealed that KdpD-KdpE Regulates Bacterial Virulence Against Host Poplar Trees.

Poplar, which is a dominant species in plant communities distributed in the northern hemisphere, is commonly used as a model plant in forestry studies. Poplar production can be inhibited by infections caused by bacteria, including Lonsdalea quercina subsp. populi, which is a gram-negative bacterium responsible for bark canker disease. However, the molecular basis of the pathogenesis remains uncharacterized. In this study, we annotated the two-component signal transduction systems (TCSs) encoded by the L. quercina subsp. populi N-5-1 genome and identified 18 putative histidine kinases and 24 response regulators. A large-scale mutational analysis revealed that 19 TCS genes regulated bacterial virulence against poplar trees. Additionally, the deletion of kdpE or overexpression of kdpD resulted in almost complete loss of bacterial virulence. We observed that kdpE and kdpD formed a bi-cistronic operon. KdpD exhibited autokinase activity and could bind to KdpE (Kd = 5.73 ± 0.64 μM). Furthermore, KdpE is an OmpR family response regulator. A chromatin immunoprecipitation sequencing analysis revealed that KdpE binds to an imperfect palindromic sequence within the promoters of 44 genes, including stress response genes Lqp0434, Lqp3037, and Lqp3270. A comprehensive analysis of TCS functions may help to characterize the regulation of poplar bark canker disease.

Elevation of three subspecies of Lonsdalea quercina to species level: Lonsdalea britannica sp. nov., Lonsdalea iberica sp. nov. and Lonsdalea populi sp. nov.

Four subspecies of Lonsdalea quercina (L. quercina subsp. quercina, L. quercina subsp. britannica, L. quercina subsp. iberica and L. quercina subsp. populi) were studied by genome sequence-derived average nucleotide identity (ANI), phylogenetic analysis based on 16S rRNA gene sequences, multilocus sequence analysis (MLSA) and phenotypic characteristics. In phylogenetic trees, based on 16S rRNA gene sequences, and in MLSA data, the four subspecies were divided into four subclusters in the Lonsdalea clade with high boot strap support. The ANI values between the four subspecies were 88.71-93.38 %, respectively, lower than the proposed species boundary ANI cut-off (95-96 %) that is considered the most important criterion to reclassify these subspecies at the species level. It is proposed that three subspecies be elevated to the species level as Lonsdalea britannica sp. nov. (type strain R-43280T=LMG 26267T=NCPPB 4481T=CFCC 10822T), Lonsdalea iberica sp. nov. (type strain R-44166T=LMG 26264T=NCPPB 4490T=CFCC 10824T) and Lonsdalea populi sp. nov. (type strain NY060T=DSM 25466T=NCAIM B 02483T=LMG 27349T=CFCC 13125T).

Recovery of a phytopathogenic bacterium Lonsdalea quercina from a lesser horseshoe bat in Moravian karst, Czech Republic

SummaryWhile bats are important reservoirs and vectors of pathogenic agents with zoonotic potential, their skin‐associated microbial community could harbour organisms relevant to bat health as well as those associated with bat habitats in general. A total of 140 skin swabs collected from bats in the Czech Republic were cultured for bacteria from 2012 to 2013. A phytopathogen, isolated from a lesser horseshoe bat (Rhinolophus hipposideros), was identified as Lonsdalea quercina by MALDI‐TOF (matrix‐assisted laser desorption–ionization time‐of‐flight mass spectrometry) and characterized as Lonsdalea quercina subsp. britannica using phylogenetic analysis based on a 16S rRNA and two housekeeping (infB and atpD) genes. Lonsdalea quercina subsp. britannica is a gram‐negative facultative anaerobic bacterium reported to cause bark canker and drippy nut disease in oaks. Our finding provides evidence of Lonsdalea quercina in the Czech Republic (Moravian Karst). As the lesser horseshoe bat is a sedentary species, it may bio‐indicate the presence of the phytopathogenic bacterium in the broadleaved forests of the habitat of pathogen recovery. We therefore suggest active surveillance of the area of the Moravian Karst for signs of oak disease and/or decline.

First Report of Bark Canker Disease of Poplar Caused by Lonsdalea quercina subp. populi in Spain

First Report of Bark Canker Disease of Poplar Caused by <i>Lonsdalea quercina</i> subp. <i>populi</i> in Spain

Genome-wide transcriptomic profiles reveal multiple regulatory responses of poplar to Lonsdalea quercina infection

Key message Remarkable gene expression changes and responsive DEGs were found in poplar upon pathogen attack and provide important clues to the molecular mechanism of defense responses in plants and gene functional studies of trees.

A new method to detect Lonsdalea quercina in infected plant tissues by real‐time PCR

SummaryPresymptomatic and accurate diagnoses of pathogens are essential for disease prediction and the timely application of bactericide. The bacterium Lonsdalea quercina (=Brenneria quercina) has been reported as the causal agent of drippy nut and bark canker disease on oak in California (US) and Europe. In recent years, it is also found on Populus × euramericana trees in Henan province of China. This bacterium causes longitudinal cankers of a few centimetres in size on the bark surface of the upper trunk. In this study, we developed two species‐specific PCR assays using primer pairs LqfF/LqfR and LqgF/LqgR for the rapid and accurate detection of the pathogenic bacteria in diseased plant tissues. The results show that the LqfF/LqfR primers amplified only a single PCR band of approximately 382 bp and the LqgF/LqgR primers yielded a PCR product of approximately 286 bp. The two primers were successfully adapted to real‐time PCR based on SYBR Green I used with the ABI 7500 system. The detection limit of the reaction was 0.1 pg genomic DNA per 20 μl PCR reaction volumes. The pathogen was mainly detected in the phloem of cankers as well as in the exudates of diseased trees, but was not found in the xylem or leaves. The size of pathogen in distribution was larger than the lesion. The results demonstrate that real‐time PCR assays can be used to detect the pathogen by extracting DNA directly from infected plant tissues. This method is a rapid, reliable method for the presymptomatic and accurate detection of L. quercina, providing a useful insight into epidemiological studies.

A Canker Disease of Populus × euramericana in China Caused by Lonsdalea quercina subsp. populi.

In 2006, a new canker was observed on trees of Populus × euramericana '74/76' and P. × euramericana 'Zhonglin 46' in the Henan and Shandong provinces of China. The disease, which is characterized by canker with white exudates dripping from the bark, occurred mainly in the summer. A particular gram-negative, rod-shaped bacterium was repeatedly isolated from the infected samples and proven to infect trees of P. × euramericana by Koch's postulates. Through a polyphasic taxonomic approach using sequence, DNA-DNA hybridization, chemotaxonomic, and phenotypic data, the poplar isolates were identified as Lonsdalea quercina subsp. populi, a subspecies very recently described based on isolates from oozing bark canker of poplar (P. × euramericana) trees in Hungary.

The HrpW protein of Lonsdalea quercina N‐5‐1 has pectate lyase activity and is required for full bacterial virulence

Lonsdalea quercina N-5-1 is a bacterial pathogen that causes poplar bark cankers. It has been isolated from the branch of Populus × euramericana cv. "74/76" in Henan, China. Previous studies have revealed that the Type III secretion system (T3SS) acts as an essential pathogenic factor in L. quercina N-5-1. HrpW is a putative effector of T3SS in strain N-5-1, which has a typical harpin domain at the amino terminal and a pectate lyase (Pel) domain at its carboxyl terminal. Genetic evidence had shown that, compared to the wild-type and the complementary strain, the hrpW mutation causes a small but significant reduction in virulence when inoculated on the poplar branches. The amino terminal domain of HrpW was found to trigger tobacco hypersensitive response, but the carboxyl terminal domain of HrpW was not. Unlike most HrpW homologs in other bacteria, the carboxyl terminal domain of HrpW of strain N-5-1 exhibited detectable pectate lyase activity. Site-direction mutations (W104A, W171M) further demonstrated that two tryptophan residues were essential to its pectate lyase activity. The results of the present work suggest that HrpW in L. quercina N-5-1 possesses pectate lyase activity and acts as a nonessential but important pathogenic factor in poplar bark canker disease.

Proposal to reclassify Brenneria quercina (Hildebrand and Schroth 1967) Hauben et al. 1999 into a new genus, Lonsdalea gen. nov., as Lonsdalea quercina comb. nov., descriptions of Lonsdalea quercina subsp. quercina comb. nov., Lonsdalea quercina subsp. iberica subsp. nov. and Lonsdalea quercina subsp. britannica subsp. nov., emendation of the description of the genus Brenneria , reclassification of Dickeya dieffenbachiae as

Bacterial isolates from oak trees in Spain and Britain, showing symptoms of bark canker and Acute Oak Decline (AOD), respectively, were examined by a polyphasic approach. Both 16S rRNA gene sequencing and multilocus sequence analysis (MLSA), based on partial sequences of gyrB, rpoB, infB and atpD genes, revealed that the isolates were separated into two genetic groups according to their origin. Their closest phylogenetic relative was Brenneria quercina, the causal agent of drippy nut disease of oak, which clustered distant to the other species of the genus Brenneria. MLSA data for species of the genera Brenneria, Pectobacterium, Dickeya, Erwinia, Pantoea and Samsonia confirmed the polyphyletic nature of the genus Brenneria and indicated synonymy of Dickeya dadantii and Dickeya dieffenbachiae. DNA-DNA hybridization experiments confirmed this synonymy and also revealed DNA-DNA relatedness values of 58-73% between the new oak isolates and B. quercina. Phenotypic and/or chemotaxonomic methods allowed B. quercina and the two genetic groups of new oak isolates to be discriminated from other recognized species of the genus Brenneria and from members of the closely related genera Dickeya, Pectobacterium and Samsonia. Based on the data obtained, the following taxonomic proposals are made: (1) reclassification of B. quercina as the type species of a novel genus, Lonsdalea gen. nov., as Lonsdalea quercina comb. nov. (type strain LMG 2724(T)=ATCC 29281(T)=CCUG 48867(T)=CFBP 3617(T)=CIP 105201(T)=DSM 4561(T)=ICMP 1845(T)), (2) classification of the oak isolates as Lonsdalea quercina subsp. iberica subsp. nov. (type strain LMG26264(T)=NCPPB 4490(T)) and Lonsdalea quercina subsp. britannica subsp. nov. (type strain LMG 26267(T)=NCPPB 4481(T)) and leading to the automatic creation of Lonsdalea quercina subsp. quercina subsp. nov. (type strain LMG 2724(T)=ATCC 29281(T)), (3) emendation of the description of the genus Brenneria, and (4) reclassification of Dickeya dieffenbachiae as Dickeya dadantii subsp. dieffenbachiae comb. nov. (type strain LMG 25992(T)=CFBP 2051(T)), with the automatic creation of Dickeya dadantii subsp. dadantii subsp. nov. (type strain LMG 25991(T)=CFBP 1269(T)).