Two novel species associated with bleeding cankers of broadleaf hosts, sp. nov. and sp. nov.

Seventeen Gram-negative, facultatively anaerobic bacterial strains were isolated from bleeding cankers of various broadleaf hosts and oak rhizosphere soil in Great Britain. The strains were tentatively identified as belonging to the genus based on 16S rRNA gene sequencing. Multilocus sequence analysis (MLSA), based on four protein-encoding genes (, , , and ), separated the strains into three clusters within the genus clade.

Bacteria Associated with Acute Oak Decline: Where Did They Come From? We Know Where They Go.

Acute oak decline is a high-impact disease causing necrotic lesions on the trunk, crown thinning and the eventual death of oak. Four bacterial species are associated with the lesions-, , and -although an epi-/endophytic lifestyle has also been suggested for these bacteria. However, little is known about their environmental reservoirs or their pathway to endophytic colonisation.

Description of Dryocola gen. nov. and two novel species, Dryocola boscaweniae sp. nov. and Dryocola clanedunensis sp. nov. isolated from the rhizosphere of native British oaks.

While investigating the role of the rhizosphere in the development of Acute Oak Decline, bacterial strains belonging to the family Enterobacteriaceae were isolated from rhizosphere soil following enrichment for the Enterobacterales. Partial sequencing of several housekeeping genes showed that these strains could not be assigned to an existing genus. Overall, 16 strains were investigated using a polyphasic approach to determine their taxonomic status.

Transfer of and to a novel genus gen. nov. as comb. nov. and comb. nov. and description of sp. nov., isolated from bleeding cankers on broadleaf hosts.

Following a screening campaign of bleeding cankers of broadleaf hosts in Great Britain, numerous bacterial strains were isolated, identified by 16S rRNA and protein-coding gene sequencing and ultimately classified. During the course of the study, several Gram-negative, facultatively anaerobic strains were isolated from bleeding x (London plane) and x (common lime) cankers that could not be assigned to an existing species. Partial 16S rRNA gene sequencing placed these strains in the genus , as a close phylogenetic relative of .

Description of a novel species of Leclercia, Leclercia tamurae sp. nov. and proposal of a novel genus Silvania gen. nov. containing two novel species Silvania hatchlandensis sp. nov. and Silvania confinis sp. nov. isolated from the rhizosphere of oak.

Background: Acute Oak Decline (AOD) is a decline disease first reported on native oaks in the UK, but in recent years reports from further afield such as Europe and the Middle East, indicate that the distribution and host range is increasing at an alarming rate. The stem weeping symptoms of the disease partially develop due to polymicrobial-host interaction, caused by several members of the order Enterobacterales. While investigating the rhizosphere soil of AOD-unaffected trees, termed 'healthy' trees, and diseased oaks suffering from Acute Oak Decline (AOD), an enrichment method designed for enhanced recovery of Enterobacterales led to the recovery of several isolates that could not be classified as any existing species.

Description of three novel species of : sp. nov., sp. nov. and sp. nov., isolated from the oak rhizosphere and bleeding cankers of broadleaf hosts.

While investigating the bacterial populations of environmental samples taken from a mix of healthy and Acute Oak Decline afflicted (pedunculate or English oak) rhizosphere soil samples and swabs of bleeding lesions on spp. (lime) and (red oak) trees, several strains belonging to the order were isolated using selective media and enrichment broth. Seven strains from the rhizosphere, three strains from spp.

sp. nov., isolated from symptomatic and trees in the UK.

Several strains of a previously undescribed bacterial species were isolated from mature hybrid trees suffering from bleeding cankers at various geographic locations in the UK. The strains were Gram-negative, facultatively anaerobic, and partial sequencing of the gene revealed that the strains belong to the genus with the closest phylogenetic neighbours being and . Further investigation using a polyphasic approach was undertaken to determine the taxonomic position of the novel species.

Identifying resistance in wild and ornamental cherry towards bacterial canker caused by .

Bacterial canker is a major disease of stone fruits and is a critical limiting factor to sweet cherry () production worldwide. One important strategy for disease control is the development of resistant varieties. Partial varietal resistance in sweet cherry is discernible using shoot or whole tree inoculations; however, these quantitative differences in resistance are not evident in detached leaf assays.

sp. nov., sp. nov., sp. nov. and sp. nov., isolated from diverse environmental sources, and emended description of the genus .

Bacteria isolated from onion bulbs suffering from bacterial decay in the United States and Norway were previously shown to belong to the genus based on partial housekeeping gene sequences and/or fatty acid analysis. However, many strains could not be assigned to any existing species. Additionally, strains isolated from creek water and oak as well as a strain with bioremediation properties were assigned to based on partial housekeeping gene sequences.

growth is improved by competitive interactions with other bacterial species associated with Acute Oak Decline.

and are three bacterial species frequently isolated together from oak displaying symptoms of Acute Oak Decline (AOD), which include weeping patches on trunks. All three bacterial species play a role in lesion formation in the current episode of AOD in Britain, although is the most dominant. The ongoing research into stem lesion formation characteristic of this polybacterial syndrome has been focussed primarily on the pathogenicity, identification and taxonomy of these bacteria.

Transposon Mutagenesis of Pathovars and to Identify Genes Involved in Bacterial Canker Disease of Cherry.

Bacterial canker of , affecting economically important stone fruit crops including cherry, peach, apricot and plum, is caused by the plant pathogen (.). Strains from two pathovars- pv.

An improved conjugation method for Pseudomonas syringae.

In order to achieve saturating transposon mutagenesis of the genome of plant pathogenic strains of Pseudomonas syringae we needed to improve plasmid conjugation frequency. Manipulation of the growth stage of donor and recipient cells allowed the required increase in frequency and facilitated conjugation of otherwise recalcitrant strains.

Genotypic and phenotypic analyses reveal distinct population structures and ecotypes for sugar beet-associated in Oxford and Auckland.

Fluorescent pseudomonads represent one of the largest groups of bacteria inhabiting the surfaces of plants, but their genetic composition is poorly understood. Here, we examined the population structure and diversity of fluorescent pseudomonads isolated from sugar beet grown at two geographic locations (Oxford, United Kingdom and Auckland, New Zealand). To seek evidence for niche adaptation, bacteria were sampled from three types of leaves (immature, mature, and senescent) and then characterized using a combination of genotypic and phenotypic analysis.

sp. nov., a novel species isolated from oak in the United Kingdom, and phylogenetic considerations of the genera , and .

As the current episode of Acute Oak Decline (AOD) continues to affect native British oak in the United Kingdom, ongoing isolations from symptomatic and healthy oak have yielded a large species population. These strains could be divided into taxa representing three potential novel species. Recently, two of these taxa were described as novel species in the lineage.

sp. nov. and sp. nov., isolated from pedunculate oak affected by acute oak decline in the UK.

Twenty-two cream-coloured bacterial strains were isolated from oak trees affected by acute oak decline (AOD) in Southern England. Isolates were Gram-negative, motile, slightly curved rods, aerobic, non-spore-forming, catalase positive and oxidase positive. 16S rRNA gene sequence analysis placed the strains in two separate phylogenetic clusters in the group, with as the closest phylogenetic relative.

Pseudomonas syringae: enterprising epiphyte and stealthy parasite.

Pseudomonas syringae is best known as a plant pathogenic bacterium that causes diseases in a multitude of hosts, and it has been used as a model organism to understand the biology of plant disease. Pathogenic and non-pathogenic isolates of P. syringae are also commonly found living as epiphytes and in the wider environment, including water sources such as rivers and precipitation.

Supercoiling of an excised genomic island represses effector gene expression to prevent activation of host resistance.

The plant pathogen Pseudomonas syringae pv. phaseolicola, which causes halo blight disease of beans, contains a 106 kb genomic island PPHGI-1. PPHGI-1 carries a gene, avrPphB, which encodes an effector protein that triggers a resistance response in certain bean cultivars.

Coping with Environmental Eukaryotes; Identification of Genes during the Interaction with Alternative Hosts or Predators.

Understanding the molecular mechanisms underpinning the ecological success of plant pathogens is critical to develop strategies for controlling diseases and protecting crops. Recent observations have shown that plant pathogenic bacteria, particularly , exist in a range of natural environments away from their natural plant host e.g.

Taxonomy and identification of bacteria associated with acute oak decline.

Acute oak decline (AOD) is a relatively newly described disorder affecting native oak species in Britain. Symptomatic trees are characterised by stem bleeds from vertical fissures, necrotic lesions in the live tissue beneath and larval galleries of the two spotted oak buprestid (Agrilus biguttatus). Several abiotic and biotic factors can be responsible for tree death, however the tissue necrosis and stem weeping is thought to be caused by a combination of bacterial species.

Confocal microscopy reveals in planta dynamic interactions between pathogenic, avirulent and non-pathogenic Pseudomonas syringae strains.

Recent advances in genomics and single-cell analysis have demonstrated the extraordinary complexity reached by microbial populations within their hosts. Communities range from complex multispecies groups to homogeneous populations differentiating into lineages through genetic or non-genetic mechanisms. Diversity within bacterial populations is recognized as a key driver of the evolution of animal pathogens.

Multi-locus sequence typing of Escherichia coli isolates with acquired ampC genes and ampC promoter mutations.

Multi-locus sequence typing was used to reveal a high degree of diversity amongst the E. coli isolates with AmpC plasmid genes, and a high prevalence of the -32 mutation present.

Pseudomonas syringae Differentiates into Phenotypically Distinct Subpopulations During Colonization of a Plant Host.

Bacterial microcolonies with heterogeneous sizes are formed during colonization of Phaseolus vulgaris by Pseudomonas syringae. Heterogeneous expression of structural and regulatory components of the P. syringae type III secretion system (T3SS), essential for colonization of the host apoplast and disease development, is likewise detected within the plant apoplast.

A low frequency persistent reservoir of a genomic island in a pathogen population ensures island survival and improves pathogen fitness in a susceptible host.

The co-evolution of bacterial plant pathogens and their hosts is a complex and dynamic process. Host resistance imposes stress on invading pathogens that can lead to changes in the bacterial genome enabling the pathogen to escape host resistance. We have observed this phenomenon with the plant pathogen Pseudomonas syringae pv.

Early changes in apoplast composition associated with defence and disease in interactions between Phaseolus vulgaris and the halo blight pathogen Pseudomonas syringae Pv. phaseolicola.

The apoplast is the arena in which endophytic pathogens such as Pseudomonas syringae grow and interact with plant cells. Using metabolomic and ion analysis techniques, this study shows how the composition of Phaseolus vulgaris leaf apoplastic fluid changes during the first six hours of compatible and incompatible interactions with two strains of P. syringae pv.