Complete genome sequences of strains GM1 and GM2, isolated from the leaves of garlic mustard.

We report the complete genomes of two strains, GM1 and GM2, isolated from garlic mustard plants. strain GM1 was found to carry a HiVir pantaphos biosynthetic gene cluster, which causes onion necrosis.

Environmental alkalization suppresses deployment of virulence strategies in pv. DC3000.

Plant pathogenic bacteria encounter a drastic increase in apoplastic pH during the early stages of plant immunity. The effects of alkalization on pathogen-host interactions have not been comprehensively characterized. Here, we used a global transcriptomic approach to assess the impact of environmental alkalization on pv.

Ontogenic stage-associated SA response contributes to leaf age-dependent resistance in and cotton.

Introduction: As leaves grow, they transition from a low-microbe environment embedded in shoot apex to a more complex one exposed to phyllosphere microbiomes. Such change requires a coordinated reprogramming of cellular responses to biotic stresses. It remains unclear how plants shift from fast growth to robust resistance during organ development.

Altering cold-regulated gene expression decouples the salicylic acid-growth trade-off in Arabidopsis.

In Arabidopsis (Arabidopsis thaliana), overproduction of salicylic acid (SA) increases disease resistance and abiotic stress tolerance but penalizes growth. This growth-defense trade-off has hindered the adoption of SA-based disease management strategies in agriculture. However, investigation of how SA inhibits plant growth has been challenging because many SA-hyperaccumulating Arabidopsis mutants have developmental defects due to the pleiotropic effects of the underlying genes.

Thiosulfinate Tolerance Gene Clusters Are Common Features of Onion Pathogens.

pv. , , and are common bacterial pathogens of onion. Onions produce organosulfur thiosulfinate defensive compounds after cellular decompartmentalization.

Genomic delineation and description of species and within-species lineages in the genus .

As the name of the genus ("of all sorts and sources") suggests, this genus includes bacteria with a wide range of provenances, including plants, animals, soils, components of the water cycle, and humans. Some members of the genus are pathogenic to plants, and some are suspected to be opportunistic human pathogens; while others are used as microbial pesticides or show promise in biotechnological applications. During its taxonomic history, the genus and its species have seen many revisions.

Pantailocins: phage-derived bacteriocins from and subsp. .

Phage-derived bacteriocins (tailocins) are ribosomally synthesized structures produced by bacteria in order to provide advantages against competing strains under natural conditions. Tailocins are highly specific in their target range and have proven to be effective for the prevention and/or treatment of bacterial diseases under clinical and agricultural settings. We describe the discovery and characterization of a new tailocin locus encoded within genomes of and subsp.

Draft genome sequences for ATCC 35400 and subspecies ICMP 10132.

Here, we describe draft genome sequences for two bacterial isolates from the genus . ATCC 35400 was originally isolated from honeydew melon and was obtained from the American Type Culture Collection. subspecies ICMP 10132 was originally isolated from sugarcane and classified as , but average nucleotide identity and discriminatory PCR support species reclassification.

Shoot Maturation Strengthens FLS2-Mediated Resistance to .

Temporospatial regulation of immunity components is essential for properly activating plant defense response. Flagellin-sensing 2 (FLS2) is a surface-localized receptor that recognizes bacterial flagellin. The immune function of FLS2 is compromised in early stages of shoot development.

A critical role of a eubiotic microbiota in gating proper immunocompetence in Arabidopsis.

Although many studies have shown that microbes can ectopically stimulate or suppress plant immune responses, the fundamental question of whether the entire preexisting microbiota is indeed required for proper development of plant immune response remains unanswered. Using a recently developed peat-based gnotobiotic plant growth system, we found that Arabidopsis grown in the absence of a natural microbiota lacked age-dependent maturation of plant immune response and were defective in several aspects of pattern-triggered immunity. Axenic plants exhibited hypersusceptibility to infection by the bacterial pathogen Pseudomonas syringae pv.

Single-cell profiling of Arabidopsis leaves to Pseudomonas syringae infection.

Plant response to pathogen infection varies within a leaf, yet this heterogeneity is not well resolved. We expose Arabidopsis to Pseudomonas syringae or mock treatment and profile >11,000 individual cells using single-cell RNA sequencing. Integrative analysis of cell populations from both treatments identifies distinct pathogen-responsive cell clusters exhibiting transcriptional responses ranging from immunity to susceptibility.

Discovery of the Hrp Type III Secretion System in Phytopathogenic Bacteria: How Investigation of Hypersensitive Cell Death in Plants Led to a Novel Protein Injector System and a World of Inter-Organismal Molecular Interactions Within Plant Cells.

In the early 1960s, and other host-specific phytopathogenic proteobacteria were discovered to elicit a rapid, resistance-associated death when infiltrated at high inoculum levels into nonhost tobacco leaves. This hypersensitive reaction (or response; HR) was a useful indicator of basic pathogenic ability. Research over the next 20 years failed to identify an elicitor of the HR but revealed that its elicitation required contact between metabolically active bacterial and plant cells.

Shoot maturation strengthens FLS2-mediated resistance to .

A temporal-spatial regulation of immunity components is essential for properly activating plant defense response. Flagellin-sensing 2 (FLS2) is a surface-localized receptor that recognizes bacterial flagellin. The immune function of FLS2 is compromised in early stages of shoot development.

Genome-wide association and dissociation studies in reveal potential virulence factors affecting and × hybrid.

is a member of a species complex that causes center rot of bulb onions () and also infects other crops like leeks (), chives (), bunching onion or Welsh onion (), and garlic (). This pathogen relies on a chromosomal phosphonate biosynthetic gene cluster (HiVir) and a plasmid-borne thiosulfinate tolerance cluster () for onion pathogenicity and virulence, respectively. However, pathogenicity and virulence factors associated with other species remain unknown.

The Genetic Requirements for HiVir-Mediated Onion Necrosis by , a Necrotrophic Plant Pathogen.

is an unusual bacterial pathogen that lacks typical virulence determinants yet causes extensive necrosis in onion foliage and bulb tissues. The onion necrosis phenotype is dependent on the expression of the phosphonate toxin, pantaphos, which is synthesized by putative enzymes encoded by the HiVir (high virulence) gene cluster. The genetic contributions of individual genes in HiVir-mediated onion necrosis remain largely unknown, except for the first gene, (phosphoenolpyruvate mutase, ), whose deletion resulted in the loss of onion pathogenicity.

Evaluating Options to Increase the Efficacy of Biocontrol Agents for the Management of spp. Under Field Conditions.

Center rot of onion is caused by a complex of plant pathogenic species, which can lead to significant yield losses in the field and during storage. Conventional growers use foliar protectants such as a mixture of copper bactericides and an ethylene-bis-dithiocarbamate (EBDC) fungicide to manage the disease; however, organic growers have limited management options besides copper-protectants. Biocontrol agents (BCAs) provide an alternative; however, their efficacy could be compromised due in part to their inability to colonize the foliage.

A Novel Biosynthetic Gene Cluster Across the Species Complex Is Important for Pathogenicity in Onion.

Onion center rot is caused by at least four species of genus (, , , and subsp). Critical onion pathogenicity determinants for were recently described, but whether those determinants are common among other onion-pathogenic species remains unknown. In this work, we report onion pathogenicity determinants in subsp and We identified two distinct secondary metabolite biosynthetic gene clusters present separately in different strains of onion-pathogenic subsp.

, a new bacterial pathogen of onion causing bulb rot.

Onion bulb rot can be caused by multiple plant pathogens including bacterial pathogens. During our routine survey of commercial onion farms in 2014, 2020, and 2021, seven putative spp. strains were isolated from symptomatic onion samples in Georgia, United States.

RpoS contributes in a host-dependent manner to colonization of the leaf apoplast during plant disease.

Contaminated fresh produce has been routinely linked to outbreaks of Salmonellosis. Multiple studies have identified factors associated with successful colonization of diverse plant niches and tissues. It has also been well documented that can benefit from the conditions generated during plant disease by host-compatible plant pathogens.

In planta transcriptomics reveals conflicts between pattern-triggered immunity and the AlgU sigma factor regulon.

In previous work, we determined the transcriptomic impacts of flg22 pre-induced Pattern Triggered Immunity (PTI) in Arabidopsis thaliana on the pathogen Pseudomonas syringae pv. tomato DC3000 (Pto). During PTI exposure we observed expression patterns in Pto reminiscent of those previously observed in a Pto algU mutant.

Genome Context Influences Evolutionary Flexibility of Nearly Identical Type III Effectors in Two Phytopathogenic Pseudomonads.

Integrative Conjugative Elements (ICEs) are replicons that can insert and excise from chromosomal locations in a site-specific manner, can conjugate across strains, and which often carry a variety of genes useful for bacterial growth and survival under specific conditions. Although ICEs have been identified and vetted within certain clades of the agricultural pathogen , the impact of ICE carriage and transfer across the entire species complex remains underexplored. Here we identify and vet an ICE (PmaICE-DQ) from pv.

Validation of Species-Specific PCR Assays for the Detection of , , , and .

Species of represent a group of plant pathogenic bacteria that infect a variety of agro-economically important plant species. Among these, a complex of , , , and subsp. cause center rot in onion, resulting in significant economic losses.

Pseudomonas alliivorans sp. nov., a plant-pathogenic bacterium isolated from onion foliage in Georgia, USA.

This study provides a taxonomic characterization of three bacterial strains isolated from onion seedlings in Georgia USA. Yellow-colored colonies were isolated, and a diffusible fluorescent pigment was visible under ultraviolet light on King's medium B. Preliminary analysis of the basic phenotype tests and 16S rRNA gene sequence analysis indicated the onion strains were closely related to Pseudomonas viridiflava with the highest similarity to P.