Phylogeography, origin and population structure of the self-fertile emerging plant pathogen Phytophthora pseudosyringae.

Phytophthora pseudosyringae is a self-fertile pathogen of woody plants, particularly associated with tree species from the genera Fagus, Notholithocarpus, Nothofagus and Quercus, which is found across Europe and in parts of North America and Chile. It can behave as a soil pathogen infecting roots and the stem collar region, as well as an aerial pathogen infecting leaves, twigs and stem barks, causing particular damage in the United Kingdom and western North America. The population structure, migration and potential outcrossing of a worldwide collection of isolates were investigated using genotyping-by-sequencing.

Detection of Borrelia burgdorferi infected Ixodes scapularis (Acari: Ixodidae) associated with local Lyme disease transmission in Nebraska, USA, 2021.

In August 2021, the Nebraska Department of Health and Human Services was notified by a local public health department of a cluster of two Lyme disease cases in patients with local exposure to wooded areas in a county located in their jurisdiction. Epidemiological investigations revealed that the two patients had similar symptom onset dates and had likely exposure to ticks at wooded sites located directly adjacent to one another. Two environmental investigations were completed in October 2021 and consisted of tick surveys at the patients' reported sites of tick exposure.

First Record of Causing Anthracnose on Avocado Fruits in Chile.

Anthracnose caused by species is one of the most frequent and damaging fungal diseases affecting avocado fruits ( Mill.) worldwide. In Chile, the disease incidence has increased over the last decades due to the establishment of commercial groves in more humid areas.

Essential Components of Borreliella (Borrelia) burgdorferi In Vitro Transcription Assays.

Borreliella burgdorferi is a bacterial pathogen with limited metabolic and genomic repertoires. B. burgdorferi transits extracellularly between vertebrates and ticks and dramatically remodels its transcriptional profile to survive in disparate environments during infection.

Cataloging Species of Agriculture, Forests, Horticulture, and Restoration Outplantings in California, U.S.A.: A Sequence-Based Meta-Analysis.

California contains a diverse flora, and knowledge of the pathogens that threaten those plants is essential to managing their long-term health. To better understand threats to California plant health, a meta-analysis of detections within the state was conducted using publicly available sequences as a primary source of data rather than published records. Accessions of internal transcribed spacer (ITS) ribosomal DNA were cataloged from 800 Californian isolates, analyzed, and determined to correspond to 80 taxa, including several phylogenetically distinct provisional species.

A Barcode-Based Phylogenetic Characterization of Identifies Two Cosmopolitan Lineages with Distinct Host Affinities and the First Report of in California.

A collection of 30 and 12 (subclade 1a) strains isolated from several recent surveys across California was phylogenetically compared to a worldwide collection of 112 conspecific strains using sequences from three barcoding loci. The surveys baited from soil and water across a wide variety of forested ecosystems with a geographic range of more than 1000 km. Two cosmopolitan lineages were identified within the widespread , one being mainly associated with strawberry production and the other more closely associated with apple orchards, oaks and ornamental trees.

Identification and Characterization of Species Associated with Crown and Root Rot of Pistachio Trees in California.

Pistachio is one of the most widely cultivated nut crops in California, with approximately 115,000 ha of bearing pistachio trees. In recent years, several orchards were identified, with declining trees leading to substantial tree losses. Symptoms included trees with poor vigor, yellowing and wilting of leaves, crown rot, and profuse gumming on the lower portion of trunks.

DksA-dependent regulation of RpoS contributes to Borrelia burgdorferi tick-borne transmission and mammalian infectivity.

Throughout its enzootic cycle, the Lyme disease spirochete Borreliella (Borrelia) burgdorferi, senses and responds to changes in its environment using a small repertoire of transcription factors that coordinate the expression of genes required for infection of Ixodes ticks and various mammalian hosts. Among these transcription factors, the DnaK suppressor protein (DksA) plays a pivotal role in regulating gene expression in B. burgdorferi during periods of nutrient limitation and is required for mammalian infectivity.

First report of leaf blight caused by Phytophthora ramorum on periwinkle (Vinca minor) in Washington State, USA.

Phytophthora ramorum (Werres, De Cock & Man in't Veld) was recovered from symptomatic foliage of periwinkle at a botanical garden in WA in March 2015. Symptoms were tan colored lesions with a dark brown margin visible on both surfaces of the leaf and were found on wounds or around leaf margins. Periwinkle is native to Europe and is commonly used for ground cover in ornamental landscapes.

Gene Regulation and Transcriptomics.

() , along with closely related species, is the etiologic agent of Lyme disease. The spirochete subsists in an enzootic cycle that encompasses acquisition from a vertebrate host to a tick vector and transmission from a tick vector to a vertebrate host. To adapt to its environment and persist in each phase of its enzootic cycle, wields three systems to regulate the expression of genes: the RpoN-RpoS alternative sigma factor cascade, the Hk1/Rrp1 two-component system and its product c-di-GMP, and the stringent response mediated by Rel and DksA.

Failure To Detect Prion Infectivity in Ticks following Prion-Infected Blood Meal.

Chronic wasting disease (CWD) is an emerging and fatal contagious prion disease that affects cervids, including mule deer, white-tailed deer, black-tailed deer, red deer reindeer, elk, and moose. CWD prions are widely distributed throughout the bodies of CWD-infected animals and are found in the nervous system, lymphoid tissues, muscle, blood, urine, feces, and antler velvet. The mechanism of CWD transmission in natural settings is unknown.

The population of oomycetes in a recycled irrigation water system at a horticultural nursery in southern California.

Recapture and recycling of irrigation water is often required to meet enormous water demands at horticultural nurseries. We tested four water types associated with a recycled irrigation system at a commercial container nursery in southern California for presence of oomycete plant pathogens from July 2015 to December 2017. These water types included: the main source of water originating from a reservoir, retention water from an on-site collection pond, irrigation water received by different growing areas within the nursery, and irrigation runoff captured in polyethylene sheet-lined runoff channels.

Establishment of an in vitro RNA polymerase transcription system: a new tool to study transcriptional activation in Borrelia burgdorferi.

The Lyme disease spirochete Borrelia burgdorferi exhibits dramatic changes in gene expression as it transits between its tick vector and vertebrate host. A major hurdle to understanding the mechanisms underlying gene regulation in B. burgdorferi has been the lack of a functional assay to test how gene regulatory proteins and sigma factors interact with RNA polymerase to direct transcription.

Molecular Detection of Spotted Fever Group Rickettsiae (Rickettsiales: Rickettsiaceae) in Dermacentor variabilis (Acari: Ixodidae) Collected Along the Platte River in South Central Nebraska.

Dermacentor variabilis is the predominant tick species in Nebraska and is presumed to be the primary vector of Rickettsia rickettsii associated with cases of Rocky Mountain spotted fever (RMSF). Interestingly, RMSF cases in Nebraska have increased on a year-to-year basis, yet the prevalence of R. rickettsii in D.

Assessing the Contribution of an HtrA Family Serine Protease During Mammalian Infection.

Tick-borne relapsing fever (TBRF), characterized by recurring febrile episodes, is globally distributed and among the most common bacterial infections in some African countries. Despite the public health concern that this disease represents, little is known regarding the virulence determinants required by TBRF during infection. Because the chromosomes of TBRF show extensive colinearity with those of Lyme disease (LD) , the exceptions represent unique genes encoding proteins that are potentially essential to the disparate enzootic cycles of these two groups of spirochetes.

Digital PCR-based Competitive Index for High-throughput Analysis of Fitness in Salmonella.

A competitive index is a common method used to assess bacterial fitness and/or virulence. The utility of this approach is exemplified by its ease to perform and its ability to standardize the fitness of many strains to a wild-type organism. The technique is limited, however, by available phenotypic markers and the number of strains that can be assessed simultaneously, creating the need for a great number of replicate experiments.

Genetic and phenotypic variation of Phytophthora crassamura isolates from California nurseries and restoration sites.

Phenotypic and sequence data were used to characterize 28 isolates resembling Phytophthora megasperma from 14 host species in 2 plant production facilities and 10 restoration sites across the San Francisco Bay Area (California; USA). Size of the oogonia and DNA sequences (nuclear internal transcribed spacer (ITS) and mitochondrial cytochrome c oxidase subunit 1 (COX 1)) were compared, and sensitivity to mefenoxam and pathogenicity were measured. Based on ITS 61 % of isolates matched ex-type sequences of Phytophthora crassamura from Italy, and the remainder matched or were close to the P.

The relapsing fever spirochete Borrelia turicatae persists in the highly oxidative environment of its soft-bodied tick vector.

The relapsing fever spirochete Borrelia turicatae possesses a complex life cycle in its soft-bodied tick vector, Ornithodoros turicata. Spirochetes enter the tick midgut during a blood meal, and, during the following weeks, spirochetes disseminate throughout O. turicata.

DksA Controls the Response of the Lyme Disease Spirochete to Starvation.

The pathogenic spirochete senses and responds to changes in the environment, including changes in nutrient availability, throughout its enzootic cycle in ticks and vertebrate hosts. This study examined the role of DnaK suppressor protein (DksA) in the transcriptional response of to starvation. Wild-type and mutant strains were subjected to starvation by shifting cultures grown in rich complete medium, Barbour-Stoenner-Kelly II (BSK II) medium, to a defined mammalian tissue culture medium, RPMI 1640, for 6 h under microaerobic conditions (5% CO, 3% O).

serovar Typhimurium has three transketolase enzymes contributing to the pentose phosphate pathway.

The genus is responsible for many illnesses in humans and other vertebrate animals. We report here that serovar Typhimurium harbors three transketolases that support the non-oxidative branch of the pentose phosphate pathway. BLAST analysis identified two genes, _ and _, that together encode a putative transketolase (TktC) with 46-47% similarity to the known TktA and TktB isoforms.

Multiple origins of downy mildews and mito-nuclear discordance within the paraphyletic genus Phytophthora.

Phylogenetic relationships between thirteen species of downy mildew and 103 species of Phytophthora (plant-pathogenic oomycetes) were investigated with two nuclear and four mitochondrial loci, using several likelihood-based approaches. Three Phytophthora taxa and all downy mildew taxa were excluded from the previously recognized subgeneric clades of Phytophthora, though all were strongly supported within the paraphyletic genus. Downy mildews appear to be polyphyletic, with graminicolous downy mildews (GDM), brassicolous downy mildews (BDM) and downy mildews with colored conidia (DMCC) forming a clade with the previously unplaced Phytophthora taxon totara; downy mildews with pyriform haustoria (DMPH) were placed in their own clade with affinities to the obligate biotrophic P.