Diagnosis and detection of the main bacterial pathogens of stone fruit and almond

Diagnosis and detection are key aspects related to plant health status. A critical review of the available diagnostic methods utilised for Agrobacterium rhizogenes and A. tumefaciens, Pseudomonas amygdali, P. yringae pv. mors-prunorum, P. syringae pv. persicae, P. syringae pv. syringae and Xanthomonas arboricola pv. pruni, the main pathogens of the stone fruit trees, is presented. As there is a general lack of updated standardized protocols for the detection of most of these bacteria, the most appropriate media for their isolation are reported along with serological reagents, PCR and real-time PCR protocols with comments on their accuracy for the analysis of these pathogens in plant samples. There are many selective media for isolation, especially for Agrobacterium spp., but fewer for Pseudomonas spp. and X. arboricola pv. pruni. Serological techniques are not very useful for these pathogens due to the current lack of specific antibodies commercially available. As to molecular methods, it is surprising to find so many PCR protocols for Agrobacterium species, very few and unspecific for the Pseudomonas species pathogenic to stone fruit trees, and several recent PCR protocols for X. arboricola pv. pruni. The new advances in genomics and proteomics will provide information for selecting new targets to develop specific and sensitive techniques for the diagnosis and detection of these bacterial pathogens in plant material.The authors thank the contributions of the participants in the EU-COST Action 873 and the project RF2009-00002-C04-01 “Prospección, ecolección, conservación y caracterización de nuevo germoplasma de melocotonero”

Draft genome sequence for virulent and avirulent strains of Xanthomonas arboricola isolated from Prunus spp. in Spain

Xanthomonas arboricola is a species in genus Xanthomonas which is mainly comprised of plant pathogens. Among the members of this taxon, X. arboricola pv. pruni, the causal agent of bacterial spot disease of stone fruits and almond, is distributed worldwide although it is considered a quarantine pathogen in the European Union. Herein, we report the draft genome sequence, the classification, the annotation and the sequence analyses of a virulent strain, IVIA 2626.1, and an avirulent strain, CITA 44, of X. arboricola associated with Prunus spp. The draft genome sequence of IVIA 2626.1 consists of 5,027,671 bp, 4,720 protein coding genes and 50 RNA encoding genes. The draft genome sequence of strain CITA 44 consists of 4,760,482 bp, 4,250 protein coding genes and 56 RNA coding genes. Initial comparative analyses reveals differences in the presence of structural and regulatory components of the type IV pilus, the type III secretion system, the type III effectors as well as variations in the number of the type IV secretion systems. The genome sequence data for these strains will facilitate the development of molecular diagnostics protocols that differentiate virulent and avirulent strains. In addition, comparative genome analysis will provide insights into the plant-pathogen interaction during the bacterial spot disease process.Publishe

Comparative Genomic and Phenotypic Characterization of Pathogenic and Non-Pathogenic Strains of Xanthomonas arboricola Reveals Insights into the Infection Process of Bacterial Spot Disease of Stone Fruits

Xanthomonas arboricola pv. pruni is the causal agent of bacterial spot disease of stone fruits, a quarantinable pathogen in several areas worldwide, including the European Union. In order to develop efficient control methods for this disease, it is necessary to improve the understanding of the key determinants associated with host restriction, colonization and the development of pathogenesis. After an initial characterization, by multilocus sequence analysis, of 15 strains of X. arboricola isolated from Prunus, one strain did not group into the pathovar pruni or into other pathovars of this species and therefore it was identified and defined as a X. arboricola pv. pruni look-a-like. This non-pathogenic strain and two typical strains of X. arboricola pv. pruni were selected for a whole genome and phenotype comparative analysis in features associated with the pathogenesis process in Xanthomonas. Comparative analysis among these bacterial strains isolated from Prunus spp. and the inclusion of 15 publicly available genome sequences from other pathogenic and non-pathogenic strains of X. arboricola revealed variations in the phenotype associated with variations in the profiles of TonB-dependent transporters, sensors of the two-component regulatory system, methyl accepting chemotaxis proteins, components of the flagella and the type IV pilus, as well as in the repertoire of cell-wall degrading enzymes and the components of the type III secretion system and related effectors. These variations provide a global overview of those mechanisms that could be associated with the development of bacterial spot disease. Additionally, it pointed out some features that might influence the host specificity and the variable virulence observed in X. arboricola.Publishe

Soil organic matter fractions under long-term conservation tillage in rainfed Aragon (NE Spain)

1 Pag.Peer reviewe

El fuego bacteriano ‘Erwinia amylovora’

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La implantación de las tecnologías en el mercado laboral.

El trabajo se estructura en seis capítulos comenzando sobre la legislación sobre las nuevas tecnologías y las medidas tomadas por Europa para afrontar esta nueva era.En el capítulo segundo lo centramos en la Web 2.0, analizando a través de tres puntos, lo qué es, como es su implantación en la empresa, así como una entrevista hacia un pequeño grupo de emprendedores que aprovechando este boom tecnológico ha decidido centrarse en esta actividad.En el siguiente capítulo, se trata el tema del registro de la jornada, así como las diferentes tecnologías utilizadas para el mismo, unido a la obligatoriedad de su implantación que se exige a las empresas.En el cuarto capítulo, debido a la veloz implantación de las tecnologías en las empresas, hablamos del derecho de dirección y control del empresario, y su enfrentamiento con el derecho a la intimidad de los trabajadores.El quinto capítulo hace referencia a empresas como Glovo y Deliveroo, las cuales han implantado innovadores sistemas de gestión que no cumplen completamente con la legislación, pero a su vez dan una nueva visión de negocio el cual no se había regulado.Finalmente analizaremos los capítulos anteriormente estudiados en las conclusiones. <br /

Criteria for efficient prevention of dissemination and successful eradication of Erwinia amylovora (the cause of fire blight) in Aragón, Spain

Erwinia amylovora was detected on pome fruits in the Aragón region (North-Eastern Spain), in a ca. 5 km radius area located in the mid Jalón river (mid Ebro Valley) in the province of Zaragoza, during 2000‒2003. Eight years have now passed since this pathogen was last detected, without new infections being reported in the same area. The bases for surveys and rapid eradication performed have been analyzed in detail to understand the reasons for the success in removing fireblight. The results demonstrate that intensive surveillance, risk assessment, plant analyses using accurate identification methods, and, especially, rapid total or selective eradication of infected trees in the plots have been very effective in preventing the generalized spread of fireblight and in delaying economic losses associated with this disease. Eradication and compensation to growers, estimated to cost approx. € 467,000, were clearly counterbalanced by the economic value of apple and pear production in the 2000‒2003 period (approx. € 368 million). Fire blight risk-assessment, using the MARYBLYT system, showed that climatic conditions in the studied area were favourable to infections during the analyzed period (1997‒2006). Molecular characterization of E. amylovora strains had revealed their homogeneity, suggesting that these fire blight episodes could have been caused by just one inoculum source, supporting the hypothesis that there was a unique introduction of E. amylovora in the studied area. Spatial spread of E. amylovora to trees was analyzed within six orchards, indicating an aggregated distribution model. This Spanish experience demonstrates the success of scientifically-based prevention methods that lead to the deployment of a fast and strict containment strategy, useful for other Mediterranean areassurveysrisk-assessmentspatial analysisstrain characterizationPublishe

A reliable qPCR technique for detecting viable Xanthomonas arboricola pv. pruni cells

Xanthomonas arboricola pv. pruni (Xap) is the causal agent of bacterial spot of stone fruits and almond (Prunus spp). Detection of Xap is typically carried out using quantitative real-time PCR (qPCR) combined with culture-based isolation. However, qPCR does not differentiate between viable and dead cells, potentially leading to an overestimation of the infective population in a sample. Such overestimation could result in unnecessary phytosanitary measures. The present study aims to develop a specific protocol ideally targeting to detection of only live Xap bacterial cells. To address this challenge, the viable quantitative PCR (v-qPCR) method was evaluated using three nucleic acid-binding dyes: propidium monoazide (PMA), a combination of PMA and ethidium monoazide (EMA), and PMAxx™, an improved version of PMA. PMAxx™ proved to be the most suitable dye for the detection and quantification of living bacterial cells. This methodology was also evaluated in infected plant material over time and can be considered a rapid and reliable alternative to PCR methods for detecting only those putative infective Xap that may pose a risk for Prunus crops.Este trabajo fue financiado por el proyecto PID2021-123600ORC44, con el apoyo de MICIU/AEI/https://doi.org/10.13039/501100011033 y por el FEDER, UECut-off CtLODXanthomonas arboricola pv. pruniV-qPCRIntercalating dyeViable cell detectionPublishe

Protocolo de detección de bacterias viables por QPCR

Este trabajo forma parte de los proyectos RTI2018-96018-R-C31 y PID2021- 123600OR, financiados por MCIN/ AEI /10.13039/501100011033/ y por “FEDER Una manera de hacer Europa”