Genome sequence of Xanthomonas fuscans subsp. fuscans strain 4834-R reveals that flagellar motility is not a general feature of xanthomonads

Abstract\ud \ud \ud \ud Background\ud Xanthomonads are plant-associated bacteria responsible for diseases on economically important crops. Xanthomonas fuscans subsp. fuscans (Xff) is one of the causal agents of common bacterial blight of bean. In this study, the complete genome sequence of strain Xff 4834-R was determined and compared to other Xanthomonas genome sequences.\ud \ud \ud \ud Results\ud Comparative genomics analyses revealed core characteristics shared between Xff 4834-R and other xanthomonads including chemotaxis elements, two-component systems, TonB-dependent transporters, secretion systems (from T1SS to T6SS) and multiple effectors. For instance a repertoire of 29 Type 3 Effectors (T3Es) with two Transcription Activator-Like Effectors was predicted. Mobile elements were associated with major modifications in the genome structure and gene content in comparison to other Xanthomonas genomes. Notably, a deletion of 33 kbp affects flagellum biosynthesis in Xff 4834-R. The presence of a complete flagellar cluster was assessed in a collection of more than 300 strains representing different species and pathovars of Xanthomonas. Five percent of the tested strains presented a deletion in the flagellar cluster and were non-motile. Moreover, half of the Xff strains isolated from the same epidemic than 4834-R was non-motile and this ratio was conserved in the strains colonizing the next bean seed generations.\ud \ud \ud \ud Conclusions\ud This work describes the first genome of a Xanthomonas strain pathogenic on bean and reports the existence of non-motile xanthomonads belonging to different species and pathovars. Isolation of such Xff variants from a natural epidemic may suggest that flagellar motility is not a key function for in planta fitness.AI is funded by a PhD grant from INRA-SPE and region Pays de la Loire, France. EG was funded by a PhD grant from the French Ministry of National Education and Research and French Guyana. SC, EG, MA, EL and LDN are funded by the LABEX TULIP (ANR-10-LABX-41), LSG is funded by ANR-2010-GENM-013 Xanthomix

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Rôle des biofilms dans les stratégies de colonisation par Pseudomonas fluorescens des feuilles de scarole destinées à la 4ème gamme

* INRA Unité de Pathologie Végétale, Domaine St Maurice, 84143 Montfavet cedex Diffusion du document : INRA Unité de Pathologie Végétale, Domaine St Maurice, 84143 Montfavet cedex Diplôme : DE

Cires partiellement recristallisées comme modèle pour étudier l'adhésion bactérienne et la formation de biofilms à la surface des plantes

* INRA, Equipe Régionale Documentation, Domaine St Paul, Site Agroparc, 84914 Avignon cedex 9National audienc

Use of Chlorophyll Fluorescence Imaging to phenotype effectors impacts on Nicotiana benthamiana

National audienc

Thermography versus chlorophyll fluorescence imaging for detection and quantification of apple scab

Fluorescence imaging has recently been shown to be useful for the detection of apple scab, and thermal imaging for both detection and quantification of apple scab. We undertake a comparison of these two techniques and demonstrate the advantages of thermal imaging compared to fluorescence imaging to detect and quantify the presence of apple scab at the surface of leaves. We demonstrate, in practical environmental conditions of growth chambers, the advantages of thermal imaging compared to fluorescence imaging in terms of detection in the framework of a Neyman-Pearson strategy with the Bhattacharrya distance and ROC curves and in terms of quantification by establishing a linear relationship between percentage of leaf diseased area estimated visually and percentage of leaf area estimated by imaging segmentation. This opens perspectives for quantitative aspect of pathogenicity in the study of apple scab and constitutes a general framework for the comparison of nonconventional optical imaging applied to plant pathology. (C) 2012 Elsevier B.V. All rights reserved

utilisation de la thermographie et de l'imagerie de fluorescence pour la détection et la quantification de la tavelure à la surface de feuilles de pommier

International audienc

The AvrE superfamily: ancestral type III effectors involved in suppression of pathogen-associated molecular pattern-triggered immunity

International audienceThe AvrE superfamily of type III effectors (T3Es) is widespread among type III-dependent phytobacteria and plays a crucial role during bacterial pathogenesis. Members of the AvrE superfamily are vertically inherited core effectors, indicating an ancestral acquisition of these effectors in bacterial plant pathogens. AvrE-T3Es contribute significantly to virulence by suppressing pathogen-associated molecular pattern (PAMP)-triggered immunity. They inhibit salicylic acid-mediated plant defences, interfere with vesicular trafficking and promote bacterial growth in planta. AvrE-T3Es elicit cell death in both host and non-host plants independent of any known plant resistance protein, suggesting an original interaction with the plant immune system. Recent studies in yeast have indicated that they activate protein phosphatase 2A and inhibit serine palmitoyl transferase, the first enzyme of the sphingolipid biosynthesis pathway. In this review, we describe the current picture that has emerged from studies of the different members of this fascinating large family.</p

The impact of phenotypic and genotypic traits on integration of Pseudomonas fluorescens into epiphytic biofilms

* INRA, URD, Domaine Saint-Paul, Site Agroparc, 84914 Avignon, Cedex 9 Diffusion du document : INRA, URD, Domaine Saint-Paul, Site Agroparc, 84914 Avignon, Cedex 9International audienc