Test de détection de Xanthomonas axonopodis pv. allii

La présente invention se rapporte à de nouveaux outils de détection de Xanthomonas axonopodis pv. allii, en particulier la détection moléculaire de séquences polynucléotidiques spécifiques de cette souche. (Résumé d'auteur

Variation in physiological host range in three strains of two species of the entomopathogenic fungus Beauveria

Knowledge of the host range of a biocontrol agent (BCA) is fundamental. Host range determines the BCA's economic potential, as well as the possible risk for non-target organisms. Entomopathogenic fungal strains belonging to the genus Beauveria are widely used as BCA, but our knowledge of their physiological host range is only partial. The aim of this study was to improve our understanding of the physiological host range of three Beauveria strains belonging to two species, B. hoplocheli and B. bassiana. We performed laboratory mortality bioassays to assess their pathogenicity and virulence against nine insect pests, belonging to three orders: Lepidoptera, Coleoptera and Diptera. Mortality rate, mean survival time and mycosis rate were used to estimate virulence. Pathogenicity was assessed as the capacity to cause a disease and induce mortality. Virulence was assessed as the severity of the disease based on mortality rate, mean survival time and mycosis rate. The results of this study revealed significant differences in the physiological host range of the three Beauveria strains tested. The three strains were pathogenic to all Diptera and Lepidoptera species tested. In the case of the Coleoptera, only the B. hoplocheli strain was pathogenic to the white grub Hoplochelus marginalis and only the B. bassiana strains were pathogenic to Alphitobius diaperinus. The B. hoplocheli strain was less virulent on Lepidoptera and Diptera than the two B. bassiana strains. The latter both exhibited very similar virulence patterns. The fact that B. hoplocheli and B. bassiana strains have different host ranges means that they can be used as BCA to target different pests. Impacts on non-target insects across multiple orders cannot be ruled out in the absence of ecological host range studies

Adaptation of genetically monomorphic bacteria: evolution of copper resistance through multiple horizontal gene transfers of complex and versatile mobile genetic elements

Copper-based antimicrobial compounds are widely used to control plant bacterial pathogens. Pathogens have adapted in response to this selective pressure. Xanthomonas citri pv. citri, a major citrus pathogen causing Asiatic citrus canker, was first reported to carry plasmid-encoded copper resistance in Argentina. This phenotype was conferred by the copLAB gene system. The emergence of resistant strains has since been reported in Réunion and Martinique. Using microsatellite-based genotyping and copLAB PCR, we demonstrated that the genetic structure of the copper-resistant strains from these three regions was made up of two distant clusters and varied for the detection of copLAB amplicons. In order to investigate this pattern more closely, we sequenced six copper-resistant X. citri pv. citri strains from Argentina, Martinique and Réunion, together with reference copper-resistant Xanthomonas and Stenotrophomonas strains using long-read sequencing technology. Genes involved in copper resistance were found to be strain-dependent with the novel identification in X. citri pv. citri of copABCD and a cus heavy metal efflux resistance-nodulation-division system. The genes providing the adaptive trait were part of a mobile genetic element similar to Tn3-like transposons and included in a conjugative plasmid. This indicates the system's great versatility. The mining of all available bacterial genomes suggested that, within the bacterial community, the spread of copper resistance associated to mobile elements and their plasmid environments was primarily restricted to the Xanthomonadaceae family

Method and kits for detecting SARS viral infection in a biological sample

The invention relates to a method of detecting the presence of a SARS coronavims nucleic acid, comprising: - contacting the biological sample with a sample buffer comprising a set of loop-mediated isothermal amplification primers specific for the SARS .. nucleic acid under conditions sufficient for a loop-mediated isothermal amplification, i.e. LAMP, of the SARS nucleic acid, wherein the set of LAMP primers comprises six primers of SEQ ID NOs: I- 7, thereby producing a SARS amplification sample; - carrying out the LAMP from the SARS amplification sample, thereby producing a SARS amplification product ; and - detecting the SARS amplification product, thereby detecting the presence of the SARS nucleic acid in the sample

Pathotyping Citrus Ornamental Relatives with Xanthomonas citri pv. citri and X. citri pv. aurantifolii Refines Our Understanding of Their Susceptibility to These Pathogens

Xanthomonas citri pv. citri (Xcc) and X. citri pv. aurantifolii (Xca) are causal agents of Citrus Bacterial Canker (CBC), a devastating disease that severely affects citrus plants. They are harmful organisms not reported in Europe or the Mediterranean Basin. Host plants are in the Rutaceae family, including the genera Citrus, Poncirus, and Fortunella, and their hybrids. In addition, other genera of ornamental interest are reported as susceptible, but results are not uniform and sometimes incongruent. We evaluated the susceptibility of 32 ornamental accessions of the Rutaceae family belonging to the genera Citrus, Fortunella, Atalantia, Clausena, Eremocitrus, Glycosmis, Microcitrus, Murraya, Casimiroa, Calodendrum, and Aegle, and three hybrids to seven strains of Xcc and Xca. Pathotyping evaluation was assessed by scoring the symptomatic reactions on detached leaves. High variability in symptoms and bacterial population was shown among the different strains in the different hosts, indicative of complex host-pathogen interactions. The results are mostly consistent with past findings, with the few discrepancies probably due to our more complete experimental approach using multiple strains of the pathogen and multiple hosts. Our work supports the need to regulate non-citrus Rutaceae plant introductions into areas, like the EU and Mediterranean, that are currently free of this economically important pathogen

Pathotyping Citrus Ornamental Relatives with Xanthomonas citri pv. citri and X. citri pv. aurantifolii Refines Our Understanding of Their Susceptibility to These Pathogens

Xanthomonas citri pv. citri (Xcc) and X. citri pv. aurantifolii (Xca) are causal agents of Citrus Bacterial Canker (CBC), a devastating disease that severely affects citrus plants. They are harmful organisms not reported in Europe or the Mediterranean Basin. Host plants are in the Rutaceae family, including the genera Citrus, Poncirus, and Fortunella, and their hybrids. In addition, other genera of ornamental interest are reported as susceptible, but results are not uniform and sometimes incongruent. We evaluated the susceptibility of 32 ornamental accessions of the Rutaceae family belonging to the genera Citrus, Fortunella, Atalantia, Clausena, Eremocitrus, Glycosmis, Microcitrus, Murraya, Casimiroa, Calodendrum, and Aegle, and three hybrids to seven strains of Xcc and Xca. Pathotyping evaluation was assessed by scoring the symptomatic reactions on detached leaves. High variability in symptoms and bacterial population was shown among the different strains in the different hosts, indicative of complex host-pathogen interactions. The results are mostly consistent with past findings, with the few discrepancies probably due to our more complete experimental approach using multiple strains of the pathogen and multiple hosts. Our work supports the need to regulate non-citrus Rutaceae plant introductions into areas, like the EU and Mediterranean, that are currently free of this economically important pathogen

INDICANTS project : INnovative DIagnostiCs for bANana paThogens Surveillance

The aim of the INDICANTS project is to develop innovative diagnostics for four banana wilt pathogens, including Fusarium oxysporum f. sp. cubense (Foc) TR4 (Fusarium wilt), Ralstonia solanacearum (Moko disease), R. syzygii subsp. celebesensis (Blood disease), and Xanthomonas vasicola pv. musacearum (Xanthomonas wilt). The main objectives are to: (I) develop low-cost LAMP (loop-mediated isothermal amplification) assays (II) compare simplified DNA extraction methods for field application; (III) validate the LAMP protocols via inter-laboratory and field tests. LAMP primer sets were designed for the bacterial pathogens, using in silico comparative genomic analysis of target and non-target genomes, and showed 100% specificity when tested with a wide range of target and non-target strains. A limit of detection of 104 CFU/ml was obtained for the LAMP assays. A simplified DNA extraction method from banana tissue was developed and successfully validated in a banana plantation infested with Foc TR4, using several candidate LAMP primer sets. Ready-to-use diagnostic kits, based on these protocols, are currently being developed by a private company. These point-of-care diagnostic tools will allow rapid identification of the different pathogens in the field for disease management

Indicants Project: Innovative diagnostic for banana pathogens surveilance [P4.2-086]

The aim of the INDICANTS project is to develop innovative diagnostics for four banana wilt pathogens, including Fusarium oxysporum f. sp. cubense (Foc) TR4 (Fusarium wilt), Ralstonia solanacearum (Moko disease), R. syzygii subsp. celebesensis (Blood disease), and Xanthomonas vasicola pv. musacearum (Xanthomonas wilt). The main objectives are to: (I) develop low-cost LAMP (loop-mediated isothermal amplification) assays (II) compare simplified DNA extraction methods for field application; (III) validate the LAMP protocols via inter-laboratory and field tests. LAMP primer sets were designed for the bacterial pathogens, using in silico comparative genomic analysis of target and non-target genomes, and showed 100% specificity when tested with a wide range of target and non-target strains. A limit of detection of 104 CFU/ml was obtained for the LAMP assays. A simplified DNA extraction method from banana tissue was developed and successfully validated in a banana plantation infested with Foc TR4, using several candidate LAMP primer sets. Ready-to-use diagnostic kits, based on these protocols, are currently being developed by a private company. These point-of-care diagnostic tools will allow rapid identification of the different pathogens in the field for disease management