Pest survey card on Pseudocercospora angolensis

This pest survey card was prepared in the context of the EFSA mandate on plant pest surveillance (M-2020-0114), at the request of the European Commission. Its purpose is to guide the Member States in preparing data and information for Pseudocercospora angolensis surveys. These are required to design statistically sound and risk-based pest surveys, in line with current international standards. The fungus P. angolensis is a clearly defined taxonomic entity affecting Citrus species. Pseudocercospora angolensis is a Union quarantine pest not known to occur in the EU. The import of host plants is prohibited from third countries while special requirements are in place for the import of host fruit, which is the main pathway for the entry of this pest into the EU. Pseudocercospora angolensis produces conidia on lesions in plant tissues that can be disseminated by wind and/or rain, but dispersal distances are not known. Mild temperatures and prolonged periods of wetness are necessary for infection. Lesions on the leaves and fruit appear two to three weeks after infection. All commercial citrus species are susceptible to the fungus. Due to the wide availability of host species and climatic suitability, all citrus-growing areas in the EU are considered potentially suitable for the establishment of the pest. Long-distance spread is likely to occur through the movement of infected plant material. To increase the likelihood of detecting the pest, visual examination of symptoms should preferably be conducted in autumn before the harvest period. Symptoms caused by P. angolensis are non-specific; therefore, visual examination should be followed by molecular tests to identify the pest. Three main approaches for identifying P. angolensis in the laboratory are presented. Based on the analyses of the information on the pest–host plant system, the various units that are needed to design a survey should be defined and tailored to the situation in each Member State

Pest survey card on Elsinoë australis, E. citricola and E. fawcettii

This pest survey card was prepared in the context of the EFSA mandate on plant pest surveillance (M-2020-0114), at the request of the European Commission. Its purpose is to guide the Member States in preparing data and information for Elsinoë australis, E. citricola and E. fawcettii surveys. These are required to design statistically sound and risk-based pest surveys, in line with current international standards. The fungi E. australis, E. citricola and E. fawcettii are clearly defined taxonomic entities causing scab on citrus. Elsinoë australis, E. citricola and E. fawcettii are Union quarantine pests. The import of citrus plants is prohibited while general requirements are in place for the import of citrus fruit, which are the main pathway for entry of these pests into the EU. Elsinoë australis and E. fawcettii produce ascospores in the leaf litter and conidia on lesions in plant tissues that can be disseminated by rain splash and wind, but dispersal distances are not known. Mild temperatures and wetness are necessary for infection and lesions appear after four to six days. The commercial citrus species most relevant for the EU are susceptible to these three fungi. Due to the wide availability of host species and climatic suitability, all citrus-growing areas in the EU are considered potentially suitable for their establishment. Long-distance spread is likely to occur through the movement of infected plant material. To increase the likelihood of detecting the three fungi, visual examination of symptoms should be preferentially conducted in autumn before the harvest period. Symptoms caused by E. australis, E. citricola and E. fawcettii are non-specific, so visual examination should be followed by molecular tests to identify the pests. Based on the analyses of the information on the pest–host plant system, the various units that are needed to design a survey should be defined and tailored to the situation in each Member State

A New Resource for Research and Risk Analysis: The Updated European Food Safety Authority Database of Xylella spp. Host Plant Species.

Following a series of requests for scientific advice from the European Commission starting in 2013, the European Food Safety Authority (EFSA) conducted a pest risk assessment and created a comprehensive Xylella fastidiosa host plant database. The last update of the database, published in September 2018, includes information on host plants of both X. fastidiosa and X. taiwanensis, together with details on botanical classification, infection conditions, geographic location, pathogen taxonomy including information on subspecies, strain and sequence type, detection techniques, and tolerant/resistant response of the plant. This updated database of host plants of Xylella spp. reported worldwide provides a key tool for risk management, risk assessment, and research on this generalist bacterial plant pathogen

Pest survey card on Citrus leprosis viruses

This pest survey card was prepared in the context of the EFSA mandate on plant pest surveillance (M-2020-0114), at the request of the European Commission. Its purpose is to guide the Member States in preparing data and information for surveys of citrus leprosis viruses. These are required to design statistically sound and risk-based pest surveys, in line with current international standards. Six of the seven viruses that cause citrus leprosis (CiLV-C, CiLV-C2, HGSV-2, OFV, CiLV-N sensu novo and CiCSV) are clearly defined taxonomic entities, while the status of CiBSV is unclear. CiLV-C, CiLV-C2, HGSV-2, the citrus strain of OFV, CiLV-N sensu novo and CiCSV are Union quarantine pests. Citrus leprosis viruses do not cause systemic infections and they are all exclusively transmitted by mites of the genus Brevipalpus. Brevipalpus mites associated with the transmission of the leprosis disease are present in some regions of EU territory. The commercial citrus species most relevant to the EU are considered susceptible to citrus leprosis disease. There are no ecoclimatic constrains known for the citrus leprosis viruses, except for those affecting their host plants and their mite vectors. Therefore, due to the wide availability of host species and the presence of Brevipalpus mites, all citrus-growing areas in the EU are considered potentially suitable for the viruses to become established. Long-distance spread is likely to occur through movement of viruliferous mites phoretically associated with commodities. Detection of citrus leprosis viruses in the field should be performed by visual examination of symptoms followed by sampling and molecular identification in the laboratory. Visual examination should be preferably conducted in late summer / early autumn. Based on the analyses of the information on the pest-host plant system, the various units that are needed to design a survey should be defined and tailored to the situation in each Member State

Effectiveness of in planta control measures for Xylella fastidiosa

This opinion updates the information included in the previous EFSA Scientific Opinion concerning the in planta control measures for Xylella fastidiosa, with a systematic review and critical analysis of the potential treatment solutions that have been published against this pest so far. The output of this opinion focuses on the application of chemical or biological treatments on living plants. In vitro studies, hot water treatments, use of resistant varieties and vector control are excluded from the review. The use of antibiotics is not considered due to the risk of antimicrobial resistance development. The use of weakly virulent or avirulent strains of X. fastidiosa is covered in this review, although this organism is an EU quarantine plant pest and its introduction in the EU territory is banned. Experiments were recently conducted to assess the effect of application of zinc, copper, and citric acid biocomplex, of N-acetylcysteine, and of ‘diffusible signal factor’ (and of its homologs). Their results showed that these control measures were sometimes able to reduce symptoms caused by X. fastidiosa. Recent experiments also showed that several species of endophytic microorganisms, some bacteriophages and inoculation of weakly virulent/avirulent strains of X. fastidiosa could offer some protection against the Pierce’s disease. However, based on the reviewed results, the Panel concludes that, although several published experiments show some effects in reducing symptoms development, the tested control measures are not able to completely eliminate X. fastidiosa from diseased plants. The Panel confirms as previously stated that there is currently no control measure available to eliminate the bacteria from a diseased plant in open field conditions

Mécanismes moléculaires à l'origine de la pathogenicité de phytovirus de betterave sucrière transmis par un vecteur tellurique

The genus Benyvirus includes the most important and widespread sugar beet viruses transmitted through the soil by the plasmodiophorid Polymyxa betae. In particular Beet necrotic yellow vein virus (BNYVV), the leading infectious agent that affects sugar beet, causes an abnormal rootlet proliferation known as rhizomania. Beet soil-borne mosaic virus (BSBMV) is widely distributed in the United States and, up to date has not been reported in others countries. My PhD project aims to investigate molecular interactions between BNYVV and BSBMV and the mechanisms involved in the pathogenesis of these viruses.BNYVV full-length infectious cDNA clones were available as well as full-length cDNA clones of BSBMV RNA-1, -2, -3 and -4. Handling of these cDNA clones in order to produce in vitro infectious transcripts need sensitive and expensive steps, so Ideveloped agroclones of BNYVV and BSBMV RNAs, as well as viral replicons allowing the expression of different proteins.Chenopodium quinoa and Nicotiana benthamiana plants have been infected with in vitro transcripts and agroclones to investigate the interaction between BNYVV and BSBMV RNA-1 and -2 and the behavior of artificial viral chimeras. Simultaneously I characterized BSBMV p14 and demonstrated that it is a suppressor of posttranscriptional gene silencing sharing common features with BNYVV p14.Le virus des nervures jaunes et nécrotiques de la betterave (Beet necrotic yellow vein virus, BNYVV) est l’agent infectieux responsable de la rhizomanie de la betterave sucrière, une maladie caractérisée par une prolifération anarchique du chevelu racinaire. Le Beet soil-borne mosaic virus (BSBMV) appartient également au genre Benyvirus mais n’est retrouvé qu’en Amérique du Nord. Ce virus, identifié pour la première fois au Texas, est morphologiquement et génétiquement semblable au BNYVV mais sérologiquement éloigné. Compte tenu des différences moléculaires existant, le BSBMV et BNYVV correspondent à deux espèces virales distinctes. Mon projet de thèse a consisté à étudier les interactions moléculaires entre le BNYVV et le BSBMV et rechercher les mécanismes impliqués dans la pathogénicité de ces deux virus. Des clones complets cDNA infectieux du BNYVV étaient disponibles, tout comme ceux de BSBMV. Compte tenu de l’aspect versatile de l’obtention de transcrits infectieux de ces différents clones, j’ai entrepris de produire des clones cDNA de chacun des ARN viraux sous contrôle d’un promoteur constitutive végétal pour initier l’infection par agroinfiltration. Les plantes hôtes Chenopodium quinoa et Nicotiana benthamiana ont été inoculées par des transcrits et agroinfiltrées pour initier l’infection virale et étudier l’interaction entre les ARN génomiques 1 et 2 des deux virus et étudier les propriétés de constructions chimères. En parallèle à ce travail, j’ai réalisé la caractérisation du suppresseur de RNA silencing du BSBMV en le comparant à celui du BNYVV

Mécanismes moléculaires à l'origine de la pathogenicité de phytovirus de betterave sucrière transmis par un vecteur tellurique

Le virus des nervures jaunes et nécrotiques de la betterave (Beet necrotic yellow vein virus, BNYVV) est l’agent infectieux responsable de la rhizomanie de la betterave sucrière, une maladie caractérisée par une prolifération anarchique du chevelu racinaire. Le Beet soil-borne mosaic virus (BSBMV) appartient également au genre Benyvirus mais n’est retrouvé qu’en Amérique du Nord. Ce virus, identifié pour la première fois au Texas, est morphologiquement et génétiquement semblable au BNYVV mais sérologiquement éloigné. Compte tenu des différences moléculaires existant, le BSBMV et BNYVV correspondent à deux espèces virales distinctes. Mon projet de thèse a consisté à étudier les interactions moléculaires entre le BNYVV et le BSBMV et rechercher les mécanismes impliqués dans la pathogénicité de ces deux virus. Des clones complets cDNA infectieux du BNYVV étaient disponibles, tout comme ceux de BSBMV. Compte tenu de l’aspect versatile de l’obtention de transcrits infectieux de ces différents clones, j’ai entrepris de produire des clones cDNA de chacun des ARN viraux sous contrôle d’un promoteur constitutive végétal pour initier l’infection par agroinfiltration. Les plantes hôtes Chenopodium quinoa et Nicotiana benthamiana ont été inoculées par des transcrits et agroinfiltrées pour initier l’infection virale et étudier l’interaction entre les ARN génomiques 1 et 2 des deux virus et étudier les propriétés de constructions chimères. En parallèle à ce travail, j’ai réalisé la caractérisation du suppresseur de RNA silencing du BSBMV en le comparant à celui du BNYVV.The genus Benyvirus includes the most important and widespread sugar beet viruses transmitted through the soil by the plasmodiophorid Polymyxa betae. In particular Beet necrotic yellow vein virus (BNYVV), the leading infectious agent that affects sugar beet, causes an abnormal rootlet proliferation known as rhizomania. Beet soil-borne mosaic virus (BSBMV) is widely distributed in the United States and, up to date has not been reported in others countries. My PhD project aims to investigate molecular interactions between BNYVV and BSBMV and the mechanisms involved in the pathogenesis of these viruses.BNYVV full-length infectious cDNA clones were available as well as full-length cDNA clones of BSBMV RNA-1, -2, -3 and -4. Handling of these cDNA clones in order to produce in vitro infectious transcripts need sensitive and expensive steps, so Ideveloped agroclones of BNYVV and BSBMV RNAs, as well as viral replicons allowing the expression of different proteins.Chenopodium quinoa and Nicotiana benthamiana plants have been infected with in vitro transcripts and agroclones to investigate the interaction between BNYVV and BSBMV RNA-1 and -2 and the behavior of artificial viral chimeras. Simultaneously I characterized BSBMV p14 and demonstrated that it is a suppressor of posttranscriptional gene silencing sharing common features with BNYVV p14

Molecular mechanisms involved in the pathogenesis of beet soil-borne viruses.

The genus Benyvirus includes the most important and widespread sugar beet viruses transmitted through the soil by the plasmodiophorid Polymyxa betae. In particular Beet necrotic yellow vein virus (BNYVV), the leading infectious agent that affects sugar beet, causes an abnormal rootlet proliferation known as rhizomania. Beet soil-borne mosaic virus (BSBMV) is widely distributed in the United States and, up to date has not been reported in others countries. My PhD project aims to investigate molecular interactions between BNYVV and BSBMV and the mechanisms involved in the pathogenesis of these viruses. BNYVV full-length infectious cDNA clones were available as well as full-length cDNA clones of BSBMV RNA-1, -2, -3 and -4. Handling of these cDNA clones in order to produce in vitro infectious transcripts need sensitive and expensive steps, so I developed agroclones of BNYVV and BSBMV RNAs, as well as viral replicons allowing the expression of different proteins. Chenopodium quinoa and Nicotiana benthamiana plants have been infected with in vitro transcripts and agroclones to investigate the interaction between BNYVV and BSBMV RNA-1 and -2 and the behavior of artificial viral chimeras. Simultaneously I characterized BSBMV p14 and demonstrated that it is a suppressor of post-transcriptional gene silencing sharing common features with BNYVV p14

Mécanismes moléculaires à l'origine de la pathogenicité de phytovirus de betterave sucrière transmis par un vecteur tellurique

Le virus des nervures jaunes et nécrotiques de la betterave (Beet necrotic yellow vein virus, BNYVV) est l agent infectieux responsable de la rhizomanie de la betterave sucrière, une maladie caractérisée par une prolifération anarchique du chevelu racinaire. Le Beet soil-borne mosaic virus (BSBMV) appartient également au genre Benyvirus mais n est retrouvé qu en Amérique du Nord. Ce virus, identifié pour la première fois au Texas, est morphologiquement et génétiquement semblable au BNYVV mais sérologiquement éloigné. Compte tenu des différences moléculaires existant, le BSBMV et BNYVV correspondent à deux espèces virales distinctes. Mon projet de thèse a consisté à étudier les interactions moléculaires entre le BNYVV et le BSBMV et rechercher les mécanismes impliqués dans la pathogénicité de ces deux virus. Des clones complets cDNA infectieux du BNYVV étaient disponibles, tout comme ceux de BSBMV. Compte tenu de l aspect versatile de l obtention de transcrits infectieux de ces différents clones, j ai entrepris de produire des clones cDNA de chacun des ARN viraux sous contrôle d un promoteur constitutive végétal pour initier l infection par agroinfiltration. Les plantes hôtes Chenopodium quinoa et Nicotiana benthamiana ont été inoculées par des transcrits et agroinfiltrées pour initier l infection virale et étudier l interaction entre les ARN génomiques 1 et 2 des deux virus et étudier les propriétés de constructions chimères. En parallèle à ce travail, j ai réalisé la caractérisation du suppresseur de RNA silencing du BSBMV en le comparant à celui du BNYVV.The genus Benyvirus includes the most important and widespread sugar beet viruses transmitted through the soil by the plasmodiophorid Polymyxa betae. In particular Beet necrotic yellow vein virus (BNYVV), the leading infectious agent that affects sugar beet, causes an abnormal rootlet proliferation known as rhizomania. Beet soil-borne mosaic virus (BSBMV) is widely distributed in the United States and, up to date has not been reported in others countries. My PhD project aims to investigate molecular interactions between BNYVV and BSBMV and the mechanisms involved in the pathogenesis of these viruses.BNYVV full-length infectious cDNA clones were available as well as full-length cDNA clones of BSBMV RNA-1, -2, -3 and -4. Handling of these cDNA clones in order to produce in vitro infectious transcripts need sensitive and expensive steps, so Ideveloped agroclones of BNYVV and BSBMV RNAs, as well as viral replicons allowing the expression of different proteins.Chenopodium quinoa and Nicotiana benthamiana plants have been infected with in vitro transcripts and agroclones to investigate the interaction between BNYVV and BSBMV RNA-1 and -2 and the behavior of artificial viral chimeras. Simultaneously I characterized BSBMV p14 and demonstrated that it is a suppressor of posttranscriptional gene silencing sharing common features with BNYVV p14.STRASBOURG-Bib.electronique 063 (674829902) / SudocSudocFranceF

EFSA activities on Pest Surveillance - EPPO Panels on Diagnostics in Virology, Mycology, Entomology, Bacteriology and Nematology

Presentations of EFSA activities on Pest Surveillance for EPPO Panels on Diagnostics in Virology (3 May), Mycology (7 September), Entomology (14 September), Bacteriology (11 October) and Nematology (8 November).EU; en; PDF; [email protected]