Suchergebnisse

Depuis l'adoption d'une politique de libéralisation de l'économie, "le Doi moi", à la fin des années 1980, et son adhésion à l'OMC en 2007, le Vietnam connaît une croissance économique rapide qui touche tous les habitants. Cette croissance a transformé les structures et les habitudes alimentaires vietnamiennes. La demande de consommation de produits riches en protéines d'origine animale comme la viande fraîche, augmente. Par tradition, les vietnamiens continuent de consommer du porc mais diversifient aussi leur alimentation et adoptent de plus en plus le boeuf et la volaille. On observe aussi que les niveaux de consommation des ruraux se rapprochent de ceux des urbains. L'article propose donc une grille de lecture renouvelée, c'est à dire une analyse régionalisée des caractéristiques de la consommation de viande basée notamment sur l'enquête 2010 sur le niveau de vie des ménages (VHLSS) réalisée par l'Office Général de Statistique (GSO). Ainsi, après avoir identifié trois types de régions selon leur niveau de développement socio-économique, les auteurs montrent que ces dynamiques spatiales permettent de distinguer des niveaux de consommation de viande différenciés. On trouve alors que les différences de revenu expliquent moins les niveaux de consommation et que des régionalismes ressortent dans l'achat de viandes fraîches de boeuf, de poulet et d'autres volailles. Les régions pauvres concentrent la plus grande part de consommateurs de poulet ; dans les régions riches, c'est le cas pour la viande de boeuf ; les régions intermédiaires se tournent plus vers les autres volailles. Ainsi, comme dans tous les pays émergents, la transition alimentaire, débutée il y a 25 ans, a conduit à l'augmentation des besoins en viande mais elle s'appuie sur des dynamiques spatiales qui dans le cas du Vietnam restent encore à mieux caractériser.

International audience ; Xylella fastidiosa (Xf) is a quarantine plant pathogen bacterium originating from the Americas and that has emerged in Europe in 2013. Xf can be detected directly on plant macerate using molecular methods such as real-time PCR, which is a sensitive technique. However, some plants may contain components that can act as PCR reaction inhibitors, which can lead to false negative results or an underestimation of the bacterial concentration present in the analyzed plant sample. Droplet digital PCR (ddPCR) is an innovative tool based on the partitioning of the PCR reagents and the DNA sample into thousands of droplets, allowing the quantification of the absolute number of target DNA molecules present in a reaction mixture, or an increase of the detection sensitivity. In this study, a real-time PCR protocol, already used for Xf detection in the framework of official surveys in the European Union, was transferred and optimized for Xf detection using ddPCR. This new assay was evaluated and compared to the initial real-time PCR on five plant matrices artificially inoculated and on naturally infected plants. In our conditions, this new ddPCR enabled the detection of Xf on all artificially inoculated plant macerates with a similar limit of detection, or a slight benefit for Quercus ilex. Moreover, ddPCR improved diagnostic sensitivity as it enabled detection of Xf in samples of Polygala myrtifolia or Q. ilex that were categorized as negative or close to the limit of detection using the real-time PCR. Here, we report for the first time a ddPCR assay for the detection of the bacterium Xf.

International audience ; Xylella fastidiosa (Xf) is a quarantine plant pathogen bacterium originating from the Americas and that has emerged in Europe in 2013. Xf can be detected directly on plant macerate using molecular methods such as real-time PCR, which is a sensitive technique. However, some plants may contain components that can act as PCR reaction inhibitors, which can lead to false negative results or an underestimation of the bacterial concentration present in the analyzed plant sample. Droplet digital PCR (ddPCR) is an innovative tool based on the partitioning of the PCR reagents and the DNA sample into thousands of droplets, allowing the quantification of the absolute number of target DNA molecules present in a reaction mixture, or an increase of the detection sensitivity. In this study, a real-time PCR protocol, already used for Xf detection in the framework of official surveys in the European Union, was transferred and optimized for Xf detection using ddPCR. This new assay was evaluated and compared to the initial real-time PCR on five plant matrices artificially inoculated and on naturally infected plants. In our conditions, this new ddPCR enabled the detection of Xf on all artificially inoculated plant macerates with a similar limit of detection, or a slight benefit for Quercus ilex. Moreover, ddPCR improved diagnostic sensitivity as it enabled detection of Xf in samples of Polygala myrtifolia or Q. ilex that were categorized as negative or close to the limit of detection using the real-time PCR. Here, we report for the first time a ddPCR assay for the detection of the bacterium Xf.

International audience ; Xylella fastidiosa (Xf) is a quarantine plant pathogen bacterium originating from the Americas and that has emerged in Europe in 2013. Xf can be detected directly on plant macerate using molecular methods such as real-time PCR, which is a sensitive technique. However, some plants may contain components that can act as PCR reaction inhibitors, which can lead to false negative results or an underestimation of the bacterial concentration present in the analyzed plant sample. Droplet digital PCR (ddPCR) is an innovative tool based on the partitioning of the PCR reagents and the DNA sample into thousands of droplets, allowing the quantification of the absolute number of target DNA molecules present in a reaction mixture, or an increase of the detection sensitivity. In this study, a real-time PCR protocol, already used for Xf detection in the framework of official surveys in the European Union, was transferred and optimized for Xf detection using ddPCR. This new assay was evaluated and compared to the initial real-time PCR on five plant matrices artificially inoculated and on naturally infected plants. In our conditions, this new ddPCR enabled the detection of Xf on all artificially inoculated plant macerates with a similar limit of detection, or a slight benefit for Quercus ilex. Moreover, ddPCR improved diagnostic sensitivity as it enabled detection of Xf in samples of Polygala myrtifolia or Q. ilex that were categorized as negative or close to the limit of detection using the real-time PCR. Here, we report for the first time a ddPCR assay for the detection of the bacterium Xf.

In the frame of a project funded by the European Food Safety Authority (Prima Phacie), effort was put into identifying and testing qualitative plant-pest risk assessment schemes for their suitability in supporting risk management decisions for the European Union. Five schemes were tested, two largely based on the EPPO scheme and three adapted from schemes used in non-European countries. We report the results from the application of these schemes as applied to Xanthomonas citri strains causing Citrus Bacterial Canker, in regard to the risk of its entry, establishment and spread, as well as its potential impact. For this pathogen, three entry pathways into the EU risk assessment area were considered: a) import of fresh citrus fruits, b) import of ornamental rutaceous plants or plant parts, and c) illegal entry of plant propagative material. With the current EU measures in place, of the five schemes tested, two indicated path (c) as that of the highest risk, whereas the other three suggested path (a) as such. This discrepancy is due to the different level of details the components of the risk of entry are considered in each scheme. Most schemes suggested that the establishment potential lay around the mid-range of possible values. All schemes indicated a high rate for potential spread (primarily through human activities) and a medium to high rate for impact potential. The effectiveness of risk management measures was evaluated by comparing results of assessments with and without management measures in place. (Texte integral)

Asiatic canker, caused by Xanthomonas citri pv. citri, is a major threat to worldwide citriculture. Three pathotypes differing in host range and hypersensitive reactions toward citrus species have been defined. Whereas pathotypes Aw and A* have a restricted host range, X. citri pv. citri pathotype A infects a broader range including most commercial citrus species and hybrids and can cause important economic losses in tropical and subtropical areas. Pathotype A strains, especially those assigned to lineage 1, were implicated in the major geographical expansion of X. citri pv. citri during the 20th century from their native area, Asia (Pruvost et al. 2014). X. citri pv. citri is listed as a quarantine pathogen in the European Union (EU) – Directive 2000/29/EC annex II A1. Martinique (France) is an outermost region of the EU in the eastern Caribbean Sea. Canker lesions were first observed at Morne Rouge, Martinique in June 2014 on grapefruit (Citrus paradisi), mandarin (C. reticulata), Tahiti lime (C. latifolia), and Valencia and Washington Navel oranges (C. sinensis). Official diagnostics, including bacterial isolations on YPGA or KC semiselective medium (Pruvost et al. 2005), PCR-based identification with 4/7 primers (Hartung et al. 1993), and pathogenicity tests, were performed following the EPPO standard PM7/44 (www.eppo.int) and identified isolates as X. citri pv. citri. Three strains isolated in Martinique in 2014 from grapefruit or Tahiti lime were further characterized (LL074-4, LL077-2, and LL079). Multilocus sequence analysis (MLSA) targeting six housekeeping genes (atpD, dnaK, efp, gltA, gyrB, and lepA) (Almeida et al. 2010; Bui Thi Ngoc et al. 2010) identified Martinique strains as X. citri pv. citri with 100% sequence identity to the type strain LMG 9322. Using MLVA-31 targeting 31 minisatellites, Martinique strains were assigned to lineage 1 composed of pathotype A strains (Pruvost et al. 2014). All strains were inoculated by a detached leaf assay onto Mexican lime SRA 140 (C. aurantifolia), sweet orange Washington Navel SRA 102, and grapefruit Henderson SRA 336 (Bui Thi Ngoc et al. 2010). All inoculated leaves produced typical erumpent, callus-like tissue at wound sites. Xanthomonas-like colonies were reisolated from lesions that had developed. Boiled suspensions were assayed by PCR with 4/7 primers and produced the expected amplicon, fulfilling Koch's postulates. No lesions developed on the negative control consisting of sterile 0.01M tris buffer pH 7.2. This is the first report of X. citri pv. citri in Martinique and to our knowledge in the Caribbean region. Surprisingly, all strains collected to date in Martinique grew on YPGA supplemented with 300 mg liter−1 copper sulfate even when no extensive copper spray programs have been used, suggesting that copper-resistant strains may have been introduced. Disease is contained by tree removal and burning and the situation is presently under apparent control although positive trees were sporadically detected in 2015 in backyards or small orchards at Le Lorrain and Saint Pierre. An extensive surveillance program is currently implemented in Martinique for quarantine pathogens of citrus. (Texte intégral)