36 research outputs found

    Ultrastructural effects of PVYNTN infection of Capsicum annuum L. cv. Yolo Wonder generative organs; a first step in describing seed transmission

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    Potato virus Y NTN (PVYNTN), a member of the family Potyviridae, is one of the most important plant viruses. Despite common occurrence of seed transmission process in the Potyviridae, the number or routes of virion entry into seeds are still unclear. Embryos could probably be infected either through host embryogenesis processes or via infection of reproductive tissues, therefore both processes of virus transmission in seeds and pollen grains are likely to be related. Infection by PVY has been studied in detail in host vegetative organs. We investigated, for the first time the impact of infection by the necrotic strain of PVY on Capsicum annuum reproductive organs. We found PVYNTN particles inside C. annuum pollen grains and on the exine surfaces, and PVY epitopes were also found in pollen tubes. We postulate that the male gametophyte in C. annuum could be a source of PVY infection, which may have significance in self-pollinated hosts. We also demonstrated that PVYNTN particles could be detected inside C. annuum seeds on embryo surfaces, while particles and Potyvirus inclusion bodies were observed in endothelium layers. These were mainly detected inside ovarian tissues, that is, in the ovular integuments and nucelli. Changes in both gametophytes strongly indicate that generative organs were a source of PVYNTN infection. Furthermore, we have demonstrated that in C. annuum, PVY was transmitted vertically via seeds

    Detection of Banana mild mosaic virus and Banana virus X by polyvalent degenerate oligonucleotide RT-PCR (PDO-RT-PCR)

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    Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceViruses are important constraints to the movement and propagation of plant germplasm, especially for vegetatively propagated crops such as banana and plantain. Their control relies primarily on the use of virus-free plant material, whose production and certification requires sensitive and reliable detection methods. An existing polyvalent degenerate oligonucleotide RT-PCR (PDO-RT-PCR) assay was adapted to the detection of Banana mild mosaic virus (BanMMV) and Banana virus X, two Flexiviridae infecting Musa spp. PDO inosine-containing primers were found to be well suited to the detection of BanMMV, despite its high molecular diversity, but not to that of the highly conserved BVX, for which species-specific primers were designed. Sampling and sample processing steps were optimized in order to avoid nucleic acid purification prior to the reverse transcription step. A polyclonal anti-BanMMV antiserum was raised and successfully used for the immunocapture (IC) of BanMMV viral particles from leaf extracts, leading to the development of a PDO-IC-RT-nested PCR assay. Although the anti-BanMMV antiserum could to some extent recognize BVX viral particles, direct binding (DB) was shown to be a more efficient method for processing BVX-infected samples and a PDO-DB-RT-nested PCR assay was developed for the detection of BVX from leaf extracts

    Detection du virus de la mosaïque atténuée du bananier (BanMMV) et du virus X du bananier (BVX) par PDO RT PCR

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    National audienceDeux membres de la famile des Flexiviridae infectent des espĂšces du genre Musa, le virus de la mosaĂŻque attĂ©nuĂ©e du bananier (BanMMV) et le virus X du bananier (BVX). En infection simple, le BanMMV provoque des chloroses foliaires lĂ©gĂšres et transitoires sur les cultivars sensibles, et aucun symptĂŽme sur les autres. Cependant, il est responsable d'importantes nĂ©croses foliaires en infection mixte, notamment avec le CMV. Le BanMMV est majoritairement transmis par voie vĂ©gĂ©tative. En consĂ©quence, ce virus est devenu une contrainte importante pour la conservation, l'Ă©change et la propagation des musacĂ©es. Le BVX a pour sa part Ă©tĂ© dĂ©crit rĂ©cemment sur musacĂ©es en Guadeloupe. Aucun symptĂŽme n'a pu ĂȘtre associĂ© Ă  sa prĂ©sence. La mise au point d'outils sensibles et spĂ©cifiques de dĂ©tection de ces virus est nĂ©cessaire Ă  la certification du matĂ©riel vĂ©gĂ©tal, notamment celui produit par micropagation. Un test de detection des Flexivirus par polyvalent degenerate oligonucleotide RT-PCR (PDORT-PCR) a Ă©tĂ© adaptĂ© avec succĂšs Ă  la dĂ©tection du BanMMV et du BVX. L'utilisation pour les Ă©tapes de RT-PCR et de nested PCR d'amorces dĂ©gĂ©nĂ©rĂ©es contenant des bases inosine s'est avĂ©rĂ©e particuliĂšrement adaptĂ©e au niveau de diversitĂ© molĂ©culaire Ă©levĂ© du BanMMV. La mĂȘme approche n'a pas permis la dĂ©tection du BVX. Aussi, des amorces spĂ©cifiques ont-elles Ă©tĂ© dessinĂ©es et utilisĂ©es pour l'Ă©tape de nested PCR, permettant la dĂ©tection spĂ©cifique de ce virus. Afin de simplifier la prĂ©paration des Ă©chantillons, un anticorps polyclonal dirigĂ© contre le BanMMV a Ă©tĂ© obtenu. Il a permis de mettre au point un test de dĂ©tection du BanMMV par immunocapture (IC) PDO-RT-PCR. En l'absence d'un rĂ©actif sĂ©rologique Ă©quivalent dirigĂ© contre le BVX, un protocole de dĂ©tection par direct binding (DB) PDO-RT-PCR a Ă©tĂ© mis au point pour la dĂ©tection de ce virus. Ces tests de dĂ©tection ont Ă©tĂ© validĂ©s Ă  grande Ă©chelle lors de campagnes d'indexation de masse
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