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SESSION 1 - Discovery - New horizons in plant pathology - page 52 / 65





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What is PVYNTN? The reaction of potato cultivars to inoculation with a range of PVY isolates

I Browning1, K Charlet2, M Chrzanowska3, P Dedic4, C Kerlan2, A Kryszczuk3, J Schubert5 , C Varveri6, A Werkman7 and I Wolf8

1Scottish Agricultural Science Agency, Edinburgh, Scotland, 2INRA-ENSA, Rennes, Le Rheu, France, 3Plant Breeding and Acclimatization Institute, Mlochow, Poland  4Institute for Potato Research, Havlikuv Brod, Czech Republic. 5Federal Centre for Breeding Research on Cultivated Plants, Institute for Resistance Research and Pathogen Diagnostics, Aschersleben, Germany. 6 Benaki Phytopathological Institute, Athens, Greece. 7Plant Protection Service, Wageningen, The Netherlands. 8University of Vesprem, Georgikon Faculty of Agriculture, Regional Potato Research Certre, Hungary

PVYNTN is a variant of PVYN which causes Potato Tuber Necrotic Ringspot Disease (PTNRD). It was first reported from Hungary in 1979 and since then has occurred in many countries throughout the world. In some European countries the occurrence has been devastating for the potato industry. In view of the fact that separation of necrosing from non-necrosing isolates is not clearly defined there is some doubt regarding the reliability of molecular tests that have been developed for detection of PVYNTN. A prerequisite for development of any test method for detection of PVYNTN is the identification of a range of PVY isolates whose propensity to develop tuber necrosis has been clearly established. This study involved three potato cultivars and eight single lesion PVY isolates. Plants were manually inoculated in the glasshouse in eight countries and the severity of tuber necrosis was calculated by means of a disease index based on the proportion of tubers with PTNRD and the surface area affected. In some countries tests were also carried out in the field using varying numbers of isolates and cultivars. The PVYO and PVYC isolates tested induced little or no tuber necrosis in the cultivars examined. All PVYN isolates, including PVYN-605 and PVYNWi-P that have never been reported to be tuber-necrosing, were capable of inducing tuber necrosis to varying degrees depending on cultivar and country testing. Most severe tuber necrosis was obtained with a PVYNTN isolate from New Zealand. The cultivar Nadine proved to be particularly sensitive. Results in the Czech Republic, Hungary and France indicated that there was no greater propensity for tubers to develop PTNRD in glasshouse rather than field conditions. Further tests are required to establish the propensity of other PVYN and PVYN-W isolates to induce tuber necrosis in field and glasshouse conditions. Identification of isolates that are likely to cause significant tuber necrosis may be possible by setting a DI threshold.


Some Findings of a Potyvirus naturally infecting Yellow Oat-grass in the Czech Republic

Lenka Širlová, Mohammed Hassan, Josef Vacke, Milan Jokeš

Department of Virology, Research Institute of Crop Production, Drnovská 507, 161 06, Praha-Ruzyně, Czech Republic Tel: +420233022438 E-mail: sirlova@vurv.cz

The some characteristics of a potyvirus caused a mosaic-like disease of yellow oat-grass [Trisetum flavescens (L.) P. Beauv.] were studied. The cylindrical inclusions (pinwhells), characteristic for the family Potyviridae, were observed in ultra-thin sections from infected leaves. The identity of enquired virus with family Potyviridae was confirmed by RT-PCR using specific potyvirus primers (Gibbs & Mackenzie 1997). Virus was mechanically transmitted to Avena abyssinica (Hochst.), Avena barbata (Pott.), A. fatua (L.), A. ludoviciana (Dur.), A. nuda var. chinensis (L.), A. sativa (L.), A. sterilis (L.), Bromus mollis (L.) and Lagurus ovatus (L.). The transmission of the potyvirus to Agrostis tenuis (Sibth.), Alopecurus pratensis (L.), Arrhenatherum elatius (L.) P. Beauv., Bromus tectorum (L.), Dactylis glomerata (L.), Deschampsia caespitosa (L.) P. Beauv., Festuca arundinaceae (L.), F. pratensis (Huds.), Holcus mollis (L.), H. lanatus (L.), Hordeum vulgare (L.), Lolium multiflorum (Lam.), L. perenne (L.), Phleum pratense (L.), Poa anua (L.), P. pratensis (L.) and Triticum aestivum (L.) was failed. The filamentous virus particles about 650x12 nm were observed in sap from plants with mosaic symptoms by electron microscopy, whereas no particles were observed in sap from symptomless plants. The possible identity of the potyvirus was checked with Oat mosaic virus, OMV (Potyviridae: Bymovirus) by two-step RT-PCR (Clover et al. 2002) and with Oat necrotic mottle virus, ONMV (Potyviridae: Tritimovirus) by DAS-ELISA (Clark & Adams 1977). The results suggest that virus is not identical with previously described European isolates of OMV and is also not serologically identical with ONMV.


Occurrence of Pepper mild mottle tobamovirus (PMMoV) in Czech Republic

Svoboda Jiří, Červená Gabriela*) and Jokeš Milan,

Research Institute of Crop Production, Division of Phytomedicine, Drnovská 507, 16106 Prague 6, Czech Republic, *) State Phytosanitary Office of the Czech Republic, Division of Diagnosis, Šlechtitelů 11, 783 71 Olomouc, Czech Republic; (jiri.svo@vurv.cz)

Symptoms of viral infection on pepper seedlings cv. Stalagnit F1 were observed in a greenhouse in 2002. Infected plants showed mosaic symptoms or mottling on leaves, and necrotic spots on fruits. The leaf tissue was examined by an electron microscope, and straight rod-shaped viral particles of about 300 nm were found, indicating a tobamovirus group. Serological and pathological tests with biological characterization of the

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