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SESSION 1 - Discovery - New horizons in plant pathology - page 53 / 65





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isolates followed. In serological tests by ELISA the negative results for Tobacco mosaic virus (TMV) and positive reactions to the specific antiserum of PMMoV were obtained. For the biological characterization a broad range of test plants was inoculated. Based on reactions on different pepper cultivars with the TMV resistance genes L1, L2, L3 and L4, the Czech isolate was classified as PMMoV isolate belonging to the P1-2 pathotype. This is the first report of an isolate of PMMoV in the Czech Republic. Because this virus spreads through the seeds of infected plants, its chemical by NaOH was successfully checked.


Elimination of Potato virus S (PVS) from basic seed-potato in Czech Republic

Petr Dědič1, Jiři Ptáček1, Vendulka Horáčková1, Jaroslav Matoušek2

1Potato Research Institute Havlíčkův Brod, Czech Republic, 2 Institute of Plant Molecular Biology, AS CR České Budějovice, Czech Republic.

In the Czech Republic, an improved procedure of multiplication breeding was adopted in 1985, incorporating post-harvest ELISA laboratory and field testing of selected plants and clones. Limited efficiency was attained mainly owing to an uneven distribution of viruses in the plants and tubers after primary infection. Certification schemes of seed potatoes have changed substantially in recent years mostly because of the widespread availability and utilisation of pre-basic (nuclear stock materials), obtained from tissue-cultured plantlets, maintained and rapidly multiplied free of known potato pathogens in in vitro conditions. Virus-free pre-basic transplants or tubers grown in protected greenhouse / nethouse are further propagated through open field “space isolators” and consecutive limited generation certification scheme. The main requirements for seed-potato production in the Czech Republic (set down by Law 92/1996, notice 191/1996 and renewal law 219/2003) are fully compatible with EU recommendations. The fields intended for seed multiplication must be free of quarantine pests and infection sources; additionally, well isolated from other fields infested with viruses; basic grades of seed potato are allowed to be maintained in closed areas only; and post-harvest laboratory test (ELISA) for viruses and IF test for quarantine bacteria are obligatory for all the seed grades. The certification agency, the Central Institute for Supervising and Testing in Agriculture (CISTA) in collaboration with State Phytosanitary Administration (SPA) are in the Czech Republic responsible for the whole official procedure of inspections and approval. To ensure satisfactory final product quality strict attention to recommended management practices for maintenance breeding and seed-potato production have to be observed. Since 1995, PVS was experimentally included into evaluation of basic seed materials. In the framework of research projects different aspects were investigated e.g. preparation and annual supply of virus-free pre-basic propagation material for maintenance breeding; systematic laboratory checking of health state of pre-basic and basic grades of cultivars; susceptibility of cultivars to PVS; field allocation of healthy lots according to degree of PVS infestation; occurrence of PVS in basic materials of imported cultivars; effect of different crop management practices etc. The results of the long-term effort to eliminate PVS in basic seed potato were evaluated in the final post-harvest laboratory ELISA test. Since 1998, when nearly all the domestic potato cultivars were severely infested with PVS (76,6 % of samples), and only 1,4 % of samples (belonging to two cultivars) were virus-free, on the contrary in 2003 severe infestation with PVS was found at 35,3% of samples from fifteen (i.e. 39,5%) of cultivars. The results clearly demonstrate the possibility of production of virus (PVS)-free basic seed-potato material also in less favourable conditions. This work was supported by the National Agency for Agricultural Research, project QE 1168.


Nucleotide sequence analysis of apple stem pitting virus sources from apple and Pear in Czech Republic

M. Hassan, J. Kundu, J. Salava

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

Apple stem pitting virus (ASPV) and the closely related pear yellow vein virus (PYVV) occur world wide and are associated to complex growth disorders of apple and pear. The genetic variability of ASPV and PYVV was investigated by nucleotide sequence of the coat protein gene. Different ASPV isolates from pear and apple originated from Czech Republic, amplified by RT-PCR and the DNA products were cloned and sequenced. The Obtained results confirmed the high molecular variability already reported for ASPV. The nucleotide sequences of the coat protein gene of all isolates were compared and will be presented and discussed.  


Non-Host Resistance: Is it Really a Durable Source of Resistance?

Paula C Rodrigues*,1, Jacqueline M. Garrood*, Qian-han Shen*,2,Phil H. Smith* and Lesley A. Boyd *3

*Department of Disease and Stress Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK

1Departamento de Biologia, Escola Superior Agrária de Bragança, Campus de Santa Apolónia, 5301-855 Bragança, Portugal. 2 Max-Planck Institut fur Zuchtungsforschung, Dept. of Plant-Microbe Interactions, Carl-von-Linne-Weg10, D-50829, Koln, Germany.

Yellow rust, caused by Puccinia striiformis West., is an important foliar disease of wheat and barley throughout the world, and the development of resistant cultivars is the most economical and environmentally friendly method of control. Breeding for resistance to yellow rust has, for decades, been based on the use of race-specific resistance genes, which have shown to be short-lived. Non-host resistance has been studied as a possible source of durable resistance. A non-host resistance associated with hypersensitivity has been

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