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Tobacco veinal necrosis determinants are unlikely to be located within the 5' and 3' terminal sequences of the potato virus Y genome

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Chachulska, A.M. | Chrzanowska, M. | Robaglia, Christophe | Zagorski, W.

Edité par CCSD ; Springer Verlag -

International audience. Three potato virus Y isolates, representatives of distinct PVY groups, identified in potato fields in northern Poland were submitted to biological and molecular analysis. Phenotypically, two isolates, PVYN-Ny and PVYN-Wi, belong to the necrotic strain and the third one (PVYO-LW) to the common strain. PVYN-Wi, however, did not react with monoclonal antibodies directed against the necrotic strain isolates which recognise PVYN-Ny. To characterise the isolates, coat protein genes were sequenced and compared with sequences from databases. The necrotic PVYN-Wi isolate showed 99% amino acid homology with the common one–PVYO-LW and significantly differed from the second necrotic isolate (PVYN-Ny). Sequence based homology matrix and phylogenetic analysis lead to classification of PVYN-Ny into group I, encompassing solely necrotic strain isolates, whereas PVYN-Wi falls into a phenotypically heterogeneous group II. The sequence analysis allowed for identification of putative group I–specific epitopes. 3′NTR (non-translated region) sequences were identical for PVYN-Wi and PVYO-LW. The 5′NTR, P1 gene, coat protein gene and 3′NTR sequences of the common (PVYO-LW) and the necrotic (PVYN-Wi) isolates are 99–100% homologous. This suggests that tobacco veinal necrosis determinants are located outside the 3′ and 5′ terminal sequences of the PVY genome.

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