|Valkonen,, J. P.|
Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2007
Publication Date: 1/15/2008
Citation: Singh,, R.P., Valkonen,, J.T., Gray, S.M., Boonham,, N., Jones,, A.C., Kerlan,, C., Schubert,, J. 2008. The naming of Potato virus Y strains infecting potato. Archives of Virology. 153(1):1-13. Interpretive Summary: Potato virus Y (PVY) is currently considered to be economically the most harmful virus in cultivated potatoes. In recent years unknown strains of PVY have evolved in or spread to new geographical areas. Emergence of molecular techniques and a switch in the emphasis from host response to nucleotide sequence differences in characterization of PVY isolates has led to the assignment of new acronyms to PVY isolates and strains. The results from many different labs working independently has led to a much better understanding of the virus, but it has also complicated the nomenclature and classification of PVY. This paper analyzes the reasons behind the names currently used with PVY strain groups and strains. Its purpose is to stimulate discussion over the naming of PVY strains to help overcome the current confusion in PVY strain and isolate nomenclature. We proposed that more systematic accumulation of biological data on host responses, especially those corresponding to the criteria of the established strain group concept for PVY from potato, and sequence data covering the whole genome of each isolate will be needed. Furthermore we propose how newly discovered isolates should be classified and named within a defined set of strains so that there is biological meaning to the nomenclature.
Technical Abstract: Potato virus Y (PVY) strain groups are based on host-response and resistance-gene interactions. The strain groups PVYO, PVYC and PVYN are well-established for the isolates infecting potato in the field. A switch in the emphasis from host response to nucleotide sequence differences in the virus genomes, detection of isolates recombining sequences of different strains, and the needs to recognize isolates that cause necrotic symptoms in potato tubers have led to the assignment of new acronyms especially to isolates of the PVYN strain group. This discussion paper proposes that any newly found isolates should be described within the context of the original strain groups based on the original methods of distinguishing strains (i.e., tobacco and potato assays involving use of ‘differential’ potato cultivars). Additionally, sequence characterization of the complete genomes of isolates is highly recommended. However, it is acceptable to amend the names of PVY isolates with additional, specific codes to show that the isolate differs at the molecular, serological or phenotypic level from the typical strains within a strain group. The new isolates should preferably not be named using geographical, cultivar, or place association designations. Since many new variants of PVY are being discovered, any new static classification system will be meaningless for the time being. A more systematic investigation and characterization of PVY from potato at the biological and molecular levels should eventually result in a biologically meaningful genetic strain concept.