Submitted to: Archives of Virology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/12/2005
Publication Date: 5/25/2006
Citation: Lorenzen, J.H., Meacham, T., Berger, P.H., Shiel, P.J., Crosslin, J., Hamm, P.B., Kopp, H. 2006. Whole genome characterization of Potato virus Y isolates collected in the western USA and their comparison to isolates from Europe and Canada. Archives of Virology. 151:1055-1074. Interpretive Summary: Potato virus Y (PVY) is a serious pathogen of potatoes wherever the crop is grown. The virus occurs as numerous biological types, or strains. The ordinary strain, PVY-O, occurs worldwide and infects many other crops besides potatoes. PVY-O produces relatively mild discoloration in potatoes and in tobacco. Strains of the virus that cause necrosis (death) in tobacco plants are called PVY-N. Many PVY-N isolates are nearly symptomless in potato foliage. A subgroup of PVY-N that causes symptoms in potato tubers is called PVY-NTN. Additional strains of the virus have been described that share characteristics of both PVY-O and PVY-N. These have been called recombinants or PVY-N:O. The PVY-N, PVY-N:O, and PVY-NTN strains are widespread in Europe and have only recently been described in the potato-producing regions of North America. The research in this paper describes, for the first time, the elucidation of the entire genetic sequence (genome) of several isolates of PVY from potatoes grown in the western US and compares these sequences with those of viruses previously described in Europe and Canada.
Technical Abstract: Potato virus Y (PVY) is a serious potato pathogen that affects the seed production system. In recent decades, novel PVY strains have arisen that cause necrotic symptoms on tobacco foliage and/or potato tubers. The major PVY strains that affect potato include PVY-O and PVY-N, which have distinct serotypes that can be differentiated by immunoassay. Other economically important strain variants are derived from recombination events. These include types that cause tuber necrotic symptoms (Eu-PVY-NTN) or PVY-O serotypes that cause tobacco veinal necrosis (PVY-N-W, PVY-N:O). Although the PVY-NTN and PVY-N-W variants were first reported in Europe, apparently similar strains have been appearing in North America. Confirmation of the existence of these recombinant strains in North America is important, as is whether they were imported from Europe or derived from independent recombination. Whole genome sequencing can be used to positively identify strain variants and begin to address the issue of origins. Symptomology, serology, and partial sequencing of the coat protein region were used to identify isolates of the Eu-PVY-NTN, Eu-PVY-N, NA-PVY-N, and PVY-N:O for whole-genome sequencing. Sequencing confirmed the presence of PVY-NTN and Eu-PVY-N; these isolates were 99% identical to European sequences deposited in GenBank in the 1990s. Sequences of the NA-PVY-N and PVY-N:O types were 99.0% and 99.5% identical to known sequences, respectively. There was no indication that recombinant strains PVY-NTN and PVY-N:O had different parental origins than recombinant strains previously sequenced. This is the first confirmation by whole-genome sequencing that European-type strain variants of PVY-N and PVY-NTN are present in North America.