Potato virus X isolates from potato collected in eastern Canada with different symptoms in tobacco differ in their coat proteins

Three Canadian isolates of potato virus X (PVX) that produced distinctly different symptoms in tobacco (Nicotiana tabacum cv. Samsun) were analyzed for differences in their coat proteins using SDS-PAGE, denaturing isoelectric focusing, peptide analysis and nucleotide sequencing. The amino acid sequence of the coat protein in a mild isolate differed from that of isolates that produced severe or intermediate symptoms at two locations. However, the amino acid sequences of the Canadian isolates that produced severe or intermediate symptoms were identical and were the same as the coat proteins of PVX isolates from Argentina, China, The Netherlands, and United Kingdom. These results suggest that regions of the PVX genome in addition to the coat protein gene may be involved in viral-host interactions.