Partial molecular characterization of plum pox virus isolates occurring in Canada

Abstract

Plum pox virus (PPV), recently detected for the first time in Canada, induces serious disease in stone fruits. Serological analyses along with reverse transcription – polymerase chain reaction and subsequent analyses with restriction enzymes indicate that Canadian isolates correspond to the Dideron strain of PPV (PPV-D). Sequence analysis of the 3'-terminal 1.47 kilobases of the genomes of 11 Canadian PPV isolates obtained from peach, nectarine, and plum from different orchards confirmed that all isolates so far analyzed correspond to PPV-D. In addition, these sequencing studies show that: (1) all Canadian PPV-D isolates retain the DAG tripeptide sequence (aspartate–alanine– glycine) known to be required for transmission by aphids, (2) none of the Canadian isolates are identical in nucleotide or amino-acid sequence to any other sequenced PPV isolate, (3) no two Canadian isolates contain identical nucleotide sequences, and (4) the greatest degree of sequence heterogeneity exists in the N-terminal region of PPV coat protein. Sequence comparisons suggest that Canadian isolates fall into two main subgroups, the most prominent subgroup being, by far, the least represented in the sequence databases. The two Canadian subgroups may represent isolates that were independently introduced into Canada