Analysis of the genetic diversity and relationships of selected Canadian isolates of Plum pox virus.

James, D., Sanderson, D.J., Varga, A., Greig, N., and Stobbs, L.W. (2015). "Analysis of the genetic diversity and relationships of selected Canadian isolates of Plum pox virus.", Acta Horticulturae (ISHS), 1063, pp. 33-40.

Abstract

Plum pox virus (PPV) was first detected in Canada in commercial orchards in 2000. Isolates of the virus were characterized and determined to belong to Strain D. Subsequently isolates of PPV strain W and strain Rec were detected in Prunus spp. growing on residential properties, found only on a single homeowner property in each case. D strain isolates were detected also in susceptible tree fruit and ornamental Prunus species growing on residential properties. To date only D strain isolates have been found infecting trees in commercial orchards in Ontario and Nova Scotia, Canada. Initially two subgroups (I and II) of PPV D were identified as encompassing Canadian D isolates (Theilmann et al., 2006). Most D isolates appear to fall within the putative Subgroup II, but there is evidence of more diversity, especially within Subgroup II, that may necessitate further subdivision to better define the population structure. Subgroup I isolates appear to constitute a minor group with no new isolates represented. Also there is at least 1 Canadian D isolate from a commercial orchard that falls outside both subgroups. A D isolate (PPV D-BP) that clusters with Subgroup II isolates, was found associated with severe and bumpy symptoms on fruit on a ‘Harrow Fair’ peach tree. Tests for other viruses and viroids known to infect peach were negative. PPV D-BP was sequenced completely and the entire genome is 98-99% identical to other D isolates. Interestingly PPV D-BP has several unique amino acid changes in the P1, NIb, and CP regions that may or may not be associated with the unusual bumpy symptoms.

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