Molecular analysis of the complete genomes of apricot and plum isolates of Plum pox virus detected in a Prunus germplasm collection in Almaty's Pomological Gardens, Kazakhstan

Partial molecular characterization of isolates of Plum pox virus (PPV) from Kazakhstan was described by Spiegel et al. (2004). The isolates were classified as members of the Dideron (D) strain based on: a) RFLP analysis of a 243-bp amplicon in the region of the C terminus of the coat protein (CP) fragment, b) RFLP analysis of an 836-bp amplicon in the P3-6K₁ coding region and c) analysis of the CP coding region. The plum isolates were detected in plum trees maintained in the plum selection-orchard of the Pomological Garden, Almaty, Kazakhstan. The apricot isolates were detected in wild apricot seedlings obtained originally from Zailiyski Alatou at the northern edge of the Tien-Shan Mountains, but maintained in the Pomological Garden, Almaty, for about 15 years. Disease symptoms were observed on fruit from one of these infected apricot trees and on the leaves of the infected plum trees. PPV was never detected in any wild apricot plants growing in their natural habitat in Zailiyski Alatou. In this recent study, the virus genomes were sequenced completely and their analysis confirmed their identities as members of the D strain of PPV. Interestingly, in some cases, the genomes of the apricot and plum isolates were very similar, with identities of approximately 99.7% (nucleotide and amino acid sequence). Phylogenetic analyses seem to indicate a close relationship of the Kazakhstan apricot and plum isolates to each other, and to the PPV isolate BIII/2 (GenBank accession no. GU461890), a plum isolate from Slovakia. The Kazakhstan isolates and the Slovakia isolate are approximately 99% identical (nucleotide and amino acid sequence). The deletion event described by Spiegel et al. (2004) in the plum isolate P5R8 (KZPLa1) was confirmed.