Archivio Journal of Plant Pathology

Abstract:

Plum pox virus (PPV) is a potyvirus causing economic losses to stone fruit trees. In the present study we have analyzed more than 40 PPV isolates collected from different western, eastern, central European and north African countries To preserve the originality of these isolates, the majority was maintained in GF305 peach (Prunus persica), some in apricot (P. armeniaca), plum (P. domestica, P.insititia), or ornamental (P. tomentosa) trees. Serological tests conducted in 2004, 2005 and 2006 with polyclonal antisera by Agdia (USA) validated the high rate of response with all PPV tested. Two primer pairs were designed to amplify 1200 nucleotides (nt) of the 3‘ region of the PPV genome spanning from the carboxy-terminal part of the Nib cistron to the carboxy- terminus of CP, and 500 nt starting from the conserved EcoRI site of the CP cistron to the polyA tail, respectively. Nucleotide sequences of these isolates were determined either from the amplified fragment or the recombinant plasmid cloned into E. coli. Two regions with variable nucleotides were found, the first 110 nt upstream the cleavage site, and the second in nucleotides encoding the cleavage site of NIa-Pro between the Nib and CP cistrons. Sequence homology among the viral isolates was very high. However, phylogenetic analysis of the sequences coding for CP indicated that diversity resided in the amino-terminal section. This finding was corroborated by the use of monoclonal antibodies to PPV D (Durviz, Spain) and PPV M (Agritest, Italy). We discuss the results of these analyses and, particularly, the significance of these nucleotide diversities.