V. Kajic, S. Cerni, M. Krajacic, I. Mikec, D. Škoric
doi: 10.4454/jpp.v90i1sup.608
Previous studies have ascertained the presence of Plum pox virus strain M (PPV-M) and D (PPV-D) in various Prunus species all over Croatia. Susceptible plum varieties, known as particularly endangered by recombinant PPV strains (PPV-Rec), were taken into consideration for the molecular typing of PPV isolates carried out in this study. Samples were collected in commercial orchards established with imported plant material, except for one sample coming from the urban Zagreb area. Six out of seven samples tested PPV positive by DAS-ELISA. A modified IC-RT-PCR approach was used for amplifying two target sequences, the carboxyterminus part of the capsid cistron (Cter)CP and the virus segment spanning the carboxy-terminus part of NIb (Cter)NIb to the amino-terminus part of CP [(Nter)CP]. PCR amplification based on the use of the primers targeting the (Cter)CP region revealed the presence of PPV-M in all positive samples. The presence of PPV-D was found in three samples in mixed infection with PPV-M. Two samples harbored PPV-Rec (Valjevka, wild plum). Six sequences of (Cter)CP amplicons clustered in two groups, in accordance with the strain differentiation (PPV-M, PPV-D), while two (Cter)NIb/ (Nter)CP sequences clustered within the group of well known PPV-Rec isolates. Phylogenetic analyses suggest different origin of two PPV-Rec isolates in accordance with biological data. If distinct geographical location and different source plant genesis are considered, higher molecular diversity of PPV in Croatia than previously reported is predictable from this first PPV-Rec report.