FIRST DETECTION AND MOLECULAR CARACTERIZATION OF PLUM POX VIRUS RECOMBINANT STRAIN IN ROMANIA

Abstract

Plum pox virus (PPV) is the most dangerous viral pathogen of stone fruits causing serious yield losses. Although PPV is widespread in Romanian plum orchards, very limited information about the variability of isolates is known. In this study we collected an d investigated twenty PPV isolates from two experimental plots from Fruit Research and Development Station Bistrita . PPV strains were serologically determined by TAS- ELISA using PPV-D and PPV-M specific monoclonal antibodies. Molecular strain typing was performed by I C- RT-PCR targeting three genomic regions (Cter)CP, (Cter)NIb - (Nter)CP and CI. RFLP analysis was used t o distinguish the two major strains, D and M based on a Rsa I polymorphism located in (Cter) CP. PCR products spanning (Cter)CP and (Cter)NIb - (Nter)CP regions were sequenced. All PPV isolates typed as PPV-M by serological analysis and also by molecular differe ntiation in (Cter)CP region proved to be recombinan ts between PPV-D and PPV-M when the molecular analysis were performed in (Cter) NIb - (Nter)CP region. The sequencing results revealed a high homology with di fferent sequences of PPV recombinant (PPV-Rec) previously reported. All these recombinant isolates share the same recombination breakpoint and have c onserved the DAG motif, which is considered essential for po tyvirus aphid transmission. This genetic similarity confirms that PPV-Rec may represent an ancestral group with a common evolutionary origin. This is the first rep ort of naturally infected plum trees with recombinant PPV strain (PPV-Rec) in Romania and predicted a widespread in the other areas where plum is growing.