With the paucity of natural resistance sources to sharka virus, substantial progress has been  achieved by pathologists in understanding the  plum pox virus (PPV) genome. The alternative approach that we developed to create resistant plants is a case study in the interactions between  PPV and it host. The endemic presence of PPV in Central, Balkan, and Mediterranean Europe, with the distinct environments of each area, and the multiplicity of isolates provides a particularly useful field for the assessment of virus resistant germplasm. Under these conditions the genetically engineered PPV resistant plum clone C-5 expressed its resistance phenotype over a long period. Among the basic criterion for genetically modified plant (GMP) acceptance is the preservation of the environment. Studies of emerging PPV variants have received particular research attention. Virus resistance in C5 was triggered by the silencing machinery involving the PPV transgene which involves the production of small interfering RNAs (siRNA) which are constitutively activated. While lesser information about the consequent molecular interactions between PPV and the virus transgene can be depicted from susceptible clones, the investigations we conducted allowed to demonstrate the safe use of transgenic woody perennial plums that will grow for more than 10 years in field. Our studies revealed the molecular stability of PPV and subsequently no any emerging PPV have derived from virus/transgene interactions.