TRANSGENIC PLUMS EXPRESSING PLUM POX VIRUS COAT PROTEIN GENE DO NOT ASSIST THE DEVELOPMENT OF VIRUS RECOMBINANTS UNDER FIELD CONDITIONS

SUMMARY The serological and genetic variability of Plum pox virus (PPV) isolates from transgenic plum trees expressing the PPV coat protein gene and conventional plums was analyzed. PPV isolates were characterized serologically by TAS-ELISA using PPV-D and PPV-M specific monoclonal antibodies and by molecular typing across three genomic regions as well as RFLP analysis of the 3’ terminus of the CP gene. PCR products spanning the (Cter)CP and (Cter)NIb-(Nter)CP regions were sequenced. Sequence information revealed no significant difference between serological and molecular features of PPV isolates from transgenic and conventional plums that were growing together in experimental orchards for 6-8 years. These results show that transgenic plums do not promote the emergence of new PPV variants under field conditions.