COMPARATIVE TECHNIQUES TO PERFORM KOCH'S POSTULATES WITH PLUM POX VIRUS

Koch’s postulates reflect a basic concept that confirms the host recognition by a given pathogen. Knowledge about Plum pox potyvirus (PPV) enables the easy transfer of PPV in diverse experimental hosts (Nicotianae, Chenopodiacea…) and permitted to perform the molecular characterization of any isolates. Our works tended to investigate the parameters, factors, virus isolates involved in back-inoculation studies of PPV from herbaceous to woody perennial hosts. Two techniques have been compared, the grafted-inoculation of vitro-plants and the mechanical inoculation. Works have been focused on Prunus domestica. Laboratory-based analyses (DAS-ELISA, RT/PCR) for assessing PPV transfer indicated at the early stages of inoculation (from 3 to 4 weeks after inoculation) that any techniques are relevant for PPV Bor-3; however, the results have diverged when using other PPV isolates. For this reason, our interest has been moved in the investigation of partial segment of PPV genome possibly involved in Prunus adaptation. The successful replication of an hybrid variant of PPV-Bor3, designated as PPV-D-T12, in Prunus pointed out the involvement of the 4 first cistrons encoding to P1-HC-P3 and 6K1 of PPV genome in these adaptative responses in woody hosts.