ARS | Publication request: LONG TERM STABILITY OF GENE SILENCING BASED RESISTANCE TO PLUM POX VIRUS IN TRANSGEIC PLUM (PRUNUS DOMESTICA L.) UNDER FIELD CONDITIONS

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 30, 2004
Publication Date: N/A

Technical Abstract: Plum pox virus (PPV) is one of the most devastating diseases of Prunus species. Since few sources of resistance to PPV have been identified, transgene-based resistance offers a complementary approach to developing PPV-resistant stone fruit cultivars. C5, a transgenic clone of Prunus domestica L., containing the PPV coat protein (CP) gene, has been described as highly resistant to PPV in greenhouse tests and displays characteristics typical of post-transcriptional gene silencing (PTGS). In 1996 a field test of C5 that included susceptible transgenic and untransformed controls was developed at the Research Institute of Pomology and Floriculture near Skierniewice, Poland under the approval of the Polish Ministry of Environment. To date this field test has shown that C5 trees exposed to natural aphid vectors in the field remain uninfected after 7 years. In contrast, all trees other than C5 were infected within 6 years, some susceptible transgenic and untransformed trees having developed severe symptoms within the first year of the test. C5 trees inoculated by chip budding exhibited only mild symptoms on a few leaves, and PPV could be detected in symptomless leaves on these trees only by using immunocapture RT-PCR. Molecular tests indicated that the PPV-CP transgene in C5 was specifically hyper-methylated, a finding consistent with PTGS. These results indicate both the long-term stability and efficiency of PTGS-based PPV resistance in plum under field conditions.