ISHS Acta Horticulturae 472: XVII International Symposium Virus and Virus-Like Diseases of Temperate Fruit Crops
TRANSFERRING POTYVIRUS COAT PROTEIN GENES THROUGH HYBRIDIZATION OF TRANSGENIC PLANTS TO PRODUCE PLUM POX VIRUS RESISTANT PLUMS (PRUNUS DOMESTICA L.) |
| Authors: | R. Scorza, A.M. Callahan, V. Damsteegt, L. Levy, M. Ravelonandro |
| Keywords: | breeding, genetics, transformation, tree fruit |
| Abstract:
Sharka or plum pox, caused by plum pox virus (PPV) is a major disease of stone fruit and causes severe economic losses in Europe. With the paucity of natural resistance to PPV in Prunus, the concept of non-conventional protection based on the integration of viral coat protein (CP) genes into the host's genome offers potential for protection against PPV. Transgenic plums (Prunus domestica L.) expressing the heterologous papaya ringspot virus (PRV) or the homologous PPV-CP gene were produced through Agrobacterium tumefaciens- mediated transformation. These transgenic plum clones were grafted onto P. domestica rootstock and evaluated for resistance to PPV infection under greenhouse conditions by graft or aphid inoculation with PPV. While symptoms of PPV-CP appeared to a lesser or greater extent on most transgenic clones, all plants of PPV-CP transgenic clone C5 were symptomless and ELISA or PCR negative for over three years following inoculation with two strains of PPV. Clone C5 contains multiple copies of the PPV-CP transgene. It produces a low level of PPV-CP RNA and no detectable PPV-CP (Scorza et al., Plant Cell Repts 14:18–22, 1994). PRV-CP transgenic plants were hybridized with the resistant PPV-CP clone C5 or self-pollinated, and progeny were obtained containing only the PPV-CP, only the PRV-CP or both the PRV-CP and PPV-CP transgenes. Seedlings were graft-inoculated with PPV. After 5 and 11 months post inoculation seedlings containing only the PPV-CP gene from C5 were symptomless and PPV ELISA negative. Seedlings containing only PRV-CP transgenes or non-transformed controls showed symptoms and were ELISA positive for PPV infection. These results indicate that the PPV-CP transgenes can be transferred to progeny through hybridization and that these genes impart resistance to PPV in transgenic seedlings. The inheritance of the multicopy inserts of the PPV-CP and PRV-CP transgenes is being analyzed. The combined effects of both transgenes on resistance to PPV, and the stability of PPV resistance in the progeny of the resistant C5 transgenic line are currently under evaluation. | |
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