Characterization of phenotype resistance to plum pox of transgenic plums expressing plum pox virus capsid gene

Resistance to plum pox virus (PPV) infection can be obtained in transgenic plants that express the virus capsid gene. An Aggrobacterium-mediated trans formation was used to introduce the PPV capsid gene into Prunus domestica p lants. Over Il regenerated plants (clones) were observed for the developmen t of the disease symptoms and analysed for the presence of PPV by enzyme-li nked immunosorbent assay (ELISA), Western blot analysis, and reverse transc ription-polymerase chain reaction (RT-PCR) through 4 dormancy cycles. The l evel of protection against PPV was determined in the transformed plants, no ntransformed plants, and a control transgenic plant "transformed" with the plasmid vector alone. One clone, C-5, appeared fully protected, while PT-6 and C-4 clones accumulated a low concentration of virus and the rest of the clones was entirely susceptible. Little is known about the mechanisms of r esistance to virus infection in transgenic woody plants. To investigate thi s aspect, comparative studies based on the characteristics of resistant and susceptible clones have been started. A question, whether the phenotype re sistance of clone C-5 is similar to that observed in transgenic herbaceous plants or not, has been addressed. Recent progress in this investigation is presented.