Inheritance of resistance to plum pox potyvirus (PPV) in 'Stella' apricot seedlings

Resistance to sharka (plum pox potyvirus) was studied in 74 seedlings resulting from open pollination of the resistant apricot cultivar 'Steila'. Each seedling was inoculated at the base by a chip-bud from a diseased GF305 peach tree. To follow the spread of virus into the seedlings, a chip-bud of a healthy GF305 and another from a healthy sensitive Manicot apricot were grafted above the inoculation point in the order described. Sh observations of symptoms were made in the leaves of the GF305 used for inoculation, the GF305-control, the Manicot-control and the 'Stella' seedlings during four growth cycles. An enzyme-linked immunosorbent assay (ELISA) was applied to the leaves of the 'Stella' seedlings. No 'Stella' seedling showed symptoms of sharka. Only three seedlings reacted positively to the ELISA. Substantial differences were observed in the speed of virus propagation through the 'Stella' seedlings. some of them showing a strong resistance to virus translocation. The: possible use of the 'Stella' cultivar in apricot breeding programmes ro obtain resistant cultivars is discussed.