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

Resistance to sharka (plum pox potyvirus) was studied in 74 seedlings resul ting from open pollination of the resistant apricot cultivar 'Steila'. Each seedling was inoculated at the base by a chip-bud from a diseased GF305 pe ach 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 gr afted above the inoculation point in the order described. Sh observations o f symptoms were made in the leaves of the GF305 used for inoculation, the G F305-control, the Manicot-control and the 'Stella' seedlings during four gr owth cycles. An enzyme-linked immunosorbent assay (ELISA) was applied to th e 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 'St ella' seedlings. some of them showing a strong resistance to virus transloc ation. The: possible use of the 'Stella' cultivar in apricot breeding progr ammes ro obtain resistant cultivars is discussed.