Mapping Plum pox virus Resistance in Apricot

One of the most economically important virus diseases of stone fruit trees in Europe is Sharka disease, which is caused by the Plum pox virus (PPV). The introduction of resistant cultivars of stone fruit into orchards would provide the best long-term solution to virus control. Resistance to PPV in apricots is found only in certain North American cultivars. The identification of genomic regions involved in PPV resistance could facilitate the breeding process. An F1 progeny issued from a cross between 'Harlayne', a PPV resistant parent, and 'Vestar', a susceptible parent, were used to identify PPV resistance loci. These were grafted simultaneously and subsequently inoculated with the PPV-M strain by chip-budding. Symptoms of PPV infection on leaves were scored over 5 consecutive growing seasons. Marker - trait associations were analysed using the Kruskal-Wallis (KW) nonparametric test and the PPV resistance loci were mapped using composite interval mapping (CIM). A combination of parametric and non-parametric statistical methods confirmed the presence of regions in the upper part of linkage group 1 which are involved in resistance to PPV in the apricot cultivar 'Harlayne'.