Genetics of resistance to Plum pox virus in apricot
Plum pox virus (PPV) causes serious damage in apricots grown in the Czech Republic and other countries where it is<br />present. The virus spreads in orchards from infected trees by aphids to healthy trees of susceptible cultivars. Chemical<br />control is ineffective from epidemiological point of view. For this reason growing of resistant apricot cultivars is the only<br />way how to solve one of the most significant phytopathological problem. To study PPV resistance in apricot, three crosses<br />between an apricot cultivars or a selection resistant to PPV and an apricot cultivars or a selection susceptible to PPV<br />(LE-3218 × Stark Early Orange, LE-3241 × Vestar and LE-3246 × Vestar) were performed at Faculty of Horticulture<br />of Mendel University of Agriculture and Forestry in Lednice na Moravě in 1999. The BC1 seeds were stratified and the<br />subsequent seedlings were grown in a greenhouse. The seedlings were repeatedly inoculated with PPV-Vegama isolate<br />(PPV-M strain) by an infected chip. The resistance of the plants was evaluated by symptom observing and ELISA in<br />three consecutive growth periods. The χ<sup>2</sup> test was used to analyse the data. It was found that two independent dominant<br />complementary genes conditioned PPV resistance in apricot. The significance of these findings in relation to other reports<br />is discussed. Knowledge of PPV resistance inheritance will help in planning apricot breeding programmes.