Dědičnost rezistence meruněk k viru šarky švestky u potomstev odrůdy 'Harlayne'

Abstract

Natural resistance toPlum pox virus(PPV), the agent of sharka disease, is one of the most important traits of interest to stone fruit breeders, although few sources of resistance have been identified. One of the few apricot cultivars which does show resistance, ‘Harlayne’, was chosen for a study of the genetics of PPV resistance. It was crossed with three different cultivars, two susceptible (‘Vestar’ and ‘Strepet’) and one immune (‘Orangered’). Four different lines (since there was one reciprocal combination) were established and the F1 crosses were subsequently inoculated with the PPV-M and PPV-D strains by grafting infected buds. A woody indicatorPrunus persica‘GF 305’ was then also top-grafted onto the plants of three of these F1 populations. The observations of leaf symptoms and accompanying ELISA tests were performed over three, or in one case five, growing seasons and then hybrids were classified accordingly, as either resistant or susceptible. The resistant : susceptible ratios were calculated and compared with expected theoretical ratios using the χ2-test. The ratios of resistant to susceptible plants in the progeny derived from the four apricot crosses are compatible with the hypothesis of three dominant genes being responsible for PPV resistance, with ‘Harlayne’ being heterozygous for all three genes. However, the possibility that resistance is controlled by just two dominant genes can not be ruled out just yet.