Inheritance of resistance to Plum pox virus in the progeny of the apricot cv. 'Harlayne'

Abstract

PILAŘOVÁ, P., KRŠKA, B.: Inheritance of resistance to Plum pox virus in the progeny of the apricot cv. 'Harlayne'. Acta univ. agric. et silvic. Mendel. Brun., 2009, LVII, No. 5, pp. 243-250 Natural resistance to Plum 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 identifi ed. 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 diff erent cultivars, two susceptible ('Vestar' and 'Strepet') and one immune ('Orangered'). Four diff erent 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 gra ing infected buds. A woody indicator Prunus persica 'GF 305' was then also top-gra ed 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 fi ve, growing seasons and then hybrids were classifi ed accordingly, as either resistant or susceptible. The resistant : susceptible ratios were calculated and compared with expected theoretical ratios using the χ 2 -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.