Until now there have been many investigations according the inheritance of the hypersensitivity resistance against the Plum pox virus (PPV) in European plum (Prunus domestica L.). For establishing an effective breeding program for PPV resistance it is important to know more about the inheritance and the genetic determination of the hypersensitivity resistance. There have been investigations concerning the inheritance of the hypersensitive resistance by screening seedlings of selected crossing combinations. These seedlings resulted from crossings between two hypersensitive parents, between hypersensitive and sensitive parents and between two sensitive parents. Moreover quantitatively resistant genotypes were crossed with hypersensitive resistant genotypes. One can show that the inheritance depends on the degree of hypersensitivity resistance in the parent genotypes. The higher the degree of hypersensitivity the higher is the amount of hypersensitive progenies. Furthermore it strongly depends on the selection of the crossing partners. In combinations with two hypersensitive partners, the percentage of hypersensitive seedlings is higher, than in combinations of hypersensitive genotypes with sensitive ones. The amount of hypersensitive progenies in crossing combination of hypersensitive genotypes with a quantitative resistant one is lower than in combination of hypersensitive genotypes with a sensitive one. In order to clarify the origin of the hypersensitivity resistance, progenies of crossing combinations from `Ortenauer' $\times$ `Stanley', `Ortenauer' $\times$ `Ortenauer' and `Stanley' $\times$ `Stanley' have been tested. This refers to `Jojo', the first completely hypersensitive cultivar, which is a descendant of a crossing between `Ortenauer' and `Stanley'. The results show that the donor of the hypersensitivity resistance is the cultivar `Ortenauer'.     «

Until now there have been many investigations according the inheritance of the hypersensitivity resistance against the Plum pox virus (PPV) in European plum (Prunus domestica L.). For establishing an effective breeding program for PPV resistance it is important to know more about the inheritance and the genetic determination of the hypersensitivity resistance. There have been investigations concerning the inheritance of the hypersensitive resistance by screening seedlings of selected crossing co...     »