Towards an understanding of the inheritance of hypersensitivity resistance against the sharka virus in european Plum (prunus domestica l.): Generation of interspecific hybrids with lower ploidy levels

Hypersensitivity resistance to the sharka virus is one of the most promising resistance mechanisms used in breeding for European plum cultivars. Its genetic determination is poorly understood as the hexaploid genome of P. domestica hampers the investigation of the inheritance of the resistance trait. A monogenic dominant inheritance can be excluded. Hypersensitive genotypes of P. domestica were crossed with genotypes of diploid myrobalan (P. cerasifera) and tetraploid sloe (P. spinosa). The descendants were tested for hypersensitivity against PPV. In order to investigate their parentage, their chromosome number was determined using a new staining technique for chromosomes in Prunus root tips. In both crossing combinations, the interspecific hybrid nature of the seedlings could be shown. Some of them showed strong hypersensitive response when inoculated with PPV. The hypersensitive interspecific hybrids are used for further crossings in order to investigate the inheritance of the trait of interest. Moreover, they are tested for their potential use as rootstocks for different Prunus species.