Spontaneous hybrids of Prunus fruticosa Pall. in Hungary

The European ground cherry ( Prunus fruticosa Pall.) as a potential dwarfing rootstock attracted the attention of cherry rootstock researchers in several breeding projects. In order to clarify some doubtful classification of collected and promising specimen of supposed hybrids, we compared morphological characteristics to literature data. Genetic analysis was also undertaken using simple-sequence repeat markers. Our results suggest that the investigated P. fruticosa forma fruticosa specimens are tetraploid and the genetic analysis did not contribute to distinguish the P. fruticosa forma fruticosa and forma aucta . Based on morphological characters, we identified few specimens of spontaneous hybrid P. fruticosa × P. mahaleb ( P. × jávorkae ). Our genetic analysis supports the hypothesis that the sample shrub is triploid and show genetic relationship with P. mahaleb . This triploid hybrid due to the flower sterility represents a blind alley in its evolution. We identified from each investigated habitat specimens of supposed hybrid derivatives of ground cherry P. fruticosa × P. avium ( P. × mohácsyana ). This hybrid clearly showed distinct morphological characteristics, easily distinguishable from the P. fruticosa f. fruticosa and f. aucta and the genetic analysis suggests that the accessions are triploid. The flower sterility limits the usage of this hybrid derivative for further cross-breeding but allows usage as clonal cherry rootstock. Our genetic analysis suggests that samples of P. × eminens are tetraploid, fertile hybrid derivative of ground cherry occurring in some habitats of the basic species and show similar morphological characters to the cultivated sour cherry.