Reducing juvenility allows an acceleration of the generation cycle which is crucial in breeding perennial fruit tree species such as apple (Malus domestica Borkh.). This becomes even more important when wild Malus species are used for the introgression and stacking of new resistance genes (R-genes) against the same or different diseases. In such a case, at least four to five pseudo backcross generations in the pre-breeding process are necessary to improve fruit quality up to a commercial level.