Meiotic Behaviour of Hybrids between P. cerasifera, P. spinosa and P. persica: An Approach to the Peach-Plum Genome Relationship.

Abstract

The genomic relations between the peach (P. persica, 2n=2x=16) and the plums (P. cerasifera, 2n=2x=16, and P. spinosa, 2n=4x=32) are not very well established. Such a knowledge will be necessary if interspecific hybridization has to be used for genetic improvement of fruit varieties.The present cytological study based on meiotic behaviour analyses of new diploid, triploid and tetraploid hybrids between plum and peach provided new information on the peachplum genome relationship.The diploid hybrids (P. cerasifera×P. persica) show a relatively regular pairing between the two genomes whereas the tetraploid form is characterized by the presence of an average of 13.75 bivalents per cell and a low frequency of multivalents (0.60 III and 0.42 IV). These results indicate a partial homology between the two species.Concerning the [P. spinosa×P. persica] hybrids, the meiotic behaviour shows that two out of the three constitutive genomes are almost homologous.Considering the meiotic behaviour already observed in related species P. spinosa and in [P. spinosa×P. cerasifera] triploid hybrids, together with the meiotic behaviour of [P. spinosa×P. persica] hybrids, it is likely that the bivalent pairing result from association between the two spinosa genomes.A comparative analysis of these different results leads to the conclusion that the peach genome is more remote from the P. spinosa genomes than the P. cerasifera is.