Genetic diversity of Prunus rootstocks analyzed by RAPD markers

We have used RAPD markers to characterize Prunus rootstocks from different species, both commercial, and selected clones from the breeding program at Aula Dei Experimental Station (Zaragoza, Spain). Molecular markers were used to study the genetic variation among different species, and within species. Forty one genotypes were used in this study. They included P. amygdalo-persica, and P. persica x P. davidiana hybrids; P. cerasifera, P. domestica, and P. insititia clones, and other diverse interspecific hybrids, which were divided in three groups according to postulated taxonomic classification. Diversity patterns obtained from 80 RAPD primers were evaluated in a representative subset of genotypes. This screening helped to identify 7 RAPD primers that were selected to produce a combined classification of the whole set of rootstock clones. This analysis successfully clustered rootstocks according to the classification scheme widely used to characterize Prunus clones, mainly based on morphological descriptors. Further than that, it supported the alleged origin of some interspecific materials, and confirmed a case of possible misclassification ('Myrobalan 29 C'). A more thorough diversity analysis was conducted within each group of materials, using larger sets of primers (12-14). After this analysis, disjointed clusters were formed for P. amygdalo-persica and P. persica x P. davidiana hybrids in one group, and for Myrobalan ( P. cerasifera) and Marianna ( P. cerasifera x P. munsoniana) plums in another group. P. insititia and P. domestica clones, however, formed a jumbled cluster, possibly due to genetic interchange among them during their domestication and breeding history.