Genetic diversity revealed via molecular analysis of moroccan and foreign plum ( Prunus domestica ; Prunus salicina ) genotypes from an ex-situ collection

There is a need for plum breeding in Morocco to release efficient and adapted varieties, which requires the existence of genetic variability in the studied material. Molecular characterization of 29 plum cultivars, from a Moroccan ex-situ collection, was carried out using 20 Inter Simple Sequence Repeats (ISSR) primers. A high level of genetic variability was obtained among these plum cultivars with a polymorphism rate of 95.68% by finding 224 polymorphic bands among the 236 bands revealed by the primers used. Polymorphism information content (PIC), ranged from a minimum 0.19 to a maximum 0.47, showing that used ISSR markers are informative and relevant for discriminating the cultivars evaluated. Moreover, the resolving power (Rp) ranged from 0.72 to 1.70 with an average value of 1.17. The effective multiple ratio (EMR) ranged from 3.60 to 22 and the marker index (MI) ranged from 0.70 to 9.46. The similarity coefficient of ISSR data ranged from 0.136 to 0.619, with an average of 0.365. The ‘Stanley’ and ‘Prune d’ente’ varieties which are suitable for drying and belonging to the same species P. domestica are the closest genetically and the ‘INRA-PR43’ and ‘INRA-PR41’ genotypes are the most distinct. The results obtained showed that the ex-situ collection of plum is characterized by a high genetic diversity. Cluster analysis data revealed three main clusters and which are subdivided into 6 subgroups and a few isolated branches which presumably correspond to the different gene pools. The results confirm that ISSR detected high polymorphism level and represented high genetic variation in the plum ex-situ collection.