Genetic relatedness among Tunisian plum cultivars by random amplified polymorphic DNA analysis and evaluation of phenotypic characters

Analysis of differentiation among local and introduced plum cultivars using morphological, pomological and RAPD markers revealed considerable genetic diversity. The phenotypic analysis shows that pomological and tree growth traits were permitted to evaluate morphological variability of plum cultivars. Ten arbitrary primers used to assay 27 cultivars revealed 143 RAPD markers. The percentage of polymorphic bands (97.28) and the resolving power (Rp) (82) showed the efficiency of used primers. The revealed RAPD markers permit to distinguish all considered cultivars and resolve homonymy problem. Cluster and principal component analysis were performed to assess patterns of diversity among cultivars and showed unstructured genetic diversity. In fact, the cultivars distribution occurs undependably of their geographic origin. The overall distribution pattern of molecular variation suggests that about 94.79% of the total variance was accounted within group component of variance. The remaining 5.21% of the variation was hierarchically structured between components due to differentiation among groups. A significant correlation (r = 0.30; P = 0.00) was verified between morphological descriptors distance and distance generated by molecular data. These results proved the importance of both morphological and RAPD markers to elucidate in part denomination problems and elucidate relationships among cultivars. Wide phenotypic and molecular diversity found in local plum germplasm indicates a considerable potential for improving this crop. The combined analysis of phenotypic and molecular markers was a valuable tool for assessing the genetic diversity in plums.