Genetic relationships of Spanish olive cultivars using RAPD markers

Eighty-two Spanish olive cultivars from the World Germplasm Bank of the Centro de Investigacion y Formacion Agraria (CIFA) Alameda del Obispo in Cordoba (Spain) were analysed by RAPD markers to assess their genetic relatedness and to study patterns of genetic variation. The dendrogram based on unweighted pair group cluster analysis using Jaccard's index included two major groups that consisted mostly of cultivars from the southern and central part of Spain. Clustering together of cultivars from the Levante zone was also observed. The pattern of genetic variation among olive cultivars from three different Spanish zones (Levante, central and Andalusia) was analysed by means of the analysis of molecular variance (AMOVA). Although most of the genetic variability was attributable to differences of cultivars within each zone (95.88%), significant phi-values among zones (phi(st)= 0.041; p < 0.001) suggested the existence of phenotypic differentiation. These results are consistent with the predominantly allogamous nature of Olea europaea L. species. Significant values of phi(st) for the pair Andalusia/Levante indicate the presence of differentiation. The negative value of phi(st), observed in the case of the Andalusia/central pair suggests that some varieties from central Spain are more similar to the Andalusian ones than to the varieties of their own geographic area, and vice versa.