Agronomic and molecular analyses for the characterisation of accessions in Tunisian olive germplasm collections

In this study, a total of 14 agronomic traits, five AFLP primer combinations and ten SSR loci were used to describe and to classify a group of Tunisian olive genotypes into groups based on molecular profiles and agronomic traits. The analysis of variance of the agronomical data revealed significant differences among accessions for all measured traits. The mean phenotypic dissimilarity (0.34 with a range of 0.08-0.6) was low in comparison to dissimilarity calculated using AFLP (0.50 with a range of 0.16-0.70) and SSR markers (0.76 with a range 0.35-0.94). The correlation between the agronomical dissimilarity matrix and the matrices of genetic dissimilarity based on SSR and AFLP markers was very weak: 0.156 (p = 0.05) and 0.185 (p = 0.05), respectively. The SSR-AFLP dendrogram based on unweighted pair-group cluster analysis using Jaccard’s index revealed that the genetic diversity was predominantly structured according to fruit size. A trend of clustering together of accessions originating from the same or adjacent regions was also observed. The data obtained can be used for the varietal survey and construction of a database of all olive varieties grown in Tunisia and providing also additional information that could form the basis for the rational design of breeding programs.