Characterization of olive progenies derived from a Tunisian breeding program by morphological traits and SSR markers

An olive breeding program was conducted in Tunisia since 1994 using controlled crosses and open pollination on 'Meski' cultivar mainly used for table olives in northern Tunisia. From a total of 200 progenies, thirteen genotypes were subsequently selected and are potentially suitable for both oil processing and table olive uses. The study aimed to identify the aforementioned genotypes as well as the pollen donors used for cross breeding using morphological and molecular approaches. The morphological study showed high variation between genotypes and permitted their repartition into two groups according to the main discriminative parameters, which are the fruit and endocarp weights based on principal component analysis. The parentage of thirteen olive progenies and the molecular identification of 26 olive cultivars, including 8 olive varieties used as the parents in the cross breeding program, were analyzed using a set of six co-dominant polymorphic Simple Sequence Repeats (SSRs) selected among the most suitable markers for olive identification. SSR analysis revealed a high polymorphic information content value and a low probability of identity among genotypes, indicating the efficiency of SSR for detecting genetic diversity among genotypes and their potential use for olive breeding. Progenies were grouped into two groups, according to the crosses. Transmission of alleles from parents to offspring was observed, in which ten of the thirteen progenies sampled were matched consistently to their maternal parent 'Meski' and the paternity was confirmed. Three did not match, but their parents were identified and they appear derivatives from other breeding crosses. These genotypes remain to be evaluated for their agronomic performances.