Exploring olive trees genetic variability in the South East of Tunisia

Tunisia is one of the most important olive growing countries in the Mediterranean basin and it is classified in fourth rank on world scale in terms of olive oil production. Since the emergence of the modern oliviculture, the identification, the evaluation and conservation of the local genetic resources have been considered as a priority in countries like Tunisia. Molecular studies for genetic characterization allowed to enhance knowledge about the autochtonous olive germplasm, but currently it lacks a systematic and extensive work to compare and validate Tunisian olive varieties. This work focused on the molecular characterization and identification of 21 olive accessions grown mainly in the South East of Tunisia using a set of 16 microsatellite molecular markers. An extent of authentication process was also carried out by comparison with molecular profiles from Tunisian cultivars already characterized from official collections obtained from a set of 12 commonly shared macrosatellite markers by different authors. Population structure analysis of the Tunisian olive germplasm was also conducted using structure software. The results highlighted that no correlation between geographical and genetic origin occurred. New alleles were individuated, and two new genotypes were characterized contributing to enhance the Tunisian germplasm biodiversity. This work allowed individuating a few olive accessions that should be considered as reference cultivar in the authentication process and contributed to clarify the genetic pattern of the Tunisian germplasm.