Effect of Cryopreservation on the Ex Vitro Establishment of Olive Plants Regenerated via Somatic Embryogenesis

Cryopreservation is considered the best technique for the safe, long-term conservation of embryogenic cultures. However, before integrating it into a somatic embryogenesis system, the influence of cryopreservation on the final production of plants should be investigated. The objective of this investigation was to evaluate the effect of cryopreservation on the regeneration performance of olive embryogenic cultures as well as on the quality of the plants obtained and their response to ex vitro establishment. In order to analyze the influence of the genotype, all the investigations were carried out in two genetically distinct embryogenic lines. The results obtained revealed no variation in the regeneration potential or the quality of the regenerated plants due to cryopreservation. The subsequent multiplication, rooting, and acclimatization steps were not influenced by cryopreservation either, although a significant genotype x cryopreservation interaction was found for shoot length during the multiplication step. The genotype played an important role, determining the quality of the regenerated plants and some aspects of the multiplication and rooting phases. This investigation revealed that the droplet-vitrification procedure optimized for the cryopreservation of olive somatic embryos can be efficiently used for the long-term conservation of olive embryogenic lines.