The olive (Olea europaea L.) is one of the most ancient cultivated fruit trees.
Olive trees are considered to be one of the most widely grown fruit crops in the
countries of the Mediterranean basin. Olive products, such as olive oil, table olives and
olive pastes are staple foods of the Mediterranean diet due to their benefits for human
health, as well as other applications such as in cosmetics.
More than 2600 olive plant cultivars have been described using morphological analysis,
although many of them might be synonyms, homonyms, ecotypes or the result of
crosses between neighbouring olive cultivars. The high number of olive cultivars causes
a considerable problem in germplasm collection management and both the traceability
and authenticity of olive oils produced, once there is an uncertainty about its correct
olive cultivar denomination. Until recent years, cultivar identification was only based on
morphological and agronomic traits. However, recognition of olive cultivars based on
phenotypic characters was revealed to be problematic, especially in the early stages of
tree development. In recent years molecular markers have been applied in olive
germplasm to identify cultivars and to determine the relationships between cultivars.
The increasing openness of genetic markers in olive trees allows detailed studies and
evaluations of genetic diversity. This will provide a view of what has been attained and
what still needs to be done in order to better understand this crop that has lived for
centuries and still remains to be fully discovered and understood.
Although current breeding strategies can now benefit from the availability of new
polymorphic genetic markers, the characterization of olive germplasm is still far from
complete.
A wider gene characterization of loci related to the quality of plant products and
adaptive mechanisms could provide new information and tools to support Marker
Assisted Selection (MAS) strategies and new biotechnological approaches to develop
suitable growing techniques and increase productivity and product quality of this
species which is unique in its kind.
Keywords: Abiotic stress, DNA sequencing, ex situ collections, expression
sequence tags, gene identification, genomic approaches, marker assisted selection,
molecular markers, next generation sequencing approaches, olive breeding, olive
germplasm, plant breeding.
