*Crossing models based on historic methods and genetic based-hypotheses*

[57] Breton applied the same methods to the cultivar set. Although other methods could not split the cultivars into different groups based on biological criteria [47], nine clusters were clearly defined. Furthermore, domestication centers have been revealed by crossing the oleaster and cultivar clusters. Nine domestication centers appeared. The main features from all these results are that the genetics suggests clusters and relationships that remain obscure without data to confirm them. Coincidences between the pre-domestication evidence in Portuguese Extremadura [29] and one refugee zone in central Spain [57] strengthen each other. Carrión et al. points out that the accurate records of all archaeological sites where the oleaster or the olive was found sustains some other sites in the west (Spain, see fig. 3 in [35]) and in the east (Cyprus).

Using the same methods (Wide sampling, Bayesian clustering, FCA and dendrograms) [64] have shown that by admixture analyses for some olive cultivars it is feasible to attribute different origins in the glacial refugees and furthermore the proportion of each origin is quantitatively computed by the Structure software. The application of this method to cultivars will enable us to have a clear view of the cultivars' origins. Data supports that in a western country most cultivars have been introduced from the eastern Mediterranean, but that some cultivars have their origin in local oleaster [72] Ozkaya. [30] Hannachi et al. used this method to reveal three olive origins in Tunisia from the north of Africa (Maghreb), the Near-East, and the west (Spain).

Archaeological remains could release more information by studying the DNA for other species. The method has been applied successfully to olive stones [73]. Many olive remains could be analyzed, but the method is still risky. Today, all these data converge to sustain that in each region the present olive cultivar diversity is either or both the result of ancient introductions from the Near-East and/or from other area (North of Africa, Cyprus, Turkey), local selection from oleaster trees, and from crosses between oleaster and ancient cultivar trees. More details on the history of the oleaster tree could be obtained at local levels and with reference to sampling the whole Mediterranean. Dialogue between researchers from the different fields will be required.

All these data converge to sustain that in each region the present olive cultivar diversity is either or both the result of ancient introductions from the Near-East and/or from other area (North of Africa, Cyprus, Turkey), local selection from oleaster trees and from crosses between oleaster and ancient cultivar trees. However, the self-incompatibility system in the wild olive and the olive is still not yet known, leaving the selection pressures that occurred along the domestication processes unknown, which are required to gather enough S-alleles in a region to enable fruit set. [74] Breton & Bervillé have recently deciphered S-allele pair wise combinations for a few varieties, and it appeared which varieties may combine efficiently, at least *in silico*, but it remains to experimentally check coincidence in blossoming and other compatibility levels, which may affect development of pulp and embryo. The model developed infers which genotypes may coexist to ensure correct fruit set, even though self-compatibility appears inherent to most varieties.

14 Olive Germplasm – The Olive Cultivation, Table Olive and Olive Oil Industry in Italy

probably due to limited sampling in Spain and continental Italy.

and in the east (Cyprus).

Near-East, and the west (Spain).

the different fields will be required.

*Crossing models based on historic methods and genetic based-hypotheses* 

origins and those introduced from the Near-East and western regions, making Tunisia in central Mediterranean a key-place for olive and oleaster diversity. [57] Breton concluded that the oleaster populations were structured in at least eleven ancestral populations, which colonized the Mediterranean basin after the last ice age, following mostly the sea-coasts. Based on coincidence of the sampling area and the clusters, some geographic zones for the refugee populations have been suggested: 1) Four in the East (Turkey, Cyprus (2) and Israel+ Lebanon), 2) four in the central Mediterranean (including North of Africa, and main islands Sicily, Sardinia, and Corsica) and 3) three in the western Mediterranean (Continental Spain (2) and South France). The zones were well defined in the East and wide in the West,

[57] Breton applied the same methods to the cultivar set. Although other methods could not split the cultivars into different groups based on biological criteria [47], nine clusters were clearly defined. Furthermore, domestication centers have been revealed by crossing the oleaster and cultivar clusters. Nine domestication centers appeared. The main features from all these results are that the genetics suggests clusters and relationships that remain obscure without data to confirm them. Coincidences between the pre-domestication evidence in Portuguese Extremadura [29] and one refugee zone in central Spain [57] strengthen each other. Carrión et al. points out that the accurate records of all archaeological sites where the oleaster or the olive was found sustains some other sites in the west (Spain, see fig. 3 in [35])

Using the same methods (Wide sampling, Bayesian clustering, FCA and dendrograms) [64] have shown that by admixture analyses for some olive cultivars it is feasible to attribute different origins in the glacial refugees and furthermore the proportion of each origin is quantitatively computed by the Structure software. The application of this method to cultivars will enable us to have a clear view of the cultivars' origins. Data supports that in a western country most cultivars have been introduced from the eastern Mediterranean, but that some cultivars have their origin in local oleaster [72] Ozkaya. [30] Hannachi et al. used this method to reveal three olive origins in Tunisia from the north of Africa (Maghreb), the

Archaeological remains could release more information by studying the DNA for other species. The method has been applied successfully to olive stones [73]. Many olive remains could be analyzed, but the method is still risky. Today, all these data converge to sustain that in each region the present olive cultivar diversity is either or both the result of ancient introductions from the Near-East and/or from other area (North of Africa, Cyprus, Turkey), local selection from oleaster trees, and from crosses between oleaster and ancient cultivar trees. More details on the history of the oleaster tree could be obtained at local levels and with reference to sampling the whole Mediterranean. Dialogue between researchers from

**Figure 4.** Abandonned olive trees along the Mediterraean coast (North of Catalogna, Spain) © Catherine Breton
