THE PORTUGUESE OLIVE (OLEA EUROPAEA SUBSP. EUROPAEA) GERMPLASM

The Portuguese cultivated olives occupy around 640.000 ha, mostly in traditional orchards, according to the last census of the Ministry of Agriculture (MADRP, 2004). 55% of that area is covered with the Portuguese cultivar ‘Galega’ (Fig. 1), sometimes referred to as ‘Galega vulgar’. The region of Baixo Alentejo (Moura, Serpa and Beja) has the greatest occupied area, with 64.000 ha of olive orchards, followed by Trás-os-Montes with 52.000 ha and Castelo Branco with 27.000 ha. The cultivated germplasm is characterized by the presence of numerous ecotypes, some of them constituting synonyms of the cultivars in use. Wild olives (oleaster) populations are present across the country. This image is being changed by the establishment of new intensive or super intensive orchards which mainly use the cultivar ‘Arbequina’.
Portugal is one of the biggest world olive oil producers, but the germplasm that is the basis for this production is still poorly known. The cultivars used for olive oil production have been described by Leitão et al. (1986), but phenotypic as well as genotypic differences within each cultivar evidence that most of them have not been subjected to selection processes. Using dominant molecular markers Gemas et al. (2004) have shown that, for the case of ‘Galega’, substantial biomolecular diversity is still contained within the cultivar (Fig. 2). That study also showed that the region of Santarém was probably where this cultivar was first selected.
A preliminary study using four microsatellite loci and a small number of trees of ‘Galega’, ‘Cordovil de Serpa’ and ‘Verdeal Alentejana’ has shown that within each of these cultivars there is a noticeable variability. It also showed that ‘Galega’ was the cultivar more closely related to oleasters.
A set of ten microsatellite (SSR) loci were then used to analyze collections of ‘Galega’, of ‘Cobrançosa’ (the most important cultivar of Trás-os-Montes) and the accessions of the collections maintained at the INRB (National Institute of Biological Resources - Ministry of Agriculture): Collection of Herdade do Reguengo, Elvas (D.O./ENMP); Collection of Herdade dos Soidos, Santarém (DRARO); and Collection of Quinta do Valongo, Mirandela (DRATM). We also genotyped 120 oleaster trees from 5 different populations.