Seven polymorphic microsatellites were developed in olive. Six of them came from a genomic library enriched for GA and CA repeat sequences. They showed single locus polymorphism in a set of 23 olive cultivars (from six to nine alleles per locus). Three different pairs of loci were sufficient to discriminate all cultivars. The other polymorphic primer pair was designed from a published sequence for olive lupeol sgutase and revealed just two alleles. The seven primer pairs were tested on two accessions of five other species of the Oleaceae and three, EMO2, EMO13 and EMO90, revealed polymorphism in two, four and three species, respectively.
Random amplified polymorphic DNA (RAPD) analysis was performed on the main Mediterranean cultivars of olive (Olea europaea L.) from the Germplasm Bank of the Centro de Investigación y Formación Agraria “Alameda del Obispo” in Cordoba, Spain. One hundred and ninety reproducible amplification fragments were identified using 46 random primers followed by agarose gel electrophoresis. Some 63.2% of the amplification products were polymorphic, with an average of 2.6 RAPD markers obtained for each primer. The combination of polymorphic markers resulted in 244 banding patterns. The high degree of polymorphism detected made identification of all the cultivars (51) possible by combining the RAPD banding patterns of just only four primers: OPA-01, OPK-08, OPX-01, and OPX-03. Cultivar-specific RAPD markers and banding patterns were also found. A dendrogram based on unweighted pair-group method cluster analysis was constructed using a similarity matrix derived from the RAPD amplification products generated by the 46 primers. Three major groups of cultivars could be distinguished by RAPD analysis: 1) cultivars from east and northeast Spain, 2) Turkish, Syrian, and Tunisian cultivars, and 3) the majority of common olive cultivars in Spain. The dendrogram thus showed a good correlation between the banding patterns of olive cultivars and their geographic origin. A higher level of polymorphism was observed when polyacrylamide gel electrophoresis was used to separate the amplification products. Thus, adequate use of RAPD technology offers a valuable tool to distinguish between olive cultivars.
A first attempt to determine the effect of vigor and parents on the length of the juvenile period of olive seedlings is here reported. Vigor seems to have a significant influence on the percentage of flowering seedlings, especially in the first 2 years of bearing. The different parents used have produced differences in the juvenile period of their descendants. A correspondence between the length of the unproductive period of the parents and the length of the juvenile period that they transmit to their descendants has been observed. The seedling forcing growth protocol described here has been able to produce flowering seedlings 28 months after germination, with >93% of seedlings flowering 65 months after germination.
Eight microsatellite primers were used to distinguish 23 olive cultivars that were parents, or potential parents, in a Spanish breeding program. Four of these microsatellites were particularly informative and were used to check the paternity of 11 olive progenies thought to come from selfings or controlled crosses involving nonemasculated flowers. Seven progenies were found to be highly contaminated, i.e. many seedlings had unexpected alleles, and only four were found to be pure or almost pure. Almost all the contamination detected came from outcrossing, indicating that placing the pollination bags well before anthesis is important and that emasculation to avoid selfing is unnecessary. More than two nonparental alleles per primer were found in each contaminated progeny, showing that more than one cultivar caused contamination. However, the allele data are consistent with `Picual' (the main commercial cultivar growing in the area where the crosses were made) being the contaminant in 48% of the nontrue seedlings (excluding `Picual' self progenies). Some other cultivars planted near the female trees were also found to be sources of contamination. The results obtained show that microsatellite analysis is a convenient technique to assess routinely the crosses made in breeding programs and to check self-incompatibility in olive. The pure progenies identified will be useful for reliable inheritance studies in olive, which have rarely been reported in the literature.
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