Molecular characterization of some Egyptian olive (Olea europaea L.) cultivars and their taxonomic relationship [electronic resource].

Includes references.

RAPD analysis technique has been used extensively for varietal identification, phylogenetic relationships, parentage determination and marker assisted selection in a wide range of plant species because of its simplicity. Figure (1) shows PCR-RAPD pattern of different olive cultivars: six from Siwa region (Aspany, Hamady, Kosha, Marake, Petagn and Toffahi), four from Borq El-Arab region (Chemlali, Kalamata, Toffahi and Yonani) and the wild type of Siwa Oasis, Egypt, while, Table (2) shows the unique positive and negative RAPD markers respectively for the same olive cultivars characterizations. RAPD assay permitted the identification of the ten olive cultivars besides wild type by unique positive and negative markers. Twenty-one positive unique RAPD markers were identified to characterize the selected cultivars. Fortythree negative unique RAPD markers were identified to characterize the selected cultivars. Certain primers were more informative than the others e.g., OPB-12 and OPC-05 which, together, had the potential to identify eight and seven respectively. In this respect, Radwan (2004) found that twenty-three positive unique RAPD markers were identified to characterize seven olive cultivars. Nevertheless, negative RAPD markers were also able to characterize the selected olive cultivars. Certain primers were more informative than the others e.g., OPA-01 and OPG-16 that, together, had the potential to identify four cultivars. Hu and Quiros (1991) stated that Broccoli and Cauliflower could be distinguished by using only two and three arbitray primers, respectively. Similarity, Wolf and Rijn (1993) demonstrated that, only two primers were necessary to distinguish 18 Chrysanthemum cultivars. Aruna et al. (1995) presented a key for 7 blackberry genotypes based on 11 markers amplified by four primers. The presence of unique RAPD markers among the various olive cultivars indicates the utility of the approach for fingerprinting purposes. RAPD fingerprinting has a number of potential applications including the determination of cultivar’s purity, efficient use and management of genetic resources collection, particularly in identification of mislabeled accessions (Ahmed, 1999). The output of SAHN-clustering program was presented in the form of a phenogram by using the tree display graphic (TREEG). The resulting dendrogram, (Fig. 2), shows that cultivar 1 (Siwa Toffahi) is separated from other olive cultivars it may be referred to changing of environmental factors which made Siwa Toffahi is different from Borq El-Arab Toffahi. The remaining cultivars were differentiated into two main groups cultivar 4 (Kosha) and other cultivars which divided into two groups; group 1 includes wild and Hamady and group 2 includes two subgroups; subgroup1 includes Chemlali and Kalamata and subgroup2 includes other cultivars. The dendrogram shows that the studied cultivars have an average taxonomic distance of about 0.52. At this level, the branch of cultivar 1 (Siwa Toffahi) is split off from the cluster whose the branch of cultivar 4 (Kosha) is split off at a distance of about 0.45. At a distance close to 0.42 a two cultivars were also delimited as one group these are cultivars wild and Hamady, which are split off at the 0.33 level. At a distance level of about 0.40 cultivars Chemlali and Kalamata were also delimited from the remaining cultivars and regarded as distinct groups which are split off at the 0.30. At a distance level of about 0.35 the cultivar 8 (Borq El-Arab Toffahi) is separated as a single taxa. The remaining is split at a distance of about 0.28 into a branch of cultivar 7 (Aspany) and a subgroup which is delimited in two cluster, one includes cultivar 11 (Yonani) at a distance of about 0.26 and the second includes cultivar 5 (Petagn) and 6 (Marake) as one subgroup at a distance of 0.14. Radwan, (2004) found that the genetic similarity ranged from 65.5% to 81.7%. Constantly, the highest genetic similarity (81.7) revealed by the RAPD analysis was that between Yonani and Kalamata, both belonging to the same geographical location (Greece). This was followed by 78.8% and 78.7% between Toffahi and Chemlali and between Manzanello and Kalamata, respectively. These results are consistent with the predominantly allogamous nature of Olea europaea L. species. This work indicates the importance of the study of the amount and distribution of genetic diversity for a better exploration of olive genetic resources and the design of plant breeding programs.

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