الفهرس 
REVIEW OF LETERATUREOnly 14 pages are availabe for public view
 |  | from | 95 |  |  |
| | | from | 95 | | |
Abstract
The olive tree (Olea europaea L.) family Oleaceae is an evergreen open-pollinated subtropical species, mostly vegetatively propagated, with diploid chromosome number (2n=46). Both cultivated and wild forms are fully interfertile, some isolates of triploid and tetraploid have been isolated (Rugini et al., 2011). The olive is a long-living (at least several hundred years) and considered one of the oldest agricultural tree crops in the Mediterranean basin which lasts about 5,000 years (Zohary and Spiegle-Roy, 1975). Olives are one of the most, extensively, cultivated fruit crops in the world. In 2009, there were 9.9 million hectares planted with olive trees, which is more than twice the amount of land devoted to apples, bananas or mangoes, produced about 18.24 million tons (FAO STAT, 2010). Statistics of Egyptian ministry of agriculture for the year 2009 indicated that a total area of about 158,058 feddans are grown to olive of which 90,344 feddans outside the Nile valley as newly reclaimed land. The total production is about 449,009 tons. The International Olive Council published a report for products of 2009/10 crop year indicated that olive production in Egypt geared toward table production reaches 300,000 tons representing 14% of the total world production, the majority are locally consumed.
Olive, Olea europaea L., is a Mediterranean fruit species that is cultivated mainly for oil but also for canned fruits. Because of the traditional cultivation, most orchards include several cultivars. Numerous cases of homonymy (one denomination for several genotypes) and synonymy (one genotype with several denominations) were reported in olive cultivars in different traditional olive areas (Bronzini de Caraffa et al., 2002a; Khadari et al., 2004; Lamantia et al., 2006). The olive trees have been manipulated by man for so many thousands of years that varieties in one country have been found to be identical to differently named varieties in another. Distribution of incorrectly labeled olive and the global spread of vegetative propagated cuttings over hundreds of years changing their names have caused the current problem of homonyms and synonyms (Cimato and Attilio, 2008). Moreover, Cavagnaro and Masuelli (2002) evaluated genotypic homogeneity in olive nurseries using RAPD. They found that only one of five Argentine olive nurseries plant materials was in complete genetic homogeneity with its respective materials kept in the germplasm bank of INTA Juin.
Tremendous diversity exists within plant spices as a result of mutation and genetic recombination. This diversity is the core ingredient of a species’ evolution and survival. This diversity in genotypes is characterized using morphological and molecular descriptors. In the case of olive, up to 30 conventional morphological descriptors were used to identify different genotypes (Bari et al., 2003). Highly heritable descriptors such as those of the olive stone can easily help to identify olive genotypes, and this has been confirmed using the molecular marker pattern results of Barranco et al. (2000). In the same context, variation can be evaluated on the phenotypic and genotypic levels. Assessment of phenotypic variation focuses on morphological traits characteristics. Some of these traits can be considered as ‘genetic’ if their presence in related individuals is heritable, meaning that they are associated with a particular DNA sequence. Morphological characters did not ensure a complete characterization. Indeed, environmental factors render difficult the cultivar identification on the basis of the phenotype (Bronzini de Caraffa et al., 2002b). Morphological descriptors have been used for characterization and identification of olive cultivars. For example: Fruit, endocarp and leaf traits (Abdine et al., 2007 and Cimato and Attilio, 2008). Fruit, endocarp, leaf and infloresence traits have been used for characterization of olive cultivars (Idrissi and Ouazzani, 2007; Hosseini-Mazinani et al. 2008 and Ulas and Gezerel, 2008). It was found that Fruit, endocarp and leaf traits had a high identification potential for the studied varieties (Idrissi and Ouazzani, 2007). Also (Del Río and Caballero, 2008) used fruit weight, flesh/stone ratio and oil yield for characterization of olive cultivars. Al-Ibrahem et al. (2008) found that up to 60% of the observed variation may be ascribed to the olive stone aspect ratio descriptor alone.
On the other hand, genotype reflects the particular genetic make-up of an organism. Assessment of genotypic variation is at the level of the DNA molecule responsible for transmitting genetic information. The advantage of using DNA molecular markers in variation assessment that it is not subjected to environmental influences. The major disadvantage is the need for technically more complex equipment (De Vicente and Fulton, 2003).
Isoenzymes are used for cultivar identification and to determine the genetic relations between them. The first attempts at the use of biochemical markers for understanding the domestication process in the olive started in the 1980’s using isoenzymes extracted from pollen or from leaves, and they were able to distinguish the polimorphism between the cultivars (Pontikis et al., 1980; Trujillo et al., 1990; Ouazzani et al., 1993). Malic enzyme and esterase were the most effective enzymes for identifying the cultivars; most could be individually distinguished based on the banding patterns of these two systems only. Five enzymatic systems have made possible the identification of 132 olive cultivars (Belaj et al., 2008). Malic enzyme (ME), glucose phosphate isomerase (GPI), esterase (EST) and leucine aminopeptidase (LAP) were the most useful isozyme systems for identification of olive cultivars using pollen samples. Different combinations of banding patterns of these systems allowed identifying 85% of the cultivars (Trujillo et al., 1995) studied.
The molecular markers used in the Germplasm Bank of Córdoba (isozymes and RAPDs) have shown to be useful for identification purposes. However, 215 cultivars were reliably discriminated by the combination of six RAPD primers (Belaj et al., 2008). Also, RAPD analysis was able to distinguish clearly between olive cultivars (Perri et al., 1999) which provides a new method for cultivar identification in olive (Trujillo et al., 1999). The use of RAPD primers (Williams et al., 1990) has given environment independent markers. This procedure has been performed in olive to identify varieties, to study olive genetic diversity and used to determine the relationships between varieties (Belaj et al., 2008; Helally, 2008; Sesli and Yeg᷃enog᷃lu, 2009; Durgac et al., 2010; Sheidai et al., 2010 and Sesli and Yeg᷃enog᷃lu 2010). The RAPD markers proved to be highly effective in discriminating cultivars analysed (Belaj et al., 2001, Sanz-Cortés et al., 2001 and Lamantia et al., 2006) demonstrating the reliability of RAPDs to identify all studied olive cultivars and to reveal the degree of their relatedness to each other.
Likewise, the molecular markers generated by inter-simple sequence repeat (ISSR) and RAPD techniques were sufficient to discriminate among the ‘Galrga Vulgar’ accessions (Gemas et al; 2004). Two inter-simple sequence repeat (ISSR) markers (one UBC-818, rich in CA and the other UBC-849, rich in GT) used for the differentiation of 31 Olea europaea L. cultivars grown in Greece showed high degrees of polymorphism. It was conducted that ISSRs can be used for cultivar differentiation in O. europaea L. (Terzopoulos et al., 2005). Seven ISSR and 12 RAPD primers were able to distinguish individually all 38 olive (Olea europaea L.) cultivars (Martins-Lopes et al., 2007). Analysis of molecular variance from RAPD and ISSR revealed greater variation within clones than among different geographical origins. Significant genetic diversity among the ‘Cobrançosa’ olive cultivar was detected, even though the clones came from a limited geographical area (Martins-Lopes et al., 2009). It is reported that ISSR technique was able to discriminate among olive cultivars (Kattmah et al., 2011).
The present study aims to characterize and identify nine existed, locally, olive cultivars using different characterization and identification approaches (morphology, isozymes, random amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) and to establish the relative relatedness between each of these cultivars.