MOLECULAR CHARACTERIZATION AND GENETIC DIVERSITY OF SOME EGYPTIAN CITRUS CULTIVARS USING RAPD AND ISSRs MARKERS

Abstract

Citrus L. genus includes several of the most important world’s fruit crops, such as oranges, lemons, limes, mandarins, grapefruits, pummelos and kumquats. In this respect, the present study was to determine the genetic relationship of some Citrus species, including six mandarin, four Clementine and one tangerine cultivars through RAPD and ISSRs based PCR molecular marker. The obtained results showed that, the 11 tested Citrus cultivars were highly similar at the DNA level, and exhibited using the 17 and 10 random primers, 91 and 78 polymorphic bands (20.40% and 25.7%, respectively) in both RAPD and ISSRs molecular markers, respectively. The highest degree of similarity when use RAPD molecular marker was between Balady mandarin and Seedless mandarin (57%) whereas the lowest degree of similarity (40%) between Fedela Clementine and Sunburst mandarin. But the highest degree of similarity between Kara mandarin and Fedela Clementine (51%) whereas the lowest degree of similarity (34%) between Balady mandarin and Sunburst mandarin when use ISSRs technique. In this study some RAPD and ISSRs markers may be linked to some fruiting traits such as beginning of fruit maturity (RAPD primer OPA-16 - 2278 bp and ISSRs primer 844A - 385 bp), peel color (ISSRs primer 17895A - 1178 bp), average no. of seeds per fruit (RAPD primer OPA-10 - 1088 bp) and T.S.S/ acid ratio (RAPD primer OPA-7 - 909 bp). The results from both techniques, showed that the average of polymorphism percentage through the 11 Citrus cultivars was higher using ISSRs than RAPD markers and the phylogenetic relationship was more reliable, indicate that ISSRs molecular marker for fingerprinting, mapping and diversity study of Citrus and its relatives. These results confirmed the usefulness of ISSRs-PCR analysis to detect the genetic variability between cultivars which agreed with who demonstrated that ISSRs markers are a valuable method for detecting genetic variability among rice varieties and for rapidly identifying cultivars.