Use of Rapd and ISSR Polymorphisms for Detection of Molecular Diversity of Date Palm (Phoenix dactylifera L.) Cultivars from Algeria

This chapter investigated the ISSR and RAPD polymorphisms in date palm cultivars collected from Bou-Saada oasis, located at the bases of the Ouled Nail Range of the Saharan Atlas of Algeria. Date palm (Phoenix dactylifera) is an important crop plant both from nutritional and economic points of view. The assessment of genetic diversity and population differentiation of date palms are evaluative for its dynamic conservation and sustainable utilization of its genetic diversity. Samples were collected from young leaves of adult trees and kept frozen with liquid nitrogen. DNA extraction was performed according to the standard protocol. A total of 198 (RAPD) and 151 (ISSR) fragments were amplified and scored via electrophoretic gels. Fig. 2 shows examples of resulted banding patterns in the 20 cultivars for the RAPD primer OP-N01 and ISSR primer A38. Both markers resulted in high and comparable levels of polymorphisms; around 75% polymorphic loci were detected among 151 ISSR and 198 RAPD alleles. The contribution of RAPD and ISSR markers to total gene diversity was 0.225 and 0.220 and to Shannon's Information index was 0.344 and 0.337, respectively. At the group level, soft, dry, and median cultivars are distinguished by the presence of particular alleles exclusive to each group, which is seen in significant variations in gene diversity as well as Shannon's Information indexes. But rather than explaining variation between groups, the proportion of common alleles within groups led to strong variation (100% for ISSR and 98% for RAPD) explained within groups of individual cultivars. Generally, RAPD and ISSR markers resulted in disparate clustering patterns, however, both markers configured the close relationship between Rotabaya and Ghars cultivars with 84% bootstrap value (BV; RAPD) and 63% BV (ISSR). The cultivar, Baarit- djemal is strongly identified as possible progenitor of the sampled male tree. Baarit-djemal cultivar and the male tree found closely related with BV equaled to 90% for polymorphism of combined markers, 71% with RAPD markers and 50% with ISSR markers. The clustering patterns resulted from combined data, on the other hand, have confirmed the relationship among Mekarkcha and Deglet nour with 94% BV compared to that exhibited with ISSR markers (98%). Cataloguing the existing date palms at molecular level can be a mandate to support different phases of selection programs and conservation strategies.