Analysis of similarities within different date palm cultivars of Al-Ahsa oasis in Saudi Arabia

Abstract

Date palm (Phoenix dactylifera L.) is widely cultivated in Saudi Arabia, with annual production estimated to be above one million tons. Of the 450 cultivars that are commonly used, 70 cultivars are found in the Eastern province and 20 cultivars are well known and common in the Al-Ahsa oasis. In this study, thirty seven date palm samples representing nine cultivars collected from six locations in the AlAhsa oasis, Saudi Arabia. Total proteins were extracted and subjected to analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results revealed several differences within the cultivars. Overall polymorphism ranged between 12 and 76%, with the highest being 76% within Helali cultivar, and the least being 12% within OmRohaim cultivar. These results support the conclusion that some palms are grown from seeds resembling a known cultivar, which are later distributed as the known cultivar. These results revealed differences in the degree of similarity between the cultivars from 0.059 to 0.579, estimated according to Jaccard`s similarity method based on the presence and absence of protein bands. Khosab and Shehel cultivars were closely related to each other with 0.579 degrees of similarity, both separated by phylogenetic dendrogram in mini-cluster, which have been confirmed by the 1st principal components. The mini-cluster was related to OmRohaim and Khonaizi cultivars within a larger cluster. Shishi, Garrah and Helali were related cultivars, with degrees of similarities ranging between 0.250 and 0.455, and were separated in one cluster by phylogenetic dendrogram. The close relationship between the cultivars may indicate that they originated from the same ancestor. Further molecular and biochemical studies are needed to enrich our knowledge about the relationships among date palm cultivars.