Abstract
Date palm trees (Phoenix dactylifera L.) are widely distributed in the Eastern Province of Kingdom of Saudi Arabia. There are more than 70 cultivars that have been grown there for ages, Three cultivars, namely "khalas", "Shaishi" and "Ruzaiz" have been selected from each of the two localities (Al-Ahsa and Al- Qatif) and subjected to isoenzymes electrophoretic analysis. Leaflets and roots of the three cultivars were analyzed using the PAGE techniques for the occurrence of the isoenzymes EST, GOT, SOD, GDH and LAP. The results show that the three cultivars differed in their isoenzymes pattern within the same location and between different locations. The obtained results also signified that the isoenzymes patterns could be used as genetic expression markers for the cultivars and their interactions with the environmental factors in the two locations.