Confirmation of 'Medjool' date as a landrace variety through genetic analysis of 'Medjool' accessions in Morocco

We studied 66 'Medjool' date palm (Phoenix dactylifera L.) accessions from Morocco, six varieties of dates from Egypt, and four 'Medjool' accessions and one 'Deglet Noor' accession from California to investigate the hypothesis that 'Medjool' is a landrace variety in Morocco. We used four sets of fluorescent-labeled amplified fragment length polymorphism (AFLP) markers to examine these accessions. A total of 402 bands were generated, of which 217 were polymorphic (54.0%). The 66 'Medjool' accessions from Morocco shared a minimum of 79% genetic similarity. These results support the hypothesis that 'Medjool' is a landrace variety in Morocco and it is not genetically uniform. 'Medjool' is the first confirmed landrace variety of date palm in the world. This finding raises the possibility that other date palms may be landrace varieties in different growing areas. Confirmation of a landrace variety in date palm has significant implication for future date palm germplasm collection and preservation. The mechanism(s) generating the genetic variation within 'Medjool' accessions remains unknown. One possibility is that spontaneous genetic changes could occur frequently within vegetative tissues like offshoots under high temperature and drought stress.