Use of microsatellite markers for sex determination in date palm (Phoenix dactylifera L.) cv. Medjool

The date palm (Phoenix dactylifera L.) is a dioecious plant, and its sexual characteristics remain indiscernible until it reaches the reproductive stage, typically between 4 and 5 years of age. The Medjool variety is widely grown in Palestine and the neighboring regions. Early identification of male and female seedlings could significantly benefit date palm cultivation and breeding efforts. This study aimed to confirm the effectiveness of microsatellite markers in distinguishing between male and female date palms within the cv. Medjool variety. Out of eight microsatellite or simple sequence repeat (SSR) primers used, four markers (mPdCIR015, mPdCIR035, mPdCIR078 and mPdCIR093) were able to determine the sex of the date palm tree (cv. Medjool) at an early stage. Practically, a combination of any of these two SSR markers could be used to determine the sex of date palm at seedling stage cv. Medjool. mPdCIR010 and mPdCIR093 produced male specific bands (325 bp) and (156 bp) respectively. On the other side, mPdCIR015 and mPdCIR078 produced unique female bands (160 and 128 bp), respectively. 15 loci were identified, averaging 2.1 loci per primer. SSR markers were able to provide a reliable technique for sex determination in date palm (cv. Medjool) at an early stage. The utilization of SSR markers will not only advance but also facilitate the establishment of a commercial date palm cultivation through the breeding program in Palestine and the surrounding region. Primer mPdCIR035 (325 bp) and mPdCIR093 (156 bp) occurred in all date palm male samples and absent in all female samples indicates a promising candidate markers to detect the sex in date palm seedlings at early stage.