Development of molecular markers for sex determination in Phoenix dactylifera L.

Date palm (Phoenix dactylifera L.) is one of the most economically important fruit crops in hot arid regions of the world. It is presently cultivated in many areas of Thailand. However, a major production constraint is that male and female trees cannot be clearly distinguished until about five years after planting when the date palm first flowers. The objective of this research was to differentiate gender (male vs. female) at the seedling stage of the Thai date palm cultivar, KL, using a DNA marker technique. The DNA marker used was PCR based and used four specific primers. These markers showed that male date palm presented two amplicons (430 and 320 bp) while female date palm presented only one (430 bp). The result of gender identification among 100 seedlings of 'KL1' was 50 male and 50 female individuals. This 1:1 ratio between male with female seedlings agrees with the theory of gender distribution. These same markers were successful in discriminating the sex of individuals of other cultivars, including 'Deglet Nour', 'Hayani', 'Medjool', 'Tunisia' and 'Barhi' which each showed the same DNA banding patterns. This study showed that the markers that were developed for sex identification of date palm at the seedling stage could reduce the time required for identification from seven years (phenotype) to three hours (DNA marker).