Sex determination in date palm (Phoenix dactylifera L.) by PCR based marker analysis

Date palm (Phoenix dactylifera L.) is an economically important fruit crop in hot arid regions. It is cultivated in many regions of Thailand. However, during the establishment of plantations, male and female trees cannot be clearly distinguished until about five years after planting when the palms first flower. The objective of this research was to differentiate gender (male / female) at seedling stage in the Thai date palm cultivar KL1 by using a specially developed DNA marker technique. A PCR based method, which included the use of specific tetra-primers, was found to be successful using extracts from young leaf samples. With these markers, flowering male date palms were represented with two amplicons (430 bp and 320 bp) while the female date palms were represented with only one amplicon (430 bp). When 100 non-flowering seedling of cv. KL1 were screened, 50 were identified as male and 50 as being female. This ratio of 1:1 between male and female is consistent with the principle of gender distribution in dioecious plants. When the tetra-primer method was used with other cultivars, including Deglet nour, Barhi, Hayani, Medjool and Tunisia, the same DNA banding patterns were determined. This method has potential to be used for the differentiation of gender in other date palm cultivars at the seedling stage. It would reduce the time required for gender determination from five years to a few hours.