Towards Sex Determination of Date Palm

Abstract

In the date palm (Phoenix dactylifera), a dioecious mode and late initial reproductive age of 5–10 years are major practical constraints to genetic improvement. Improvement of the existing palm cultivars or selection of new ones with superior characters is a tedious endeavor due to the long life cycle of the date palm tree and its heterozygous nature. Sexual propagation method cannot be used commercially for propagating the cultivars of interest in a true-to-type manner. Currently there is no reliable method to identify sex at the early seedling stage. Early sex identification of young seedlings could enhance breeding programs and generate experimental male and female genetic stocks that will help the genetic improvement of the date palm. Moreover, the selection and identification of superior seedling characters for yield enhancement and to improve the physical and chemical properties of fruits is of great commercial interest. There has been significant progress in our understanding of sex-determining mechanisms in date palm using traditional means. But physiological and cytological methods do not give obvious differences between male and female date palms. Biotechnology, as a new tool in date palm breeding, can be useful to improve the qualities of palm trees through early sex identification. Although molecular markers have been introduced in date palm programs, few research efforts have been geared toward studying the early sex determination in the plant. This chapter will focus on genetic and molecular basis of sex determination in date palm in attempting to develop reliable methods to identify sex at an early stage of seedlings.