- Several horticulturally important species are dioecious (eg, pistachio, date palm, poplar, and others). It would be advantageous if the gender of a seedling could be determined at the vegetative stage. In this report, we present results of our search for molecular markers for sex differentiation in dioecious species. The method used was bulked segregant analysis of random amplified polymorphic DNA (RAPD) for sex. A male-specific marker fragment OPB01-1470 was obtained in Mercurialis annua. The sex linkage and characterization of this marker will be discussed.