oa Progress on fine-mapping the gender control gene in date palm

Introduction and Background: The date palm is a critical tree to Arabian Gulf agriculture, history and culture. Dates are a major source of nutrition in the region, and the tree itself plays an important role in the development of sustainable agriculture in many drought and saline-affected regions of the world. Date palm development presents a challenge, however, as the tree is a dioecious species, that is, individual plants are either male or female and are indistinguishable during the first 5-8 years, until flowering begins. We recently identified a region of the date palm genome linked to gender, which showed that the date palm employs an XY system of gender inheritance similar to that of humans. Methods and Technology: As part of a development plan we recently released a draft sequence of the date palm genome (Khalas female). In our findings, we identified sequence variations on four contigs that were strongly linked to gender and validated them in a large pedigree. We identified an additional 20 contigs with some evidence of linkage to gender. Validation of new gender-linked contigs will help in the fine-mapping of a possible single mutation, which results in gender determination in date palm. To validate linkage we have amplified the DNA of 7 male and 7 female date palm samples using 20 specifically designed primers. The PCR products obtained are sequenced by Sanger's sequencing. The sequenced regions from these contigs are from a diverse set of male and female date palms. We are studying these sequences and regions to identify a possible specific mutation or other gene content difference that determines plant gender. Result: We have confirmed linkage in many of the contigs, and these provide a set of genes within the "degraded" male sequence which may offer clues to how gender is determined biochemically and developmentally in date palm. Conclusion: There may be many more additional contigs which we are investigating to aid in the mapping of more variations and mutations, which correspond to different traits and features in the date palm, particularly dealing with gender.