Genetic transformation of date palm (Phoenix dactylifera L. cv. 'Estamaran') via particle bombardment

In this study, an efficient transformation system for gene delivery in date palm was established. The effects of different physical and biological parameters were optimized for transient transformation of uidA gene in somatic embryos of Estamaran cultivar. The tissues were bombarded with constructs harboring the uidA gene driven by CaMV 35S or rice Act1 promoter. Efficiency of expression was estimated by comparison of the number of blue spots resulted from GUS assay. Optimal transient expression was observed when explants were precultured on a media containing 0.4 M mannitol with air desiccation and bombarded at acceleration pressure of 1,350 psi, target distance of 6 cm with gold particles size of 0.6 µm which coated with 2.5 µg of DNA and at chamber vacuum pressure of 28 inHg. Significantly higher expression levels were obtained in tissues when the construct having the Act1 promoter was employed. After bombardment, somatic embryos were transferred to the regeneration media containing MS basal salts supplements with 3 mg/l 2ip, 40 mg/l adenine, 1 mg/l 2,4-D, 30 g/l sucrose and 3 g/l activated charcoal. Regenerated plantlets were checked by PCR using gene-specific primers. About 16 % of the plantlets were reported to be stably transformed. Southern analysis of genomic DNA from transformed plants showed that 1-2 gene (uidA) copies were integrated and GUS-negative plants did not contain any transgene. Achievement of these data considered as the first report of its kind is believed to facilitate transfer of desirable traits in date palm.