An Efficient Direct Somatic Embryogenesis Protocol for Genetic Stability and Gene Transfer of Egyptian Date Palm Cultivars Sewi and Hayani

Abstract

The agronomy of date palm (Phoenix dactylifera L.) has benefited significantly from biotechnology. Primary aim of current research was to develop a direct somatic embryogenesis (DSE) regeneration protocol of date palm shoot tip explant and study the genetic similarity of these directly regenerated plantlets compared to other indirectly regenerated plantlets via recommended indirect somatic embryogenesis (IDSE) regeneration protocol. Also, the DSE procedure was used for the first time to perform an Agrobacterium-mediated transformation. For the study of DSE protocol, data was collected for browning appearance degree, embryonic cell formation degree, globularization degree and number of direct somatic embryos produced. The results support that a nutrient culture medium of NAA at 0.25 mg/L for developing an efficient regeneration protocol by DSE for both date palm cultivars. Start codon targeted (SCoT) polymorphism was utilized to study the genetic stability between mother plants and regenerated plants via DSE and IDSE protocols. Results confirmed that direct plantlets regeneration had the highest genetic stability compared to indirect plantlets regeneration. Also, the genetic similarity of DSE regenerated plantlets of Sewi was higher (0.99%) than that of IDSE regenerated plantlets of Hayani (0.98%). Successful Agrobacterium-mediated genetic transformation of date palm via DSE was achieved with a transformation percentage of 4.8 for Sewi and 4.2 for Hayani. This work represents a vital step towards stable genetic transformation for this sustainable cash crop of monocot species.