Somatic embryogenesis in Egyptian extra-long staple cotton cultivar Giza 96

Egyptian Giza cotton cultivars are known worldwide for their high quality long and extra-long staple. The application of biotechnology to Giza cottons has not been explored to-date. Giza 96, an extra-long staple cultivar (ELS), has been selected to establish somatic embryogenesis and to determine factors necessary for successful regeneration. Naphthalene acetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) at concentrations of 0.1–1.0 mg L − , in addition to benzyl adenine (BA) at 0.5 mg L − were used to screen the frequency of somatic embryo induction. The highest induction frequency was 100% and 87.5% on media containing 0.25 mg L − NAA + 0.5 mg L − BA and on 1.0 mg L − NAA + 0.1 mg L − 2,4-D + 0.5 mg L − BA respectively. Explants with healthy embryos were transferred onto media containing different cytokinins BA, kinetin (K) and meta-Topolin (mTp) at concentrations of 0.25–0.1 mg L − for further embryo growth and maturation. The highest number of embryos was 224.92 ± 23.83 and 189.17 ± 35.93 on media containing a combination of NAA, BA, kinetin, and mTp, at a concentration of 0.25 mg L − for NAA and at 2 different concentrations of cytokinins 0.5 and 0.25 mg L − respectively. Explant tissue with normally developing embryos were inoculated into liquid media of the same composition adding 2 sugar concentration treatments of 3% and 4.5%. Suspension cultures of different treatments produced profuse embryos at different developmental stages up to the tulip shape. This research presents the first study towards achieving efficient regeneration of the ELS Egyptian cotton cultivars germplasm. Key embryo induction and growth factors reaching the tulip-shaped embryos were identified. Future research is needed to achieve embryo maturation and germination leading to full regeneration of plants, thus laying the foundation for applying biotechnology towards the improvement of Egyptian Giza cotton germplasm.