Somatic Embryogenesis Using Cucumis sativus (L.) Cotyledons

To improve somatic embryogenesis of Cucumis sativus , two types of explants (cotyledons and stem sections) were cultured on Murashige and Skoog (MS) media supplemented with 2,4-D (2.0 mg·L –1 ) + kinetin (0.5 mg·L –1 ). After 4 weeks, the embryogenic callus was transferred for 2 weeks to MS + NAA (1.0 mg·L –1 ) for embryo development. Stem sections failed to develop embryos while cotyledons responded with 14% embryo formation. The embryos were transferred to MS without hormones for 4 weeks to allow for plantlet growth. These embryos developed only shoots. To improve on the successful generation of embryos with root and shoot development, the procedures used above were repeated, but the cotyledons were cut into three sections to be used as explants. Each transverse section of the cotyledon was approximately 2–3 mm wide. All sections produced callus but not all of them were embryogenic. From the first section (cotyledon base), the second (between the first and third section) and the third section (furthest from the cotyledon base), respectively, 58%, 31%, and 5% embryo development occurred. Those embryos from the basal cotyledon sections regenerated 10 plantlets, 5 with shoots and roots and 5 with only shoots. Approaches to enhance somatic embryogenesis, and shoot and root development, will be discussed.