Somatic embryogenesis in perennial statice Limonium bellidifolium, Plumbaginaceae

Cotyledon explants from perennial statice Limonium bellidifolium (Statice caspia Willd.) were cultured on Murashige and Skoog's basal medium (MS) supplemented with various levels of 2,4-D, kinetin and sucrose. Embryogenic calluses developed over a period of 10 days with the highest response at 4.5 muM (1 mg l(-1)) 2,4-D, 0.5 muM (0.1 mg l(-1)) kinetin and 117 mM sucrose. Following induction, the calluses were transferred to MS media supplemented with 88 or 117 mM sucrose and 0 or 0.5 muM kinetin. Somatic embryos at the globular, heart-shaped, torpedo, and cotyledonary stages developed. Fully germinated plantlets developed with the best response in medium supplemented with 117 mM sucrose and 0.5 muM kinetin. Direct somatic embryogenesis without a callus phase was observed with some of the cotyledon explants. Induction, maturation and germination of somatic embryos on the optimized media were equally effective using cotyledon, hypocotyl and root explants. Serial sections of L. bellidifolium cotyledon explants cultured for two weeks indicated that pro-embryogenic masses originated from parenchyma cells below the epidermis. Further histological observations of embryogenic calluses confirmed the initiation and development of globular and heart-shaped embryos and repetitive somatic embryogenesis. Ultrastructural observations indicated that the embryogenic cells were less vacuolate with abundant organelles compared to the cells of the explant. This is the first report of somatic embryogenesis in the Plumbaginaceae.