Induction of somatic embryogenesis in Cynara cardunculus L. (Compositae)

This report describes procedures for the production of somatic embryos from cotyledons and first leaves of in-vitro grown seedlings of Cynara cardunculus L. (Compositae). Embryogenic calli were obtained after 4-5 weeks of culture on solid B5 medium containing selected combinations and concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (KIN) or 6-benzylaminopurine (BAP). In the presence of 2,4-D at 1 mg litre 1 and KIN at OT mg litre”', initial stages of somatic embryo development were formed on the surface of the embryogenic calli. Cotyledon explants presented a higher percentage of embryogenic induction than leaf explants. The transfer of these cultures to Bs liquid medium containing 2,4-D (OT, 0-5, 1 mg litre” *) and zeatin (ZEA) at 1 mg litre ” 1 allowed induction of more embryos and their further development. 2,4-D at the optimum concentration of 0-1 mg litre ”1 was necessary for embryo development. Some embryos presented abnormalities that were not prevented by the addition of abscisic acid (ABA) to the culture medium. Mature embryos when transferred to the same liquid medium lacking growth regulators showed root apex growth and greening of cotyledons. However, the germination of the embryos was still only occasional and plantlets obtained showed arrest of growth before development of leaves.