Improved protocol for somatic embryogenesis and calcium alginate encapsulation in Anethum graveolens L.: a medicinal herb.

An improved procedure has been developed for efficient somatic embryogenesis in Anethum graveolens. Green friable embryogenic callus was obtained from hypocotyl segments on medium augmented with 2,4-dichlorophenoxyacetic acid (2,4-D). The highest embryogenic callus induction frequency of 87 % was obtained on Murashige and Skoog (MS) medium containing 1.13 μM 2,4-D. At lower concentration of 2,4-D (0.34 μM) callus turned dark in color and slow growing. Embryogenic cultures (76 %) responded with a mean number of 43 globular and 18 heart stage embryos. Somatic embryo maturation and subsequent conversion into plantlets took place on MS lacking growth regulators. Maximum number of somatic embryos developed on MS medium was 128.3 (per flask) and a plantlet conversion of 82 % was observed. Calcium alginate beads were produced by encapsulating somatic embryos. Highest percent germination (83 %) was observed on 0.8 % agar solidified MS medium with the plantlets acquiring an average length of 2.1 cm. Encapsulated somatic embryos could be stored at 4 °C up to 60 days with a conversion frequency of 49.3 %. Highest protein and proline content has been observed in embryogenic callus with small globular embryos. During morphological differentiation of the somatic embryos, changes in the antioxidant enzymatic system were observed. Superoxide dismutase (SOD) activity increased during initial stages and decreased catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities were detected.