Induction of somatic embryogenesis and in vitro flowering from inflorescences of chamomile (Chamomilla recutita L)

A protocol has been developed for the induction of somatic embryogenesis from flower explants of chamomile (Chamomilla recuitita L.). The effects of several plant growth regulators [alpha-naphthylacetic acid (NAA), 2,4-dichlorophenoxyacetic acid,, 6-benzyladenine (BA) and kinetin (Kin), alone or in combination] and the flower type (disk or ray flower) were investigated. Both types of flowers responded to the callus and shoot induction treatment, but formation of globular somatic embryos took place only on disk-flower-derived explants after 2-4 weeks of culture on a Murashige and Skoog (MS) medium supplemented either with 8.87 mu M BA and 1.07 mu M NAA or with 26.8 mu M NAA and 11.5 mu M Kin. However, fully developed, cotyledonary-stage somatic embryos could be induced only on the NAA/Kin medium, 10 weeks after culture initiation. Germination of the embryos and plant re-generation took place after subculture for 4-5 weeks onto medium of the same composition. Plantlets regenerated from embryos flowered in vitro in a MS medium supplemented with 8.87 mu M BA and 1.07 NAA. The significance of the results with respect to chamomile micropropagation and the utilization of wild populations in breeding programs is discussed.